Haynes Competition Car Preparation: A Practical Handbook 1859606091, 9781859606094

Citation preview

COMPETITION

CAR

PREPARATION

A PRACTICAL HANDBOOK Simon McBeath Foreword by Ray Mallock

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—

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Most competitors take part in motorsport for fun, and whether on

circuits, forest tracks, hills, fields or ovals, the primary aim is to enjoy themselves. Many enter these events with a competitive spirit, and feel they have a chance of winning, while for others the thrill of participating and driving a high performance vehicle is enough in itself. Whatever the aspiration, two things are certain - you have to get your car to the venue, and it must not

break down during competition. The key to achieving these objectives is good preparation. In Competition Car Preparation, Simon McBeath looks in detail at what is involved in getting ready for competition; including organising resources and planning and coordinating the preparation of both car and driver. He then examines the practical aspects of preparation to discover what needs to be checked, modified, or uprated; what you can do in the home workshop; what needs to be carried out by a professional. The book doesn’t even assume that you have a competition car, or any competition experience, and there is much valuable guidance on how to get started in motorsport. This includes where to get the relevant rules and regulations, how to buy or build a suitable car, and how to obtain a competition licence. Experienced competitors will also find suggestions that provoke ideas for better preparation. Simon McBeath is an experienced motorsport enthusiast, a competitor, and a freelance motorsport writer who contributes regularly to Cars & Car Conversions, Racecar Engineering and The Golf magazine. During 20 years of competition in UK hill-climbs and sprints, he has prepared, developed and competed in a variety of single seaters, and tested numerous racing, rallying and hill-climbing ‘tin tops’, sports racers and racecars bravely loaned during the production of technical articles. He also designs and manufactures composite aerofoils, and lives in Farnham, Surrey.

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COMPETITION CAR

PREPARATION A PRACTICAL

HANDBOOK

Simon McBeath Foreword by Ray Mallock

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SoS” THE

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Haynes Publishing

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© Simon McBeath

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1999

All rights reserved. No part of this book may be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage or retrieval system, without permission in writing from the copyright holder. First published October 1999

A catalogue record for this book is available from the British Library Published by Haynes Publishing, Sparkford, Nr Yeovil, Somerset BA22 7JJ Tel: 01963 440635 Fax: 01963 440001

Int. tel: +44 1963 440635 Fax: +44 1963 440001

E-mail: [email protected] Web site: http://www.haynes.com ISBN 1 85960 609 1

Library of Congress catalog card no. 99-72053 Haynes North America, Inc. 861 Lawrence Drive, Newbury Park, California 91320, USA

Designed and typeset by G&M, Raunds, Northamptonshire Printed and bound in Great Britain by J.H. Haynes & Co. Ltd, Sparkford

Jurisdictions which have strict emission control laws may consider any modification to a vehicle to be an infringement of those laws. You are advised to check with the appropriate body or authority whether your proposed modification complies fully with the law. The publishers accept no liability in this regard. While every effort is taken to ensure the accuracy of the information given in this book, no liability can be accepted by the author or publishers for any loss, damage or injury caused by misuse of, errors in, or omissions from, the information given.

Contents Foreword by Ray Mallock Author's preface Acknowledgements

Chapter 1 Chapter 2

Chapter 3

Chapter 4

Before you begin Essential preliminaries Manage to win How to plan, finance, organise and keep on schedule Driver preparation Safety kit, obtaining that licence, driver training, fitness Modify, buy, or build? Getting your competition car

Chapter 5

Chapter 6 Chapter 7 Chapter 8 Chapter 9

Chapter 10

Chassis structures Chassis function, types and key features Suspension and steering Design fundamentals, optimising and modifying Brakes Basics, hydraulics and mechanics, uprating Wheels and tyres Wheels, road tyres and race tyres

~S

17

26

208) 41

58 7? 37

Engines

Choosing, modifying, looking after them, and more The transmission and driveline Clutches, gearboxes, power transfer and differentials

100

113

COMPETITION

4

Chapter 11

Chapter 12

Chapter 13

Systems Oil, cooling, fuel, hydraulic, electrical and

other systems The ‘office’ Seats, safety belts, fire extinguishers,

128

ergonomics and instruments

147

Bodywork and aerodynamics Functions,

Chapter 14

Chapter 15

Chapter 16

Appendix Appendix Appendix Appendix

1 2 3 4

CAR PREPARATION

requirements, drag, downforce,

aerodynamic evaluation Data logging From simple rpm recorders to multi-channel loggers Developing a competition car Influences, actions, weight, gearing, chassis tuning and aerodynamics Looking after it Maintenance schedules, fasteners, painting and

158

170

ye:

protecting

193

Motorsport governing bodies and clubs Driver training schools Other useful information Recommended further reading

201 203 204

Index

205

199

Foreword by Ray Mallock, Managing Director, RML* IF YOURE STARTING OUT in motorsport, either in an amateur or professional capacity, ’m sure you'll find this book an invaluable guide. And if you’ve already acquired a fair bit of experience and are taking your racing seriously, you'll still find in these pages plenty of interesting and useful information and ideas. Such knowledge would normally take a lifetime to acquire. The Godfather of racecar preparation books

is Carroll

Smith’s

Prepare

To Win,

but it’s twenty years old now, and in my view this new title is better in a number of ways: e It’s very easy to read. e It’s up-to-date, taking into account current technologies. e It’s more comprehensive, covering all areas from getting your workshop organised to fine-tuning the handling at the track. e It’s broader in its scope, not concentrating solely on single-seater preparation, but also taking a serious look at saloons and sports cars, which present their own particular technical challenges.

These strengths will make Competition Car Preparation beneficial to a wider range of people than the previously definitive work on the subject. There is a huge amount of good, down-to-earth practical information which comes from Simon McBeath’s own experience as well

as a host of other motor racing gurus. If you’re a beginner, this book will help you get your car on the pace quickly, reliably, and safely, whilst saving a great deal of time and money on the way, rather than learning by your own mistakes. If you’re a more experienced and professional racer, you'll value the many nuggets of information and ideas.

6

COMPETITION

McBeath’s enthusiasm for the sport comes through in every chapter, and he is clearly keen for everyone to share in the safe and competitive enjoyment of the sport for which he has such passion.

CAR PREPARATION

introduced the family name to racing cars with the U2 sports car of 1958, the first of many Mallock designs successfully to rival those of Lotus founder Colin Chapman. But it is really since 1982, and the

* Founded by engineer and former racing driver Ray Mallock, RML is an internationally respected motorsport engineering company with a distinguished heritage. Ray’s late father, Major Arthur Mallock,

establishment

of

RML,

that

the

Mallock name has become synonymous with engineering excellence worldwide, winning many events and championships internationally in sports cars, Super Touring, and rallying, on behalf of such companies as Aston Martin, Austin-Rover, Nissan, Opel, and Vauxhall.

Author’s preface COMPETING

IN

MOTORSPORT

should

always be fun, whether you’re one of the tens of thousands of amateur ‘weekend warriors’ who pound the circuits, forests, hills, fields and ovals, or one of the tal-

énted and lucky few who have the ability to compete for a living. Motorsport is a whole lot more fun when the car you compete in is reliable. It isn’t always vital that it’s competitive in order to have fun (though for most people, it helps), so long as the thing doesn’t break down! The key to reliability and competitiveness is good preparation. An awful lot of the likely causes of a competition car malfunctioning can be prevented by good preparation, though it must be said that in pushing for increased competitiveness, sometimes reliability can suffer, even in the best-prepared outfits. So there is a balance to be struck. But that threadbare motorsport cliché — ‘to finish first, first you have to finish’ — goes a long way towards explaining the simple philosophy

behind this book. It’s not just the car that needs attention — the driver is a vital, integral and, thankfully, indispensable part of its control

mechanism, so it pays to consider driver preparation too. This may involve putting the ego to one side (gently, for fear of bruising), but there are benefits to be had. However, before any ‘hands-on’ preparation work begins there needs to be a great deal of thought and planning, to ensure that you end up going in the desired direction. This is an aspect of preparation at which the professional teams excel, and their example can provide extremely useful guidance. I have long thought that there was the need for a book that not only covered practical preparation, but which also considered the broader principles. In addition it should help both the novice who, though not yet owning a competition car, has a hankering to get on the nursery slopes but needs guidance on how and where

to

start;

and

the

intermediate

driver seeking to improve his performance. These were the reasons which motivated the writing of this book. I hope it helps you get involved in and have fun with motorsport.

Acknowledgements LISTING THE PEOPLE who have helped directly, or indirectly, with this book, or who have helped me learn more about

Graham

competition car preparation in one way or another, is bound to get me into trouble,

Engines; Malcom ‘Puddy Pullen; Dell Quigley, DJ Racecars; RAC Motor Sports Association; Bert and Gavin Ray, Ray

because I’m sure to have missed someone out. To the people in that category, my humble apologies, and I hope you don’t mind being lumped into the catch-all group at the end. My thanks, then, to Phil Abbott and Mick

Hyde, Radical Motorsport; Paul Atken and Graham Kendall, Fluids Group, MIRA; Steve

Bagnall, VW

Motorsport

Duncan Barnes; Tim Knight, Mother Racing;

UK; Rob Betts Steve

Barker;

and Helen Black, SBG

Oates;

Pashley;

Ray

Nick

Payne;

Padmore;

Nick

Pierce;

Tony

Mike

Pilbeam; Dave Price; Phil Price, Connaught

Formula Cars; Fred Reeves, Ian Taylor Racing School, Darryl Reach, Alison Roelich, Peter

Nicholson,

Ian

Heath

and

all

at

Haynes Publishing; Colin Richardson, First Overall Racewear (formerly RRS Racewear); Brian Ricketts, BR Motorsport; Cavan Riley, Racing Transmission Services; Ray Rowan, Rowan Racing; Kate Scott-Simmers, Motor Sports Association; Enid Smith, BARC;

and

Sports Car Club of America (SCCA); Jerry Sturman, Speedscene magazine; Sports Car

Lee Sherwin, SBD Developments; Grahame

Club of America (SCCA); Neil Simpson and

Sport; Tony Broster; Steve Broughton Butterworth

and

all at Impact

PR;

Nick

Carter, Max Communications; Vic Claydon; Eamonn Cleere, Tech 2000 Dampers; John

Corbyn, Gordon

Jedi Racing Cars; John Fellows; Francis; Franco Fratton, Dynamic

Suspensions; Goozée,

Sean David

David

Penske

Gould,

Gould

Grace;

Garthwaite;

Cars;

Dave

Engineering

Martin

Groves;

Nick

Gould

and

Services;

Simon

and

Jane Harratt; Nick Hayes, Cosworth Racing; Jim Hersey, AstraTech Racing Technology; Mike Holmes, George Lundrum and all at Pi Research; Robin Knight, 750 Motor Club; Mick Kouros and Andrew Chisholm, Martello Racing; Shaun and Jeff Macklin;

Andy

McBeath;

Kevin

Molloy,

Aero

Tec

Laboratories Ltd; Neville and Tina Moon; John Moore and Alistair Fergusson, Alcon Components; Roger Moran; Bill Morris;

Steve Martin; Tony Sinclair and Owen Jones,

Jade Motorsport

Engineering;

Paul

Smith,

BMTR Tyres; Ken Snailham, Quorn Engine Developments, Allan Staniforth, Terrapin Services; Mike Steley, Spyder Formula Cars; Tim Styles, TSR Performance; Jon Tate, Formula Palmer Audi; Tony Tewson, Superclutch; Two Four Sports Ltd; Derek Tye, Motor Sports Association; Geoff Thomas, Volksport; John Uprichard, Van Diemen International; Dave Walker, Emerald Cams; Pete Wallen, Avon Tyres; Allan Warburton, DTA Race Electronics; Dave Whitehead; Jim Whiteside; Dave Wild, DTW Engines; and all the other competitors, mechanics, and race engineers I’ve

had the pleasure and privilege of talking to about competition cars. And special thanks, as ever, to Tracey.

Ghapterr

Before you begin What it’s all about Competition

car

preparation

is

about

more than working on the car to ensure it doesn’t let you down. Good preparation starts, probably, in an armchair, or maybe

a bath tub, or wherever it is that you do your best thinking, because thinking and planning are probably the most important elements of preparation. You need to have a clear idea of what it is you want to do before you can go out to the workshop and do it. Then you need to work out exactly how you’re going to achieve your aims, and what facilities and resources you'll need. Only once all that is in place do you actually set about the tasks

that

need

doing;

and,

of course,

along the way you have to make sure that everything gets done properly. All of this applies just as much to designing and building a competition car from scratch as it does to checking a car between

events,

or even

between

runs,

or between practice and race. The basic principle outlined in the opening paragraph is, after all, the basis for how most jobs are tackled (unconsciously or otherwise), whether or not they’re anything to do with motorsport competition, and this ‘management process’ — for that is what it is — is discussed in more detail in Chapter 2. Using the term ‘management’ might make it sound unappealing, but in reality it is no more and no less than the application of common sense and thoroughness, and it truly is the only way to do a good job. And if you have any doubts

regarding the validity of that statement, just take a look at the way that the most successful motorsport teams are managed. All categories of motorsport are governed by rules and regulations, and before you can make any decisions at all, you need to know what these are. Know the rules of the game There is a wide variety of motorsport disciplines in which you can choose to compete, including racing, rallying, hill-climbing, sprinting, autocross (two different disciplines on opposite sides of the

Atlantic),

autograss,

rallycross,

dirt

and asphalt ovals, autotests, and trialling. Within each discipline are even more different categories, and these are further sub-divided into classes. In addition there are various levels you can compete at, from local club level to regional, national,

or even international level. Selecting which class to have a go at, whether you're

an existing

competitor

wanting

a

change, or are entirely new to motorsport, is very much a personal decision and, as with most things in life, it comes down to your own preferences and, naturally, your financial situation. The specifics of preparation will, of course, depend on your car, and the class and branch of the sport you run in. But the general principles of good preparation are pretty much the same, based, as we have

seen,

oughness.

on

common

Without

sense

exception,

and

thor-

though,

10

there

COMPETITION

is a common

starting

point:

you

have to know the rules relating to the category and specific class you are going to compete in. If this isn’t a statement of the obvious, I don’t know what is. And yet there are, for instance, plenty of cases of newcomers to motorsport who have come along to a meeting with a street car that has been lightly modified for road use in such a way that it ends up running not with other lightly-modified road cars, but with heavily-modified racing variants. The reason for this is that the rules often only permit certain types of modification to be carried out in the various

classes, and a

car modified without reference to those rules will likely end up competing not where

its Owner

wants

to be! At worst,

the car may not even be eligible to compete at all. So the well-prepared competitor first of all gets to know the relevant set of rules extremely well, and certainly well enough not to need to make constant reference to them. Addresses of the major motorsport The ‘Blue Book’.and other useful paperwork.

CAR PREPARATION

governing bodies in the UK and USA, as well as those of some of the big organising clubs, are given in Appendix 1 at the end of this book. These organisations are only too pleased to provide you with all the reading matter and advice you need to get started in pretty well any motorsport category, and this information is absolutely essential. They will also put you in touch with relevant local clubs and organisations. There are plenty of

rules

which

are

common

to

a_ broad

cross-section of categories, but there are also rules which can be quite specific to each separate class. So before you begin any work on the car itself, get all the information you can on what is and what is not allowed in the way of preparation and modification in your intended class. Another valuable source of information is the group of competitors you intend to join. They’ve already had to figure their way through the rules and regulations, and by and large will be happy to talk, at least in general terms, about the things

BEFORE YOU BEGIN

Jet

ey)

The paddock — an invaluable source of information.

you need to know. They may not be quite so willing to tell you about their own ways of navigating the inevitable grey areas in the rules, or how they have achieved their particular level of competitiveness, but then perhaps you shouldn't expect that level of assistance. There are some things that can only be learned through experience. Different branches of the sport have different prevailing attitudes to sharing information in this way, and drivers and teams also vary in the type and amount of information they are willing to share. As one might expect, amateur categories tend to be more open than professional ones, but you can pick up a lot by visiting paddocks, watching and listening carefully, taking photographs, and making notes — though be warned, even though their cars may be on public display, there have been cases of team owners getting unreasonably upset by ‘prying’ camera lenses, however innocently they were aimed! And watching who’s best out on the track, or stage, or whatever, will soon give you clues as to who does, and who does not, know what they’re talking about.

Facilities So you've class

you’re

decided going

which

category

to compete

and

in. You

may also have a general idea at this stage about which car you’re going to obtain (see also Chapter 4), or at least what type of car. But where is it going to be kept? And what items of equipment and tools will you need to work on it? More so than an everyday road car, a competition car is best kept under cover in a proper garage or workshop. Not only will such a workshop be secure, it will also be dry, and given that the car may well end up with sealants and corrosion proofing being stripped off it Gf it’s a production based vehicle and it may not have them in the first place if it’s purpose-built), it will corrode considerably less than if it’s kept outside. But more than anything, it’s far more comfortable working on a car in a closed, dry garage or workshop, and a lot more work gets done in a comfortable workshop. Nobody enjoys working in the rain or the wind, so the first priority is to ensure you have the use of a dry, lockable workshop with suitable access.

12

COMPETITION

Life

is a lot easier,

too,

if electrical

power is readily available. Although it’s possible to run cars out of garages without electricity, the lack of supplementary lighting, the inability to use mains power tools, and the lack of opportunity to generate a bit of extra warmth when needed,

all make life difficult. You’ll have noticed

CAR PREPARATION

another reference to personal comfort creep in there! No apologies offered for that. But it is also worth noting that corrosion can be minimised by a heated garage, though constant heating could produce a nasty shock when the power bill comes in. Naturally, your workshop needs to be

The small garage workshop requires a tidy approach — unlike this! That’s more like it!

BEFORE YOU BEGIN

spacious enough to physically work on the car, but it’s surprising how many competition cars are very effectively prepared in (or occasionally built from scratch in) and run out of traditional British ‘single garages’, little brick boxes generally about 16ft by 8ft (roughly 4.9m by 2.4m) — with a tidy and organised approach it is possible, though at times you'll curse it. Of course, it helps if your chosen competition car is a small one. If you intend to use the family garage to house your soon-to-be-acquired pride and joy, it could be a wise move to ensure that the space is, in fact, up for grabs. The spouse’s or partner’s shopping car may

not appreciate

living out in the

rain, and nor will the kids’ bicycles or the lawn mower. These factors may not be relevant to you, but if they are, open negotiations about them before negotiating for the competition car.

15

— Pliers, circlip, internal and external. — Pliers, taper nose. — — —

Pliers, side cutters. Screwdrivers, slot end. Screwdrivers, cross head.

— Electric drill (plus cordless type for powerless paddocks). — High-speed steel twist drills. —

Punches, drifts.

— Hammer, soft-faced. — Hammer, ball-pein. — Engineer’s rule, stainless, 6in and 12in (150mm and 300mm). — Tape measure, 10ft (3m). — Feeler gauges, imperial and metric. — Vernier calipers. — Files, flat, half-round and round. — Hacksaw, to take 12in (800mm) blades. —

Hacksaw, mini, and blades.

—

Pad saw.

—

Fret saw.

— Pop rivet pliers, with ‘nozzles’ for !/sin,

Tools You will need a reasonably comprehensive set of basic tools to enable you to carry Out most jobs, though it seems that a tool kit is one of those things that’s never complete. There are also specialist

tools that you may or may not need, depending on which jobs you intend to tackle yourself, as opposed to contracting out. Some specialist kit, such as suspension setting-up equipment, will be discussed in later’ chapters, but the basics, and some other useful items, are worth

3/32in, and 3/16in (8mm, 4mm, and

4.8mm) rivets. — Hole saw. — Chisels. — —

Knives, retractable blade. Scissors.

— Sheet metal shears. — Sheet metal ‘nibblers’. — Tap and die set. —

G-clamps, various sizes.

— F-clamps, various sizes. — Box(es) or chest(s) to store and “transport most, if not all of the above.

listing here:

— Sturdy bench. —

Vice.

— AF/metric open-ended spanners (wrenches if you prefer). — AF/metric ring spanners. — Torque wrench. — Adjustable spanners. — AF/metric Hexagon key wrenches (Allen keys). — AF/metric socket set, 3/sin and/or 1/2in drive, including appropriate spark plug socket. — Pliers, standard engineer’s.

If you have the space to store them, it is worth saving up for, begging, borrowing, or just putting on your Christmas wishlist, various other useful tools which can

either save time or enable you to bring still more jobs ‘in-house’. These include: — Larger sockets. — Angle grinder. Bench grinder. — Sander/polisher. Jig saw (powered). | Drill stand. — Axle stand or chassis stands.

14

COMPETITION

CAR PREPARATION

do want is to be able to call on someone and have them fit your job into a busy schedule if at all possible. There’s no reason on earth why they should do this for you, unless you create it, by being friendly, perhaps by offering tickets to

— Engine hoist. — Trolley jack. — Welding and/or brazing gear (or access to). — Lathe (or access to). — Sheet metal guillotine (or access to). — Sheet metal folding machine (or access to). — Milling machine (or access to). — Electrical multi-meter. — Soldering iron, electrical crimping tools.

your car somewhere, or just by putting some cash in the canteen coffee fund. More on this in Chapter 2. The point here is that it helps to have all the services you need locally available if at all possible.

You will also need various basic consumables such as sealants, solvents, lubricants

To finish first, first you have to get there

and greases, abrasives, cleaning equipment and fluids, and cloths, rags or rolls of paper towels for keeping yourself as well as your work reasonably clean. This is probably also where workshop safety items like fire-extinguishers and such like

In some motorsport disciplines it is possible to drive your competition car to and from events. It is also mandatory in some that you do so. There are also disciplines where it makes no sense to drive your

should be mentioned, but I have no wish

it is mandatory that you do not, because the car is not road legal. In all cases, it is nevertheless necessary for you to get there, and to get back to base again afterwards. This is yet another statement of the blindingly obvious, but the subject has to be confronted at an early stage because of the practical and financial implications. It’s all too easy for this topic to be put aside as an afterthought, so let’s break with tradition and consider it in the first chapter. First of all we'll look at driving the competition car to and from a meeting. Obviously this can only apply if the car is still road legal, which means it has to have the appropriate road worthiness cer-

to insult your intelligence or common sense by presuming that I know any better than you do in this regard. Besides, I’m not responsible for you — you are. The actual range of tools that you buy should reflect the skills at your disposal, and possibly your willingness to learn new skills if you think it could save you time, or money, or you just want to do as much as possible yourself. For example, it is often possible to pick up secondhand lathes at auctions very cheaply, and if you haven't already been trained, learning how to machine simple parts is not all that hard — it can’t be, I’ve done it! But

there are almost bound to be some jobs that you cannot do yourself, either because you are not able to do them, or the equipment is beyond your budget. Not a problem — even the world’s foremost motorsport teams have to contract out some jobs. In these cases you will need to cultivate friendly relations with a_ local machine or fabrication shop, or whatever service you may need. This is not to say you want the work done for free, though you might be lucky enough not to have to pay for occasional jobs. But what you

meetings, putting their company name on

competition car to the meetings, or where

tificate,

be

insured,

taxed,

and

have

all

equipment relevant to road use still fitted and functional. Specific legislation will differ from country to country, so make yourself aware of the requirements where you live. The major plus of being able to drive your competition vehicle to and from events is that you don’t need a trailer or transporter. The major drawback is that if something goes wrong with the car at the event, you have no transport home, so this potential eventuality needs considering and covering. The fact that

BEFORE YOU BEGIN

15

Some championships cater for road-legal cars, like this road saloon series.

you need the vehicle to get home also tends to put an additional constraint on your driving style in the event itself. Another obvious disadvantage is that considerable extra wear and tear is inevitably put on the car, and whilst the stress levels it endures on these journeys will probably be a lot less than in competition, the actual mileage is likely to be a lot greater, which has to be borne in mind when considering maintenance intervals. If the car needs to be transported or trailered to and from events, then the first consideration is that an extra cost ele-

ment is involved. Some of that hardearned cash that was going to make your car a winner is going to have to be diverted into the purchase or hire of a

transporter or trailer, unless you can borrow one. The second point is that you also need space to store the transporter or trailer (hereinafter referred to solely as a trailer for brevity). And thirdly — and very definitely the most often overlooked aspect — the trailer itself also needs frequent care and maintenance. It’s all very well burning the midnight oil preparing

your car for that imminent season-opener, but if the trailer brakes are seized on and the tyre walls are perished because the trailer hasn’t been looked

at for months,

you're not going to get there. So build in the time and the cash to take care of this angle — and see if you can go the extra distance and buy a trailer with some sort of cover, either panelling or flexible; the competition car will arrive in much better condition,

and

will not

have

to endure

being sand-blasted by grit thrown up from the tow vehicle. Not only does this spoil the paintwork, it also accelerates wear in suspension joints and anywhere else it can invade. At the very least attach some form of shield, in aluminium sheet or plywood, perhaps, to the front and the

underside of the trailer. This isn’t really the place to go into a deep technical discussion on loading a trailer correctly so that the nose weight is correct, and the weight properly distributed. But useful information on this topic is to be found in the manuals put together by trailer manufacturers. Anything that helps you get to an event

16

COMPETITION

CAR PREPARATION

The trailer needs care and maintenance too ...

Ifyou can go the extra distance, buy a trailer with some sort of cover.

Benetton ==

fresher and more relaxed is surely worth looking into, and a well-balanced trailer can definitely contribute here. Save all that adrenaline for competition, not for dealing with a weaving trailer. So those are the very basic basics.

We'll now go into each aspect of preparation individually, starting in Chapter 2 with a description of how to manage the preparation of your competition car, which is, after all, quite a complicated project.

ha pier 2

Manage to win IF YOU ARE in any doubt about the relevance of this chapter to the preparation of your competition car, look no further than any successful senior level professional motorsport team to see how it operates. Whilst success in motorsport is undoubtedly about a good car being driven well, it is equally certain that this is just the tip of the iceberg, and that getting the right car in the first place is all about obtaining the necessary resources, and making the right decisions to utilise them effectively. And that’s what management is all about, whether you’re a one-

man band or a team. The Oxford Concise English Dictionary (ninth edition) defines the verb ‘to manage’ as meaning ‘to meet one’s needs

with limited resources’. It’s a most appropriate phrase, especially the bit about ‘limited resources’, which is surely relevant to the majority of motorsport competitors. But even Ron Dennis has limited resources to work with, despite the fact that his might appear to be infinite by clubman’s standards. The common

factor,

therefore, is making the best of what you’ve got in order to get where you

Figure 2-1 Basic project management stages.

MANAGE TO WIN

|

:

PLAN/ORGANISE DO/GET DONE

a

x

CONTROL/REVIEW

bos Saa

18

COMPETITION

want to be. Or in other words, managing effectively. Modern management seems to be full of buzz words and phrases, but it all boils down to some pretty simple principles, founded in common sense, which could just as easily be applied to cooking a stew, painting a room, or running a mega corporation, as to preparing a competi-

tion car. There’s nothing special here beyond defining a simple system that helps to keep your task or project on track. The whole thing can be distilled down to three phases, as shown in Figure 2-1, namely: planning/organising; doing/ getting done; and controlling/reviewing.

CAR PREPARATION

want car’! Even if you are already competing, it’s still usually fairly obvious what your

situation

is, because,

in common

with other sports, your competitors are right there next to you, if not literally then at least on the time sheets and results lists. And if you run against pretty much the same group of people at most meetings, as tends to happen, you will have a very clear idea of where you stand. Be honest with yourself in this analysis, because it will help you focus on what you need to do to improve. Having analysed what your present situation is, you next need to define your aims and objectives, or where you want to be at, say, the end of the next season.

Planning/organising Figure 2-2 charts the elements of the planning and organising phase. The first

This part of the planning process may require a degree of realism in order to

step

example, if you’re just setting out on your first season the chances are you won’t be on the top step of the podium too many times, at least initially, and a target of

is to assess

your

current

situation.

This is remarkably simple if you are just starting out on your motorsport career, and could be defined as ‘haven’t got car;

temper

any

excess

ambition.

Figure 2—2 The planning/organising phase.

PLAN/ORGANISE What is your current situation? What are your aims and objectives? How will you achieve them financially and practically? What tasks need doing?

Who is going to do them?

For

MANAGE

simply gaining experience would not be unreasonable. If you compete already, it could be that you may be _ perfectly happy with just maintaining your position, or you may want to become more competitive and move up the order. Alternatively, you may decide that this is going to be your year, and you are going to commit to winning, whatever it takes. Whichever of these routes you set out on, the important thing at this stage is to be clear about what it is you aim to achieve, because it will define the next, most important part of the planning stage. Having decided what you want to achieve, the next step is to work out what it will take to achieve that aim, financially and practically. This is probably the most difficult part of the whole process, and also the one where the most mistakes are likely, because in some instances you will have no option other than to make your best guess. But going through the exercise helps you.to work out what practical and technical resources you need — for example what chassis, engine and tyres you have to get, how many spares must be bought, what size trailer is needed, what accommodation needs booking, what travel expenses there will be, and a whole host of other details that can’t be ignored. All of these have to be listed and costed, and it’s easy to get things wrong, especially if you’re just starting out, though — curiously — experience doesn’t necessarily prevent mistakes or naive decisions being made. However, the financial part of this planning stage is vitally important, because it is the size of the available budget which ultimately determines what your aims and objectives can realistically be. So if, having listed what you want to buy, you come up with a 50 per cent cash shortfall, go back and rewrite your wishlist again, and this time be a bit more realistic about it. Although basic budget forecasting is vital, another financial angle which warrants close attention is cash flow; that is, when payments have to be made. Most people have a certain amount of cash

TO WIN

19

coming in each month, a proportion of which will be put into the motorsport fund. Paying for engine rebuilds, suspension set-up services, and so on makes large dents in these funds, and planning when these payments have to be made is obviously crucial if you’re to avoid difficult personal interviews with your bank manager. Really careful planning means you get to control when the payments have to be made, which is an altogether better situation. The same goes for entry fees and travel expenses through a season.

Plan

it all out

on

a chart,

or a

personal computer, showing the dates money comes in and when it has to go out, and you should be OK. Next, you have to put together a schedule to indicate when things have to happen. There are two _ principle approaches to doing this: you can either look ahead and decide when the car must be fully prepared and ready, which will often be governed by the date of the first test session

or event

of the new

season,

and then work backwards to slot everything in so that you will be ready in time; or you can work the other way around, and give your project a start date, plot out all the jobs that need doing, and let that determine when you will be ready to go competing. The latter method is rarely used, however, most people striving to be ready for that all-important first session or event. This is understandable when entering a championship, and certainly nothing less would be expected of any professional outfit, but if you’re an amateur competitor for whom

motorsport is meant

to be an enjoyable and fun hobby, the ‘go competing once everything’s ready approach might be more appropriate. Giving yourself deadlines is fine when achieving them actually matters, but if they are artificial they can serve as personal stress raisers; you and those close to you could suffer as a result, and you could end up paying a high price. If you do decide you want to be ready by a given date, then this aspect of the planning is crucial. You really do have to

20

COMPETITION

CAR PREPARATION

make accurate estimates of how long each task is going to take, and you need to be realistic about it. If any work is going to be contracted out, get an accurate estimate of time-scale from each contractor. Then add a substantial contingency to the whole plan to allow for the inevitable delays — at least 25 per cent and more likely 50 per cent. This will probably give you a project start-by date that may well have passed already, in which case you didn’t start your planning soon enough! Another point worthy of notice at the scheduling stage is that as you chart out the jobs, it becomes apparent that certain of them have to be done before others. This helps to define what your priorities are, and

derived

is another

from

preparation

useful

actually

project.

benefit

plotting

As an

out

example,

to be

your you

won't be able to plumb in a new drysump oil system until you get the oil tank made. Nor will you know exactly where the oil pipe runs will be until the engine has been rebuilt with its new dry-sump and oil pump installed, and the engine is fitted into the chassis. It becomes obvious immediately that the engine rebuild needs to be carried

out first, with the oil tank

fabrication running in parallel; then when both are fitted into the chassis you can

order the pipes and unions. Of course, this assumes that you don’t have 3D Computer Aided Drafting (CAD) capability, on which you could work out your pipe runs without even getting your hands dirty. As with each phase in your preparation management, constant reviewing is vital to keep track of where you are, and to make adjustments to budgets and schedules as required. Having come up with a definitive list of what you need to do, when it has to be done, and how much it’s all going to cost, you now have to get organised. In essence, you can divide the tasks up into those which you can do yourself, and those which somebody else will have to do for you. Once again, an honest appraisal is needed, this time to determine who is best at what. For example, if you have been preparing your own engine, but the evidence suggests that you are short of performance relative to competitors with — professionally-built engines, then you have to say to yourself that you might be better off spending money

on

getting

your

engine

profes-

sionally built. There will be budgetary considerations that impact on your planning here, but equally, you will now have the time available to concentrate on a task at which you might be more skilled

Computer aided draughting — nice ifyou can afford it.

MANAGE

— say, laminating some new lightweight carbon fibre bodywork instead of paying somebody else to do it. By doing this you could save some money, which can go towards that engine build. This goes back to making the best use of the resources available to you. The other key aspect to getting organised is to make sure you have all the necessary

raw

materials,

tools,

equipment,

and space that will be needed for each part of your car preparation. Now you're ready to actually start work.

Doing/getting done Working for yourself is easy — theoretically. Insofar as you don’t have to spend time telling yourself what needs doing, how,

when,

or

to

what

standards,

it’s

easy. But getting others to do things for you is never quite so simple. Some guide-

lines might help. (See Figure 2-3). First, its useful to explain to people who don’t know you, and are unfamiliar with what you’re up to, just what it is you are doing. Quite often they get interested when you tell them you’re into motorsport, especially, as is likely, if you're talking to an engineering firm where the people can probably identify with your engineering project. Tell them you’re in

TO WIN

21

the process of preparing a car, and once they’re interested they'll probably listen to your needs that much better. You then have to explain, very clearly and unambiguously, exactly what it is you want them to do. If the job can be put in writing and in a drawing too, so much the better. You may be greeted with a patronising look that says: “Yes, we have done this sort of thing before’; but ignore it, and just make sure that they do understand your requirements. It’s your money they’re going to take, after all. You should also agree the completion date and the cost of the job, and put these on your written order or instructions too. If you don’t, you could be in for a nasty shock later on. If a company won't commit to any of these conditions, you’re probably going to be better off finding one that will, or else you might lose control of a key aspect of preparation, and maybe miss that target start date. Steer well clear of companies or individuals with a reputation for promising completion dates and then failing to keep them, because you will definitely miss your planned first event if you involve yourself with such people. Which brings us to the last phase of managing the project.

Figure 2-3 The work phase.

DO/GET DONE | Communicate overall aims and objectives to people working for you

Tell them clearly what their specific tasks are

Agree the standards and timescales to which the job is to be done

ee

j

| :

22

COMPETITION

Controlling/reviewing It's easy to keep control of any work you are doing yourself, and you know immediately, without having to ask anyone, just how far behind schedule you are! This allows you to adjust the schedule when nobody is looking, thereby ensuring that you get back on track again without doing any extra work. Facetiousness and laziness aside however, you do need

to review how you’re doing on a regular basis, because it is possible for things to slip, or jobs to take longer than you thought they would. Frequent self-checks keep you in touch with your schedule, and allow you to adjust the plan if necessary (see Figure 2-4). If you have people working for you, or work is contracted out, then it’s even

more important to keep a regular check on progress. If, for example, you have given your engine to a specialist for a winter rebuild, failure to enquire after its progress on a regular basis may result in the company assuming that you are not particularly bothered about when they finish. On the other hand,

CAR PREPARATION

phoning once a week will let them know that the job is a priority to you, and with luck they’ll make it one of their priorities too. Naturally, you have to rely to some extent on the honesty of the individuals concerned,

but occasion-

ally calling in on them in person, if you can, should enable you to confirm actual progress. By keeping in touch in this way you will also get an early warning if such difficulties as a parts supply problem arise, enabling you to adjust your programme if necessary. By the way, you may wonder at the choice of ‘engine builder’ as an example here,

but somehow they always come to mind when discussing the scheduling of key elements of competition car preparation. This is probably because (a) an engine rebuild is one of the bigger elements of such a project, and (b) because, rightly or wrongly, this particular profession seems to have a reputation for lateness. It is just as unfair as saying all journalists

are

dishonest,

but,

sadly,

mud

sticks, which does the reliable majority an unwarranted disservice.

Figure 2-4 Keeping control.

CONTROL/REVIEW Know the state of play at all times

Keep a close eye on details of costs and timescales

Assess how people working for you are doing Apply corrective actions when necessary

MANAGE

Sponsorship The upper echelons of motorsport are almost entirely funded by commercial sponsorship. Companies pour vast sums of money into the top race and rally

teams for one primary reason — brand exposure in front of audiences and readerships of millions, maybe even billions of people. Then there are the tax concessions on advertising, of course. It’s relatively easy to see the benefits of this type of sponsorship, and in a sense it’s a lot easier for the big teams to sell advertising space on their cars when they know

TO WIN

2S)

roughly what level of exposure will come their way. But the vast majority of motorsport gets minimal mass media exposure. So how are sponsors who will pay for some (or all) of your motorsport to be attracted? In short, they need a reason for getting involved, and since you are unlikely to be able to guarantee them headlines on TV,

in the

national

dailies,

or

even

in

specialist weeklies, you have to look for other reasons. If you're lucky, you may chance upon a sponsor who simply wants to be involved for the fun of it.

Sponsorship pays for top level motorsport ... and contributes significantly at club level too. BNE,

Bern

24

COMPETITION

Such philanthropists are a bit thin on the ground, but they do exist. Why should they get involved with you? Because yours is going to be the best-prepared car in its category, you’re going to have fun together, and he is going to be proud to be associated with you. He certainly won't put his name on another car that isn’t as well-prepared if he is faced with the choice. You may have more chance of attracting a local company to back you if you can offer the possibility of local media coverage of your competition activities. Cultivating the local papers and _ local radio (and possibly TV) stations, via motoring or sports desks, is a worthwhile exercise, and they are often keen to follow these types of exploits. If you are going to compete in a_locally-based championship this may help, because the local media will probably already know something about the series, and may already be covering it. Similarly, if you compete at a higher level, then there is a valuable angle on stories there too. Perhaps a more likely way of getting ‘sponsorship’ is to do deals that save you money, rather than looking for hard cash donations. The net result is the same — you have to find less of your own money to go competing. And it’s a whole lot easier

prising a discount

out

of a com-

pany that knows they’ll at least get some money out of you than it is to get a bank cheque out of them. It’s even possible sometimes to get products or services that you need at no cost at all, in return for putting advertising decals on your car; but everybody tries this angle, so you have to be either lucky or skilful with the timing of your approach to succeed at this particular game. Another angle might be to look for a resource that you need but don’t have, such as workshop space in which to store and prepare the car, or a trailer on which to take it to meetings. Providing you with these facilities won't cost your benefactor anything, at least for as long as he doesn’t need them, so any advertising

exposure

he

gets

in return

CAR PREPARATION

represents pretty good value. Any or all of these approaches are worth a try, so long as you have done your homework and know that there are good reasons why the companies you approach could benefit from exposure on your car. The top motorsport teams spend vast amounts of time studying potential sponsors, the markets they are involved in, and the ways they do business, before they make any approaches at all. This makes it much easier to get a receptive response at the outset, which in turn just has to give a better chance of ultimately doing a deal. There is another important aspect of sponsorship that should not be forgotten or ignored. That is, once you have taken something from a sponsor and put his name on your car, you have an obligation towards him. He has the right to expect you to attend the meetings you told him you were entering, and to show up well prepared, looking smart, and reflecting well on his company name. It’s not for nothing that motorsport superstars have to meet with the sponsors and their guests,

as well as the media,

and seem-

ingly spend as much of a race weekend dealing with these aspects as they do working with their teams and driving the cars. You may not have that level of public relations to cope with, but, to a greater or lesser extent, once you’ve undertaken to carry a company name on your car, you are no longer a free agent. You also need to do basic things, such as ensuring your sponsors

receive tickets

to come and watch you, or that you keep them informed of your activities and results if they don’t attend. You have to think about keeping the local media informed, if local exposure was part of the deal. And you have to do all of this as well as keeping your car well prepared, and yourself in the best frame of mind to do a good driving job. If you are a oneman band, this all takes precious time and energy. If you’re lucky enough to have assistance, or are able to hire PR services, then this will obviously help. Some com-

MANAGE

petition categories actually provide PR services from a central press office, even tailoring each driver’s coverage to meet the needs of the specific local media concerned, an enlightened approach which takes into account how and where most drivers obtain sponsorship. Paperwork Not many people actually like doing paperwork, especially if it relates to a hobby like weekend motorsport. But like it or not, there is a surprisingly large amount that has to be done, and at least as much that you benefit from if you knuckle down and do it. The compulsory elements relate to applying for club memberships, competition licences, general regulations, supplementary event regulations, and championship registrations, if applicable. These cannot be avoided, so get used to attending to them. But keep in mind that, in a lot of cases, the person who receives your completed paperwork is also dealing with a whole batch of the same forms, or whatever, from every other competitor

in the

category

or

event

in

which you are involved. This means that their administrative job is a lot more onerous than yours, so the least you can do is help them by filling out your forms legibly, and preferably tidily. If you make a mess of it, there is a very good chance the recipient will not feel well disposed towards you, and if that same person has an influence on who gets their entries accepted and who gets rejected in the case of an over-subscribed event, it’s best

to be on the safe side and do the job properly. You will also find that you receive a lot of paperwork. We’ve already covered technical rules and regulations as they apply to your car and your chosen competition category, but you also end up with further sets of regulations applying to the events and championships you wish to enter. It is apparent that the proportion of competitors who actually read these is somewhat lower than 100 per

TO WIN

2S)

cent. The ones that don’t read and take note of these rules and regulations are the ones who, potentially at least, will have to endure problems and aggravation sooner or later, perhaps relating to technical infringements they were unaware of, or local rules about starting engines before a certain time, and other assorted

possibilities. Don’t become a member of the ‘Nobody Told Me’ club. It’s the competitor’s responsibility to be familiar with all the rules and regulations, and crying ‘nobody told me’ as you are turned away from the meeting will do you no good. So do read all the information that comes to you, including the final instructions that come with your entry confirmation — not least because the latter may contain important details that couldn't be announced at an earlier stage. Records The voluntary aspect of related work concerns keeping records.

paperIn the

earlier sections on managing your prepa-

ration project, we covered controlling and reviewing

what’s

going

on.

It’s a great

help if you keep notes of when you set things in motion, be it delivering the engine to the engine builder or sending off for your annual competition licence. Apart from anything else, you can remind yourself that you have done certain jobs, as well as when you did them. How you record this kind of thing is up to you — a small notebook may suffice, or you may prefer to prepare checklists that you can file away, perhaps even on a personal computer. It doesn’t matter how you do it, so long as the system you adopt suits you and doesn’t take too long. In time you will be able to look back on the previous year’s notes, and perhaps adjust the time-scales of some jobs if you experienced problems. You will also be wise to keep records that relate directly to the preparation of each aspect of the car, as well as what happened at each event. This will be covered in the chapters on practical preparation that follow.

Chapter 3

Driver preparation Prepare thyself In every respect, the driver is an integral and essential part of ‘the mechanism’ that is the competition car. Some

competition

car designers and engineers seem to regard the driver as something of a nuisance that disrupts and compromises their attempts at creating or engineering a

perfect vehicles There have even been well-documented cases in the very highest formula where the car hasn’t even fitted the driver, and this must surely constitute a fundamental and unforgivable design error. It also misses the very reason for the existence of the competition car, which is to serve as a tool to be

used by the driver for fun and/or for sport (though let’s assume professional drivers derive some fun too). A car is a device for transporting one or more people in the manner required, and it must therefore be engineered to do this effectively. It is the car that must be ‘moulded’

to suit the driver, and it is the

designer or engineer’s job to do that. However,

the

driver

must

also

from

at

some

point,

and

continue

to

suffer from to a greater or lesser extent, is that our egos somehow manage to convince our brains that we already possess the necessary levels of skill to drive a competition car effectively. Generally this delusion is put to rest, if not during the first event — which can be a sobering, and even humbling experience — then at some later date. It all depends on your approach, and on your willingness to accept that you probably won't win first time out. Experience will usually help to refine your basic skills, but the whole purpose of this book is to maximise your chances of ‘being there’ at the finish, and being as competitive as you had hoped, so it would be an omission if we didn’t consider what you can do as a driver to best prepare yourself, whether you’re a novice or not.

But first, here is a safety announcement

Depending

on the category and level of

be

competition you intend to enter, there are

adaptable enough to cope with different layouts, different set-ups, and different techniques, and, as with every other part of the car, he or she can always be better prepared. As the primary control mechanism, a driver is no use if not properly prepared; and, as with anybody who wishes to use any tool as effectively as possible, the right level of expertise is necessary. But one of the problems that we, as drivers, have probably all suffered

some minimum requirements that may be imposed with regard to protective clothing which we can cover here. Low-speed discipline events such as trials and autotests in the UK, and autocross

in the

USA, don’t require that a flame resistant racesuit needs to be worn, but in virtually all officially-sanctioned higher speed categories it is now compulsory to wear a racesuit approved to a minimum. stan-

dard. The relevant standards are stated in

DRIVER PREPARATION

2H,

the governing bodies’ yearbooks (see Appendix 1), and as these standards are liable to be updated from time to time it will be left to you to contact the relevant body to get the latest information. This is not just laziness on my part, but rather a means of ensuring that you are not misin-

formed. A racesuit is not a cheap item, and, as with most things, you get what you pay for. It is for you to judge what value you place on your hide, and to allocate the necessary funds to obtain an appropriate racesuit. But a decent suit, well looked after, will last for some time,

so get the best you can afford. This almost certainly means buying a_ twolayer Nomex suit as a minimum.

A helmet is another safety item that is compulsory in most motorsport categories,

and

once

again

minimum

stan-

dards, obtainable from the governing bodies, are in place. The rule of ‘you get what you pay for’ applies equally to the crash helmet, and once again, it’s your head, so you judge what its protection is worth. Various materials and constructions are available, with equally varied price tags, but three rules that should be stated here are: (1) make sure your helmet fits properly; (2) if your helmet suffers an impact, replace it; and (3) don’t buy a used helmet — you simply don’t know what its history is, and if it has already suffered an impact it could be totally useless should you have to rely on it again. It’s also worth keeping in mind that helmet materials can degrade with age, and this degradation can be accelerated if they come into contact with some solvents and chemicals. The manufacturers offer guidelines on the use of paint and stickers on helmets. Again, a decent helmet will last for some time if it’s well looked after. Other items of protective clothing to consider and budget for include competition gloves, boots, and underwear. All of these items offer additional protection against fire, and in the case of gloves and boots are likely to help with your control of the car; gloves by providing non-slip

Racesuit, gloves, (Tracey Inglis)

boots —

all worth

Don't buy a used helmet — you what its history is.

the cost.

don’t know

28

COMPETITION

contact with the steering wheel, and racing boots by allowing a sensitive feel of the pedals. Even if they are not compulsory in your chosen category, they may be worth trying.

Qualifications required The bare minimum qualification required to enter motorsport

competition,

in spite

of what you may conclude by watching some drivers perform, is that you are capable of driving a car. In most cases you need to be able to demonstrate this by possessing a road driver’s licence, and this is usually enough to enter events at club level. However, in the UK you do not need a driver’s licence to participate in certain

types

of events

such

as 2CV

and Minicross, autotests, and trials — you simply have to meet the minimum age criterion, generally 16 years. Higher status events require that you obtain a competition licence, but for the majority of events the only criteria for qualifying for an

CAR PREPARATION

appropriate licence are firstly that you have a driver’s licence, and secondly that you are willing to part with the relevant fee: However, certain types of competition, specifically circuit racing, are regarded by the sanctioning bodies as requiring a basic level of standardised training, consisting of a course in which you have to demonstrate a knowledge of procedures, flag signals, and so forth, as well as a driving capability that meets minimum criteria. In the UK this is known as the Association of Racing Drivers Schools (ARDS) course. In the USA the SCCA runs its Driver’s Schools. Prior to enrolling for your ARDS course, you are required to purchase a ‘Go Racing’ pack, which includes information and a video on such topics as flag signals. Having done this you must register for a medical examination by your doctor. The SCCA procedure is very similar. Once passed fit for duty you do

The UK Motor Sport Association’s ‘Go Racing’ pack.

OR ai SPORTS ——__ ASSOCIATION

DRIVER PREPARATION

your race school course, upon successful completion of which you are eligible for your basic race licence, designated National B in the UK, and Regional in the USA (though you need to complete two Driver’s Schools and two regional races in the USA prior to being granted your first regional licence). A further difference between the USA and the UK is that in the UK the Schools provide a car, usually a fast road model, whilst in the USA you need to take along a raceprepared

competition

car.

You

are

rec-

ommended to hire one if you don’t already own one. Congratulations, you are now a qualified racing driver! To compete in higher status events, you have to collect signatures from the relevant race official at a number of the events in which you are eligible to compete, to confirm that you performed to the required standard and did not misbehave yourself in any way that caught the eye of said official. The No place for an untrained novice.

29

specifics of upgrading procedures can be obtained from the sanctioning bodies. Additional training You might think that for events such as club

level

autotests,

trials and

so forth,

where there is no compulsory training, that technique can only be learned by entering

events

and

gaining

experience

the hard way. But talking to fellow competitors is always a valuable way to gain insights, and people tend to be particularly friendly and open at this level of the sport. By going along to events and talking to competitors, before you even start

work on your car, you will find out a lot about driving technique as well as getting car preparation tips. In circuit racing, where

the basic

on-

track training is compulsory, there is a very high pass rate (over 95 per cent in the UK), perhaps not too surprising when it is only the basics that are taught (though my own test was not without

30

COMPETITION

hiccups!). This is not to denigrate the value of such training, but isn’t it possible to prepare yourself better than this? The answer is yes, in some motorsport disciplines. It is possible in the UK, for example, to get extra training at circuit racing, hill-climb, sprint and rally schools from

qualified and experienced instructors, most of whom are well-versed and eminently skilful at their art. You will learn something at these schools whether you are a complete novice or an experienced competitor. But you are likely to come up against that old ego problem again — for some reason we all like to think we can already drive better than the next guy, and if we’re not winning, there’s always the

‘A to

Z of drivers’

excuses’,

all of

which naturally refer to external factors rather than the driver. Try not to fall into this trap — none of us is ever too experienced to learn. So whether the category and level of motorsport you want to enter requires a compulsory school course or

CAR PREPARATION

not, if it’s available,

give extra

‘voluntary

training’ serious consideration. Then there is driver coaching.

Most superstars in sports like tennis, golf, and athletics, to name but three, are only too pleased to give credit to their coaches for the beneficial influence the latter have exerted on them. Yet how often do you hear top motorsport drivers in their victory rostrum speech say: ‘And_ special thanks to my coach for really helping me to improve my lines on this track.’ The fact is, driver coaches

do exist in circuit

racing and rallying, and it is possible to get special one-to-one

tuition on general

or specific techniques. You might argue that a race engineer does this job in a pro-team, and to an extent this is true, but the main role of the engineer is to provide an efficient car, and he may not be the right person to advise on changes of driving technique. In fact it is incredibly difficult to define what makes a good coach, and it is prob-

Even if it’s not compulsory, driver training is an invaluable aid.

DRIVER PREPARATION

ably no coincidence that various driver coaches have gone on record as saying that they teach a different method to all the other coaches. This doesn’t mean that any of them is wrong. Think of all the best teachers that taught you at school; they probably all had different methods, but you probably learned a lot from each of them. And that’s the point really — a good coach will have that special blend of relevant knowledge and experience coupled with the ability to put it across in a way from which you can learn. So if you think it’s appropriate to where you are or where you hope to be in motorsport, research driver coaches, and maybe give one a try.

Personal fitness The drivers in all the top motorsport categories are supremely fit these days. Such was not always universally the case, and it is partly the technical advances in competition car technology that have required the drivers to be fitter so that they can cope with the physical stresses involved in piloting their projectiles. But this is not the only reason that fit drivers do well. It is also to do with being mentally fit, something which goes hand in hand with physical fitness. Even if, like me, you only have vague recollections of being moderately fit once upon a time, you may also recall Gf the memory hasn’t gone too) how mentally sharp you felt at that time, and how tiredness eluded you. It surely wasn’t ail to do with your lost youth, either — it was because you were physically fit. Any fit, and (probably) young readers yet to discover the perils of middle age and involuntary personal ballast increases will be wondering what this is all about, but you’ll find out soon enough... Until then, capitalise on the fact that you are lean and sharp. There’s an old saying that age and experience will always overcome youth and enthusiasm.

So how

come

most

racing

drivers

are way past their use-by date at 40? A more certain statement would be that a fit racing driver will always overcome an

oil

unfit one, irrespective of age. Then there’s the other obvious benefit of weight. In most categories of motorsport, surplus weight is to be avoided, and even where minimum weights applicable to car plus driver are imposed, the lighter the driver is, the more scope there is for putting weight in the car in locations that will be to the least detriment to performance. So a lightweight driver is usually preferable to a heavyweight, all other factors being equal, which is another very good reason for being fit and lean. So the next time you contemplate spending vast sums of your hard-earned on a set of magnesium Wheels that save 1.5kg (3.3lb) each corner, give some thought as to how difficult it would be to lose 6kg (13.2lb). That might seem like a lot of weight to shed, but it will definitely be cheaper than the wheels, you'll get the same power to weight ratio benefit, and you'll probably perform better in yourself. Those of us without the benefit of a personal trainer or regular invites to Willy Dungl’s sports clinic could probably benefit from

advice

on

these

matters,

and

your general medical practitioner is the best person to ask first. You may be able to find fitness and weight loss courses at your local sports centre or adult education centres. See if you can get exercises organised for your own specific purposes — Mike Tyson’s exercise programme won't give you the lean look you're after. You may consider, for example, that stamina is important, especially if endurance events are your objective or if you are a one-man band and need plenty of durable energy to keep on top of all the jobs that need doing. Diet — that is, the food you eat as opposed to not eating food — is also an integral part of keeping fit, and again you can get good advice from your local health centre, who will tell you all about energy-rich carbohydrates and low amounts

of fat, and offer other beneficial

advice. The extent to which you go into all of

32

COMPETITION

this will be reflected in your motorsport aspirations. If you’re a dedicated, ambitious driver destined for the top, you'll already be doing all the above, and more besides, whilst if you are happy as a weekend

of us

warrior,

are,

your

CAR PREPARATION

most probably centre around a good feed between practice and the event, quite probably washed down with an appropriate beverage in the company of like-

and tens of thousands

minded chums. Whatever you do, if it prepares you for the way you want to

dietary

compete then that is surely what matters.

considerations

Chapter 4

Modify, buy, or build? THERE IS A limited list of options when it comes to converting that burning desire to Own a competition car into actually obtaining one. They are: modify a road car for competition use; buy a used competition car; buy a new competition car;

or assemble a competition car from scratch. There are practical as well as financial pros and cons involved with each possibility, and in this chapter we'll look in general at the benefits and disadvantages of each route, starting with the option

on

which

many

competitors

cut

their competition teeth.

any additional outlay required. Then as the bug bites, and you want to go faster (both these eventualities being virtual certainties), you can modify and uprate as and when you have the funds. Ultimately the ‘grocery getter’, formerly no doubt an economical, tractable little runabout,

starts

compromised

to

become

tions, and sooner or later it ceases to be a If you're going to use mother’s car, at least name your team after her! This is Tim Betts’ and Helen Knight's Golf.

Modifying a road car for competition This has to be the most popular route into motorsport competition, whether it be into club level events on an occasional basis, or a more serious activity such as a

one-make racing series. The reason for this is simple — it is almost always the cheapest way into motorsport, one of the major benefits being that you can carry out modifications as and when you have the budget to do so. In fact it is sometimes possible to perform the absolute minimum modifications required to make a car legal and safe for the sport in which you are going to compete, and lay out absolutely no cash whatsoever. You just need to invest time and a liberal application of elbow grease. Take club autotests, for example. There is a set of technical and safety regulations that applies, yet armed with these and a road-legal, or at least roadworthy, vehicle there is little if

somewhat

by the go-faster modifica-

>

COMPETITION

34

CAR PREPARATION

‘road car’. But let’s not worry about that here — you will have discussed all of the implications with nearest and dearest before embarking on this project, so there’s no point in repeating the issue — is there? One of the major practical benefits of modifying a road car in this way is that you can keep track of what is actually done to it. You know exactly what components are put on. You know to what standard the work has been done if you do it yourself. You know when parts were fitted, which gives you a better chance of knowing when they will need replacing. None of these benefits are guaranteed to apply to any modified car which you might buy. You also have the choice of doing your own modifications, including fitting uprated parts or actually modifying components yourself if you have the necessary skills. Providing you really can do work to an adequate standard, the latter may save you money by reducing or Hard

work

and. determination

Garthwaite competitive.

made

David

eradicating at least some labour costs. Parts availability is rarely a problem when modifying a popular road car model — there is, after all, an entire indus-

try out there dedicated to producing uprated ‘tuning’ parts for the majority of the most popular production models. Make sure that a modified component you think will be just the job for you is actually not specifically excluded by the rules applying to your branch of the sport. And if it’s standard parts you need, regular dealers, motor factors and scrap yards can all provide components to suit every budget. Be certain, if you decide to get parts from a non-authorised dealer or factor,

or

vehicle

dismantlers,

that

the

components will do the job before you use them — seek advice, and inspect parts as thoroughly as you can before fitting them to your competition car. Your life may depend on it. It is well within the bounds of possibility to build a highly competitive racecar using the principles outlined here. Take, as an example, the Mk 1 Volkswagen Golf GTi

shown

here, that was

used

in

the 750 Motor Club’s ‘Hot Hatch’ Championship in 1996. This category caters for cars that must have a current roadworthiness

(MoT)

certificate,

but

restricted modifications to the engine and suspension are permitted. The car originally cost the princely sum of £300 ($490), though it was actually an old, worn-out rally car, complete with roll cage. The shell and the roll cage were the only components that were of any use, though, and with judicious purchasing, and help from a friend (and sponsor) who ran a car spares business, the car became a winner. The then owner, David Garthwaite, had one other advantage in his favour: he is a time-served motor mechanic,

which

enabled

him

to do all

his own preparation, including buildingup the engine and transmission. After a couple of seasons’ development, during which both car and driver improved, David finished the championship as runner-up, proving that a modified road

MODIFY, BUY, OR BUILD?

car can be a fully competitive proposition with the right approach — and lots of hard work and forethought. This example is something of an exception these days, as professionallybuilt engines, and even professionallyprepared cars, become the norm even in so-called low-cost categories. Nevertheless, you-—can still get into these categories, and gain experience and track-time in a car modified entirely in the home raceshop, though getting fully competitive will be harder. A cost-effective compromise can be to buy professionally-made or modified components, and do the assembly yourself, but once again you need to know what you're doing, especially with engine and gearbox work.

35

Buying used Buying a used competition car can often work out to be the most cost-effective

aggravation than you ever thought was possible with a car that has already competed. Which way the cookie crumbles depends very much on how well you do your research prior to making the fateful purchase. A key phrase to bear in mind when seeking to purchase a used competition car, though, is ‘fitness for purpose’. This is intended to mean not only ‘of merchantable quality’, a phrase that is usefully borne in mind when making pretty well any purchase, but ‘fitness for the purpose for which you intend to use it’. This is something which only you will be able to judge, and even if a vendor tells you it is suitable, it is not his responsibility to make that judgement. In a perfect world, however, buying a used competition car should get you something that is already developed to a particular, known level in its category, with a commensurate price tag, and which may well have the potential to

route to getting competitive.

become

However,

it

can just as easily turn out to be a nightmare that generates more work and

a more

competitive

proposition

in your hands, once you have seen to it practically and technically; and, of course,

The following season Glyn Richards won in the car built by David Garthwaite.

COMPETITION

36

CAR PREPARATION

once your consummate driving skills are put to use behind the wheel. It will have been cheaper to buy than a new car, obviously, and will probably have been cheaper than building-up a car of your own to the same state of competitiveness. And it will almost always be quicker to buy something ready developed than to create something yourself. It is possible, again in ideal circumstances,

to go out at

the end of a season, and buy this year’s championship winner, including spares and a trailer, for less than the previous owner paid for the new car alone just 12 months previously. On the face of it, that would represent a good deal — though you then have to be able to drive the car at least as well as its previous owner if you wish to match or better his results. At the other end of the spectrum is the advertisement selling, shall we say, an obsolete circuit racecar, which says something like ‘ideal for hill-climbs and sprints’. This actually translates to ‘the advertiser doesn’t know what he is talking about’. Advertisements,

and vendors,

that say these things should be regarded with the utmost suspicion, and this brings to mind the general point that if you do intend to buy a car that wasn’t originally built for the category in which you want to_compete, then you have to be prepared to make quite a number of modifications to make it at all suitable. For example, that circuit car that was said to be ‘ideal for hill-climbs’ will almost certainly have incorrect gearing because of the different speed regimes of the two disciplines, possibly necessitating the purchase of a new final drive, and maybe a whole new box of gear ratios too. It will also, probably, have incorrect spring stiffnesses, which could mean that the dampers are incorrect too, and this may require costly rebuilds, if not complete replacement of the dampers. In addition the steering ratio and the amount of available steering lock may be incorrect — and so on. The point is, if one of these advertisements

looks attractive, be aware

that there will be considerable work and

cost involved in adapting such a car for a different use. Having said that, there may be such positive advantages to be gained overall that you still deem the purchase to be worthwhile. Whichever of these routes you follow, or whether you spot an advertisement that sounds like it describes just the car for you, much grief will be avoided if you research the car’s background, perhaps by tracing previous owners and looking up results in that dusty pile of motorsport magazines in the corner. If you are following the track progress of a particular car, speaking to the drivers and owners of its competitors can sometimes produce facts that the car’s actual owner may be more reticent in sharing with you. And if a car has a history of competing in one category over a period of years, then that category’s championship co-ordinator will more than likely have some background knowledge on it that could be useful. In short, try to get as much history as you can on the car before parting with any cash. There are no handy competition car price guides that you can purchase from a news stand, such as those you can buy for road cars. So judging if an advertised price is fair is difficult unless you get to know the particular market. This can only really be done by asking around, and looking at advertised prices over a period of time, seeing what sells and what does not. And of course, a competition car’s price will reflect not only its condition, but its technical specification, and its (recent) results record too. Another factor may also be whether or not one of its previous drivers was famous; but don’t be taken in by claims of ‘ex-Heinz Alaziburger’ unless proof can be offered that the famed Herr Alaziburger really did drive it regularly. Even then, the inflationary effect on the value may be illusory. Of more interest, probably, will be practical things like the number of spares that come with the car and whether a trailer is included,

both of which

items will need

to be purchased if they do not come part of the package.

as

MODIFY, BUY, OR BUILD?

The last word on buying a used competition car has to be ‘don’t use it without a thorough check-over, if not a complete rebuild’. The only exception to this rule is when you have been working on the car yourself already before you buy it. It might appear disparaging to the car’s previous Owner, who may well be, or who may employ, the most thorough, conscientious mechanic

in the world, but there

will almost certainly be things that have been done which are not up to your own high standards. A detailed check on every nut and bolt, fastener and cable-tie, hose clip, and hydraulic union, will give you peace of mind that things are unlikely to drop off when you first get in the car and drive it in anger. If you don’t do this, you will be putting great faith, not to say your life, in the hands of the previous owner. You'll also find out if the thing is as straight and square as said previous owner told you it was. So buying used is, not surprisingly, fraught with potential pitfalls, perhaps

even

more

37

so than buying a used road

car. Even if you purchase from a broker,

it is very unlikely you'll get any kind of warranty in the way that you would when buying a road car from a registered dealer. So as the Roman salesman would have said at the competition chariot dealership, caveat emptor, amicus — or ‘buyer

beware, mate!’ But if you exercise appropriate caution, you should be able to get a good value competition car this way. Buying new For those fortunates with the budget to buy a new competition car, there are probably more advantages than disadvantages to be had. The best thing about buying new is that your competition car comes pristine, unused and undamaged. You know that it will be as straight as it can be, to the limit of manufacturing tolerances at least, and this gives you a good starting point from which to work. You will also be able to get the latest specification, incorporating all the devel-

Buying new has its advantages, and with the Radical Clubsport, for example, it needn't cost the same as a house.

COMPETITION

38

opments

and tweaks

CAR PREPARATION

that earlier models

didn’t have, and this, in theory, can only

help your level of competitiveness. You will be able to specify particular details, if your

competition

category

permits

any

variations from base specification. The car will, again in theory, come ‘on the button’, race-ready, needing only fuel, oil,

and water to get it (and keep it) going. Then there is after-sales service. Though this appears to be variable in quality throughout the motorsport industry, good after-sales service should follow on from the exchange of substantial sums of money for a company’s product in any sphere of commerce, motorsport included. So you ought to be able to expect technical support, at the very minimum over a phone line and preferably at track-side, from the constructor of your car. You should also have access to upgrades at decent prices as they become available. One thing you can bank on, though, is that you will usually have ready availability of spare parts, because this is where the manufacturers make their best profit margins. Having said that, there are times when even the volume racecar manufacturers struggle to keep up with the demand for spares, such as at the start of a new category, or after a particularly torrid and incident-packed weekend’s racing. Just get your order in early for the parts you know are going to get damaged, like suspension links, front wings and such. - The disadvantages of buying new are mostly to do with cost. The initial purchase price is inevitably high, compared to buying used. There will also be tax to add on to a new car purchase — VAT in the UK adds 17.5 per cent to the purchase price, which is a substantial extra chunk of money to find. All the ‘extras’, like additional sets of wheels and tyres, gear ratios and spare suspension, will all be at additional cost (plus tax), rather than coming as part of the package as they often do with a used car purchase. Buying new does not necessarily mean instant competitiveness. For _ starters,

others will have also bought new; but at least by doing the same you don’t fall behind. However, to get your new car to produce front-running performances still requires that it is very carefully assembled, checked, set up, and ‘sorted’ — more

of all of these aspects in later chapters. The introduction of a new car can sometimes produces a temporary backward step in performance, and only by testing, developing, and refining a new design does it actually accomplish what it was designed to achieve. This is normal. More often than not, though, cars are said to be ‘quick straight out of the box’; but a test driver hired to shake down the new chassis is hardly likely to say ‘actually I preferred last year’s model’, is he? A new model will generally incorporate design elements that must, and do, contribute to a more competitive package, such as a stiffer chassis or reduced frontal area, so

if the car is not as quick as its predecessor to start with, it will usually be down to track and weather conditions, or the new car being unsorted. Getting the car to the front of the field will be more

about lots of effort, and good driving.

good

preparation,

Building from scratch There is a hardy minority of motorsport enthusiasts for whom the only way to go competing is to build their own car. In recognition of this desire, there are also,

fortunately, quite a number of competitive arenas that not only allow this, but actively encourage it, such as the various classes run by the 750 Motor Club in the UK, an organisation which has been referred to as the ‘first motorsport engineering college’ because of the number of top-level designers that have emerged from its ranks — Eric Broadley, Colin Chapman, and Gordon Murray are but three who spring readily to mind. Other competition

categories

also

encourage

the self-build route, including a number of SCCA-run

classes

in the

States,

and

hill-climbing and sprinting in the UK, where there is also wide technical free-

MODIFY, BUY, OR BUILD?

dom to try out ideas that would not be permitted elsewhere. Also included in this ‘self-build’ definition is the ‘self-assembly’ competition car builder, who puts a car together from parts obtained from one or more sources, rather than designing and manufacturing everything. Analogous to the ‘flat-pack furniture’ assembly approach, there are also positive advantages to be gained from putting a car together this way. The big plus of self-build (which definition will be taken to include design, manufacture, and assembly) is that the practical enthusiast can start with the proverbial clean sheet of paper, and incorporate every concept, idea, and whim that he or she believes to be worth trying — and put them to the test. Other advantages include ending up with a known quantity, rather like modifying your road car for competition, and the financial burden may be spread out to meet one’s own ability to put cash aside for the project. The total cost can be significantly reduced relative to buying a new or even a used car, given that you

a9

are using your own labour for the majority if not all of the necessary tasks. And the personal satisfaction to be had from creating

your

own

competition

car, and

then competing in it (not all self-builders compete as well, but most do) is not to be underestimated, though for some creating the car seems to be more important than driving it. A number of wellknown racecar constructors started out this way, including Lola and Mallock. The advantages of self-assembly also include big cost savings by virtue of using your own labour. You also end up with a car that you know as intimately as is possible. Expenditure may once again be spread out over time to ease the pressure on your bank balance, and the satisfaction of completing such a project is still considerable, especially when you produce a car which is competitive, but which you know cost a fraction of the opposition. But there are downsides, of course, not

the least of which is the sheer amount of work involved. Most people can only do projects such as these in the evenings

Tony Pashley’s self-designed and constructed hill-climber.

COMPETITION

40

The beginning of a ‘self re-assembly’ project, which eventually turned back into a Pilbeam.

and at weekends,

when

CAR PREPARATION

may just help keep you saner than flogging on regardless, and taking breaks from the whole thing will probably do you no harm from time to time, providing you haven’t set yourself too rigid a schedule for no particularly good reason. And if you’re an amateur competitor, keep reminding yourself that you’re involved in motorsport for fun! Perhaps one of the greatest fears of first time self-builders is that they may believe there are gaps in their personal skills that prevent them from tackling certain tasks. This is not the problem it might seem, and there are always solutions. For example, if you do not possess a particular skill, you can either sub-contract the work to a company that can do it for you; or you can search among your friends until you find one who has the required skills and then try to involve him or her in your project, and given that their only reward is likely to be little more than your undying gratitude and the odd free meal, they need to be at least as keen as you are. Alternatively you can learn the requisite skill yourself. There are numerous enthusiasts out there who have taught themselves to weld,

they are not at

braze, turn, mill, fold, press, and mould,

work earning a crust to support their families and themselves. As such, you

purely because they wanted to do those jobs on their competition car for themselves. If you are reasonably practical with your hands, and have a decent set

really need to be one of those people for whom this kind of project is a positive relaxation technique. Otherwise the lack of real time off ‘work’ can get pretty wearing. The risks of the family forgetting what you look like ought to be kept in mind too — they may conclude that the scruffy individual in the overalls who occasionally wanders into the kitchen uninvited is just some itinerant tradesman who happens to work in your garage. It can take a long time between initiating a self-build or assembly project and actually getting in the car to make it go. This lengthy timespan can be somewhat depressing and de-motivating, and you need to be prepared for days when you just don’t feel like working on the project at all. Actually, giving in to this feeling

of tools, most things can be done, and if

you are within easy reach of a moderatesized town a considerable amount of help can be obtained from libraries and adult education classes. The decision as to how you obtain a competition car is entirely yours — only you can judge how your finances pan

out, what your own technical skills level is, and what resources and facilities you have at your disposal to put a competition car together. But one thing is virtually certain: if you've got this far, you’ve probably already made up your mind how you're going to achieve ownership of that competition car. If you haven’t already got it, that is!

Chapter 5

Chassis structures THE LATE ENZO Ferrari apparently thought of the engine of a racing car as its heart. If we take the liberty of extending his analogy, the chassis may be regarded as its skeleton — the structure of bones that holds everything in the required locations. Whatever type of chassis your competition car has, it has to do the same basic jobs.

The role of the chassis Technically the chassis has multiple roles, some of which are to a greater or lesser extent conflicting. The key roles are: — To accommodate the driver (and codriver) safely. — To accommodate the engine, transmission, ancillaries, and systems.

— To provide and locate suspension mounting points. — To provide bodywork and aerodynamic aid mountings. — To meet the regulations on dimensions, construction, and

materials. — To be as light as possible. — To cope with all the complex loads fed in by dynamic and aerodynamic forces.

This last point is perhaps the nub of the matter as far as performance is concerned, and needs expanding. It means that a competition car chassis has to be strong enough and stiff enough to resist all of the considerable loads fed into it

with the minimum

of deflection, twist, or

bending.

be good if we

It would

could

say ‘without deflection, twist, or bending’,

but that idealistic state of affairs is simply unattainable, because regardless of structure all materials distort in one way or another when under load — that much is a fact of life. However,

some

materials

are inherently stronger and stiffer than others, and some structures are inherently better than others, and a well-designed chassis structure will use the materials it is constructed from in a form that allows it to be as light as possible, whilst dealing efficiently with all of the loads involved. Accommodating the occupant(s), engine,

transmission

and so forth, whilst

retaining optimum strength and stiffness, is not easy. Getting the driver in and out of the car, for example, requires that a

big hole is left to facilitate this, and big holes do not add anything positive to a chassis structure’s properties. Similarly, the engine. and transmission usually require a large interruption to the chassis, though because of the reduced frequency of removal some of the — structure’s integrity in these areas may be recovered using bolt-in reinforcement members. In some installations the engine and gearbox may contribute significantly to the structure, acting as ‘stressed members’.

The occupants and all the major and minor components also have to be located and positioned — or ‘packaged’ to use a term in vogue — in such a way as to

achieve

the

desired

weight

distribution

42

COMPETITION

CAR PREPARATION

front and rear (as well as side to side),

with the centre of gravity CC of G’) as low as possible, and with the desired ‘polar moment of inertia’. This means that these items must be positioned low down in the chassis, to achieve a low C of G,

which helps primarily to improve cornering as well as acceleration and braking capacity, and with no heavy components positioned way out at the front or rear to produce the high polar moment which endows a chassis with sluggish response (the converse, a low polar moment, endows a chassis with rapid response but

taken

to. extremes,

can

result

me it

being nervous and twitchy). All these parameters create compromises between The dashboard roll hoop and cross bracing on his Chevron saved Jim Whiteside from injury.

sensible, practical packaging, and physical and mathematical ideals. As an example, the driver is heavy, and therefore ideally should be placed as low as possible in the chassis, preferably lying prone. But the driver also needs to be able to operate the controls and see where he or she is going, which requires raising the driving position. Safety is a paramount concern, and a substantial part of the chassis structure’s job is to protect the occupant(s) in the event of impact with the scenery or another car. Again, this requirement tends to conflict with the desire for a_lightweight structure, but with careful consideration driver-protection structures can be used to enhance the overall strength and stiffness of a chassis to the benefit of its performance. Impact absorption or ‘crumple’ zones are also an intrinsic part of occupant safety, and need not be heavy to be effective. Low weight is a must-have in virtually all forms of motorsport (the only probable exception being trials, where ballast to increase traction is often voluntarily added), and a lightweight chassis can contribute significantly to keeping overall weight down. But this criterion, superficially

at

least,

conflicts

with

structural

integrity and safety, as well as chassis longevity, the latter an aspect of possibly greater import to the impecunious amateur competitor than to top professionals. So a chassis design has to be a compromise that deals with all these overlapping

areas

of

conflict,

and

which

produces something for the end user that is fit for its purpose, safe, competitive, and reliable. But there are obviously various different types of chassis, depending on the type of car you have, its end use, and the technical and performance requirements of the motorsport category in which you intend to compete. It may also be, if you are going to self-build your competition car, that the type of chassis you end up with owes more to your skills in working with particular materials and construction techniques

CHASSIS STRUCTURES

than any particular technical advantage that one of the chassis types may offer. That’s a perfectly valid selection criterion. For our purposes we'll regard chassis as falling into the following types:

Production shells. — Tubular spaceframes. — Sheet-metal monocoques. Composite material monocoques. It’s true to say that chassis can also be a combination of these basic types, but by and large one or other of the above will be the predominant construction, and its easier to categorise them in this way.

Production car chassis The shells of production cars are not inherently very stiff relative to purposedesigned competition cars. They were never meant to be, given that the loads encountered by their chassis in normal road use are nothing like as high as those confronted in the heat of competition. Production

cars were,

after all, designed

to accommodate the occupants in relative comfort, not for hurtling around circuits or pounding along rough forest tracks as fast as their drivers can make them. They have large apertures in them to cater for between

two

and

five doors,

accessible

engine bays, uninterrupted load spaces, and large areas of resiliently-mounted glass. They are never going to be very stiff structures. It could be argued that in most production car competition categories this lack of chassis rigidity is not important, because its the same for everybody. The fact is, however, that it isz’t the same for everybody, because some production shells are inevitably better than others in this regard. And furthermore,

the stresses

and strains

of repeated use in competition, especially if engine power and cornering capabilities are significantly uprated, can cause serious structural defects to occur which can ultimately lead to cracks and potentially hazardous failures. So shell reinforcement becomes a necessity.

43

Most, though not all, competition categories that cater for production cars require some form of mandatory roll-over protection on the grounds of safety. This is good sense, and for this reason alone a roll-over structure is certainly worth considering even if your motorsporting arena doesn’t require it. But a properlydesigned and integrated roll structure can also markedly enhance shell rigidity, and provide taut, more consistent handling, resulting in a faster vehicle and a safer cabin in which to work. This is one of those rare cases of extra weight actually working for you, not against you. The sanctioning bodies lay down the law with regard to the permitted steel The bolt-together,

bolt-in roll cage in Duncan

Barnes’ modified production Mini.

44

COMPETITION

CAR PREPARATION

alloys that may be used in roll structure tubing, the tube type, diameter and tube wall thickness, and manufacturing methods. They also specify the minimum structures that must be used in any given category. However, they then, quite sensibly, leave it up to the manufacturers to design a specific roll structure for each production car model, and in this way an optimised and reasonably economic product can be made. So unless you really do know what you are doing, there is no question that buying a proprietary roll structure is the best route to follow. This will not only provide you with the best protection you can get, but will also give you a structure that has been optimised

for stiffness

too,

not

to mention

ease of installation (in most cases). The minimum roll-over structure consists of a basic roll hoop with rearward inclined braces, but safety and _ stiffness advantages can be obtained by going to a ‘roll cage’ which incorporates a front roll hoop too. In addition to this, diagonal bracing, attachments to door pillars and the roof, door bars, and braces extending

forwards and rearwards to suspension mounting points, all enhance the roll cage to the benefit of personal safety and chassis stiffness. The extent to which you go will obviously depend on your budget, the category and number of events in which you are likely to compete, and a judgement as to when adding weight will stop bringing gains. The roll cage manufacturers will proffer good advice, and it’s worth bearing in mind that they are concerned about your safety because their reputations depend on it. When it comes to attaching a roll cage to your car — the methods for which, incidentally, are also covered by regulations — you have the choice of bolting the cage in place or welding it. The plus side to welding is that the cage may be attached to the shell at more points, giving increased strength and stiffness; but it is also quite likely to be an irreversible process. So, rather obviously, you need to be certain that the car is going to be a

dedicated competition car from the point at which you make this particular decision. Welded-in cages are also more costly. Before installing a roll cage by either method, it’s a very good idea to make sure that your car is straight. You could visit your local friendly bodyshop to get it checked on their chassis alignment jig. Its a lot easier installing a roll cage in a straight shell. There are also other techniques for improving the structural integrity of a production shell. ‘Seam welding’ is one such technique, if permitted by the regulations of your chosen category; in this the small spot welds holding together the multiple panels that form a shell are supplemented with longer, closer-spaced welds. The analogy here is of very coarse stitching being over-sewn with closer, neater stitches, and not surprisingly, structural properties are enhanced. The welds used will be of the order of an inch (25mm) long, separated by perhaps 2—3in (50-75mm). It is imperative that seam welding is done after the roll cage is fully installed so that the resultant heating does not create unwanted distortion of the shell. And in line with good welding practice, the process should take place in short stages, swapping from one side of the car to the other between stages in order to even out the thermal stresses created within the shell. It will be obvious that seam welding can only be done when the car has been stripped back to a bare shell, with all internal trim, linings and carpets removed, the fuel tank and systems drained and removed, and the battery and all electrics removed. The chances are you will also have to remove soundproofing, sealants, anti-rust treatments and a lot of paint too, so you might at this point consider taking the car along to

be ‘acid dipped’ if that service is available locally. The process will remove vast amounts of various treatments applied during and possibly after manufacture, and respectable weight savings will be achieved. Of course, regulations may

CHASSIS STRUCTURES

45

Seam welding (centre) on a works VW Golf rally shell.

require that you put a lot of these items back on again for competition, and you will certainly want to repaint your steed so that it looks good and doesn’t corrode. But welding will have been made easier and safer, and some surplus weight will have been removed. You need to strip down to basics in some cases.

Other means of strengthening and stiffening the structure include strut braces, which bolt to the top of suspension turrets to stiffen the space between them. These have to be removable for the obvious reason that extracting the engine, for example, would otherwise be impossible.

COMPETITION

46

CAR PREPARATION

Li

The roll cage is welded to the reinforced strut top on the rally Golf.

Other means of engine bay bracing may also be permitted. In addition to such bolt-on bits, further welded reinforcement

of the areas around strut tops may be permitted, and is often desirable, especially in a category like rallying, where the repeated impact of a car returning to earth can punch struts through an unreinforced shell.

Tubular spaceframes The tubular spaceframe chassis structure is probably the most common competition

car

construction

technique.

Large

numbers of single-seaters, sports racers, and even so-called silhouette saloons have, over spaceframe

such as use of others number

the years, been chassis. In some

based on categories,

the ubiquitous Formula Ford, the a.spaceframe is compulsory. In it is used through choice for a of very good reasons:

— Spaceframes are relatively easy to make, providing you know how to cut, fit and weld steel tubing. — They are also relatively cheap to make. — They are relatively easy to repair after accident damage. — They are relatively easy to modify or re-design in certain areas, for example

to cater for a new engine — Internal components are accessed. — A reasonably lightweight, stiff chassis structure can

installation. more easily strong, and be built using

spaceframe principles.

All in all, then, a fairly convincing list of pluses, especially for the lower-cost end of the motorsport spectrum, where a decent, good value for money chassis is an imperative. Ultimately a_ stronger, stiffer chassis can be made using one or other of the monocoque construction methods, which we will go into a bit later, but with penalties of one sort or another, usually (at least) of the financial variety.

Modern constructor-manufactured spaceframes have evolved over the years to the point where they are now far removed from the simple three rectangular bays joined by four longitudinal outer tubes, with diagonal triangulation bisecting most of the rectangular spaces. Triangulation is, naturally, still the cornerstone of strength and torsional rigidity (resistance to twisting), but the shapes of the chassis are far more complex, defined now on computer aided design (CAD). systems, with, in the case of well-heeled construc-

CHASSIS STRUCTURES

tors, finite element analysis (FEA) to assist with the design of structures and load paths. Indeed, such has been the march of progress that the torsional rigidity values of current Formula Ford and Formula Ford 2000 spaceframes are now up to and in excess of those obtained from Formula 3 folded aluminium monocoques not too many years ago.

The resultant chassis are in all probability beyond the scope of the most determined home constructor to create, or even to improve upon. But it is within

the realms of possibility for the practical DIY constructor to modify and improve older spaceframes, or to build a decent one from scratch. It might not match the torsional rigidity figures of a CADdesigned Van Diemen spaceframe, for example, but then the home-builder probably won’t be competing head-tohead against the latest specification frontrunning designs anyway. What,

then,

are the key features

of a

good spaceframe chassis? Undoubtedly, the first principle of spaceframe design is

47

that all tubes must be in either tension or compression, mever having to endure bending loads. What this means is that loads must be fed along the length of the chassis tubes, and not straight into them at an angle. So, tubes should never meet other tubes in the middle of an unbraced length, because that would put a bending load into the unbraced length. All tube joints should be three-way affairs at least, that is with a minimum of three tubes meeting at each junction. This happens as a matter of course in a design that is properly ‘triangulated’. This term has been used earlier without proper definition. So what does triangulation actually mean? Imagine four 3/4in (19mm) tubes joined (by welding) at right angles to each other to form a perfect square, say about 2ft (610mm) along each side, lying flat on your work bench. Now imagine grasping opposite sides of the square and moving one hand away from you, the other towards you. The only thing that resists the distortion of the square is the rigidity inherent in the

A spaceframe designed with computer aid — this is the Diemen International)

1999 Van Diemen Formula Ford. (Van

48

COMPETITION

CAR PREPARATION

welds. Basically, the square is pretty floppy, and can easily be distorted into a parallelogram shape. Now imagine cutting another piece of tube, and carefully fitting and welding it across the diagonal of the square. Now when you try to skew the square as before, it is far harder, if not impossible to do. The square has been converted into two triangular structures, which are inherently very stiff and strong in the plane of the structure. The diagonal tube is either put into tension or compression as you try to distort the square, and resists strongly. This is what triangulation is all about — making use of structures that do not want to distort. Of course, in a competition car chassis

it isn’t possible to triangulate every rectangular bay for the reasons already stated, such as allowing the driver in and out of the cockpit. In this instance, solutions to recovering lost rigidity vary from adding additional structures to the outsides of the cockpit — in the way that the excellent and highly successful (even now in retro FF2000 series) Patrick Head-

designed

Delta

1T78/79/80/81 _ series

FF2000 chassis did — or by using highlevel bracing between the main and front roll hoops, as in many modern spaceframes. Engine bays also create a problem of reduced rigidity, and various solutions

include bolt-in tubular braces connecting the main roll hoop to the rear upper chassis rails, which

serves the additional

function of improving the integrity of the roll hoop. If the engine in use was designed to withstand it, then the block and cylinder head castings can serve a structural or semi-structural purpose too — in fact it is logical to presume that any solidly mounted engine must contribute to the stiffness of its bay, even if the majority of loads are carried around the engine in a triangulated tubular structure. But it is equally logical to assume that such a mounting will also put loads into the engine that may distort it more than is good for it, so be wary of relying on your precious engine too much for this purpose. Just because Fl engines are structural members, feeding all the rear-end loads into the chassis, doesn’t mean that

an engine whose origins are under the bonnet of a series production car will have been designed to do the same job — it won't.

You also have a choice of tube shape and type, not to mention the type of steel from which it is made. Suffice to say that square tube is generally easier to cut and fit than round, but not quite as strong or stiff, size for size; and square tubing also permits the riveting of outer panels for stiffening or cladding. Then there is the

IrzZ

Figure 5—1 Triangulating rectangles.

Triangulated rectangle resists skewing

Non-triangulated rectangle skews when under load

CHASSIS STRUCTURES

ZY)

Tony Pashley’s self-built Marengo chassis 1vn reinforced by structures external to the cockpit, and by bracing up to the roll hoop.

choice of cold drawn seamless (CDS) expensive than the latter, but is usually tube and electric resistance welded specified as mandatory for the roll-over (ERW) tube. The former is somewhat — structures. And then there are the highbetter structurally, and considerably more strength alloy steel alternatives to The Radical Clubsports demonstrates good engine bay bracing to keep suspension loads away Jrom the engine/transmission.

50

COMPETITION

CAR PREPARATION

common-or-garden mild steel, which are much more expensive and_ generally regarded as more difficult to join. These latter types may, perhaps, be best left to the experts who know how to handle them (and can afford to use them in the first place). There are well-written sections in books such as Allan Staniforth’s Race and Rally Car Source Book and Peter Herbert and Dick Harvey’s 750 Racer (see Appendix 4 for details of these and others) detailing spaceframe chassis construction and welding techniques, so we won't go over the same ground here, other than to touch on a few basic principles. The first is that to achieve a light, rigid structure it is better to go to a bigger tube size with a thin wall than to use thicker wall tubing — the bigger tube size is inherently stronger and stiffer. And secondly, a point touched on earlier: if you are a DIY home-builder intending to create a car that is durable as well as competitive, then it is probably as well to build a chassis structure that errs on the heavy side, using slightly thicker A protected chassis is a smart chassis.

and maybe

even

slightly bigger tubing.

These two points are not as contradictory

as they may seem. It is just a case of horses for courses. A professional Formula Ford team might be able to update its chassis every year, and maybe even during the year, but it’s different for us weekenders. Both the excellent abovementioned texts go into detail on how to make a 1/8 or 1/10 scale model of your proposed chassis design in balsa wood obtained from your local model shop — a very worthwhile exercise if ever there was one. Spaceframes, being steel, will corrode rapidly unless covered in a suitable protective coating. The cheapest method of achieving this is by hand-painting, using suitable primers and top coats, and though this is also the least durable finish it is extremely easy and quick to retouch any damaged areas. Stove enamelling is a more durable finish, and a smart one, and

epoxy or urethane paints do a good job. Powder coating is possibly the most durable of all the available finishing

CHASSIS STRUCTURES

51

The Jedi shows how to panel with swaged lightening/stiffening holes.

materials, but as a result it is also very difficult to remove should you need to weld or bond anything else to the chassis. As ever, the choice is yours. So with the importance of never putting a bending load into a spaceframe in mind, together with the knowledge that triangulation makes for a good, stiff structure, any chassis that may not fully adhere to these basic tenets may now be modified and improved with confidence. A few relatively light tubes added here and there where triangulation is lacking will more than pay you back in rigidity what they add in weight. Another way of stiffening a chassis, briefly alluded to earlier, is to panel it in. In some competition categories there are restrictions on how closely spaced attachment points may be, but assuming the rules in your chosen

category

permit

it,

a smooth, low-drag flow of air beneath the car. Rivets would normally be placed at about

2in

(SOmm)

the fitting of riveted (and _ possibly bonded) panels of, say, reasonably thin (18swe/1.2mm or 20swg/0.9mm) alu-

which

minium

forced composite panels.

sheet to the flat sides, underside,

and possibly the front upper section of a spaceframe can make a useful contribution to overall chassis rigidity, as well as acting as basic body panels and ensuring

intervals,

and

so

long as you have no thoughts of removing the panelling, additional strength and stiffness can be obtained by bonding the panels to the spaceframe with a structural epoxy adhesive suitable for use with aluminium and steel. Doing this successfully negates one of the advantages of a spaceframe — giving good access to inboard components. That may be a price you are willing to pay. Alternatively, you can win back some access by cutting and swaging holes in the panelling, which loses a bit of weight and adds some stiffness too. Aluminium may be the most common material for spaceframe panelling, but others include plywood, especially for the underside (where it makes a relatively inexpensive ‘sacrificial’ choice for an area

always takes a pounding);

sheet

steel, if low weight is not a primary consideration;

and

pre-moulded,

fibre-rein-

Sheet metal monocoques The reason that panelling a spaceframe is beneficial is that the sheets used are

COMPETITION

a

CAR PREPARATION

extremely stiff in their own planes, and once firmly attached to a chassis bay they stiffen it very effectively. So a completely panelled spaceframe constitutes a fairly rigid box structure. We know, intuitively, that a box with all its sides substantially complete is a stiff structure. Consider a rectangular plastic food container: with the lid firmly on, it is really quite stiff in torsion — that is, as you hold each end and try to twist it — even though it is made of flexible plastic; but take the lid off, and the box is much

easier to twist.

You could try cutting holes in the sides of the box to see what effect they have on the -structure’s

stiffness,

and

it becomes

clear that once the holes get large, relative to the size of the side you cut them in, the box loses rigidity again. The interesting thing about this kind of box structure is that it doesn’t rely on a frame of tubes for its rigidity. It has an inherent stiffness by virtue of its construction. A monocoque chassis is effective for the same reasons. But a competition car monocoque can't really be regarded as a single-box structure; rather it’s a set of box structures which are joined together at the main bulkheads. In the case of sheet-metal monocoques, the construction is almost always in aluminium, folded into twin-box sections running longitudinally either side of the cockpit, joined by a flat underside and a partial, flat upper side at least over the front bay, probably reinforced by triangular panels that reach to the top of the front roll hoop. Sometimes the structure stops at the main roll hoop, though some midengined cars have rearward-extending box sections that attach directly or indirectly to the engine/gearbox adapter plate or bell housing, thus providing a stiff engine bay, and a structure into which the rear suspension loads can be fed, usually via the gearbox casing. Bulkheads made as tubular sub-frames panelled in sheet aluminium, or perhaps cast in aluminium, are generally located at the front of the chassis, probably a further one just to the rear of the front one

to take the rear mounting points of the front suspension, in the front roll hoop/dashboard region, and at the main roll hoop. The sheet-metal monocoque was very common in a wide variety of competition categories (we’re ignoring the fact that production shells are actually sheet-metal monocoques, in case you’re wondering), but has tended to be supplanted by one or other of the composite materials at which we shall shortly be looking. Prior to the advent

of such

materials,

folded

aluminium chassis were used wherever possible for the very simple reason that a much stiffer structure could be made for the same weight, compared to a spaceframe, or a much lighter chassis for the same _ stiffness could be produced, if weight was critical and minimum weight was not an issue. There was also a spinoff safety benefit in the intrinsic ‘crumpleability of folded aluminium, which made it quite good at progressively absorbing the energy of an impact. But there are a number of disadvantages to a sheet-metal chassis which made it less prevalent in club competition than

in pro

competition.

Compared

to

spaceframes they are more expensive and more difficult to make, are more easily damaged, harder to repair and modify, and offer poorer access to internal components. They also present special problems when it comes to feeding loads into the chassis, at suspension and engine mounting points, for example, with attachments needing to spread loads over a wide

area

of chassis,

in line with the

planes of the chassis panels or the transverse bulkheads, and probably with sheet steel reinforcement. For these reasons sheet-metal monocoque — construction tended to be the preserve of the bigger manufacturers, though that is not to say that some specialist constructors have not been brave enough to have a go and produce some very effective chassis. There have been highly-competitive examples of sheet-metal monocoque cars in F750 racing, and in hill-climbing and sprinting.

CHASSIS STRUCTURES

This

53

1976 March Formula 1 chassis was constructed from sheet aluminium.

As with spaceframe construction, the key to a successful monocoque manufacture is the application of considerable thought at the design layout stage, probably accompanied by another balsa model for the DIY constructor, and then very careful construction and assembly. The requisite sheet bending equipment is necessary, Of course, though you may be able to get the use of somebody else’s at your friendly fabrication shop, and careful drilling and de-burring technique, together with suitable structural ‘break-

stem’ rivets, are also needed. Cheap hollow pop rivets are not intended for structural use — their hollow construction means they are weak in shear when asked to join two sheets of metal together. Stronger types include ‘closed end’ rivets, which retain the mandrel and seal the rivet body. The shear strength of a l/sin (8mm) aluminium closed end rivet with steel mandrel is approximately 40 per cent higher than the comparable hollow rivet. If an adhesive is used to supplement

The Harrison was a light, competitive aluminium monocoque single-seater.

CAR PREPARATION

COMPETITION

54

the rivets, then it and the pre-treatment of the aluminium have to be suitable for the job — an appropriate structural epoxy adhesive may be obtained from such companies

as

3M,

Ciba

Geigy,

or

Permabond (who glued Thrust SSC together), who will be pleased to advise on the right product to bond aluminium. Roll-over hoops will still be of the round, CDS tubular material specified in regulations, and careful integration of forward and/or rearward bracing can help to stiffen up the unpanelled cockpit and engine bay areas. The roll-over hoop attachments will be via sheet-steel mountings-that are riveted or bolted to strong or reinforced areas of the chassis over a substantial area. Repairing

a

bent

monocoque

is no

easy task. If damage is localised, it is possible to cut out the damaged sections, and affix a patch, cut slightly over size and joggled to enable it to be bonded and riveted flush with the original panels. Carefully done, such a repair will recover the original strength. However, more extensive damage could make repair a non-cost effective exercise, and _ total replacement may be required. A common medical side-effect that may afflict the unfortunate owner on such occasions is a severe pain in the wallet, accompanied by chronic watering of the eyes... Care and maintenance of a sheet-metal monocoque should include _ regular inspection of riveted joins. If there is any movement

in the

rivets,

it will

be

evi-

denced by dark deposits around the rivet heads or, if the chassis is painted, by paint flaking off over and adjacent to the rivet heads. It may be sufficient to drill out such loose rivets, and replace them with new

ones of the same

size, but if move-

ment has been more extensive the original hole may have fretted and increased in size, in which case holes of the next size up should be drilled and appropriatesized rivets used to make good. Aluminium resists corrosion far better than steel, by forming a practically inert film of its own oxide on its surface very

rapidly after the metal is exposed to air. Nevertheless, it will show signs of corrosion if neglected and kept in damp conditions, so tender loving care and frequent cleaning and polishing are necessary to keep this at bay. However, contact with other metals can accelerate corrosive action,

and

where,

for

example,

it is

joined to steel a coat of zinc chromate primer is recommended on the touching surfaces. Composite material monocoques Nowadays the sheet-metal monocoque has been virtually replaced by various forms of composite material chassis. There are two basic types of composite chassis construction. Either flat, pre-fabricated panels of honeycomb-cored sandwich material are cut and/or folded and joined into the required shape to form a chassis, or the sandwich materials can be formed in a mould to the exact shape required, either in one piece or in sections that are subsequently bonded together. The former production method is considerably simpler, requiring far less in the way of tooling and equipment than the latter, though moulded chassis have very definitely taken over in the upper echelons of racing the world over. But let’s look at a little bit of history to see

why composite chassis came about. In the late 1970s, ground-effect aerodynamics had made their way into Fl and cornering forces had taken a giant leap. This put much greater loads into the chassis, and all the leading teams responded by reinforcing the latter with panels of aluminium honeycomb skinned with aluminium sheet, later constructing their chassis entirely out of such material. Actually the Grand Prix chaps were

beaten to it in 1966 by the Mk IV Ford GT40, which, using an aluminium honeycomb chassis — to apparently debatable advantage in this instance — won Le Mans

in 1967. But why is aluminium honeycomb a better material than aluminium sheet? Because a material’s stiffness is related to its thickness, and honeycomb-

CHASSIS STRUCTURES

cored sandwich is much thicker than plain sheet, but barely any heavier than the two outer skins of aluminium sheet, given that the honeycomb core is extremely light. The resultant sandwich is therefore vastly more rigid than the

equivalent weight of sheet aluminium. The late-1970s Fl monocoques were designed with airflow to the underside of the sidepods as a prime consideration, that being the source of their massive downforce. So the monocoques were made considerably narrower than had been the norm previously, in order to maximise the area of sidepod that the newly-created low pressure could act upon, which in turn maximised the amount of downforce — generated. Narrowing the chassis would, ordinarily, have made them much less stiff, but with

the adoption of aluminium honeycomb panels the required stiffness — which, remember, was now much greater than before — was won back with interest. It wasn’t long afterwards that carbonThe Williams

55

fibre reinforced, epoxy replaced the aluminium the ability to mould the a female mould (or set developed. From there

resin-based skins skins, and soon whole chassis in of moulds) was improvements in

materials, in combination with other rein-

forcement fabrics like kevlar for strength and impact resistance, and tremendous progress on structural design techniques, have seen chassis go from strength to strength and stiffness to stiffness. Driver safety has also come along in great leaps in parallel with this trend, so there has been a very positive benefit from the performance spiral. So the pluses of composite chassis are unparalleled (so far) stiffness and strength for the low weight involved, and improved driver safety. In the case of flat honeycomb sandwich materials (which nowadays can be skinned with aluminium, or your choice of reinforcing fibre such as carbon or glass), making a chassis is not a great deal more difficult than making a sheet-metal monocoque,

FWO8 chassis was constructed from aluminium honeycomb.

Fhe SSS s

56

COMPETITION

CAR PREPARATION

and in some respects is probably easier, given the stability of the panels with which you work. On the down side, though, these materials are generally in the price range of costly to prohibitive for the home-constructor; they can be difficult to repair; and in the case of moulded composites, it can be difficult to know if damage has occurred — internal delamination is not that easily spotted. Moreover, moulded chassis are not easy to make. But with the Holy Grail Gow weight and high stiffness and strength) within reach, there are always those prepared to have a go, and some brave individuals and. low-volume constructors have ignored the apparent disadvantages and made their own moulded composite chassis, and in some cases sell composite chassis cars for remarkably low prices. One of the pioneer home-builders to make a composite chassis — using aluminium-skinned “honeycomb, in fact — was

hill-climber

David

Gould,

who

was

not so far behind the leading lights of F1 Pilbeam

Racing

Designs’

chassis, built in 1983.

first

honeycomb

when he brought out the Gould 84 in 1984. That the car won the British Hillclimb Championship the following year is, in part, testimony to the materials used, as well as owing a great deal to Gould’s all round engineering ingenuity and good preparation, plus top driving from the champion pilot Chris Cramer. Specialist hill-climb constructor Pilbeam Racing Designs had produced a part honeycomb chassis, the MP54, the year before that, with

a central

bonded

and

riveted

honeycomb panel tub which had sheet aluminium forming outer box sections. This car was to become one of the most competitive 2-litre class hill-climbers in the late 1980s and early 1990s, when (amongst others) I had the pleasure of benefiting from its capabilities. There have also been some very brave souls who have produced their own moulded monocoques, perhaps the most noteworthy being Ian Scott, whose F1inspired Megapins are works of art as well as fine pieces of engineering. A sort of in-between construction method has also been used to combine the handling advantages of flat honeycomb panels with fibre-reinforced skins by other ‘home-constructors’, including — Brian Walker (Brytec). He utilised glass-fibre skinned honeycomb panels, cut and bonded to form the chassis, and also clad the chassis inside and out in carbon fibre,

baking the whole monocoque in a selfconstructed oven to get full cure and full strength from the resin system employed. In terms of basic construction, composite monocoques are made using similar principles to both spaceframe and sheetmetal monocoques. In this case, though, transverse bulkheads are joined by the outer sandwich panels, be they fabricated or moulded, to form a_ single slim, fuselage-style chassis. Aluminium-skinned panels are generally cut and routed out to permit the outer skin to be folded to create a U-shaped ‘tub’, and the inner joins are then brought back up to strength using epoxy filler/adhesive, and a folded aluminium sheet strip, bonded

CHASSIS STRUCTURES

D7

and riveted to overlap the join. The top section would most likely be folded to shape,

reinforced

underneath,

and

then

bonded and riveted to the tub to create the front box sections. Roll-over structures are bolted or riveted over a large area on to strong points (corners and panel edges) of the honeycomb chassis. Suspension attachments are likewise spread over large areas, at strong points where the loads can be fed into bulkheads. In the case of moulded chassis, the process is rather lengthy, involving the creation of a master pattern, or ‘buck’, from which moulds are taken, and then the chassis mouldings are laid up in the moulds, with outer and inner skins of resin-impregnated carbon fibre, perhaps with

local

kevlar

reinforcement,

sand-

wiching aluminium honeycomb core. Finally the components are bonded together, incorporating the bulkheads, to create an immensely strong, rigid chassis. Load attachment points are at so-called ‘hard points’, metal plates or bushes bonded

into the chassis

material,

which

spread the loads into a wider area. There is a wide range of materials that can be used to make a moulded chassis, from ‘wet lay-up’ systems, where dry

reinforcing fabrics are laminated with an ambient

temperature-cure

epoxy

resin,

through to professional ‘pre-preg’ fabrics (pre-impregnated with resin), which are cured at elevated temperature, with vacuum suction and external pressure applied in an autoclave to maximise material consolidation, and hence optimise the strength and stiffness for a given weight. The results of the ‘hand-made’ system can, with care, be very good, whilst the results of the professional methods are nothing short of miraculous. The care and maintenance of composite chassis is first and foremost — as with any component — about regular inspection. If there are signs of damage or delamination,

then remedial

measures,

if

Carbon

composite

monocoque

‘Open Fortuna by Nissan’

chassis on an

racecar.

they are possible, are clearly needed. But as mentioned previously, damage may not be at all obvious. An ‘old’ method of checking composite material integrity was to gently tap the surfaces with the edge of a coin. Delaminated areas sound ‘dead’ compared to properly bonded areas. Not surprisingly, leading teams now use a more sophisticated technique (ultrasound) to perform this type of inspection, but the principle is similar. The edges of sandwich panels would usually be sealed with a lightweight filler to prevent the ingress of water, oil, dirt and so forth into the middle of the sandwich, which could compromise _ its integrity. The skins, if aluminium, can be treated in the same way as sheet aluminium, so painting with suitable primers is possible, whilst resin-based skins can usually be painted in the same way as moulded bodywork.

Chapter 6

Suspension

and steering IF THE ENGINE of a competition car is its heart, and the chassis is its skeleton, we could continue the analogy by regarding the suspension as its limbs, connecting

the skeleton to the feet (ie the wheels and tyres). But that particular angle is getting a bit tired now, so we won't. What we can say is that the job of the suspension in a competition car is to keep the tyres in optimum contact with the road under as many different sets of conditions as possible, so that acceleration, braking, and cornering can all be maximised. This ‘The job of the suspension is to keep the tyres in optimum contact with the road ...’

is somewhat different to the requirements of the suspension on a road car, which has to provide safety and a comfortable ride, outright performance being either ignored or at best compromised by the former demands. To a great extent it is the tyres that determine the ultimate performance of any competition car, but it is the suspen-

sion that facilitates the best exploitation of the tyres. There are, when you stop to think about it, just four remarkably small areas of rubber in contact with the road at any one time (the number can reduce to less than four in different situations, planned and un-planned), and these are

all that stop you from flying off into the undergrowth. So it pays to do everything you can to exploit these little rubber patches efficiently, and that’s where good suspension design comes in.

Suspension is one of a number of areas of competition car design which remains a blend of science, engineering, and art. If all the variables were fully understood,

then all cars would have the

same suspension configuration, and _ this chapter, plus a host of specialised books on the topic, would not exist. The problem is that there are so many interdependent variables involved that it just isn’t possible to nail down an ideal configuration. If the leading Fl, Champcar, and GT constructors all have different ideas on the topic, and are constantly searching for something better, then there is no single solution. You’d be forgiven for thinking

SUSPENSION AND STEERING

By)

TREN RRNA LWOORY yy

Vj %

Gy4 y Z)

%

on

Nobody said getting a good set-up would be simple.

that this makes achieving an optimum set up for the rest of us a bit of a lost cause. Well, nobody would tell you it’s easy, but equally, you are just as likely to be able to make a car handle and perform as the next competitor if you make the effort to understand what’s going on, and which factors are important. There are no hard and fast rules here, just well-worked compromises, which will be based as much on theory as on personal preferences and experience.

Design fundamentals If there is one key criterion in the function of the suspension on a competition car, it is, as was mentioned briefly above,

keeping the contact patches of rubber working as effectively as possible. By and large this means — assuming that the tyre size is correct for the vehicle (see Chapter 8) — that the contact patch area has to be kept as big as possible at all times. Whenever a car changes its dynamic state, say from running straight to braking, then to turning into a corner, there

are

changes

caused

in the attitude

of the car,

by weight transfer forwards,

then

sideways, which make the suspension move relative to the chassis. In the braking case, weight transfers forwards, making the chassis load up the front springs, which compresses them resulting in the car adopting a nose-down attitude, or positive pitch. In the cornering case, weight

transfers

sideways,

compressing

the springs on the loaded side (the outside) so that the car leans, or rolls, out-

wards. Accompanying the compression of the springs in each of these cases, the suspension links pivot about their chassis mounting points, and about their outboard mountings on the wheel uprights. These movements cause the wheels to adopt different angles to the static settings, which in turn alter the size and shape of the contact patches. The fix appears simple — design suspension links that keep the wheels at their optimum angles at all times, and that way the contact patches wouldn’t alter, and grip and

60

COMPETITION

balance would be perfect. The problem is, a design which keeps the wheels upright, or at their original angles, under the pitch caused by braking will cause large angular changes to the wheels during the roll induced by cornering, with consequent loss of contact patch area. And this is where the choices and the compromises begin. Everybody and his dog has their own thoughts from this point on; and the thing is, probably nobody is wrong. It all depends on the type of competition you are involved in, and such things as how much time you

spend in your type of events cornering as compared to braking and accelerating. Clearly, if the demands of each places different design requirements on a suspension system, then the final solution is bound to be a compromise. There

are,

it would

seem,

two

basic

ways of approaching this problem, which are all a matter of degree (no pun relating to wheel angles intended). A suspension design can either concentrate on keeping the wheels upright during changes of pitch (braking and accelerating), or it can aim to keep the wheels upright during roll (cornering). As we have seen, if it does one well, it can’t do

CAR PREPARATION

the other, so how are these circumstances

dealt with? Well, if the suspension is optimised for pitch changes, then the car needs methods of limiting roll in order to limit wheel angle changes. And if the design is optimised for roll, then the car needs methods of controlling pitch. A good compromise might well be somewhere

in the middle,

but cars that have

adopted one extreme or the other have been made competitive, proving again that there is no wrong answer. It will be evident that the magnitude of the changes of a car’s attitude, and hence the magnitude of the wheels’ angular changes, are not only related to the loads generated by acceleration, braking, and cornering, but also to the amount of suspension travel available, and on how stiff the car’s suspension is. The precise suspension geometry can also play a role in

how much movement occurs in certain situations too, by incorporating ‘anti-dive’ or ‘anti-squat’ geometry, for example, which limits pitch changes in braking and accelerating respectively. We won’t dwell too much on these aspects here, except to acknowledge their potential influence. For a really detailed discussion on suspension design, try Allan Staniforth’s

Figure 6-1 Zero camber change in ‘compression’ with parallel, equal length suspension links, compared to significant camber change in roll with this suspension geometry.

SUSPENSION AND STEERING

Competition Car Suspension (details in Appendix 4). In a large number of cases, especially if you compete in a production-based car, there will be little if anything you can do about the fundamental design of the suspension.

Indeed,

in some

categories you

are expressly forbidden from altering the original design. In other cases it may simply be impractical to make such alterations. Nevertheless, there are plenty of things that can be done in order to get the best out of whatever suspension you've got.

Optimising suspension set-up Whatever you compete in, it makes good sense to ensure that what you’ve got is working as well as its design permits. With suspension this means making sure that everything is pointing in the required directions, at the designed angles, and at the requisite distance from the ground. There are other niceties too, all of which need to be set statically, if your car per-

mits such adjustments, before it goes anywhere. If you have no numbers available for the static set-up of your car, then a

61

certain amount of intelligent guessing will be needed to arrive at some initial settings. In a lot of cases, though, you will end up making fine adjustments to the Static set-up once you have done some running. For the purposes of this section, we will assume that static set-up does not include spring stiffness, anti-roll bar stiffness, or damper settings. The chassis parameters we are interested in here are: ride height, corner weights, camber, toe-in and toe-out, and

steer. Let’s ponder some of all.

definitions first

— Ride height, as distinct from ground clearance, is the height of a particular reference point on the chassis above the Cidealised, perfectly smooth) ground. The static ride height is the basic reference setting at which all other settings are determined and set. — Corner weight is the weight supported at each tyre contact patch. Naturally, all four corner weights add up to the total weight of the car, but they are unlikely to be equal given that the front to rear weight distribution is

Figure 6—2 Ride height and camber.

x

Camber angle

caster, bump

A = ride height (to a reference point) B = ground clearance

COMPETITION

62

rarely 50:50. Furthermore, and of more interest here, there is likely to be side to side variation, even in a supposedly symmetrical single-seater racecar, which comes about because of discrepancies in measurements during

CAR PREPARATION

adjustment of this parameter, but it needs to be checked, and at least needs to be the same side to side, so you may have to visit your friendly

bodyshop again if there are discrepancies. Camber is the angle, viewed from the

building, and because it’s impossible to store all components symmetrically. The aim here will be to balance corner weights side to side. Caster (or castor) is the angle, when

front of the car, between vertical and a line passing down through the wheel, parallel to the hub face. Camber is said to be negative when the top of the

viewed from the side of the car,

wheel leans in towards the car, and

between vertical and a line drawn through the upper and lower outboard suspension pivot points (the steering axis). The upper pivot is always slightly behind the lower one, ensuring that the steering axis, when projected forwards, intersects the ground ahead of centre of the tyre contact patch. This creates a self-aligning force which helps pull the steering (front) wheels back to ‘straight ahead’ on exiting a bend, and which helps straight-line stability. Production-based cars may not have the facility for easy

positive when the top of the wheel leans out. Once again, productionbased cars may not have adjustment of

Figure 6—3 Caster.

as

Caster angle

Top suspension mount

rae

Bottom suspension mount

camber available, so correction of side to side discrepancies may require the bodyshop’s help. Toe-in is when the front of a pair of wheels (on one axle) is closer together than the rear of the wheels, when seen from above. The opposite is described as toe-out. Bump steer is a condition that occurs when wheels moving through their range of suspension travel undergo

SUSPENSION AND STEERING

changes in their steering angle without any change in the steering wheel position. But be aware that bump steer may also occur on rear wheels if the geometry permits it and it is not adjusted out (assuming it’s not supposed to be there). To measure all of the above parameters you need to put your car on a flat, smooth,

Jevel

floor.

There

are

various

ways to obtain a suitable surface. The cheapest is to use whatever floor your workshop has, and put thin metal or wood shims under each wheel contact patch until all is level and true (checked with a spirit level or similar device). You can also make a flat floor by pouring selflevelling floor cement in between wooden battens nailed to the workshop floor. When set, you end up with a smooth, flat patch. Or you can buy proprietary set-up pads, or a huge, thick metal plate (thick aluminium honeycomb, for example). You could even have a polished granite block set into the workshop floor — don’t laugh, it’s been done! The self-levelling floor cement has to be the best value; it costs relatively little, and it’s

more or less permanent. Then you need the relevant measuring equipment. Once again, if you’ve got the funds there is a range of excellent proprietary equipment out there to choose from, but with some ingenuity you can make a lot of what you need very cheaply. The end result of setting-up your car depends more on the care you take than the amount of money you spend on measurement tools. But you will still need the following:

— A lot of patience: the procedure takes —

a lot of time, but it’s worth it. A camber gauge: this can be a piece of

wood with a good, straight edge and a plumb-line, and a carefully-marked scale in 1/4 or 1/2 degree increments. — A caster gauge: this can be the same gauge as used for camber, perhaps with another scale marked in a

63

different position. — An accurate steel rule: increments of 1/32 and 1/64 of an inch (1.0mm and 0.5mm). — A good steel tape measure long enough to measure your car’s wheelbase (front axle line to rear axle line distance). — A spirit level or some other accurate gradient level measuring device. Digital devices help avoid possible reading errors such as can occur with conventional bubble gauges. — A pair of parallel bars, probably lengths of sturdy aluminium angle or Ibeams, a little bit longer than the maximum outside of wheel to outside of wheel width of your car. You need to be able to bolt or clamp these centrally to the foremost and rearmost extremities of the chassis, perpendicular to the car’s centreline, and at or near wheel centre height. — Strong, thin string: fishing line is good. The string is attached to the parallel bars and run around the car to make a ‘tracking rectangle’.

— Corner weight scales: these can be proprietary electronic scales, or domestic bathroom scales if your car is light enough. The latter go up to 330Ib (150kg) these days, so a set of four will do for a car of 1,100lb (S00kg) with no more than 60 per cent of the weight on either axle. The alternative is to use a lever-type device, which has a pressure gauge calibrated in terms of weight, and is used to lift each wheel in turn to measure the weight. The really budget-conscious can make a DIY version of this device using some stout timber, a few bits of metal, and a set of bathroom scales or

a pressure gauge to measure the weight necessary to lift each wheel. Other

useful

tools

to

have

available,

which may or may not be applicable to your

Car,

are:

— A pair of steering rack stops, equal

64

COMPETITION

CAR PREPARATION

Figure 6—4 The tracking rectangle, and toe-in.

ee a

AR - BR = right front toe-in

iii

f

ae

AL - BL= left front toe-in

Beam

CR - DR = eae rear toe-in

line ee

CL-— DL= left rear toe-in iS cam

NB: AR =AL, BR = BL, CR =CL and DR = DL

W=X=Y=Z

Only if car is absolutely symmetrical

Figure 6—5 A cheap ‘do ityourself corner weight gauge.

Apply load at same place every time Wheel rim Scales

Se

ones

a

_

ait

|

| con)

ee

mer

SS

—

SUSPENSION AND STEERING

sized pieces of half-tube cut to length so that when the steering is put in the straight-ahead position the rack stops can be inserted to lock the steering. (Note: it’s a good idea to paint these a bright, contrasting colour so that you can’t inadvertently leave them in place.) If your steering rack is fitted with rubber gaiters it will probably be impossible to lock the rack in this way. — A pair (at least) of dummy dampers: these replace the spring/damper units during parts of the set-up that require free and full travel of the suspension. They can be made from a pair of tubes, one of which fits freely inside the other, cut to length, with a rod end, or a drilled plate at each end, to

enable it to be bolted in place of the regular damper unit. Holes drilled through to allow a pin to be inserted at the suspension fully compressed, full droop, and static ride height positions are a useful refinement. — Ride height chocks, cut from timber to whatever thickness is required front and rear, to enable the car to be

placed on them so that it rests at the static ride height. — A bump steer gauge: again, this can be a proprietary item, or a home-made device which either enables you to quantify amounts of bump steer or simply allows you to tell whether there is any. You can just about make do with the tracking rectangle to qualitatively assess bump steer. Right, you now need the following set-up information: — The wheelbase dimension. — Front and rear track dimensions (centre of tyre to centre of tyre). — All suspension link and joint lengths and settings, if known. — Front and rear ride heights with driver aboard and a known fuel state (usually half load). — Front and rear cambers at static ride height.

65

— Front and rear caster at static ride

height. — Front and rear toe at static ride height. Most, if not all, of this data will be avail-

able from the manufacturer or previous owner of your car. If you built it yourself, you ought to be able to obtain all this data from your drawings. The first three measurements are the ones that your car will have been assembled to, and will get you to within striking distance of the ideal set-up. But you still need to go through everything carefully before venturing out into competition.

Furthermore,

you also need to check the set-up fairly frequently — there seem to be some categories where even experienced competitors like to think that an annual set-up is sufficient. It isn’t. Despite our fervent wishes that chassis are rigid, settings can and do alter, seemingly all on their own. Just a few more preparations and you'll be ready to start. You need to: — Clean all adjustment threads on links, joints, and spring platforms, and apply a suitable anti-seize compound to the threads. — Check that the wheels are tight, that there is minimal bearing play, and that the wheels run true and are not buckled. —

Set the tyres to hot running pressures,

make sure they are free of debris and stones, and that they are of equal circumference, side to side, within 1/4in (Smm). If tyre wear during an event is

going to be significant enough to alter ride height, use tyres for set-up that have equivalent wear to that at the end of a competition (you won't fall foul of post-event ride height checks that way). — Set the weight to include fluids at halfevent distance levels, with driver (and

co-driver) or weight to simulate these aboard. — Set the car perfectly level on its set-up pad(s). — Disconnect front and rear anti-roll bars

Gf fitted).

66

COMPETITION

CAR PREPARATION

— Back off the dampers, if they are adjustable, to full soft all round. — Check that the suspension moves freely without any tight spots or sticking. — Have your notebook or log sheets at the ready. You are now fully prepared to start taking measurements and making adjustments. Different folk will tell you different orders in which to do things, but however you tackle it the whole process is one of reiterations, or chasing your tail if you prefer, going through the process over and over — especially the first time around — until you get discrepancies down to acceptable levels. However, the start point really has to be ride height, which forms your basic datum.

Ride height This is most conveniently measured to a reference point on the chassis such as an inboard suspension mounting point, rather than to the chassis underside. The latter is usually more difficult to measure and prone to error, as the underside inevitably gets damaged in competition. If you are working on floor shims you need to establish a datum line representing the ground plane — a straight-edge placed over the top of the shims will probably suffice. Adjustment of ride height will most probably be carried out by screwing threaded spring platforms up or down, or by installing more or less spacers under coil springs. Note that raising and lowering the chassis in this way has an effect on the amount of compression and droop travel available. If your car has pull-rod or push-rod actuated — spring/damper units, bump and droop travel can be set with the spring platforms, and ride height can be adjusted by altering the lengths of the pull or push rods. If possible, seek the advice of the car’s manufacturer on this point. You will probably need to jack the car up to enable ride height adjustments to be made. When you let the car down

again, roll it to and fro a few times and bounce it up and down to settle the suspension and tyres again. Check the new measurement, and repeat until correct. Remember, changing the front may affect the rear, and vice versa.

Corner weights If you are using scales for this job, check that they all read the same by zeroing them and then standing on each in turn. If you are using a lever device you will need an assistant. The weight on each corner is measured by taking a load reading at the ‘wheel just clear of the ground’ point. This is most easily determined by your assistant using some form of tough, thin shim, like a sheet of strong paper, as a feeler gauge under the tyre. As you push down on the lever, he or she will tell you when the wheel is just raising, and you can read the load. After a few readings you will get a pretty accurate value. Repeat for all four wheels, or write down all four scales’ readings, and study the results. In most cases equal weights side to side are the target (some experienced racers deliberately use unequal corner weights to influence the handling in positive ways, but some

very negative

effects usually accompany any gains — perhaps it would be safer initially if you keep it simple). With a car with offset weight, aim to get the front corner weights equal at least; an imbalance at the rear can be regarded as the lesser of two evils. Weight always transfers diagonally, which means that if you wind up the spring platform on the left rear wheel

you put more weight on the front right. So by adjusting at one end or the other you can keep close to the desired ride height, and still balance the corner weights. As you make adjustments, take a note of the magnitude of weight change. This will help you develop a feel for how much adjustments change things, something that will undoubtedly prove useful at a later date. Once corner weights are set, it should be possible to make

SUSPENSION AND STEERING

67

Corner weight scales make light work of this part of setting-up.

changes to ride height by equally on each side without the corner weight balance.

adjusting upsetting

rocker-actuated springs, or bushed wishbones, the rocker or wishbones may be shimmed for and aft to alter caster.

Caster angle Most cars run between 2° and 6° of positive caster angle, and most racecars between about 2.5° and 4.5°, meaning the upper outboard pivot is behind the lower one. So in the absence of a figure, setting 3° to 4° will be a reasonable first guess. Caster is measured at static ride

equalise caster side to side than to achieve a specific value. Also, keep a

Remember,

height, with driver aboard, or on the ride height chocks with the dummy dampers

fitted at the appropriate setting. If your car has been designed and made by a thoughtful manufacturer, there will be a machined face or perhaps a pair of lugs on the hub carrier against which you rest your caster gauge and take your readings. If you are not this lucky, you will need to make up some means of measuring the caster angle on your particular installation.

If you have adjustable suspension, caster may be altered by changing the length of either the leading or trailing link of the upper or lower wishbones, which pushes the top of the hub carrier either forwards (less caster) or backwards (more caster),

or

does

the

converse

to

the

bottom of the hub carrier. In the case of

it

is

more

important

note as before, of the amount

to

that caster

changes as you make adjustments. Camber angle Camber is measured at static ride height by placing your gauge across the outer wheel rim from top to bottom. Make sure the rim isn’t buckled and that you avoid balance weights. If you have to place the gauge against the tyre, do so ahead of or behind the bulge at the bottom, and also avoid any raised lettering on the tyre wall. If you have no figures for required camber, start with the wheels vertical or with a small amount of negative camber, say 0.5° to 1.0°. Tyre wear and temperature profiles across the width will soon enable you to refine the settings. Various means may be available for adjusting camber, depending on what features were built into your car. You may have to alter the upper or lower outboard rod end, which may usefully be screwed into a lockable camber adjuster; or you may have to adjust both the upper or the lower inboard rod ends simultane-

68

COMPETITION

CAR PREPARATION

ously. With transverse links the length of the top links alone can be adjusted, and some

constructors

use

various

thickness

shims clamped between the wishbone ends and their attachment on the upright. To

any

avoid

measurement

lock-nuts

before

errors

re-tighten

taking

readings,

and, once more, keep a note of the magnitude of changes as you make them. The increments by which you can

Checking camber. A lockable camber adjuster.

adjust camber may be dictated by the thread size on the rod ends, and if you don’t have the camber adjusters mentioned above then the smallest incremental change you can make is a half-turn of the rod end. This is usually a pretty small change, though. With shims, the thinnest shim available dictates the smallest adjustment — again, this will be fairly small. So camber can be set pretty finely whichever method is available to you. With a production car, ‘eccentric’ strut top kits do offer some adjustment of camber and caster. Toe-in There are various methods of checking the toe, or tracking, on a car. Many car servicing operations and tyre fitting depots have extremely accurate laser alignment equipment available, and if your car is road legal you could do a lot worse than driving to one of these places to get this job done. But if the car has to stay in the workshop, then once again you've got the choice of buying proprietary tracking gear or using your ingenu-

ity and a healthy dose of care to make up some kit yourself. Assuming you are the DIY type (it’s pointless describing here how to use proprietary kit, because the instructions that come with it will do that), then you will need the aforementioned parallel bars, and your fishing line, from which you create a tracking rectangle. This is what you do. First, very carefully establish the centreline of the car at the front and rear by measuring relative to the inboard suspension pick-up points (this naturally

SUSPENSION AND STEERING

69

Measuring toe-in.

assumes the chassis is straight and true). A little improvisation will be needed if these points are recessed within the chassis. Then mark the centreline permanently on a convenient, visible place on the front and rear of the chassis. Now fix the parallel bars at wheel centre height at the front and rear of the chassis so that they are perpendicular to the centre line, and horizontal. Mark accurately on each bar a point equidistant from the centreline, a few inches out-

board of the wheel outer rim. Drill small holes through the bars at these points, then pass the string through each of these holes, pulling it tight down the sides of the car to form the tracking rectangle, which will have parallel sides equally spaced from the centre line of the car. Toe-in is now determined by measuring the distances from the front and rear of each wheel rim to the string. The differences in the values on each wheel represent the total toe-in or toe-out. But first,

centralise the steering rack, and fit the rack stops to lock the rack in position. Make sure that the track rods are equal

length, and that the wheels are tight and not damaged at the points where you are going to take measurements. Use a steel rule, or vernier calipers if you prefer, to take the measurements. Adjustment at the front is sometimes made by undoing the lock-nut on the track rod end, removing the track rod end from the steering arm, and rotating the rod ends in or out as required. On racecars, track rods will normally have left- and right-hand thread rod end bearings on each end, so it is just a matter of slackening the lock-nuts, then rotating the track rod to shorten or lengthen it as required. Production cars tend to have similar adjusters these days so that disassembly is not required, and kits are available to provide this facility if it isn’t standard on your car. Measurement is carried out in the same way at the rear, but adjustment is different. Sometimes upper and lower track control arms are part of the design, making toe adjustment relatively straightforward. If the suspension is by upper and lower wishbones, then adjustment is

COMPETITION

70

CAR PREPARATION

pretty much the same, and if radius rods are used then lengthening or shortening these will alter toe. Changing toe may

to try to minimise

well have an effect on camber and caster, so these may need re-adjusting. Once more, make a note of the effects of

quantify

changes. Generalising on a suitable amount of toe-in or toe-out is next to impossible. For example, consulting the Haynes

Manual

for my Peugeot

106 shows that

the road-going 1.0-litre and 1.1-litre cars both require 0.5mm (0.02in) toe-out at the front, whilst the 1.4-litre car requires the same amount of toe-in. All models need 0.9mm (0.035in) of toe-in at the rear. A rule of thumb for front-wheel drive cars is that static toe-out is set, because under power the wheels pull themselves straight again — or so the theory goes. This only really applies when there is plenty of compliance in the suspension, of which more in a while. Toe-in is a more stable set-up, because if there is any unsettling force, such as a bump or a gust of wind, toe-in pushes the car back on-line. Toe-out, conversely, tends to pull the car off line. Road cars run very little toe-in or toeout to avoid fuel-wasting, power-absorbing scrub from the tyres. Competition cars, however,

can utilise a bit more toe-

in to help generate heat in the tyres, which can ultimately lead to more grip. But excessive toe-in can cause instability as well as scrub, and by and large any toe-out is an inherently unstable condition. Strange, then, that some people swear by toe-out, and get away with it. As stated above, it’s next to impossible to generalise. Bump steer

To facilitate the checks for bump steer, put the car on suitable chassis stands, remove the spring/damper units, and fit the dummy dampers. This makes it a lot easier to raise and lower the suspension through its range of available travel. Next you need a method of checking or measuring bump steer. If you simply intend

or

eradicate

bump

steer (not a bad idea in most cases), there

seems

little point

in actually

it, so an expensive

trying gauge

to isn't

really necessary. But you do need to establish a datum, which can be the tracking rectangle, and a flat plate clamped to each front wheel rim. Now as the suspension is raised and lowered through its travel you will be able to easily gauge by eye if the angle between the plate and the reference rectangle changes. You can measure it if you really want to.

If there is a change in toe-in through the range of suspension travel you will almost certainly want to get rid of it. Bump steer like this comes about at the front because the track rods are moving through different arcs to those prescribed by the upper and lower links, and the hub carrier is rotated slightly as a result. Improving this situation is generally done by either raising or lowering the steering rack, or (sometimes more easily) by raising or lowering the outer track rod end on or within the steering arm. A considerate designer will have left provision for this adjustment. A modified steering arm

may prove necessary. Bump steer can also occur at the rear, though it obviously has nothing to do with track rods moving through different arcs to the rest of the suspension, unless you have four-wheel steering. In this case it comes about because the suspension links themselves create a rotation of the hub carrier during normal suspension movement. Eradicating rear bump steer requires alterations to the suspension link lengths that either tilt the hub carrier rearwards or forwards — tilting the hub carrier top rearwards will increase toe-in in bump, whilst tilting it forwards should reduce it. A situation to avoid, though, is one that creates toe-out in bump at the rear. This can create a condition known as ‘roll oversteer’ as you corner, and the suspension compresses in roll. It is an unstable condition... It will be necessary to re-check

SUSPENSION AND STEERING

HA

Shimming the outer track rod up or down can eradicate bump steer.

camber,

making

caster,

bump

and

static

toe-in

steer adjustments,

be on the safe side. As ever, make on the effects of alterations.

after

just to notes

Tidying up Once you’ve spent hours chasing yourself in ever-decreasing circles, checking and re-checking every parameter and compleuine, all” syour . notes, refit, the spring/damper units; re-attach the antiroll bars, altering link lengths to eradicate any pre-load if necessary; tighten up any lock-nuts you may have left slack; centre all the rod ends; apply locking wire where appropriate; take out the rack stops: and reset the dampers to their normal settings. It might help later on if you now make a note of all the installed link lengths and inclinations too — if you have a damaging ‘off at some point this information could speed up re-assembly. Modifying suspension In this section we will look briefly at the types of modifications that can be made

to suspension systems that don’t entail major design changes. Starting with the shopping-cum-commuter car that has been the subject of a ‘change of use’ declaration, there are plenty of relatively cheap modifications that can be made that will sharpen up the suspension, and give the driver the confidence and the car the ability to go quicker. Perhaps the simplest and cheapest of these is a decent set of replacement bushes all round, preferably of the uprated variety. Original equipment bushes get tired and lead to play in the suspension, which is not a good thing. Uprated nylon or polyurethane bushes can now be purchased, which not only claim increased stiffness over the originals, but also boast similar noise-absorbing properties — so you can still go shopping without jarring those dentures loose. Ultimately, and if permitted in your chosen category, bushed suspension may get replaced by rod end joints, which do away with compliance altogether — good for handling — not so good for the dentures.

We

COMPETITION

CAR PREPARATION

An anti-roll bar on a Mini hill-climber.

If your car has no anti-roll bars fitted, it will definitely be worth considering a front and rear anti-roll bar kit, which does what it says it does — counteracts

roll. This gives a sharper feel on a car not previously fitted with them, and will in all probability improve cornering ability. These kits don’t usually permit adjustment of the anti-roll bars, which is a pity, but they are at least tailored to fit the vehicles for which they’re available. The next modification is usually the fitment of uprated dampers and/or springs, possibly combined with lowering the car’s ride height. Of these three things, a decent set of dampers will make the biggest difference to the handling and sure-footedness of your car. Dampers don’t just deal with cornering; they look after any transient condition, be it getting on the brakes, or the throttle, or turning into and coming out of corners, so they are very important parts of the suspension. If you decide to go to stiffer springs you will probably need to uprate the dampers anyway, because the standard dampers will be matched to the standard springs. Spending a bit more cash will get

you a set of adjustable dampers, which enables you to tune the suspension to your preference, and to specific venues. It also provides another avenue of potential confusion, but don’t let that put you off, because the facility is worth it in the long run. Fitting properly shortened springs reduces the car’s ride height. The plus side of this is that it lowers the overall centre

of

gravity,

which

enables

increased levels of grip to be generated. One possible disadvantage is that the wheels will be tucked up inside the wheel arches, and there may not be enough room for them to move upwards or even to turn fully on the steering axis when you turn the wheel. Before you take the cutting torch out be certain that modifying the wheel arches to win back enough clearance is within the rules of your

competition

category.

In

some

instances shortening the springs will be the last thing you want. Stage rallying, for example, generally requires increased suspension travel compared to a road car. Some of this extra travel may be achieved by modifying the wheel

SUSPENSION AND STEERING

73

arches, but longer travel dampers, and longer springs to match, will also be required. Another potential disadvantage of lowering the car by shortening the springs is that the suspension arms will move in different arcs to their designed ones. This may make the control of the tyre contact patch worse than it was by increasing camber change during suspension movement. Some categories allow the relocation

of

suspension

mountings,

within

prescribed limits. This can be a way of getting back to original suspension movement

arcs with a lowered

car, if the sus-

pension pick-ups are lowered by an amount that compensates for the spring shortening. We'll look at tuning the suspension in the light of information gleaned during competition and testing in Chapter 15. Steering In most forms of motorsport where going quickly is one of the main aims, standard

steering can become just too slow to keep up. In this instance ‘slow’ means that the driver’s arms struggle to turn the wheel fast enough to maintain control of, dare it be said,

a wayward car, or even a

not-so-wayward one. If this is the case, then ‘faster’ steering may help. This can be achieved in one of two ways. You can substitute shorter steering arms, which move the wheels more for the same steering wheel rotation, though the steering then becomes heavier Gnore

leverage is required to move it) and more sensitive (at extremes a mistimed sneeze could put you through the hedge). This modification is fairly simple to do if the car is equipped with steering arms made from a pair of plates bolted to the hub carrier, but more difficult with production cast or forged items. Alternatively you can replace the fitted steering rack with one of a higher ratio, that is, one which moves the rack further

for a given amount of steering wheel rotation. These can be purchased new and second-hand, either tailored for your

A good set investment.

of dampers

is a_

car or perhaps requiring before installation.

worthwhile

modification

Care and maintenance The suspension and steering on a competition car need frequent and _ regular checks just as every other component does. Check-tightening bolts, lubricating threads and inspecting for damage are all routines that should be carried out at the very least between events, if not actually during them. Painting or a suitable plating process will keep corrosion at bay on

COMPETITION

74

CAR PREPARATION

A racing steering rack.

exposed _ steel components. Dampers need periodic servicing and_ rebuilds, which the supplier or manufacturer will be able to advise upon. Even springs do not

have

infinite

lives,

and

should

be

tested occasionally to see if they are of the same rate (that is, they compress the

right amount under a given load) as when they were purchased. Spring testers can be purchased to do this job. Keep gaiters in good condition on productioncar steering racks, replacing if necessary, and keep things clean and lubricated on the ‘exposed’ racks on racecars.

Gliapter 7;

Brakes IT WAS JACKIE Stewart who said that the last thing a racing driver learns to do properly is brake, and yet the ability to race, and in particular to overtake another racer, has a lot to do with being able to brake really effectively. In nonracing motorsport disciplines, where competition is against the clock, critical increments of time can be gained by having good brakes that the driver has confidence in and can trust. It is often said, because the time spent actually braking is relatively small compared to the time spent in straight-line acceleration or cornering, that braking is an area of competition car performance

and preparation that is less important than those which are concerned with acceleration or cornering. But surely that has to be an over-simplification. Consider that the corner entry phase on any given course is influenced by the _ braking phase, and the ensuing balance and poise of the

car

(and

driver!);

then

effective

braking begins to look more important. In fact, being able to brake effectively, consistently, and with confidence means that braking can be left later and corner entry speeds will quite probably be higher, which may well mean in turn that mid-corner and corner exit speeds are higher, and speed on to the following

Braking is said to be the last thing a racing driver learns to do properly. The smoke is from a locked front wheel.

a3

es ,

ae econ

76

COMPETITION

CAR PREPARATION

straight is also likely to be higher. So good brakes can help around the whole lap, even when they are not being used. Of course, this assumes

that the driver is

well practised in exploiting such effective brakes. However, after watching drivers at work, even at top international level in a variety of disciplines, it is all too apparent that Jackie correct!

Stewart’s

assertion

was

Temperature management All car brakes work by converting the kinetic (movement) energy of a car into heat by using the friction between a rotating-disc (or drum) attached to the wheel, and a pad (or shoe) clamping onto the disc (or drum). It’s worth pausing just for a while to consider how much energy is involved. The kinetic energy of a moving body can be calculated by multiplying half its mass by the square of its speed,

those who can still remember their school physics, a joule per second is the same as a watt of power. So this means that 209,710 watts of heat power are generated by this single braking application. This is enough power to light nearly 3,500 average light bulbs, if only it could be harnessed. Another way of expressing this amount of power is to calculate it as horsepower. There are 746 watts to one horsepower, so we have the equivalent of over 280hp being generated during this braking effort. No wonder effective braking is all about ‘temperature management’. But it is

not just about keeping brakes as cool as possible at all times, because the friction materials that go into pads and shoes

have various temperature ranges over which they operate most effectively, and as such the type of brake material suited to one application will not suit another. It

thus:

A Formula 1 carbon brake, with cooling duct.

K.E = 1/2 x m x Vv’, or 1/2mv? in short form.

Fe

If we put some numbers at two different speeds into this equation, say 100mph (160.8kph or 44.7 metres/second) and 40mph (64.3kph or 17.9m/s), and assume a nice round mass (weight if you prefer) of 2,200Ib

(1,000kg),

we

can

work

out

how much energy must be shed to slow from the higher to the lower speed (let’s stick with the metric units for the sake of the sums, so the energy units are joules):

K.E (100) = 0.5 x 1,000 x (44.7)? K.E (40) =

999,045 joules

0.5 x 1,000 x (17.9)?

160,205 joules

The difference between these two values — 838,840 joules — is the amount of energy that has to be dissipated as the car slows from 100 to 40mph. To put this into more meaningful terms, if the car was to take, say, four seconds to perform this feat of braking (representing a modest 0.7G), the rate of energy dissipation would be 209,710 joules/second. For

HUEELE

BRAKES

all

depends

spend

on

the

on

how

brakes,

much how

time many

you times

you use them in the course of a run/lap/stage/race, what changes of speed you encounter, what the weight of car is, and what levels of grip are available from the tyres and the aerodynamics Gf applicable). Clearly a Formula 1 car that produces large quantities of downforce, and which, as a result, can deceler-

ate at around 3G for corner after corner and lap after lap, is going to have different brake requirements from the modified grocery-getter on a hill-climb that has to endure maybe two or three applications of the brakes per 40-second run. The former case will require brakes that are happy at high temperatures, the latter brakes that work from stone cold. The observant armchair or track-side enthusiast will have seen numerous images of

Wil

brake discs on F1 cars and rally cars glowing red and even orange hot. This tells us that those brakes are extremely warm, and to glow like this means that disc surface temperatures of 800°C and above are being generated. Yet even ‘light competition’ work can create transient disc and pad temperatures in the 400 to 500°C range. Any of the major reputable brake manufacturers and suppliers will be able to give you good advice on what pad type to use for your sphere of competition. Of course, there are plenty of makes

to

choose

from,

so

ask

and

look around in the paddock to see what others are using to start with, then maybe try something different when you've got more experience. Mechanics and hydraulics Let’s take

a basic,

brief run

: around

the

principles of leverage and effort as they A four-piston caliper and grooved, drilled, and ventilated discs on a Mini hill-climber.

apply to a hypothetical and very simple braking system — it helps when trying to work out how to configure a system from scratch, or how to improve a system that hasn’t been optimised. We’ll assume discs all round for the purposes of illustration. As the brake pedal is pushed, it forces a piston down the master cylinder bores, which in turn push a column of hydraulic fluid (ike all fluids, this is incompressible) down the lines to the calipers. This then forces the caliper pistons to press on the back of the brake pads to clamp them on to the disc. The force exerted by the driver’s foot is multiplied by the leverage ratio of the pedal, generally around 3:1 to 5:1. If we assume that a force of 100lb (and this time we'll stick to imperial units here, otherwise the number of conversions will get out of hand) is exerted by our hypothetical

driver’s

boot,

this will

then

be

multiplied up by, let’s say, 5:1, becoming 500lb exerted on the pair of master cylinders. We are also going to assume that (a) the hydraulic circuits are split front to rear — unlike most production cars, which

are split diagonally for safety reasons — and (b) that the mechanical effort is

78

COMPETITION

CAR PREPARATION

divided equally between the pair of master cylinders. So this means there is a force of 250lb on each master cylinder. Let’s now say that the master cylinders both have the same bore diameter, at 0.75in. Thus, the area of each piston is K0.75.5 0:5)? xin, or 0.441sqi inieSorifca force of 250lb is exerted on a piston of area 0.441sq in, the hydraulic line pressure developed will be given by force divided by area, or 250/0.441, which in round numbers equals 567lb/sq in (or psi).

This,

then,

is

the

line

pressure

which, in our simple example, is exerted on each caliper at the front and the rear. So what is the force exerted on each disc? To work this out we need to know the total piston area within the caliper. If all four calipers are the same size, with two pistons per caliper of diameter 1.75in, then the piston area per disc is 2

x (0.5 x 1.75)* x a, which equals 4.81sq in per caliper. The force on the disc is given by pressure multiplied by area, or 567 x 4.81, which comes to 2,727lb per disc. It can be seen from this simplistic case

that if a smaller used,

then

caliper piston

less force

is exerted

area on

is the

disc’ for- thew same —line> pressure: Conversely if a bigger caliper piston area is used, then more

force will be exerted

on the disc. It is the case with most competition cars that the lion’s share of braking will be done by the front end, so one option to provide greater braking capability at the front is to use calipers with bigger pistons, or with more pistons that combine to give a bigger area. Fourpiston calipers are commonplace, but sixpiston and even 12-piston calipers have been developed for specific applications such as Super Touring Cars, which rely very heavily on the front brakes. Go back to the start of our illustration, and it can be seen that another way to change the bias of effort between the front and the rear brakes is to alter the size of the master cylinders. In this case going to a smaller-bore master cylinder leads to greater line pressure being generated for the same pedal force. So to put more effort on to the front, a smaller master cylinder is used for that hydraulic

Master cylinder sizes affect front-to-rear brake balance.

BRAKES

circuit. Conversely, to reduce rear braking a bigger-bore master cylinder can be installed in the rear hydraulic circuit. It pays not to have front and rear master cylinders that are too disparate in size, though, because the linear travel encountered by a smaller-bore master cylinder is greater than that of a bigger-bore cylinder to move the pads a given distance on to the disc. This can potentially cause the linkage connecting the two master cylinders to topple. It is better, then, at the design stage, that the first estimate of front to rear braking effort is dealt with via caliper choice. There is another mechanical leverage aspect that has not yet been considered, and that is disc diameter. The pads grip the outer portion of the discs, and so exert a leverage on the wheel which is a function of the gripping force multiplied by the distance from the average point at which the pads grip to the centre of the wheel

hub, or the effective radius of the

disc if you prefer. So a bigger disc allows greater decelerative leverage to be exerted on the wheel. Spin-off benefits

Ww

include a greater surface area for heat dissipation; more available area to utilise more pistons, which provide more stopping power; and a more even distribution of pressure over the pads, which helps with more even pad wear (significant in longer-distance competitions). It is common to see larger front than rear discs on a wide variety of competition cars, especially front-engined, front-wheel drive cars that compete on asphalt, such as Super Touring cars.

So the front to rear bias of a braking system is defined basically by the diameters of the hydraulic pistons in the master cylinders and calipers, and by the disc size. Once again, the engineers at one of the reputable brake companies will come up with a good first estimate of what’s needed for you if you provide them with all the necessary details about your car and the competitive arena you're in. Modifications, if required, can follow later, with the benefit of experience. However, there is another type of device which will enable some fine tuning to be carried out, and that is a

Super Touring Car front discs are much larger than the rears.

n'viOP.” npNLOP BARD gD ULUE & © 1g fbi pide jae

NYNLUs

80

COMPETITION

CAR PREPARATION

A driver-changeable brake bias adjuster on the brake pedal of a Jade sports racer.

brake bias adjuster. These come in two types, mechanical and __ hydraulic. Mechanical bias adjusters take the form of an adjustable pivot located between the two master cylinders, which moves a fulcrum point (a spherical bearing on a rotatable threaded rod) between them. This puts more leverage onto the master cylinder to which the pivot is nearest, and offers either a paddock adjustable facility, or, by attaching a suitable cable to the adjuster — if it is permitted within the regulations for your category -— a driver adjustable facility. Hydraulic brake bias-proportioning valves are generally connected into the hydraulic line going to the rear brakes, and basically offer the ability to tune the pressure going only to the rear. This has

Uprating those brakes By now you’ve probably planned to convert the shopping car to a dual circuit front to rear split pedal box, with bigger discs and multi-piston calipers all round, and a brake bias adjuster to boot. But before going to those lengths — and they may or may not be necessary, depending on the arena of competition into which the poor car is going to be pressed — there are some cost-effective and essential avenues to explore. Let’s start off from the premise that you are just starting to modify a road car.

a similar result to the mechanical

as they still are on the rear of a lot of road cars, they are properly adjusted, and if fitted with self-adjusters that these are operating correctly. Your Haynes Manual

device,

in that the front to rear bias can be altered either in the paddock or by the driver in action, if allowed.

There’s a list of common

sense, basic ser-

vicing checks that need doing just to make sure that the standard brakes are up to par before you do anything else. First, make

sure that if drums

are fitted,

BRAKES

will tell you all you need to know in this department. Check all lines and seals to make certain there are no hydraulic fluid leaks, and if there are any, tighten or replace connections or seals as required. Also replace the hydraulic fluid itself, and do so at frequent intervals thereafter, because it is a hygroscopic fluid — that is, it absorbs water vapour out of the atmosphere. This drastically lowers its boiling point, which in turn reduces its capacity to perform at high temperatures. In the worst case, the brake fluid boils, which can lead to vapour forming in the hydraulic lines, which causes the pedal to go soft and spongy, a disconcerting phenomenon to put it mildly. Silicone brake fluids are reportedly not prone to absorbing water in this way. Check, too, that you use brake fluid with a suitable boiling point — if high brake temperatures are liable

to be encountered,

then

standard

‘road’ fluid won’t be up to the job. The flexible pipes which carry hydraulic fluid the last few inches out to the caliper get tired and prone to ‘ballooning’ when old. Pumping up these

81

pipes instead of clamping the discs gives the pedal a spongy feel, and loses brake efficiency. Replace old flexible pipes, preferably with the aerospace type of steel braided outer, Teflon inner flexible pipe, which cures this problem, gives you

back a firm pedal with sharper feeling brakes, and looks professional. It isn’t vital to replace all the ‘solid’ lines with this type of hose, but if you don’t, do make sure the solid lines are clipped securely to the chassis at frequent intervals — preferably inside, where they can’t get damaged by flying debris. Having personally suffered the effects of a solid brake pipe that fractured through the vibration of an unsupported length, with consequent sudden loss of rear brakes, it can be said that due care is now exercised in this area! Probably the next thing to look at is the pads. What action you take here will depend on your sphere of activity, and whether or not you need to go for pads that withstand more abuse than road pads. If, for example, you are entering autotests,

USA-style

autocross,

Notice the aerospace type hydraulic lines on this Formula 2 rally VW Golf.

hill-climbs

82

COMPETITION

CAR PREPARATION

or sprints, then you need a pad type that works properly from stone cold, and which does not have to cope with a high temperature range. Road pads will probably not only cope with, but will even be best suited to these types of motorsport. However,

if you are contemplating circuit

racing or stage rallying, for example, the chances are that the brakes will be used more, and for longer periods, so a ‘harder’ pad will probably be needed if ‘fade’ is not to be experienced. This phenomenon is evidenced by a pedal that still feels firm but is coupled with brakes that do not slow the car as. well as they had done a moment ago. It is caused by the pads -getting too hot. Pads which are designed to operate at higher temperatures will generally also need to be warmed up before they reach their optimum efficiency. As stated previously, get advice from the people who know -— the pad manufacturers or suppliers — because there is a bewildering variety of materials available,

conventional

and

exotic,

with

varied properties. There is also a wide choice of replacement pads for any particular type of use. For example, in a series of tests carried -—

out by The Golf magazine, a Mk 2 VW Golf GTi was used to test ten different makes of ‘road’ pads, including VW’s original equipment. Each set was ‘bedded in’ appropriately, then 15 ‘emergency stops’ from 55mph (88kph) were performed in succession, and stopping distances measured. Interestingly, all the replacement pads did a better job than the original equipment type, stopping in an average of 9.6 per cent less distance; and, remarkably, one pad make gave a 21.8 per cent reduction in stopping distance! Other characteristics were evident too, with some pads performing excellently on the first application, whilst others didn’t reach their best until after a few applications, including the original equipment

type.

As

a generalisation,

Figure 7-1 Stopping distances with different brake pads. Mintex 1144

G-Force Sport Pagid FR4151 OMP 961K Pagid T4151 Brembo Freni Italia Formula Pads Ferodo DE2000

Standard VW

50

60

it

could be said that pads from the well known manufacturers could be relied upon to perform well, the moral being that the best equipment seems to come from the experts. Prices, however, varied quite widely... Pad ‘bedding-in’, by the way, is a process in which newly fitted pads are brought up to working temperature by a specified number of reasonably firm

70

80

90

100

Relative stopping distance

Comparison of different brake pads tested in a Mk2 VW Golf Source:

The Golf, March

1998

BRAKES

applications, and then allowed to cool off. This procedure ‘boils off the volatile compounds in the chemical binders near the surface that hold the pad material together, and prepares the pad for efficient use. Failure to do this will mean that the first time the pads are relied upon, they will not slow the car in the required manner, as the volatiles form a nice slippery layer of liquid between the pad and the disc. One or two competition brake manufacturers offer a beddingin service so that pads may be installed on the car ready to go. It’s a puzzle as to why all brake pad manufacturers do not do this as a matter of course, if only from the safety and potential litigation standpoint. If the pads you buy need beddingin, do so before you need to rely on them! Eventually, as your road car becomes less and less like a road car, brake uprating may prove necessary, especially as engine power is increased and speeds rise accordingly. Bigger discs and _possibly uprated, lighter alloy calipers will then appear on your wish-list. The lighter calipers will also reduce the unsprung weight that the suspension has to try and cope with, which will help the suspension to do its job, not to mention saving overall mass, which will help with a percentage

improvement

in

acceleration,

braking, and cornering. Alloy also conducts heat better, and so can provide a more efficient path for heat to be taken

away. If, in your chosen motorsport discipline, you find it handy to use the timehonoured ‘handbrake turn’ technique to

83

More advanced braking The upper echelons of motorsport depend heavily on extremely efficient brakes that enable a driver to exploit high levels of mechanical and aerodynamic grip, yet are capable of lasting for the length of a Grand Prix, Champcar, or Winston Cup race. The last is said to be the toughest arena for brakes, in part because the cars are very heavy and the speeds are so high, but more especially because,

at

tracks

like

Martinsville,

Virginia, the actual speed differentials around the track are very high. Here the front-running brake manufacturers go to extraordinary lengths to provide a braking system that can endure for the whole race, whilst giving the driver that allimportant confidence that his brakes will work consistently and effectively throughout. Caliper details such as cooling ports, open back design, titanium-nitrided stainless steel pistons, ceramic-coated piston inserts,

insulated

external

brake

fluid

pipes, and reflective coatings adjacent to the disc pathway to reduce heat transfer, are integral features, not to mention large pad area and volume, together with differential

piston

sizes

to

maintain

con-

trolled pressure distribution on, and hence even wear of, the pads. One brake manufacturer, as mentioned previously, produced a 12-piston, six-pad caliper design for Super Touring Car racing. The benefit of the small diameter pistons with a larger than normal length to

diameter

ratio,

it was

said,

was

to

not lock it on when you pull up on the

lessen the tendency of the piston to tip, which gave more consistent, more easily modulated braking. The pistons were of different sizes to control pressure on the pads and minimise ‘taper wear’, which results from the leading edge of a pad getting hotter than the trailing edge, and the small pad size contributed to less pad distortion, both of these factors also

lever.

improving consistency.

swing the back end of the car around a tight forest hairpin bend, or an autotest bollard, it’s a very good idea to modify the handbrake so that it has a fly-off action — that is, the ratchet button This

avoids the panies the handbrake cuted 180°

makes

life a lot easier,

does and

red face syndrome that accomlack of momentum when the stays on after a neat, well exeturn!

In Formula 1 there was a spell during which ‘exotic’ new caliper materials made their appearance. Conventional aluminium alloys, even in a well-designed caliper,

84

COMPETITION

CAR PREPARATION

were capable of distortion during very heavy braking. By switching to stiffer caliper materials, the tendency for the caliper to distort was lessened, and higher pressures, and hence higher braking forces, could be produced. The FIA has attempted to legislate against what it saw aS an unnecessary expense by imposing a maximum ‘modulus of elasticity ’ on caliper materials. Needless to say, the manufacturers saw the situation differently. On the pad front, there are some exotic additions to the ‘conventional’ materials

that, where

permitted,

have

to

be considered, if only to remain competitive against your wealthy fellow combatants. Those generically referred to as ‘carbon metallic’ pads, though costly, are capable of outperforming a conventional material in friction properties as well as temperature range, and need not be that unfriendly to the conventional iron discs that they are designed to work with. The most exotic brake material has to be carbon, but we won't go into too much detail on carbon brakes — they truly could be said to be an unnecessary expense, given that it appears that a well chosen set of conventional brakes can actually perform just as well on a F1 car. The real plus_of carbon discs is not so much their stopping power as their much lower weight compared to iron discs. So what exactly is their relevance? Would anyone apart from the manufacturers notice the difference if they were banned? Disc design is also varied to improve cooling,

though

the ventilated

disc, with

its internal cast vanes which expel hot air through the disc periphery, are fairly commonplace even on relatively basic production cars. Discs may also be seen cross-drilled or slotted. To say there is little consensus on the benefits or otherwise of cross-drilling and slotting would be overstating it slightly, but opinions do vary. However, there can be little doubt that cross-drilling saves weight. It also appears to aid cooling, and so increase the fade resistance of the disc. Slotting, or

grooving, is said to be kinder to pads, and quieter in operation, factors not necessarily at the top of your list of requirements. Others say that both slots and holes help to remove the thin ‘boundary layer’ of hot air adjacent to the disc surface,

and

so

There seems

both

help

with

cooling.

to be a degree of logic to

most of these claims, so the best advice is

probably to either go with your own gut feel, or take the advice of an expert whose views you trust. Additional cooling may be necessary if your brakes do have to put up with heavy use. The most common way to cool brakes is to supply a directed flow of air through appropriate ducting to the discs, and maybe to the calipers too. The air needs to be directed at the centre of a ventilated disc so that it finds its way into the vanes, whilst with a solid disc, you need to somehow — given the limited space available within the wheel — get cooling air to both surfaces of the disc so that you don’t end up with large temperature differences on either face. At best this is liable to mean different efficiency levels from the inner and outer pads, and at worst could lead to disc distortion. The good motorsport accessory retailers sell brake cooling duct kits for a wide range of cars, though time, ingenuity and effort can, as always, save you some money if you fabricate your own. Some

disciplines,

for example

tarmac

stage rallying, benefit from and permit liquid-cooled braking, though its use tends to be confined to the upper echelons. It may take the form of a powered, pumped system that circulates cooling water through the caliper, or it may use the action of brake application itself to pump fresh, cool hydraulic fluid to the caliper. Either system helps to prevent excessive heat soaking into the hydraulic fluid itself, but it is really only relevant in excessively demanding applications. During 1997 and 1998 it became evident that some of the top F1 teams were using a form of lateral brake bias that enabled the inside rear wheel to be selec-

BRAKES

85

tively braked by the driver. This, it was said, was used on the turn-in to tight corners, where the steering effect of braking the inside rear wheel was helpful, but probably it was more usefully applied during corner exit, when braking the inside, less heavily-loaded wheel aided traction out of the corner. These systems were, rather controversially (now there’s a surprise) declared illegal after the start of the 1998 F1 season,

sport banned

categories

have

but other motor-

not

them, and at least one

specifically hill-climb

car in the UK used a simplified lateral rear brake bias during 1998. This is one of those tweaks that, unless it is to some extent cleverly controlled for the driver, is liable, if not bound, to detract from his or her concentration on the basics of getting through a corner. Unless that driver is particularly gifted and well co-ordinated, it may just be a distracting complication.

Back to basics There are two points that are worth making here that are obvious when you think about them, but which can be and often have been overlooked. One of these I have personal and slightly embarrassing experience of, but the lesson learned was a salutary one, so I'll cast my embarrassment aside in the interests of furthering competition car development and improving preparation standards worldwide! It is based on Newton’s Third Law (To every action there is an equal and opposite reaction’), and it is this: make sure the seat is rigid enough to react against when you press the brake pedal. Obvious, isn’t it? Yet for a number of seasons spent sharing the driving of a hill-climb Pilbeam with brother Andy — and he, in particular, never being wholly satisfied with the performance of the brakes — we failed to identify the root of the problem. Then along came the highly experienced Bill Morris to co-drive the car, who realised that though the top of the seat was securely attached to the chassis, the bottom was capable of sliding fore and aft to some degree, and was

The master cylinders must be sturdily mounted.

undoubtedly doing so as the brake pedal was being pressed. A_ suitably-shaped piece of rigid foam behind the seat gave a much firmer brake pedal! The second point relates to the mechanical strength and rigidity of the brake pedal, and the mounting structure for the master cylinders. The force that can be exerted by a leg pushing on a brake pedal when the seat is rigidly located is considerable, and certainly at least as great as the driver’s weight. So just as important as having a seat that doesn’t move is having a sturdy brake pedal and structure to react against behind the pedal.

86

COMPETITION

Care and maintenance Make sure all fluid lines are well out of harm’s way, ideally inside the car or chassis to prevent damage from flying debris or during an off-course excursion. Also ensure that lines are routed so that they cannot be crushed during engine or gearbox removal and installation, or just simply while jacking-up the car. Regular inspection of lines, unions, master cylinders and calipers, once everything has been cleaned and dried, will hopefully catch any weeps or leaks that may occur in hydraulic systems. Make sure that the fluid levels in master~cylinder reservoirs are topped up to maximum at the start of an event, because any pad wear will cause a drop in the level. Don’t forget that brake fluid, except the silicone type, eats paintwork! Washers and seals will need periodic replacement. Bleeding — that is, removing air from the lines — may need to be performed occasionally, especially after a rebuild if the lines had been disconnected, Once air has been removed from the system, however, it can only get back in if there is a leak, or if the fluid reservoir level is allowed to get ridiculously low, so a_ frequently

CAR PREPARATION

recurring

spongy

pedal warrants

further

investigation.

Inspect pads (and shoes) for wear at appropriate intervals. Substituting fresh pads when a set is half worn may improve performance again, but old pads will continue to work until there is only around 1/16in (1.5 to 2mm) left. When spraying lubricant on to suspension joints, make sure none gets on the pads or discs. If it does, and hopefully you'll have noticed, clean the discs with brake cleaner, and fit new pads. The oil will

soak into the surface of the afflicted pads and render them useless. Discs (and drums) should be checked for true running periodically — you will probably know if they are not right, because there will probably be evidence of ‘pad knock off, which gives some disconcerting free play to initial pedal application, and probable vibration during braking. Discs can get damaged, can crack — especially around cross-drilled holes — and can get badly worn over time, and will need replacement in these instances. Drums need frequent cleaning out to remove debris.

Chapter 8

Wheels and tyres AS STATED EARLIER, tyres determine the ability of your competition car to stay on the straight and narrow more than any other component. The make, type, size, construction, compound, tread type, and age of tyres all affect vehicle performance, and are pretty crucial criteria in determining your competitiveness. Needless to say, however, without wheels to mount them on the tyres wouldn’t be a lot of use, so let’s kick off this chapter with a look at wheels, and some criteria for choosing them.

Wheels The first thing to be clear about is what sort of wheels are permitted in your com-

petition category. If there are restrictions on the size and type permitted, you must abide by them or else face the wrath of sctutineers,

clerks

of

the

course,

and

fellow competitors. By knowing what you can do as well as what you can’t, you will be able to make the best available choice (this applies to every aspect of preparation). For example, if the rules for your championship or event require that the wheels must be those specified for the production model you drive, then make the effort to find out what optional wheels were available for that model, and

see if there are any that you could take advantage of whilst staying within the

Tyres are perhaps the most important components on a competition car.

88

COMPETITION

rules. If there was a lightweight, wider alloy option, for example, you might benefit from using it — so long as the rules don’t specify something else. If the size of wheels is open to choice,

then you have a technical judgement to make. Don’t assume that fitting the widest and biggest-diameter wheels you can get will necessarily be the best solution. The appropriate wheel size will be defined by the optimum tyre size for your vehicle, which, as we shall see shortly, is affected by a number of parameters. But the best way to find out the optimum tyre size, and hence

wheel-size,

is to talk to

the tyre companies that supply your competition category. Whilst they may be keener to advise you to use the sizes they actually make, as opposed to what might be technically best-suited, this isn’t so bad because at least the tyres they recommend will be readily available. And once you decide what. the available tyre sizes are, you can figure out what the wheel sizes are going to be. As a very rough rule of thumb, if you are going to have to use road tyres, then the wheel width is likely to be about 0.5

CAR PREPARATION

to 1.5in (13 to 38mm) less than the nominal tyre tread width. For example, a 7in (178mm) wide wheel will cater for tyre widths from around 195 to 215mm, to use

the metric designation first as is the convention with normal road radial tyres, equating to about 7.7 to 8.5in nominal tyre tread width. With racing tyres, the rule of thumb is rather different. In this case it is usual to

add one or two inches (25 to 50mm) to the nominal tyre width to get the minimum preferred wheel width. So, for example, if your friendly tyre man suggests you use a 7.0/20.0-13 front tyre (where these figures represent inches, the nearest metric equivalent being 175/510-330), he will also suggest a wheel width of around 8 or 9in (203 to 229mm), and if he’s really clever he'll advise that you use a 13in (330mm) diameter wheel too! Amongst the other practical points to watch with wheels are, firstly, the bolt or

stud pattern and the pitch circle diameter (PCD). Your wheels will probably be held on by four or five bolts, and the diameter of the circle that passes through their

Talk to the suppliers about the optimum wheel and tyre sizes.

ZOOS

EL Cane 7 2

WHEELS AND TYRES

89

centres is the PCD dimension. Clearly any replacement wheels must conform to exactly the same pattern and PCD if you do not want to be manufacturing or buying new hubs to mount them on. If your wheels are of the centrelock type, with a single large nut holding the wheel onto the hub, then it will still be necessary to match the centre diameter to the hub flange, and also to match the PCD of the drive pegs on the hub flange. The next practicality is to ensure that there is sufficient clearance between the inside of the wheel rim and the brake calipers to allow the wheel to rotate, and that full steering lock can be wound on without

the steering arm

or any suspen-

sion links coming into contact with the wheel under any conditions of suspension compression or droop. And by the way, when you get the wheels balanced make sure that the inner balance weights are stuck on where they won't collide with the caliper, steering arm, or upright. It is also important to make sure that the wheel

offset —

that is, the distance

from the wheel hub flange (or mounting face) to the wheel centreline — is not markedly different from standard, or from the original design dimension. If you draw an imaginary line from the top suspension pivot to the bottom suspension pivot (this is still referred to as the ‘kingpin inclination’ in circles where they remember what a kingpin was), and continue it until it reaches the ground, when looked at from the front it will intersect the tyre contact patch more or less in the centre. Ideally it will intersect it in the centre, so that the steering is nice and light when lock is applied. In reality, and especially with wider rims, this state of affairs can be difficult to achieve, and the

axis will intersect the contact patch at some point inboard of the centre. The amount by which it misses the centre is also, confusingly, called offset, but if we preface it with ‘steering axis’, then steering axis offset becomes distinct from wheel offset. The greater the steering axis offset, the heavier is the steering. This

A 195/50-15 road tyre on a 7in rim.

may not be a concern to you, and indeed some drivers have a preference for heavy steering, but be aware that the effect exists. Perhaps the most obvious practicality concerning wheels is that they — and the tyres, when mounted — do not foul the chassis or bodywork during any and all When wheel diameters get really big, make sure everything clears within the arch.

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90

CAR PREPARATION

combinations of suspension and steering movement. It is surprising how this little detail can be overlooked, and yes, that is personal experience speaking again, in case you were wondering! The sickening crunch of fibre reinforced plastic complete with freshly applied paint, as full suspension compression brought tyres into abrupt and intimate contact with new sidepods, acts as a sharp reminder to check clearances under all conditions... Wheel width also has to be considered in relation to a car’s overall width, especially as there may be maximum width regulations that you need to stay within, or perhaps a rule specifying by how much the wheels may protrude beyond the standard bodywork, backed up by a maximum size for wheel arch extensions. The track dimension — that is, wheel centre-

line to wheel centreline on a given axle — may be important from the point of view of cornering; theoretically, and other things being equal, wider cars should

corner

faster

than

narrow

ones,

though the track to wheelbase ratio, weight distribution, polar moment of inertia, and basic suspension design, to name but a few influential parameters, all come to bear here too. You may also want to give consideration to your car’s frontal area for aerodynamic reasons. The aerodynamic drag caused by wheels is pretty significant on any car, though it varies, of course, according to how exposed the wheels are to the airstream. The worst case is single-seaters, where the wheels can cause something like 40 per cent of the total aerodynamic drag. So its maybe a good idea not to go too wide on wheels in situations where you have a choice. Once again, another compromise has to be struck. Some choice may be available to you in the diameter of the wheels that you can use. Once again, this is likely to be determined by the optimum tyre, but in general terms a bigger diameter tyre will have a bigger contact patch with the road surface for a given width. This may be

something you can take advantage of. The car’s gearing will be altered by a bigger rolling radius, and this will need to be taken into account when calculating optimum gearing (see Chapter 15). The suspension geometry may well need changing too, by altering the pick-up points on the chassis to maintain the desired ride height and suspension linkage angles. And perhaps usefully, you will win some more space for bigger brake

discs,

if that is needed.

In some

cases a bigger wheel is not necessarily accompanied by a bigger rolling radius, if a tyre with a smaller aspect ratio is chosen (more of this shortly), and in these situations it may be possible to enjoy the benefits of more space for bigger brake discs without the need for suspension or gearing alterations. Wheels can come in various materials, such as steel, aluminium, or magnesium,

and if you have the choice and the budget you will no doubt explore your options here. Most cheaper road wheels are steel, and so-called ‘alloy’ road wheels are aluminium alloy. Magnesium is usually only used for genuine racing wheels. Steel is the cheapest option and, though generally the heaviest, it is also tough and strong. Aluminium can save some weight; and remember, it is weight of the unsprung

variety,

so savings

are

particularly worth having. But naturally, aluminium wheels cost more than steel ones. Magnesium wheels are still more expensive as a rule, but are also the lightest. They can also corrode to dust almost before your eyes if not properly finished and looked after. You can also choose between onepiece and three-piece wheel construction. The three-piece type, with a cast centre and spun outer and inner rims, have the advantages of being more cheaply fixed by replacing only the damaged section, and of offering the choice of offset and widths by altering the inner, outer, or both rims. They are usually sealed at the bolt-together face with silicone sealant, and this can leak if not carefully applied,

WHEELS AND TYRES

YOO

91

UL, Ui

This Darvi has one-piece alloy wheels.

so frequent checks on this are a good idea. The tightness of the ring of bolts also ought to be checked regularly. Other common-sense checks on wheels of any type or material include inspecting the stud holes and surrounding material for signs of damage or cracking, making sure the valves are tight and not leaking, and making sure balance This Delta FF2000 has three-piece ‘split rims’.

weights

are

taped

wheels can sometimes

in

place.

Damaged

be repaired, but in

the case of an alloy wheel that has fractured, ask yourself if you really want to trust your life to a welded-up wheel — then buy a replacement instead.

Road tyres for competition As has already been pointed out, the four

92

COMPETITION

little rubber contact patches that exist between the tyres and the road surface are really the most important components of your competition car. The way they behave,

and

the way

they are

utilised,

can make a huge difference to the way your car behaves and performs. So obtaining the right tyres, looking after them, and replacing them at the right times, can all benefit your car’s performance. How often have you heard or read phrases like ‘we were on the wrong rubber today’, or ‘the tyres were really good in the last stint’? Tyre choice is critical. Most competitors get to choose and purchase their tyres just a few times per

season, maybe even just once per season. The top professional teams get to test huge numbers of different compound and construction tyres, and then may get through several sets at any one meeting, depending on the nature of the discipline. Stage rally crews probably have the toughest choices to make, especially where surfaces vary from asphalt to gravel. So the detailed choices can be

CAR PREPARATION

very difficult to make, and even years of experience may not be enough in changing conditions.

However,

we

can

make

some generalisations on how best to be prepared if we look at the basics. Starting as usual with categories that use road equipment, there are various disciplines of motorsport that mandate the use of road-legal tyres: for example, production

car

trials,

autotests,

certain

hill-climb and sprint championship classes, and some production car circuit racing categories. The requirements are likely to be very different between trials and any other category, but some of the

general guidelines for selection are no different. First of all, in any category, make sure you know which brands, types, and sizes of tyres are permitted. In UK motorsports you will often be referred to the lists of permitted tyres in the ‘Blue Book’, the Competitors’ Yearbook of the Motor Sports Association, where permitted brands of tyres are listed; the SCCA in the USA has its own variations on this theme. The rules for

Ifyou've come a long way it pays to keep your options on tyres flexible!

WHEELS AND TYRES

your specific category or championship may go into more detail with regard to the tyre sizes that may be used, or they may specify the wheel sizes, which achieves the same end. Having found out what is and what is not ‘legal’, then, you next have to decide which brand, model, speed rating, and size is for you, assuming that your category doesn’t specify a ‘control’ tyre — that is, one of specified brand, model, and size. This is another case of looking around the paddocks and talking to fellow or future fellow competitors. Check out which brand and model the class leaders are on, and you'll soon develop an idea of what’s best at that moment. Ask the various tyre suppliers for their advice (and prices) so you can make a balanced judgement. If there is no particular make winning regularly, then you'll just have to make your decision on the basis of whatever evidence you. do ‘have. It. seems to be the case, though, that one brand and model usually becomes favourite in any category or class where there is a free choice, and in

the high-speed disciplines there is usually a close correlation here with the softness, and hence ‘grippiness’, of the tyre’s com-

pound. This is directly related to the number of times you need to replace the tyres, which in turn is inversely proportional to the contents of your bank balance at the end of the season! Tyres can be a major part of the through-season budget, unless you compete in autotests, in which case a favourite route is to get hold of some throw-aways that still just about have the legal amount of tread remaining and use those. Autotesting is notoriously hard on the tyres (and the clutch, and the transmission and driveline...), so you really don’t want to be regularly buying new rubber for that particular discipline. A long time ago racers who had to use treaded tyres with a regulation minimum tread depth discovered that the tyres were actually quickest when they were worn down to this minimum depth. The

Ws

reasons for this are probably three-fold, and are related. Firstly, the deeper the tread, the more

it will tend to flex and

move about when under the loads generated by acceleration, braking, and cornering, which the driver feels as a disconcerting

‘squirming’

sensation.

Secondly, this tread movement will generate more heat within the tyre, quite possibly leading to overheating which in its turn causes grip to reduce. And thirdly, deeper rubber also makes it more difficult for heat to dissipate into the carcase, which exacerbates the overheating problem. Even road tyres have a preferred temperature range in which they give optimum grip, and adhesion levels still fall away when you try to operate them outside this range. So the trick with treaded tyres that you intend to run in the dry might seem to be to use worn ones. But rather than actually wearing them out, which has the disadvantage of ageing and causing degradation to the rubber and the carcase stiffness, you can pass your new, perfectly good, deeply-treaded set of tyres to an expert, who ‘buffs them down’ (or wears them out without ageing them) until they are near to the minimum permissible tread depth. It is also possible to buy high performance road tyres that are basically intended for competition use which already have a shallow tread depth of around 5 to 6mm (around 1/4in). For wet weather conditions it is as well to have another, un-buffed set of tyres available — the deep tread of these was designed with displacing water in mind, and will offer a lot more grip in these conditions than ones with only 1/sin (3mm) or so of tread, especially when there is standing water on the track. It is more than a good idea to have ‘brokenin’, or ‘scrubbed-in’ these tyres with some

steady running (without any severe acceleration, braking, or cornering) prior to using them in anger too, to wear off the fresh-from-the-mould

newness,

and

ther-

mally condition the rubber to give you consistent performance and improved life.

COMPETITION

94

The question of wheel and tyre diameter was referred to in the previous section. If the rules allow you to use non-standard diameters, this is an avenue

worth exploring for a couple of potential benefits. If you can use, for example, a 15in (381mm) diameter rim instead of a 13in (330mm) one, you may be able to maintain the same or at least similar ride height and gearing by fitting a low aspect ratio 15in tyre that has the same rolling radius as a higher aspect ratio 13in tyre. Aspect ratio? That’s the ratio of the height of the tyre wall to the tread width, usually quoted as a percentage, or simply a number which represents a percentage. Thus a 205/55-15 tyre has a nominal 205mm (8in) tread width, a sidewall 55 per cent of that in height, and fits a 15in rim. The overall diameter will be approximately 606mm (23.9in). By comparison, a 195/70-13 tyre will have an overall diameter of approximately 602mm (23.7in), not too dissimilar to the 15in tyre in this example. So ride height and overall gearing will not be too different on the 15in tyres, though there will be two inches more

diameter

available for brake

discs,

and a much shorter, stiffer tyre sidewall. Actual rolling diameters will vary on different tyres, so check with your supplier before purchasing to make sure. (Note that the convention for specifying racing tyre dimensions is different to the above, as we shall see shortly). The benefits of a shorter, stiffer sidewall will be a more positive, less ‘lurchy’ feel. The tyre will give a sharper, more responsive bite, and will maintain a more consistent footprint under heavy cornering loads. Be wary of running a ridiculously low-profile road tyre for racing, though — having once seen the tyres of a competition road saloon car (that had looked very smart in the paddock) almost rolling onto the edges of the rims at not particularly competitive cornering speeds, there is clearly a limit to be drawn here, and tyre suppliers will be pleased to advise. Tyre pressures are an extremely useful

CAR PREPARATION

tuning tool with a road tyre as well as a racing tyre. The pressures that you run your road tyres at for the high-speed asphalt disciplines will almost certainly be higher than you would use on the road. This helps stiffen up the tyre carcase, which sharpens the car’s feel and helps prevent the aforementioned rolling over of the tyre sidewall in extreme cases. It can also help reduce rolling resistance. But over inflation must also be avoided if the tyre footprint is not to start getting smaller, and the contact patch is not to be overheated. The key to finding the correct hot-running tyre pressure is to do some laps or runs at various pressures, and check the temperature profile across the tyre treads. In the lower speed, short distance disciplines such as hill-climbing, you can make a fair assessment of the evenness or otherwise of tyre temperature profiles using your hand. But if you compete in a discipline where tyre temperatures get very high, this is definitely best done with a tyre pyrometer probe — the 80° to 100°C (176° to 212°F) surface temperatures of race tyres are almost hot enough to boil water, and can make fingers and palms smart a bit! You are looking for the pressure at which the tyres have the most even distribution of temperature across the tread width. Uneven temperature profiles can tell you quite a bit about your car’s set up, as we shall see in Chapter 15, but for now, consider that a tyre with a hot centre section is running overinflated, whilst a tyre with hot edges and a cooler centre section is running underinflated. Once you establish the most

even temperatures you can achieve, note these down — and remember they should be measured condition.

hot, and

set in the same

Trials are a different case altogether, and quite often, where the rules permit it, you will run at tyre pressures significantly lower than normal road pressures in the search for traction on slippery surfaces. Again,

experimentation

and

experience

will help determine the ideal, and asking

WHEELS AND TYRES

Tyre temperature profiles can help tune a chassis. The forests of the Rally of Great Britain took their toll on this tyre.

95

96

COMPETITION

CAR PREPARATION

experts for advice usually helps — until you start to put them under pressure, that is.

Rallying is another discipline with its own special requirements for tyre compounds, constructions, and tread patterns.

For a start there are rallies that require road-legal tyres, and there are single venue stage rallies that are held on wholly private ground that may permit the use of non-road-legal tyres during competition. Then there are the various types of surface, ranging from loose, wet gravel to hard, frozen forest tracks, and anything in between, and finally asphalt, which may be wet or dry. On occasion it is necessary to use a tyre which has to try to cope with ail these conditions — an impossible task really — so competitors have to make their best guess at a suitable compromise. Tyres for gravel stages have to be immensely tough to resist punctures from sharp rocks, and, in the quest for grip on extremely slippery surfaces, tread patterns are unlike those seen in any other branch of the sport except the related discipline of rallycross.

Race tyres

If their use is relevant, and is permitted in your competition category, the chances are that it won’t be long before you feel the need to fit some genuine race tyres. If you have been running on road tyres in a category or class where race tyres are permitted, it is very likely that you have struggled to be competitive. Providing you go about getting the right race tyres, you ought to be able to improve your competitiveness. The basic guidelines for getting the right tyres are pretty much the same as those for road tyres, explained above. The best people to advise you are the tyre suppliers, and fellow competitors who already run race tyres. If nobody else runs a car of the same make, model, and specification as you, it will still pay to talk to the same people. That way you might just avoid going up expensive blind alleys. Race tyres are often (but not always) more expensive than road tyres, and are almost bound to be less durable, so your budget will come under greater strain when you make the switch to race

A slick racing tyre will offer you increased grip ifsize and type are correct.

WHEELS AND TYRES

rubber. If your budget is very tight (aren’t all budgets?), consider using second-hand tyres that the inevitable few wealthier competitors cast off after relatively little use. You might find it hard to get onto the front of the grid or the head of the class with them, but at least they might enable you to replace those ex-Flintstone specials you thought you had to use in order to get started. A wide variety of race tyre makes, types, constructions, compounds, and tread patterns is available. Without going into all of these in depth, race tyres fall into some simple, broad categories according to tread type and hardness of compound; and the tread type was, until recently anyway, related to whether the track was dry or not. In dry weather, the use

of

‘slicks’

was

universal,

until

Formula 1 decided to confuse the issue by using ‘grooved tyres’ in dry weather to limit performance. Slicks have no tread, other than litthke moulded depressions to show the depth of remaining rubber, and therefore have the biggest and most stable contact patch for a given tyre size.

On

They will certainly offer the most grip in dry weather, and even in slightly damp conditions they may still be the best bet. Then there is often a choice of what compound to use, though if your category specifies a ‘control’ tyre you won’t have this choice. But if you do, you will need to select between soft, grippy compounds that heat up quickly and don’t last very long before getting too hot, at which point they lose grip; and harder, more durable compounds that take longer to heat up to give their best grip, but which survive for longer distances. In most categories, each tyre manufacturer involved will, in all probability, be able either to advise on the compound to use, or give you a very simple choice of one

recommended compound. In simplified terms, hill-climbers, for example, use ultra-soft compound tyres that give very good grip even when cold, but which would probably overheat before the end of the first lap of a race circuit, whilst circuit racers use tyres that might take a full lap to get up to their (higher) working temperature, but which will be reason-

Grooved dry-weather tyres were supposed to slow F1 cars down in the corners.

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98

CAR PREPARATION

ably consistent throughout the duration of a race. The latter would be useless on a hill-climb, because they would never get up to their working temperature. When it is raining, and there is standing water on the track, ‘wets’ become the tyres to use. These are deeply-treaded race

tyres which

are

also, usually,

of a

softer compound rubber than slicks (except, perhaps, where the slicks in use are already ultra-soft) so that they can reach an optimum operating temperature

even when they are being water-cooled. This race team seems different types of rain.

to

be prepared for

The moulded tread patterns of wets can be extremely complicated, and are the result of some pretty clever research into how best to shift lying water from beneath the tyre as it rolls along the road. The grooves are shaped to pump water out from the tyre centre and push it out at the sides. Being of soft compound rubber, wets only like wet conditions. If the road starts to dry, or is only slightly damp, a wetweather tyre can start to overheat fairly quickly, and in drying conditions one can often see drivers on wet tyres seeking out

the wetter parts of the track to keep their tyres ‘cool’. In such conditions, a better tyre to use is an ‘intermediate’, which, as the name suggests, is a compromise between a slick and a wet in terms of

tread pattern and depth, and possibly in compound. Judging the conditions and deciding which tyres to use is often little better than a lottery, especially in changeable weather, and it is often worth taking

a risk by not necessarily following what ‘the crowd’ does; make your own best guess as to which way you think the conditions will change, and then select which tyres to use. Choosing tyre size is all about getting the tyres to their optimum working temperature so that they give you maximum

grip. Assuming for the moment have

a free choice

that you

in this matter,

when

you ask for advice a tyre supplier will want to know various things about your car, including: what types of events do you do? What type of car do you run? How powerful is it? How heavy is it? Do you carry downforce-inducing wings? What wheel/tyre diameters is the car designed to run on? And what is the weight distribution? From this basic information, the supplier will be able to judge pretty quickly what sizes and compounds he would suggest from the range he has available, and he will base his assessment on not just availability, but on the basic premise of making the tyres work effectively. And this is down to getting the desired

WHEELS AND TYRES

amount of heat into the tyre contact patches. The tyres are heated up by the loads put into them during acceleration, braking, and cornering, which are related to the dynamics of your particular car, and that all comes down to the factors mentioned above. Thus there will be little point in going to a much wider tyre than you are advised to use, because the loads will be spread out over too big a contact patch and the rubber will not reach its proper working temperature. Likewise, too narrow a tyre will possibly get too hot because the contact patch is being overworked. This is a simplistic explanation, but this is, more or less, the process by which advice will be given to you.

Looking after competition tyres It is very likely that even if your competition car is your

everyday

road

car, you

will have a dedicated set (or more) of competition tyres, either of road-tyre type or actual race tyres. If you don’t now, you soon will. These are expensive items that benefit from some tender loving care. Regular inspections, and the removal of sharp objects like stones, rivet shanks, and other inherently attractive and damaging objects is just basic common sense. So too is not transporting or storing your car on its best set of tyres, though it is a point often overlooked

even by experienced competitors. Storage of tyres with the car’s weight bearing on them is likely to lead to a dis-

99

torted tyre that will create a bad vibration the next time it is used, so put the car on stands, or tyres you don’t care about. For long term storage your tyres ought ideally to be wrapped up in dark plastic to shield them from ultraviolet light and stored somewhere cool, these precautions reducing the rate of degradation of the rubber compound. Wealthier competitors probably don’t store their tyres — they scrap them and start with fresh ones next season. This option isn’t available to all of us. Needless to say, don’t let solvents or oils get on your tyres, because they will also degrade the rubber. It is probably also best. to store tyres on wheels at around the correct inflation pressure. What do you do when you get a puncture

in

one

of

your

competition

tyres, and the tyre companies are not close by? If you have plenty of sets in the paddock with you, you don’t have a problem. But if you’re a ‘one set of slicks and one set of wets’ team, or you’re out in the middle of a forest miles from service support and you’ve already used your spare, then it pays to have at least one bottle of tyre sealant with you. This is a mousse-like compound that you squirt in through the tyre valve, and is capable of sealing even multiple small punctures. A ‘get you out of trouble in most cases’ quick-fix if ever there was one. You can buy it from the main component suppliers (see Appendix 3).

Chapter 9

Engines LET’S KICK THIS~chapter off by saying what it does not cover. It is not going to be-a detailed technical guide on how to uprate an engine — there are plenty of worthy tomes out there already which fill that particular need (see Appendix 4 for a few suggestions). What we will go over, though, are some general guiding principles, as in previous chapters. We will look at the parameters to consider when selecting an engine for competition, what type of performance you will want to achieve from it, how far you can go

before you need professional help Cwith your engine build, that is...), and how to

keep the heart of your competition car in good health. Choosing your engine The engine is such an important part of a competition car that very often it plays a leading role in deciding which make and model car to pick for a given category. There are many other influences on this decision, of course, but the engine is cru-

cial. It all depends on just what field of

Enzo Ferrari reckoned the engine to be the heart of a competition car.

ENGINES

competition

you

are

going

to enter.

In

some categories there won’t be a decision to make — the one-make series, for example; and if that’s your chosen arena, then you won't be reading this section. So we'll assume that the choice of car to use is free, and that there may also be a choice of engine to put in it. First there are the fundamental practicalities to consider, such as how well you know a particular engine, how easy it is to get spare parts for it, how costly the engine and spare parts are, and so on, which are important, especially if you do your Own engine preparation. Then there is the basic strength of the type of engine you are considering — does it have a good record for robustness and reliability? Will it withstand uprating, if your chosen category permits it, and will it need expensive alternative internal components? Are the components to uprate it readily available? This sort information can be obtained from companies who specialise in uprating and selling the parts for modifying engines, and from existing competitors.

101

You need to consider the power and torque output, as well as the potential power and torque figures, of the engines on your selection list, along with the rev band they deliver them at, and compare them with the engine weight, perhaps calculating a bhp per pound or kilowatt per kilo weight figure for the engine alone (if it’s going to be installed in a car you have already chosen) or for the whole car. This sort of exercise can create a kind of league table which might surprise you, and make you think about an engine you hadn’t previously considered. You will also want to weigh up the type

of

engine

performance

that

is

needed in your chosen category, and try to match those requirements with your choice of engine. Some categories of motorsport require lots of peak power at high revs, with tractability and a wide rev band being of low priority, whilst others require just the opposite, so that usable, flexible power in a broad rev band is foremost in the selection criteria. The requirements, in general terms at least, are not hard to determine if you study

The Vauxhall 16-valve engine is one of the most popular for uprating.

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COMPETITION

CAR PREPARATION

the tracks, listen to the revs being used by engines already competing out there, and talk with current competitors. You will be able to spot the people who haven’t thought this aspect through properly — they'll be the ones who come spluttering out of the slow corners, but go like stink on the long straights. They won't be at the head of the field. This can all be described as assessing the fitness for purpose of an engine. It’s a really important aspect, and worthy of lots of research before making a purchase. Basic care, and

optimising what you’ve got Even if you intend to run an absolutely standard road-specification engine in competition, you can be sure of one thing — the engine (ike every other component on the car) is going to be worked far harder than it ever was on the road. Whilst production engines can tolerate a certain amount of this sort of abuse, they shouldn’t be expected to put up with it constantly unless pampered a little. Very basic checks like ensuring coolants and lubricants are at the correct levels should be second nature, and carried out as fre-

quently as possible. The quality of lubricants in particular should be the best available (seek advice for your particular engine), and frequent changes of oil and filter also need to be high on the maintenance schedule. If permitted by the rules, it could be worth fitting a supplementary oil cooler if the car doesn’t already have one, and if it does, perhaps give consideration to a bigger one. The oil cooler needs to be located where it is not only fed a supply of cool air, but where the air can also get away from it as efficiently as possible. This is not always easy to achieve. Nor is it always easy to get air into and out of a water radiator efficiently either, but it is well worth the effort to try. At the very least, make sure the radiator is in good condition, and the cooling fins are not damaged and bent in a way that obviously blocks off a proportion of the air-

flow. Passenger cars are notorious for having a reasonable feed of air to their radiators, but not away

from them, rely-

ing on the air finding its own way out around the engine bay. This is aerodynamically as well as thermally inefficient. If it’s permitted and practically possible to duct air to and from the radiator, then try to do it. Whilst the benefits of preventing an engine from overheating are obvious, it is equally clear that an engine has to be at its ideal operating temperature before being put under heavy load. Not only will this ensure that excessive internal component wear is avoided, it will also mean that when you call on the engine to deliver all its power and torque it will be there, providing you have followed the proper warm-up procedure. Even the manufacturer’s manual for a road car will concur with this advice — my Peugeot owner’s handbook says ‘never race the engine when cold’, so that’s pretty clear, even though ‘racing the engine’ wasn’t referring to competing! Still on the assumption that you are competing with a standard engine at this point, it makes sense to ensure that it is giving you all the performance that it is capable of delivering. Often the best way to achieve this is to take it to a specialist with a rolling-road dynamometer and have the ignition timing and fuelling set (assuming they can be adjusted easily) to deliver maximum performance. Other relatively cheap, and reversible modifications at this point — providing they are within the rules of your category — could include fitting better quality spark plugs, an improved air filter, and maybe even a good-quality replacement exhaust system. These types of external modifications are usually quoted as contributing in the region of 5 to 10 per cent additional power. A point often missed is the benefit to engine power that a feed of cool air to the induction system can make. If the inlet to the induction system is, for example, at the rear of the engine bay on a transverse, front engine layout, then the

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103

The works VW rally engine breathes from the front, unlike the production unit.

temperature of the inlet charge could be very high. On the other hand, if permitted, air fed from a collector box of some

sort mounted at the front of the engine compartment, and _ forward facing, through appropriately sized trunking to the induction system, will be at ambient temperature, much cooler than the air deep down in the engine bay. Cool air is denser, and, providing the fuelling created by the carburettor(s) or fuel injection is tuned or automatically adjusts to suit it, more fuel/air mixture will be carried into the engine, releasing more power when it is burned.

tions, there is a seemingly infinite range of tuning options. Blueprinting is something best entrusted to a professional engine preparation expert, because it involves not only very careful selection and modification of components, but also ensuring that no component falls outside the dimensional tolerances specified by the original manufacturer and the regulatory body concerned. The real art of blueprinting, however, comes in knowing exactly what the optimum dimensions within each component’s tolerance bands actually need to be in order to achieve the best engine

Modifying your engine There are in effect two ways in which an engine can be improved for competition. Firstly, in categories which stipulate the use of standard engines, there is the process referred to as ‘blueprinting’, which isn’t strictly speaking modifying, but can and does involve lots of painstaking work. And secondly, in categories that permit limited or unlimited modifica-

performance.

This

puts

a_pre-

mium on experience, which most of us just haven’t got. In categories that allow modifications, it is much more a matter of choice whether or not you employ the services of a professional engine-builder. For the best results it is almost always better to do so, and though it might seem more expensive at first, the chances are that you will endure less expensive running

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costs. Again, this is partly due to the professional’s experience, and his already having learned which pitfalls and blind alleys to avoid. It is this expertise that you pay for ‘up front’, thereby avoiding such problems. Realistically, however, not everyone can afford to pay professional rates,

The first step to internal modifications careful strip down.

is a

Then everything should be thoroughly cleaned.

and

preparing

your

own

engine

becomes the only option (assuming that not competing is not an option). You will probably never quite match the performance of the professionally-built engine, however skilled you are, because you probably won't have the facilities, or the ability to carry out development work, or your own dynamometer on which to try out modifications. But there are plenty of competitors out there who do pretty well with self-prepared engines, so if you’re confident, have a go. The important thing is to be methodical, and make sure everything is thoroughly cleaned and kept that way. Some of the more sensible tuning firms are almost as happy to supply you with the necessary components to modify your engine as they are to build it for you — they realise that not everyone is willing or able to pay their labour charges — and also to help you get the best value for your money. To track down the most reputable firms, ask around in the paddock or just take a look at the badges on the engines and see which ones do well and crop up most frequently. Most of these tuners sell uprating kits for particular engine makes and capacities, which contain all the components you need to get your engine up to a particular specification. A few firms actually help you to plan a long-term development route, and supply you with kits that you can later upgrade without throwing away any major items that you've bought already. This is a particu-

larly valuable and cost-effective service, because it’s especially frustrating being advised

to buy, for example,

a ‘Stage

1’

cylinder head now, only to be told next winter ‘no, that head is useless with the cams you need for the next stage’. The general sequence in which you

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105

The crankshaft is being checked here to ensure the correct bearing sizes are used.

proceed to modify an engine seems to depend on the make and model of engine, who you talk to, how radically you want to modify it, and what the rules allow. If ‘mild competition use’, perhaps still

combined

with

some

road

use,

is

what you envisage, then the previouslymentioned assistance with the engine’s ‘breathing’ via an improved air filter and exhaust system should be in the first stage of development, probably together with cylinder head improvements which are also aimed at enhanced gas flow into and out of the engine. For more performance, further cylinder head modifications, including bigger valves and a raised compression ratio, together with modified camshaft(s), might accompany an uprated inlet system featuring bigger carburettors or modified fuel injection throttle bodies. Improvements to the fuelling and ignition system may also be needed, perhaps by modifying the original engine management system or by fitting an improved one. More extensive modifications would entail looking at the major reciprocating and rotating internals — that is, the pis-

tons, conrods,

and crankshaft — ensuring

everything is balanced, lightened, and uses the optimum materials. And certainly the valve gear will come under scrutiny, as will the bolts that hold the ‘bottom end’ together. The flywheel, too, will be beneficially lightened, to produce a much more responsive engine. In addition the oil system will need careful thought, not just because all the extra internal stresses within the engine get greater as more power is developed, which in turn give the oil a harder life, but also because the lateral and longitudinal forces of competition tend to throw the oil around more than the original equipment sump was probably designed for, and this is a bad thing for two reasons. Firstly, it is possible that the oil can actually surge away from the pick up that feeds the engine, momentarily starving it of lubricant, which

can wreck an engine.

And secondly, because if the oil surges up in amongst the large rotating and reciprocating masses of the crankshaft and conrods, the viscous drag can absorb precious power. Thus, either the original

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CAR PREPARATION

Top A sump baffle plate ready to be welded in place. Middle Assembly lubricant the main bearings.

being applied to

Bottom Crankshaft in place, caps being assembled.

main

bearing

sump needs ‘baffling’, not by asking it difficult questions, but by welding or bolting in sheet metal plates which help to prevent — or at least reduce — oil surge; or, if permitted, a ‘dry-sump’ oil system is needed, which has a separate oil tank in which the bulk of the oil not in circulation is stored remote from the engine. See Chapter 11 for more on this topic. One general principle not mentioned so far, but implied by the suggestion of using kits from a tuning firm, is that it is better to use components developed by a single firm or tuner, rather than use a sort of ‘pick and mix’ approach. It is probable that components that have been developed by one tuner will work better together as a matched set than, say, a cylinder head from one firm with a camshaft developed in isolation by another. This principle would be especially valid in a situation where you develop an engine in gradual stages.

Professional assistance As indicated earlier, generally the best way to get a good, competitive, and reliable engine is to use a reputable professional engine-builder. Needless to say, it is imperative that you choose an enginebuilder

who

is also

good,

competitive,

and reliable. Thankfully there are lots of good ones around, and going by personal recommendations and results on the track is as safe a selection route as any. Make sure, too, that your chosen engine-builder has a clear understanding of the require-

ments of your category of motorsport, so that he builds-in the right kind of performance. As stated earlier, a peaky engine with a narrow rev band won’t be much use in the forests or on the hills. If the costs involved in using a profes-

ENGINES

Top Torqueing bearing bolts.

up and

‘angling’ the main

Middle Assembling the pistons and conrods. Bottom

Checking the piston ring gaps.

sional look high, there are good reasons. The quality of the components he uses will, or at least should, be high. The time and care taken in the assembly of your engine in particular will be fairly considerable. A thriving engine-builder will usually have overheads that he has to pay for, which adds to the bill, and he will also have to cover his development costs. In addition he will probably insist on doing a dynamometer run and test of your engine once it is built, to run it in and enable re-torqueing of cylinder head studs and so forth, as well as simply to ensure that it is working properly when he hands it over — guarantees for motorsport use are not something that anybody hands out, but at least if you know the engine is right when

you get it, you can

feel reasonably confident. You should also get a power and torque plot from a dyno run, which can help you select gearing later on (see Chapter 15). So the pain in the wallet as you drive away with your freshly-built engine may linger for a while, but you will have an engine that can be more or less ‘plugged in’ to your competition car and used in anger straight away. It will have been run-in, properly set-up, and will be as strong as it’s going to be — hopefully. As stated above, there are no guarantees, but the risk of problems will be reduced by using a good professional engine-builder. This invariably means that there will be less problems along the way, and the ‘through life’ cost of running the engine ought to be less as a result. And there is little that’s as frustrating as an engine that either won’t run at all, or refuses to run

properly. It might seem an easy thing to say in the safe confines of a book, but hiring a professional engine-builder that you can trust is usually one of those moves that you wish you’d done sooner.

107

108

COMPETITION

CAR PREPARATION

Fitting big-end bearing shells. Piston rings compressed prior to tapping the piston into the bore.

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109

fg 5s Biles $9 2 ue ol mn The head gasket is in situ, and the cylinder head is being lowered into place.

Engine management systems When engine-builders start to tell you that in five to ten years time you won't be able to buy a carburettor, you start to think about the alternatives. True, carbs will be around for some time to come,

but eventually we will be in a carburettor-less

world,

where

all

automotive

engines are controlled by engine management systems (EMSs). Current road cars are there already because of emissions regulations, but there are still a lot of competition engines around that rely on good ol’ carbs. By the same token, some ignition systems on older engines are still controlled by contact breakers, bob weights, and springs, though this type of ignition is a lot rarer than a carburettored engine. Ignition-only EMSs, and _ particularly full fuel and ignition EMSs, are the way forward at all levels of motorsport, and even mechanical fuel injection systems will be a relic of the past soon. This may come as a worry if your engine currently relies on carbs for its

fuelling. Certainly there will be capital cost involved in changing over to a management system. But with careful selection of components an EMS can be made reasonably future-proof, and once it is fully sorted will provide you with a much more flexible, responsive, and quicker engine, even though its peak power

output may not necessarily be any greater than a well set-up carburettored engine. And it is possible to do a large amount of the

installation

work

yourself,

with

appropriate care, though you will almost certainly need at least the assistance of some time on a rolling road to fully optimise the system. Why is an EMS-controlled engine better? Because once it is optimised it provides the correct ignition timing and fuel delivery, in theory anyway, at all points in the rev range, and under all combinations of ‘load’. This latter parameter, load, is generally defined by throttle

position,

in

that

a

small

throttle

opening is defined as light load, whilst a

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COMPETITION

fully-opened throttle is defined as high load. The EMS electronically stores (in a ‘map’) the ignition and fuelling requirements at a large number of rpm versus load ‘sites’, using what is known as the ‘rpm/load_ strategy’, and when _ sensors which measure the engine rpm and the throttle angle tell the EMS’s electronic brain that certain combinations of throttle opening and rpm exist, the EMS tells the ignition system to spark with a specific amount of advance, and the fuel injectors to stay open for a certain amount of time.

This offers better ‘tuning’ of the engine under far more varied circumstances than mechanical ignition timing and carburettors can achieve, and in turn this means

that the engine behaves itself far better when conditions are changing, such as when the throttle is being opened rapidly to accelerate out of a corner. This provides better ‘pick-up’ under those particular circumstances, with no flat spots, hiccups, or sluggishness. And this is the key benefit of a managed engine — the EMS deals far better with the transient, changing conditions (and more sophisti-

CAR PREPARATION

cated EMSs can also cater for throttle opening rate). A mechanically-timed, carburettored engine might be extremely well set-up for full throttle, high rpm conditions, but it will provide a relatively poor compromise under any other combinations or under changing conditions, and may even be _ practically undriveable at low rpm if, for example, race-type camshafts are employed. For these reasons the power and _ torque curves plotted out against rpm after a dynamometer run may not look vastly different on a managed engine compared to a non-managed engine, all other things being equal, especially at the top of the power curve where your engine may be already optimised; and in reality, the benefits of an EMS cannot really be expected to show up on a conventional engine dynamometer. But they will become evident, once the ‘mapping’ is sorted, in driving the car.

An engine management system can be fitted by the knowledgeable, practical DIY

competitor.

Some

even be manufactured

components

can

by those suitably

Electronically-managed fuel injection provides a more responsive, flexible, quicker engine.

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skilled and equipped. But in general a kit of parts will be purchased which contains most, if not all, of the components you need, and either fitted in the home raceshop or by a suitably-qualified professional. One thing that any EMS supplier will tell you is that 90 per cent of reliability problems are down to the electrical installation,

and electrical con-

nections in particular. So if you are not an expert in these areas, and you want your EMS to behave from the outset, give serious consideration to getting at least this part of the installation done professionally. Some EMS suppliers have available systems that are ‘pre-mapped’ for certain engines in known states of tune. This should at least enable such an engine to be started, and quite possibly be kept running reasonably well, though even supposedly identical specification engines will need careful individual mapping if they are to perform at their best. Even rolling-road testing will probably not be enough to iron out all the little nuances in tuning your engine, and on-the-road or on-track testing is probably the only way to sort out those little flat spots and hesitations. But once sorted, the engine will feel more responsive and more flexible than ever before, and will almost certainly result in improved performance against the clock. A really useful feature of an engine management system is that, should you upgrade some other components in the engine, say the cylinder head or the camshafts, then a re-mapping exercise is quite possibly all you will need to get the engine running properly again (unless you make really radical alterations that mean you need, for example, bigger throttle bodies, or additional fuel injectors). This is in contrast to the days of carburettored engines when re-jetting or even carb replacement would be needed in similar circumstances. So the initial investment may look steep, but the benefits are there in the long run, so long as you choose your system wisely.

111

It is also possible with some EMSs to get additional features that may (or may not) help your performance on the track (assuming, once again, that they are permitted by the rules of your category). With input from wheel speed sensors, some management systems can be made to alter the ignition timing, or cut out some ‘spark events’, or briefly cut the fuel injection in order to provide ‘traction control’. Essentially such a system detects whether the driven wheels are turning faster than they should be — that is, spinning excessively — and if they are, then engine power is reduced by one or more of the methods stated above until the wheel speeds reduce to pre-determined limits. The principle behind these systems is that acceleration is at its maximum with just a limited amount of wheel slip, or wheelspin, and by limiting the amount of slip that can occur traction is theoretically optimised. The jury still seems to be out on whether this type of driver aid is actually beneficial or not — some people are adamant that they are a help, whilst others like to think that the sensitive driver can do a better job of modulating the throttle to control wheelspin. Another programmable function that some EMSs can facilitate is ‘launch control’. This enables a pre-set lower rev limit to be engaged prior to a standing start,

with

the

intention

that

consistent

getaways can be achieved. The problem with this type of system is that you have to pre-programme the launch rpm, and selecting what that is going to be is as much a matter of guesswork as it is when done ‘manually’. To get a good standing start you need to know the characteristics of your engine, and you have to be able to predict and sense the level of grip that is available. Whilst computerised control can indeed ensure consistency, one wonders whether it can match the sensitivity and processing power of a good driver’s brain. So in my humble opinion, save your cash for something you know will give you benefit.

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COMPETITION

Data logging Chapter 14 will be devoted to the topic of data acquisition, or data logging if you prefer, but it is worth mentioning here in passing the benefits of recording engine parameters with even the simplest form of data-logger, the recording tachometer. A record of the rpm history of an event can be invaluable for a whole host of reasons, but is of particular importance when evaluating the rev band that your engine is actually working in. It is sometimes a surprise to see how low the revs fall in, say, a really tight corner, and having hard evidence of this sort can be a real help to you or your engine-builder when contemplating the next phase of engine development. Similarly, a record

CAR PREPARATION

of

the

occasional

‘over-revving

event

should not be looked upon as embarrassing evidence of incompetence, even if that is what it is, but rather as an aid to deciding whether the engine might need an interim internal check-over. Used objectively such evidence can be a great help. Similarly, logging additional parameters such as coolant and_ lubricant temperatures, and lubricant and _ fuel pressures, will help determine whether the relevant systems are functioning efficiently or whether modifications could be required. So rather than fit traction control and launch control, you could consider spending the cash on a data acquisition system that can log these things for you.

Chapter 10

The transmission and driveline FOR

OUR

PURPOSES

sion and driveline

here, the transmis-

is taken to comprise

the clutch, gearbox, driveshafts and CV joints, final drive(s), and differential(s). It

may incorporate a propshaft or a chain, and may involve the driving of more than just two wheels, be they at the front or the rear of your competition car. From this list, delete as applicable (as they say). We'll work through the system more or less in the order that power and torque are transferred from the engine to the wheels, which means starting at the clutch. Modular transmission on a Stewart F1 car.

Clutches The clutch on a production car usually lasts for tens of thousands of miles of everyday road use. The worst abuse they usually have to suffer is the kind of stopstart urban driving that prevails around most towns and cities during the rushhour periods at the beginning and end of each working day. Other than the odd over-competitive standing start at traffic lights, this doesn’t provide the clutch with too much of a challenge. Certain competition situations, however, do put the clutch under more load, even if the car is

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COMPETITION

CAR PREPARATION

Twin-plate clutch on a Hart 420R engine.

otherwise autotesting

unmodified. For example, is pretty hard on it, and on

the rest of the drivetrain

come

and

your

even

if you

enter

to that,

standard

original shopping/commuter car the clutch may not be able to cope. Fortunately, competition clutches are available. As with just about every other

Component parts of a twin-plate sintered metallic racing clutch.

THE TRANSMISSION AND DRIVELINE

aI)

component we've discussed up to now, though, make sure you know the rules

sintered (ceramic

pertaining

category

and carbon-carbon clutches. It’s a case of

or class before making any changes to the standard set-up. The chances are that

horses for courses. The ultimate, lowweight, small diameter carbon clutch may well allow the most positive gear disengagement and the fastest gear shift possible, but its four-figure price tag may not be appropriate to your budget, or your car — unless you’re lucky enough to own

in most

to your

competition

competition

categories

you

will

be able to replace the standard clutch driven plate with a competition one, which has a tougher, more durable friction material better able to withstand heavy-duty use. The upgrade is analogous to uprating brake disc pads or shoes, really, and is also about wear rate and heat tolerance. Increasing the power and torque of your engine will require that you give the clutch some thought too. The driven plate may need uprating, but so may the cover plate, and if you are getting really radical in the engine output department a double or multi-plate clutch may be required. This is not something you want to guess at, and the clutch suppliers will be pleased to advise if you tell them about your car and the type of competitions in which you drive. Various types of competition clutch are obtainable, from heavy-duty ones that utilise conventional road car-type friction material, through

metallic clutches, ‘cerametallic’ and metallic friction material),

a Formula

1 car,

that is. On

the other

hand, there’s no point leaving the original equipment clutch in a_ well-developed modified production car if the engine output and the discipline you compete in mean you wreck the thing in no time. The actuation of the clutch is also deserving of some thought. I have been fortunate enough to have driven a variety of other peoples’ well-developed competition cars with clutches that require an absolute minimum of pedal effort to disengage — indeed, little more effort than a road car clutch — and, conversely, one or two that moved the back of the seat more than the pedal with the strongest push my admittedly spindly left limb could manage! It doesn’t have to be like this. Even a multi-plate carbon clutch capable

Measure and note the driven plates at intervals to gauge wear.

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116

CAR PREPARATION

of dealing with Formula 1 power can be relatively light in action (1 can’t speak of the current hand-operated clutches of Grand Prix cars, but the fact that they are hand-operated proves the point in principle). As with the brakes, it’s all down to the pedal lever ratio, the hydraulic ratio between the master and slave cylinder, and the leverage of the clutch release mechanism. If, as you come to the startline, you find yourself more concerned with preventing the car from stalling than with the start itself because the clutch is extremely heavy, you won’t be concentrating on the things that really matter at that tense moment. To avoid potential problems with a worn-out clutch, it pays to measure the thickness of the driven plates when they are

first

installed,

and

to

monitor

the

thickness after an appropriate number of events (two or three races, or maybe half a season’s hill-climbs, perhaps). Your supplier will advise on tolerances, and pretty soon you will establish the frequency at which the plates need replacement. The cover or pressure plate also needs inspection to spot any signs of stress,

such

as

distortion

and

cracking,

before these can cause problems. The gearbox The same comments regarding the durability of the clutch also apply to the gearbox, which is to say that production gearboxes were not designed to take the extra stress of competition,

and, as such,

some forethought and care needs to be exercised from the outset. Needless to say, the old chestnut about knowing the rules applies here too, as to what you can and cannot do with the gearbox if you are to stay within the bounds of motorsport law. The first thing you can beneficially do in any category is change to a top-quality, recognised brand competition gear oil, which will coat and protect the gears better, and help reduce frictional losses to release a bit more horsepower for acceleration, and cope with the more extreme

temperature ranges encountered in a competition environment. The oil should be in the SAE 75 to 90 viscosity range. Go to a synthetic oil if you wish — it may be even better than current mineral-based oils, even with their own synthetic additives. They are more expensive than conventional everyday lubricants, but cheaper than replacement gears or gearboxes. If you remain with a simple mineral-based oil, it will do no harm to use a proprietary gearbox oil additive. As with your engine, it’s important to

try to get your gearbox lubricant up to a temperature at which it functions properly, and to get the oil physically circulating around the gearbox, before putting heavy loads through it. This is reputed to be less vital with today’s synthetic and semi-synthetic oils, the manufacturers of which claim that they leave a coating on the surfaces they lubricated the last time the vehicle sense to

was run, but it still makes give everything, gearbox

included, the best chance possible by treating it kindly during a warm-up period or ‘green flag lap’ prior to a start. In events like hill-climbs, sprints, and drag races, this may not be very easy to achieve, though running the engine in the paddock prior to your runs will at

leastesplash some oil around inside the ‘box, which will also benefit from some heat soak from the engine. A few years ago there was a fad in some motorsporting circles for putting engine oil into gearboxes, backed up by a logic that said that the oil was thinner and less viscous, which helped it get around the ’box better, and also reduced

frictional power losses. In some _ categories the exponents of this risky art even got away with it, but, as one gearbox specialist put it: ‘Engine oils are for engines, gearbox oils are for gearboxes. The oil companies are not stupid, and they know a lot more about oils than we do, so why not trust them, and use their

products as indicated.’ This sounds like good common sense. Speaking of frictional losses, though,

THE TRANSMISSION AND DRIVELINE

there is a fair amount of heat generated by the meshing of teeth and whirling of shafts and bearings in a competition gearbox, and in some of the more highpowered disciplines heat rejection by conduction and radiation from the gearbox case alone is not sufficient. A pumped lubrication system with an external gearbox oil cooler is often used in these cases. But whatever discipline you compete in, heat build-up has to be allowed

for and,

as

we

while, can affect the way ‘box are assembled. If your

competition

shall

see

in a

parts of the

category

requires

that you retain the standard gearbox and standard internals, then that’s what you’re going to be stuck with, so if you want to be fully competitive make sure you know whether the gear ratios are even vaguely suitable for the use you intend to put them to before you commit to a particular make of car. This is one of those choice factors, rather like the engine, that may well determine what car you buy for competition in the first place. Some categories allow the fitment of an alternative gearbox from another variant of the same model, or maybe even another model from the same manufacturer, and it pays to do your research into gear ratios (and final drive ratios) to enable you to get the most suitable option. If your car is fitted with a gearbox which allows gear ratios to be changed easily, then the choice of *box comes down to other factors, such as physical compatibility with your engine, bellhousing/adapter plate and chassis, internal and external strength, and weight. The type of trans-axle gearbox used, for example, in many different types of midengined, single-seater racing cars actually comes in various makes, models, and sizes, and the right one for your car Gf the choice is a free one) will be down to these factors. The gearbox manufacturers and suppliers are best placed to advise on the correct selection. But another factor you need to weigh up for yourself is how important reliabil-

This type of trans-axle changed easily.

allows

ratios

to be

ity is to you. It may be more sensible to choose a stronger, and therefore probably heavier, gearbox than the idealist within you would like. A lighter model may seem like a good idea, benefiting your power to weight ratio and possibly your bank balance initially, but in motorsporting arenas such as hill-climbing and sprinting where, for example, there are frequent standing starts, it may not be so durable, and the wallet may be made to suffer in the long run. Some of those who have gone the lightweight route have had to spend more of their hard-earned cash on buying and _ installing strengthened internals, whilst others have eventually switched to the next biggest ’box in the range in the quest for reliability. Yet others seem to get away with running the lighter transmissions, but they may be compromising their driving in order to be gentle on the ’box, which in turn could

COMPETITION

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CAR PREPARATION

The racing gearbox— less intimidating to strip than an engine.

be adversely affecting their competitiveness. In the same way that, up to a point, engines can be prepared by the wellequipped, knowledgeable, and confident DIY

racer/constructor,

so

too

can

gear-

boxes. In fact it is said that general maintenance and basic refurbishment of a racing gearbox is probably easier than working on an engine. But, again as with engines, the best results will almost always be had with the benefit of professional assistance. This inevitably costs more money than doing it yourself, but a properly set-up gearbox is one that lasts longer, shifts faster and more smoothly, and enables you to go quicker. The benefits are considerable, so its worth making sure that the budget allows for such work, if you can manage it. But amateur or professional, assuming the first general maxim ‘if it ain’t broke, don’t fix it’ has been applied, and the decision to refurbish has been taken on precautionary grounds, or on the more scientific basis of the box having run somany miles or hours, the first step in the refurbishment process is to remove the gearbox,

drain

it of oil, and

thoroughly

clean everything. This probably entails a

degrease followed by a warm detergent wash of all the internals, because until

everything is clean it is impossible to do a proper inspection.

Once the case and all the internals are thoroughly clean, it is much easier to spot problems. The things you'll be on the look out for include damage or cracks in the casings, which may be repairable by a specialist if not too severe. Internally, you'll be inspecting such things as the dog-teeth on the pinion gears (these thoughts obviously don’t apply to a synchromesh

gearbox), which should not be

chipped Qvhich may suggest incorrect heat treatment during manufacture) or too rounded. Similarly, the clutch rings need checking — the dog-teeth on these get a beating too. The selector forks need checking by measuring the width of the clutch ring groove adjacent to the mounting boss and comparing it with the manufacturer’s specified value. Naturally, the gears themselves come in for a close look, though they are less likely to show signs of distress than are the other features mentioned so far, and gear-tooth design in racing transmissions has now evolved to the extent where there is more than just one tooth in

THE TRANSMISSION AND DRIVELINE

119

Checking for wear on a selector fork.

engagement at any one time, which tends to spread the workload more efficiently. If the ’box is the trans-axle type, with integral differential and final drive, then the pinion especially, and also the workings of the differential, need careful checking. In fact it is suggested that a mid-season pinion inspection is no bad thing, dependent on the number of events you do, obviously, together with a check on the clutch thrust bearing and bobbin bush. When _ re-assembling, ensure all the gearbox internals are smeared with a thin coating of the same oil that you use in your gearbox. The process of blueprinting discussed in the previous chapter can also be applied to gearboxes. A gearbox specialist can spend time ensuring that all components within the ’box are installed to the ideal dimensions, within manufacturers’ specified tolerances of course, and ensure that internal friction is minimised so as to increase brake horsepower at the wheels, and maximise durability. The setup of the ‘traditional’ racing trans-axle, for example, includes the primary criterion of establishing the ‘depth setting’ of the pinion shaft, which is pre-determined by the manufacturer but which has to be

accurately set at assembly. In essence, this process locates the pinion in exactly the right place in the casing. This not only enhances pinion longevity, but also dictates how all the other internals are set. From there, the ‘pre-load’ and ‘backRegular pinion inspection is important.

7"

COMPETITION

120

lash’ of the crown wheel and_ pinion (CW&P) may be set. The pre-load is set by shimming the bearings in the sideplates to support the crown wheel with just the desired amount of what one might call ‘give’. If the CW&P is held too tightly, too much friction will be generated, power will be lost, and wear will be

accelerated. If there is too little pre-load, the CW&P

will rattle around,

detriment of performance

also to the

and longevity.

This is not an easy parameter to set, being

not

only

requiring

labour several

intensive attempts

—

possibly

at setting-up

with the aid of dummy bearings — but is also one that benefits from feel and experience. For example, an experienced specialist will set a different level of pre-load on the CW&P of an endurance sports racing car with all-enveloping bodywork than on one in a hill-climb single-seater. Why? Because of heat generation and rejection — the. former will create much higher gearbox temperatures than the latter, and given that clearances alter as gearbox casings and internals expand, a degree of experience is invaluable in

CAR PREPARATION

making judgements

here. So as you can

see, this reference to using professionals is not just an attempt to generate work for such craftsmen. It’s about giving yourself the best chance at getting things right. Extremely useful time will also be spent by a specialist ensuring that the selector mechanism within the "box is set up correctly, something which prolongs the life of gear ratios and other internals and also helps to prevent those timewasting, place-losing missed gear-shifts. This is done with a selector fork-setting jig, and requires knowledge and feel for how the selector rods should be set and finished as well as how to set components to specified dimensions. These are tasks which cannot easily be carried out by the inexperienced DIY competitor-

cum-preparer. Other internal treatments such as shotpeening the gears and final drive components may also be beneficially carried out. However, though this process does stress-relieve the components, as well as assisting lubrication by enhancing the oil retention capability of items treated thus,

Proper selector function ensures a smooth, positive gear change.

THE TRANSMISSION AND DRIVELINE

124

Assembling the gear cluster on a fork setting jig.

it is not considered

a necessity in lower

stress applications. Another vital aspect of an efficient transmission system, the actual gear-shift mechanism, will be discussed in Chapter 11.

Power transfer Whatever type of gearbox your car runs, it will be necessary to transfer the power from the gearbox output to the wheels. This may involve a pair of driveshafts emerging straight from the gearbox if it has an integral final drive unit, as with conventional front-wheel drive configurations or rear trans-axle set-ups, or by means of a propshaft taking the power back to a final drive unit in the case of a front-engined, rear-wheel drive configuration. Four-wheel drive systems inevitably combine something of each of the twowheel drive layouts, in principle at least. There aren’t too many front-engined, rear-wheel drive production cars currently manufactured which end up being used in motorsport, though BMW is perhaps a notable exception. But given the numbers of cars like Mk 1 and Mk 2 Ford Escorts that were, and still are, used in

competitions ranging from stage and road rallies to hill-climbs and = sprints, the humble propshaft deserves at least a passing mention. Naturally we are not forgetting the front-engined, rear-wheel drive sports racing car either. The propshaft is a heavy thing, and if it isn’t sensible to lighten it, it's a kindness to get it dynamically balanced so that your dentures remain in place whilst at speed. Having travelled (briefly) in a _ frontengined, rear-wheel drive modified production car with a diabolically out of balance propshaft, the din and the vibration were enough to spoil your concentration, ‘not to mention putting unnecessary loadings on connected components. Leading edge four-wheel drive World Rally Championship cars use titanium propshafts to transfer power to their rear wheels, which could assist your credit card bill to eclipse the national debt. If serious

engine

power

increases

are

contemplated, a strengthened propshaft may need to be sought, and if the engine and gearbox are to be moved back in the car a shortened propshaft may be

22

Front-engine, rear axle.

COMPETITION

CAR PREPARATION

rear-wheel drive still has a place in motorsport — this is a Formula

needed, in which case a search through the advertisements in the weekly motorsport ‘comics’ will probably set you on

750 with live

the right trail. If the engine and ’box are lowered, check the angularity of the propshaft, because the universal joints on

Power transfer on the Formula Ford Mygale is via long driveshafts.

THE TRANSMISSION

either end may object to being stressed at an angle and let you know about it by failing. With that in mind, it might be a good idea to run metal retaining ‘straps’ around the propshaft at each end, so that in the event of failure the thing doesn’t drop down under the car, or flail around doing untold amounts of damage to nearby components (which in the case of a clubman’s-style car could include you). Power still has to be transmitted out to the wheels, and this is done by a pair of driveshafts after the final drive. The majority of applications these days, though, are going to involve a pair of driveshafts transmitting the power direct from the gearbox-mounted final drive to the wheels, whether front-engined, frontwheel drive, or ‘mid-engined’, rear-wheel

drive. Stock driveshafts on production cars seem able to cope with moderate increases in power for competition use — which is just as well in those categories which require you to retain the standard parts — but if significantly increased power is available the driveshafts may become a weak link. There’s always a weak

link somewhere,

but the idea is to

AND DRIVELINE

123

make it strong enough to get from one rebuild to the next without interim breakages, with whatever rebuild interval is found to be appropriate. If the rules allow, it may be worth your while exploring a source of uprated driveshafts, for example via a transmission specialist. Certainly on more powerful cars equipped with grippy racing tyres it will be essential to make sure the driveshafts are up to the job — there’s little more deflating than breaking any part of the transmission on the startline. Your specialist will advise on what’s best, and tell you all about the desired special steel alloy and proper heat treatment. I know

from experience that improper heat treatment gives driveshafts the torsional capabilities of a fresh carrot, whereas correctly treated and specified they may look identical, but they can go on for several seasons without any problems whatsoever — depending, of course, on your application. Constant velocity, or CV, joints are the

most common drive coupling joints these days, and are used on most production

and competition cars that utilise indepen-

Constant velocity joints are the usual drive couplings nowadays.

124

COMPETITION

CAR PREPARATION

dent suspension at the driven wheels. These joints have the capability to take up a fair degree of transient angulation as well as providing the requisite low friction plunge characteristic that enables changes in the length of the driveshaft as the suspension moves through its arc of travel. Some care with the installation of CV joints is required (if your car is markedly different from a _ production original) to ensure that the joints do not run out of available plunge during suspension movement, or that they don’t run statically with significant angulation in any plane. Other than that, maintenance involves packing the joint as directed with the specified type of high-pressure capable grease, and keeping an eye on the condition of the rubber boot that retains the grease. A specialist will polish the grooves and tracks in your CVs for you to ensure they slide to and fro with the minimum. of friction. It is often said that if one driveshaft, or

one of its joints, breaks, then you must replace the others. The chances are that if

the loadings were sufficient to break one shaft or joint, then they may well have been pretty high on the other side too. Furthermore,

the

instantaneous

shock

load that passes across the driveline as a shaft breaks is likely to be enough to overload the side that hasn’t (yet) broken. So it makes good sense to start with new, unstressed joints and shafts. Unfortunately there’s sometimes only sufficient time to change the broken side prior to running again, in which case your fingers

had better stay crossed until you can change the other side. The increasing number of motorcycleengined racing and sports racing cars that have appeared during the 1990s has seen the re-emergence of chain-drive as a means of transferring power from the gearbox output to the final drive unit. The additional grip offered by a pair of wide, flat racing tyres as distinct from a narrow motorcycle tyre, even of the racing variety, should be borne in mind when selecting a suitable quality chain. Fortunately the manufacturers of the

A Jedi hill-climber with motorcycle engine and transmission, plus chain-drive to a rear sprocket.

THE TRANSMISSION AND DRIVELINE

bike-engined cars are able to supply suitable sturdy parts. Chains naturally need correct tensioning and lubrication, and the engine/gearbox and final drive units need to be mounted so as to prevent chain twist, which at the very least will absorb power.

Differentials A differential exists in its simplest form to allow the driven wheels to turn at different speeds, so that when a car goes around a corner, and its outer wheel fol-

lows a greater radius than its inner wheel, they are free to turn at the slightly different speeds that this requires. Clever stuff, but unfortunately an adverse side-effect is to allow applied power to be diverted to the more lightly-loaded of the driven wheels in a competition cornering situation that significantly un-weights the inside wheels. This causes the inside driven wheel to spin uselessly, wasting power that we would prefer to use to accelerate the vehicle. There are many A torque-biasing sprocket.

IS

competition categories where this situation just has to be tolerated, and alternative

ways

to try to

prevent

the

inside

wheel off-loading too much have to be sought. Actually some competition cars that are required to run so-called ‘free differentials’ seem not to be delayed unduly — witness the front-engined, rear-drive Supersports or clubman’s cars, for example, which even in the twisty confines of the world of hill-climbs don’t exactly hang about. But the limited slip differential (LSD) is almost always worth having if you are allowed to run one in your category. By various different methods, LSDs try to limit the amount that the unloaded wheel spins by feeding the power to the loaded wheel, with the result that the car makes better forward progress. Even cars that don’t

appear

to

waste

energy

spinning

their inside driven tyres when driving out of a corner will usually go quicker with an LSD fitted than without; and standing starts will also be improved,

limited slip differential is contained

whether

or

within the housing bolted to the rear

COMPETITION

126

not you think you were leaving two equal black marks on the road surface. Notice the reference to ‘driving out of a corner’. In an ideal world, a limited-slip differential would only come into play during the phase where power is reapplied in a corner, but would allow a free action on corner entry, where generally the driver is either off the throttle or just on a trailing throttle. That there are quite a number of different types of LSD available — some

of which,

at top level,

have clever electronic controls — is evidence that this is far from an easy ideal to achieve, and some of the early types of LSD are downright crude in the way they operate. Nevertheless, they are of benefit to performance. There may be various types of LSD available, including the ‘cam and pawl’ and the ‘Salisbury clutch pack’, to name but two

of the more

common

ones,

but

unless your budget is pretty healthy the chances are you’ll end up buying what is most commonly supplied for your car. This isn’t such a bad thing, because there will also be. plenty of advice on how to install it Gf you don’t get it done by a specialist) and how to learn to drive with

CAR PREPARATION

it, given that a car’s handling characteristics are normally altered with the fitting of an LSD. Once you’ve gained experience with a particular type of LSD, and come to appreciate its pluses and minuses, then would perhaps be a good time to search out a more sophisticated type. But such a move would have to be looked at on the scale of diminishing returns. The cost of fitting one in the first place is not inconsiderable, but then the benefits are commensurate. You have to then try to quantify for yourself whether the certainly greater expense of a new ‘trick diff would bring cost-effective benefit, or whether you’d be better off laying out cash on some other part of the car. Another point to keep in mind with LSDs is that they wear, and therefore need maintenance, so you have to add a chunk to your transmission overhaul budget. Four-wheel drive The suitability of four-wheel

drive com-

petition cars in any particular motorsport

category is a case of horses for courses; and the level of competitiveness of fourwheel drive versus two-wheel drive

Four-wheel drive is just as much the thing to have in rallying now, where it is permitted, as when this Metro OR4 was first built.

THE TRANSMISSION AND DRIVELINE

127

march) Sdvertising

e ‘}

The last time

4WD was tried in top-level hill-climbing it was soon abandoned. Could it return?

depends in part on the how the regulations in any given

category

regard such

vehicles. Take the British Touring Car Championship of just a few years ago, when Audi swept the board with its A4 Quattro. Regulatory changes involving additional weight for four-wheel drive vehicles then made these cars uncompetitive. In a totally different arena, the sport of hill-climbing has seen many successful four-wheel drive vehicles down the years, including some ingenious single-seaters, but the current state of play is that 4WD systems are too heavy, absorb too much power, and are difficult to package in a single-seater. However, looking at the World Rally Championship in its late1990s guise, it is pretty clear that under most conditions — especially on gravel stages — the 4WD is quickest, all other things being equal (which they obviously aren’t on the rally scene, or else the 4WD

teams time a tarmac The not to

wouldn’t be complaining every 2WD car gets close to them on rallies). additional weight and complexity, mention expense, of 4WD all miti-

gate against its use. But its evident superi-

ority in slippery conditions make it the requisite technical choice if those conditions are likely to prevail in your chosen category and class of motorsport. The ability of a World Rally Championship car to put its power down on slippery surfaces has to be seen to be fully appreciated, and they take ‘traction’ on to a different plane. Clearly, then, in some arenas you just have to have 4WD. If there’s a choice, though, the answers may

not be so easy to arrive at, and one highly-experienced former champion hillclimber has said to me that a well-packaged 4WD single-seater could again be competitive in the national championship.

Clagyejteie It

systems IN OUR

ANATOMICAL

analogy, the sys-

tems of a competition car are its arteries, veins, and nerves. The oil, cooling, fuel,

hydraulic, electrical, and other miscellaneous systems connect the major components — including the driver — together, to enable them to function as one, and the thorough preparation of them is ignored at your peril. Hopefully the general suggestions in this chapter will be beneficial and provoke some constructive thinking. Oil systems The engine of a competition car, as we have said, works considerably harder than its road-going counterpart, which in turn makes the job of the oil system even more

crucial.

Furthermore,

tioned in Chapter

9 when

as was

we

men-

discussed

engines, a competition car generates con-

siderably greater cornering, braking and, usually, acceleration forces than a roadgoing car is normally able to generate in everyday use on busy highways, where fast driving is not only increasingly unsafe but downright anti-social. This means the oil system had better come in for some serious study, to make sure that the engine always gets the oil circulation it needs, in order to remain lubricated at

all times and to help keep the engine at its optimum running temperature.

If it’s not too insulting to start off with some

real fundamentals,

the most

basic

things you can do to make sure your oil system works as efficiently as possible include changing to a good quality

branded oil, and keeping regular changes, replacing each time you do change making sure the oil level is start of every event,

it fresh with the oil filter the oil, and correct at the

session, or run. Prior

to starting a competition engine for the first time at an event, and especially after a rebuild, it’s a good idea to spin it over on the starter, with spark plugs removed if necessary and the ignition turned off or disconnected,

in order to circulate

some

oil and build up oil pressure. It’s a well known fact that a large proportion of engine wear normally occurs as soon as the thing is started and before the oil gets to all the critical moving parts. Even with current engineered oils with so called ‘magnetic molecules’ that are said to leave a lubricating film on moving parts, actually circulating some oil around the engine before it turns under its own power must be beneficial. The rigours of competition tend to create higher oil temperatures than road use, and two courses of action may be required to counter this. Firstly, an oil cooler may be needed if not already fitted; and secondly, it may be necessary to run somewhat higher oil pressure than normal to counter the pressure reduction caused by the higher temperature. This latter point is definitely a topic where specialist advice is recommended, and it would be as well to consult the same expert about oil coolers too, especially with respect to the requisite pipe and fittings sizes — you do not want to create a

SYSTEMS

restriction

to

oil flow.

Also,

remember

what was said in Chapter 9 about the location of and the air feed to and from an oil cooler. The aforementioned g-forces that do their best to remove the oil from where it is most needed — at the pick-up pipe in the sump — have to be lived with, and, as discussed in Chapter 9, sump baffling is

often the only way to overcome this, particularly where the rules prohibit ‘dry sump’ systems or in instances where you

do not want to go to the trouble and expense of a dry sump system. By carefully installing horizontal plates that partially mask the upper portion of the sump, the volume of oil that can surge sideways or fore and aft is reduced, and hopefully the oil pick-up pipe remains always immersed. At some point during the development of your competition car, however, you will almost certainly want to go to a dry sump system. This involves storing the majority of the oil in a remote oil tank, which ide-

ally is tall, slim, and internally baffled to

129

prevent surge occurring, and is located where the mass of tank plus oil can do least harm to the car’s handling, which is central if possible — keeping in mind that the regulations won’t permit the oil tank to be in the same compartment as you. The sump pan can now be made shallower, since it doesn’t have to store the oil and exists simply to catch oil draining down from the engine so that it can be picked up by the scavenge pump and sent back to the tank, usually via a cooler. The oil is then pumped by the pressure pump back into the engine’s main oil gallery, via a filter. Dry sump oil pumps will normally be mounted externally, and the scavenge and pressure stages are usually driven on a common shaft. As well as being the best way of preventing oil surge, a dry sump system will also provide better oil cooling and more power too, partly because the engine’s bottom end will not be suffering the viscous drag encountered by _ thrashing around in a deep oil bath. The shallower sump also gives you the opportunity to

This circuit-racing Westfield uses a dry-sump oil system. Notice the tank at bottom right, with two breathers into the top, and the return on the upper side.

130

COMPETITION

CAR PREPARATION

Figure 11-1 Schematic dry-sump oil system. Breather pipe

Breather

Main oil gallery Oil tank

eee

Pressure side

Scavenge side Oil pump Catch tank

In-line filter gauze

think about lowering the engine in the car, thereby reducing the centre of gravity to the benefit of chassis performance. The limitations on this are likely to be the flywheel and clutch diameter, and driveshaft height on front-wheel drive or rear trans-axle set-ups.

It is crucial that the capacity and pressure provided by the oil pump, and the capacity (diameter) of the pipes carrying the oil, are

correct,

and

as such

this is

another area where the knowledge and experience of a good engine specialist are invaluable. You do not want too

Externally driven oil pump on a Hart 420R engine. Notice the shallow sump pan, and double scavenge pipes on the underside of the pump.

4

SYSTEMS

much or too little oil pressure — both can be damaging, and the former can lose you power, whilst the latter can lose you an engine. Use the best fittings and pipes you can afford — the aerospace stainless steel braided type doesn’t just look good, it is good, but the less glamorous type is fine just as long as it is designed for use in oil systems and will not burst under pressure, collapse under suction, or come off its end fittings. The correct quality pipes and fittings can be obtained from a reputable motorsports accessory vendor. Be careful with pipe runs, keeping them away from any rotating components. Clip them firmly to bulkheads where you can. Make sure that the holes in bulkheads or chassis panels through which pipes pass have their edges protected with rubber grommets so as not to abrade or cut the pipes as a result of vibration and general chafing. Most people will almost always have an oil pressure read-out of some description in the dash ahead of them, and quite probably an oil pressure warning light too, to make it clear if oil pressure has been lost. A neat addition to this is an ignition cut-off device activated by an oil

131

pressure the

switch, with a relay that holds

ignition

power

on

just as

long

pressure

switch.

Some

years

ago,

in a

genuine case of shutting the stable door after the horse had bolted, my brother designed and built such a fail-safe device, using off-the-shelf automotive electrical parts, after yours truly wrecked a crankshaft when failing to notice an absence of oil

pressure

during

pre-season

testing.

No, we didn’t have a low oil pressure warning light at the time either. A hard and expensive lesson, but I pass on the experience so you can (a) have another laugh at my expense, and (b) hopefully avoid doing anything equally stupid! Cooling systems A lot of the comments made about oil systems can be applied in general terms to the requirements of cooling systems. Certainly it is fair to say that a competi-

Figure 11—2 Oil pressure protection circuit (shown

‘engine running’).

35 psi oil pressure switch +12 volts

Fuel pump(s)

¢ off

on Ignition switch

A

Relay

A

as

there is a pre-determined minimum oil pressure, dictated by the pressure switch, available. If the oil pressure falls too low, the ignition is switched off. A manual override switch on the dash enables ignition power to be maintained at start-up until the oil pressure has overcome the

2 Warning light

B

=

Ignition system

off

on Spring loaded ‘start’ switch Notes: 1 Relay, when energised, sits across AA 2 When engine stopped, or oil pressure below 35 psi, relay moves to BB; bulb lights 3 To start; ignition switch on, bulb lights, press and hold spring switch, release when oil pressure over 35 psi 4 Relay is ‘change over’ type, eg. for 2-speed motors, electrical aerials

52

COMPETITION

tion engine will give its water-cooling system more work to do. This will also be true even if the engine has not been uprated, because it will, one hopes, be driven harder in competition than in normal road use. There is a limit to how hot any engine should become, which is why cooling systems exist in the first place, but increasing the amount of heat that needs to be rejected may require that you have a re-think about the whole cooling system. The waste heat generated during the relatively inefficient internal combustion process is transferred to the atmosphere via the hot exhaust

gases, by direct con-

duction and convection from the engine’s outer surfaces, and via one or more water/ air heat exchangers, which we generally, if erroneously, refer to as ‘radiators’. The only parts of the heat rejection system we can easily do anything about are the water/air heat exchanger bit — which is to say the water-filled cooling system, its plumbing, and the radiator(s) — the feed of cool air to it, and the engine itself.

CAR PREPARATION

The cooling system’s job is not an easy one, having to cope with a wide range of ambient temperatures, depending on where in the world you live and the seasons in which you compete. Clearly the system’s job is harder on a hot day than it is on a cold one, and although your engine-builder will have recommended maintaining

a

specific

and

consistent

water (and oil) temperature, actually achieving that all of the time is not so simple. This much is apparent when you see radiator ducts partially or even wholly covered with race tape during the cool early and late racing season events, an inefficient paddock tweak that aims to get water temperatures high enough for healthy engine operation. It must make the aerodynamicists, who probably spent scores of hours carefully sculpting the inlet and outlet ducts to the radiator matrices, weep in their wind tunnels to see such crude modifications to their handiwork,

but this does

illustrate

how

hard it is to design a cooling system for all seasons.

The beautifully-shaped radiator ducting on this Dallara F3 car was somewhat marred by the tape just visible over the inlet.

SYSTEMS

In Chapter 9 we discussed, briefly, the topic of airflow to and from your radiator(s), and said that it is just as important to get air to the radiator as it is to get it away from it again. This is common

sense

really, so why the majority of production cars apparently ignore the second part of the equation is a bit of a mystery — presumably it simply isn’t cost-effective for a big manufacturer to spend time and money on the last few percentage point gains in aerodynamic and thermal efficiency. But by the time the work-load of the cooling system has been increased by competition

driving and engine uprating,

this aspect ought to be investigated. The first and most obvious thing to check is the condition of the existing radiator

core

matrix,

and

to make

sure

that the cooling fins are not flattened over, blocking the airflow. Then look at the radiator location. Production cars don’t give a lot of scope for relocating the radiator, unless you can find space for smaller ones low down in the engine bay, where you can feed air in from the front and vent it out to the sides ahead of the front wheels. You'll see such a layout on Super Touring Cars, and it is a much more efficient configuration than the orig-

133

inal central, high location of the radiator, which exhausted heated air straight into the engine bay. If this route isn’t viable there may be no alternative but to fit a larger area or a deeper (thicker) radiator matrix to achieve increased cooling. Your engine-builder will give you a very good best first estimate of what will be needed. In the interests of keeping weight down, try to stay with the plastic/alloy radiator type, and don’t necessarily confine yourself to the original manufacturer’s product — a roam around the car breakers or radiator manufacturer/refurbishers can yield different size and shape alternatives. Sports racing and single-seater racing cars normally have their radiators located in more efficient sites, aerodynamically and thermally, and racecar designers generally go to some lengths to create the least aerodynamic drag possible whilst getting the desired amount of air to and through the radiator. On a well-designed car this will mean that the inlet area is fairly small, but internal ducting expands the airflow to the radiator, which slows it

down and makes heat transfer more efficient, then the ducting converges to accelerate the heated air up again before it is exhausted into the airstream outside

This Audi Super Touring Car has low air inlet and outlets for its cooling system.

COMPETITION

134

CAR PREPARATION

The Tatuus Formula Renault Sport shows how low and sleek radiator ducts can be.

the car. More often than not a large area radiator matrix will be used, but inclined

at an angle so as to create the smallest possible frontal area, again in the interests of keeping aero drag down. Current Formula 3 or Formula Renault Sport single-seater racecars show off this aspect of the art very well, with low sidepods containing the radiator(s). The quality of the pipes carrying coolant should be as good as you can afford, and whether you use ordinary automotive hoses or genuine racing silicone tubing, make sure the hoses are in good condition and keep them that way. As with oil pipes, ensure that coolant hoses cannot be damaged by proximity to anything that rotates or reciprocates when the car is running, and prevent damage resulting from abrasion or cutting by retaining hoses to panels or bulkheads with rubber lined ‘P-clips’. Racing hose and P-clips can be purchased from good motorsports

accessory

suppliers.

Keep

hose-fastening clamps in good condition and replace them when they get damaged. For long straight runs of coolant pipe, thin-wall aluminium tubing can be used — it is lightweight, and can be

bought in a useful range of diameters. For best results, once you have cut the tubing to length get the ends flared so that when a rubber hose is pushed on to it the hose clamp can be _ tightened against the rounded shoulder of the flare. Fuel systems There are safety issues involved with both the oil and the water systems, not just because both fluids get hot enough to cause injury, but also because oil is a flammable liquid. But fuel is in a different league again when it comes to flammability, because it is so much more volatile. This is, of course, a generalisation and is specific really to petrol, or gasoline if you prefer. But whatever fuel your car runs on, be it petrol, methanol, diesel, or liquefied petroleum gas, there are specific issues to be addressed that not only relate to the transport of the fluids around the vehicle but also to its in-car storage, because of all the fluids carried in a competition car, fuel is often the most voluminous, especially at the start of a competition. Motorsport’s governing bodies the world over obviously pay close attention to fuel systems in their regulations, and

SYSTEMS

you, just as obviously, need to study these carefully, and at least do the minimum necessary to comply. Remember, if you are unlucky enough to have a fire, it probably won’t be you who has to put it out, and though it’s up to you if you really want to singe yourself there’s no excuse for putting others at risk unnecessarily. The rules for different categories of motorsport, certainly in the UK, differ quite widely, and, for example, there isn’t a lot you need to do with a road car if you enter it in, say, autotests.

But once you start to look at what one might call the more technically demanding disciplines, there are more requirements,

and

also more

recommendations

with respect to fuel systems.

For exam-

ple, if you want to go circuit racing, then

the fuel system must incorporate a means of stopping the fuel supply which the driver can operate from the normal seating position. In its simplest form, this can be the key-operated ‘ignition switch’, which also isolates the power to the fuel pump(s) when in the off position; but it may also be a separate dash-mounted switch dedicated to the fuel pump(s). It is sensible to label any switch clearly so that others who may need to turn things off for your benefit can tell without undue delay which switch fulfils what function. The label should not only say what job the switch does, but also which way is off/ Also in circuit racing, it is mandatory to have a clearly-labelled external circuitbreaker switch located in a specific position, and ordinarily the power supply for the fuel pump(s) would be isolated by this switch too. Though not a requirement in some other categories, this external safety device is a darned good idea — it’s an obvious target for a marshal who has your best interests at heart, and if you, for whatever

reason,

haven't turned

off the power when you’ve had an ‘off’, it’s easy for him, her, or them

to find. I

make no apologies for mentioning this again when we get to electrical systems. Then there are safety recommenda-

135

tions with respect to isolating the fuel tank and fuel pipes from the cockpit. The rules say that you should ‘make every effort’ to achieve this, through the use of a proper safety ‘bag tank’ or by coating a metal tank with glass fibre reinforced plastic, and in some categories foam-filled bag tanks to the appropriate FIA specification are specifically recommended, if not

compulsory.

In

some

situations

a

metal fuel tank can be located behind a sealed metal bulkhead. The particular rules for special-stage rallying state that any area of the fuel tank exposed to ‘running damage’ should be protected with substantial underbody panelling. That being the case, it might be easier and lighter to put a suitable tank inside the car, in the spare wheel well for example, and confine it within the requisite alloy panelling or box. An external circuit breaker switch. This one is electronic; others need to be manually rotated.

COMPETITION

136

CAR PREPARATION

An alloy fuel tank in the boot ofa modified production Mini.

The location of the fuel tank needs some thought, and again the recommendation is to put the tank where the vehicle’s own structure provides it with protection. Having once witnessed what can happen in the space of very few seconds when a modified production saloon sustained a heavy rear impact from a fellow competitor, and the fuel tank ruptured and burst into flames, I can only A Formula 1 ‘bag tank’. (Aero Tec Laboratories)

big. Toy.

Figs "Miys

iy fe RAL

say that if you can afford a proper bag tank, and you can locate it well within the confines of the vehicle, you will feel that much safer. Keep in mind too the general need to keep any necessary weighty objects, like a full fuel tank, as low as possible in order to keep the centre of gravity low. And also give some thought to the front-to-rear and _ side-toside weight distribution, and the change that takes place during an event as the weight of fuel is used up. The rules also spell out recommendations on ensuring that vents cannot leak in the event of the vehicle turning turtle, and on the design and location of filler caps and pipes. Also mentioned are the fuel lines, and the only requirements here are that any lines passing through the cockpit are protected, and if they are non-metallic, that they should be of reinforced (internally or externally) metal braided hydraulic pressure hose, joined solely by screwed sealing joints. This requirement could usefully be extended to all fuel lines, and anything less should be thought of as a false economy. It just doesn’t make sense to try to save a few pennies — OK, a few pounds — in this area of preparation.

SYSTEMS

On a the fuel so that safely —

more mundane, practical level, system must also be put together it functions correctly as well as that’s what it’s there for, after all.

The bag tank, as was

mentioned

earlier,

has the advantage of being filled with a foam which acts as the world’s best baffle material and, allied to an_intelligentlylocated fuel pick-up pipe, helps the fuel pump(s) suck up the last drop of fuel from the tank. It is also possible in some instances to specify internal collector and surge tanks to go inside your bag tank, which also have the aim of ensuring reliable, efficient fuel pick-up. Conversely, if

you use your car’s standard fuel tank there may be situations when, as fuel gets low, the fuel system sucks up air and the engine is temporarily starved of fuel, which does nothing positive for straightline performance. Often the only prevention is to run more fuel than you will need, which instantly means you are carrying an extra weight penalty. So proprietary racing fuel tanks have their advantages, even if they do seem expensive at first glance. Fuel pumps need to be located low down for a couple of good reasons. The first is the centre of gravity issue again — any components, no matter how relatively light in their own right, should be positioned low down in the car if at all possible. The second is that when mounted right down at the bottom of the chassis, there will always be a head of fuel above the pump(s), which helps make the system self-priming. Siting the fuel pump(s) well away from sources of high temperature is also a good idea. If the fuel pump is subjected to very high temperatures, arising from a high ambient temperature or poor fuel pump location, or both, fuel vaporisation can occur, which effectively cuts off the supply of liquid fuel. In some single-seater applications the fuel tank is often located behind the driver’s seat, in a panelled compartment. If there is room, it’s a good idea to put the fuel pump(s) down on the floor next to the tank. Though there is some

137

heat soak through from the engine compartment, this section certainly gets nothing like as hot as the engine bay itself. When

not

in

active

use,

aircraft

are

normally stored with full fuel tanks. This at first seems odd — you would think initially that it was safer to keep tanks empty. But the opposite is the case, and when you stop to think about it, it does make sense. The phase of a fuel which is prone to ignition is the vapour, rather than the liquid; and a tank empty of liquid fuel — unless it has been totally purged and ‘dried’ of all residual fuel — will be full of fuel vapour, and as such represents

a

much

greater

ignition

hazard. Even though it wouldn't actually burn of itself for very long, it would constitute a pretty good fire-starter. But there’s also another very good reason for keeping a fuel tank full of fuel, which also relates to vapour, though not fuel vapour this time. The atmosphere around us always contains water vapour to a greater or lesser extent. In hot, humid climes it contains far more water vapour than in cold, dry climes, but even in the driest desert region there is humidity in the air. This would be fine if it stayed there, but what actually happens is that when temperatures drop (towards nightfall,

for

example),

the

moisture

vapour starts to condense out of the air, especially on surfaces that cool rapidly, like the inside of (especially metal) fuel tanks that are empty of liquid fuel and hence contain air mixed with fuel vapour. Small droplets of condensation can then trickle down

into the bottom of the tank,

and accumulate without your even knowing it — until the engine starts to try to run on it... So keep that tank topped up with fuel or, if it bas to come out, say during the close season, purge it totally of fuel vapour using dry compressed air, then seal it up against ingress by moist air. Most fuel systems will have a filter element in the line from the tank to the fuel pump, which in some cases is integral with the fuel pick-up pipe inside the

COMPETITION

138

CAR PREPARATION

tank, and in others it is external. Like other filters around the car, this one needs to be checked and replaced at regular intervals. Other items to be replaced regularly include any seals that you think

might harden or perish with time. This can happen more rapidly with certain fuels, such as methanol.

Mention of methanol brings up some additional thoughts on fuel system ‘housekeeping’. Some people who use methanol religiously drain down their fuel systems after an event, and prime the whole system with regular petrol to prevent the degradation of perishable seals and possible corrosion of other components. Personal experience of running methanol on a carburettored, as opposed to a fuel-injected, engine was that problems were only ever encountered when the methanol came into contact with petrol. In this situation, a sticky white emulsion

formed

inside the carburettors,

which didn’t help the engine’s smooth running. It was probably formed by dissolved

moisture

in

the

methanol,

in

which it is soluble, emulsifying with petrol, in which it is insoluble. Some claim that the addition of a percentage of acetone to the methanol overcomes this problem, and my feeble knowledge of chemistry suggests that this should be so. Our solution was simply to keep petrol well away from the system; we never drained it down between

events, and we

stopped having problems. Fuel injection systems are a different matter, and the more thorough approach is the route to follow. Your engine-builder will have recommended the necessary fuel pump(s) to generate the required fuel pressure and flow rate for your installation, and also the requisite fuel pipe diameter to flow the volume of fuel needed. The electrical connections to the fuel pump need, of course, to be sound in order to provide a reliable power feed. But a brief cautionary tale here will illustrate the need for mixing good electrical practice with fuel systems. A friend wanted to test the func-

tionality of an electric fuel pump for his racecar. So he got a battery, some pipe, a couple of bits of cable, and a pot of super unleaded fuel. Yes, you've guessed it already. Making the electrical connection by touching the remaining cable end onto a battery terminal caused a spark, which ignited the gently wafting fuel vapour, and gave my friend nasty burns to his hands. It could have been much worse.

Of course, he knew better; we all

do — but somehow that never stops us from taking short cuts on occasion. If only he’d wired up a simple on/off switch. But the words ‘if only’ could very well be printed on many an accident report, or gravestone for that matter. The reason for telling this tale is to point out that proper electrical connections should always be assembled, and_ especially around fuel systems where there is always a risk of fuel vapour leaking. Fuel vapour and electrical sparks get on like a house on fire. A further point to make here briefly is the need to provide an adequate power supply to your fuel pump(s), which can make substantial demands for current when on full load, so the requisite cable grade and fuse rating is necessary. Check with the fuel pump supplier. Maintenance

and

inspection

routines

for the fuel system are no different to any other system really — check pipes for vibration and abrasion damage; check unions for tightness and integrity; check an underbody fuel tank for damage, especially after any off-course excursions; replace filters and seals on a regular cycle; and make sure the fuel you use is fresh, the right type and grade, and is free of debris and contamination before you pour it into your competition car.

Hydraulic systems By and large, ‘hydraulic systems’ means brake and clutch systems, and it is these two functions we shall be looking at here. Let’s look at brakes first. Other than requiring the fitment of a braking system that is functional,

and

capable

of being

SYSTEMS

demonstrated as such, the only regulatory requirements on braking systems are that at least 25 per cent of the available effort must be applied to each axle and, unless the car is a production car on which antilock braking was originally fitted, it must not have an anti-lock braking system. These are UK regulations, so check your local rules if you are competing outside the UK. We have already looked at the brakes themselves in Chapter 7 — this section will just take a brief tour around the hydraulics. As previously discussed, the braking system uses master cylinders to convert the leg’s mechanical pressure into hydraulic pressure. A reputable brake component supplier will come up with recommendations on master cylinder sizes, with smaller diameter master cylinders producing more hydraulic line pressure,

but

increased

linear

travel

for the

same force exerted by the middle pedal (or left pedal if you have a hand clutch, or no clutch). We also mentioned in Chapter 7 that original equipment production car flexible

hoses,

especially

old

ones,

can

be

replaced with steel braided, Teflon-cored ‘aerospace’ type hoses. This really is a

113)

good idea, particularly in the competition context when heavier pedal, and hence higher hydraulic pressures, are used more consistently than on the road. Old flexible brake pipes can actually ‘balloon’ in response to the kind of line pressures encountered, and pumping up the brake pipes

is

not

what

you

are

trying

to

achieve! Sharper response will result from a switch to the professional grade hoses. It isn’t mandatory to replace all brake lines with the aerospace type, and it is expensive to do so, but you'll probably only need to do it once, and you'll then have a system which is much more damage-,

vibration-,

and

corrosion-resis-

tant; so if the budget can cope, do try to do it. System seals, both in the master cylinders and the calipers, should come in for regular replacement, and the hydraulic fluid needs regular replacement too, especially if it is of the hygroscopic variety — that is, all except silicone-based ones; and make sure you use competition brake fluid unless your competition duty is no greater than normal road-use (not very likely). The usual visual checks on lines for damage,

and on unions

and connections

Neat aerospace-type hydraulic line runs here, with clips and ties at frequent intervals.

140

COMPETITION

CAR PREPARATION

helpers — one to operate the brake pedal, and the other to top-up the master cylinders whilst you slacken (when the pedal is pushed) and tighten (when the pedal is released) the bleed nipples — ought to get any air out of the system. Having done that, any reappearance of a spongy pedal indicates a leak somewhere,

Caliper manufacturers calipers.

will service

and _ test

for leakage, should be part of your regular ‘service checks’. Some people also advocate regular system bleeding to remove air from the brake hydraulic system. Clearly, air is a bad thing if it gets into the brake.lines, because it makes for

a spongy pedal and much-reduced braking efficiency. Careful system bleeding, which usually requires one or two

and investi-

gation is obviously needed. Once system integrity has been achieved, though, the ‘if it ain’t broke, don’t mend it’ philosophy could usefully be applied — the chances of letting air in by bleeding a system which didn’t need bleeding make it better to leave well alone. Anyway, you'll be taking the car apart again soon enough, so re-bleed when you've reassembled. Much of the foregoing applies equally to the hydraulic clutch system, with the exception that such high line pressures are not generated in order to actuate the clutch. Having said that, one clutch expert told me that most clutch systems could usefully benefit from going down one size in master cylinder diameter. This comment was prompted by my description to him of three single-seater hillclimb and sprint cars that I had recently had the opportunity to test. Each was

This rally team experimented with protective shrouding around rear brake lines.

SYSTEMS

powered by an ex-Formula 1 engine of one description or another, but one of them had an extraordinarily heavy, shorttravel clutch pedal. That the other two had relatively light pedals, yet still with similar specification multi-plate carbon clutches, was evidence that it was the actuation system that was different, and

specifically — in all probability — the master cylinder size that was (to put it politely, because the car was fantastic otherwise) not optimised. There is no need for clutches to be heavy, and the old excuse of ‘well it’s a competition car, it's bound to be heavy’ is nonsense. A clutch slave cylinder has to move the clutch release bobbin a fair distance, and

as such clutch lines need to be of slightly bigger internal bore diameter to facilitate the movement of more hydraulic fluid. Bleeding the clutch is, usually, quicker and simpler than bleeding the brakes, and the same comments apply about unnecessary re-bleeding - if regular bleeding is required, then there’s a leak letting air into the system (and _ fluid, however

little, out), so find the leak and

cure it. General maintenance is along the same principles as for the brake system.

Electrical systems The electrics can again be regarded as safety-critical systems, and as such there are quite a few official rules, regulations, and recommendations to be adhered to. The most basic of these is that so called ‘wet’ batteries — that is, those that could

leak their highly acidic

contents

in the

event of an impact, an inversion, or just under normal shocks and g-forces —

should preferably be contained within a non-conducting, leak-proof box or compartment so as to prevent the risk of acid burns to anybody’s skin (or flame resistant clothing, come to that). This recommendation becomes mandatory for batteries located within the cockpit, and if you have decided to move your battery from an under-bonnet location in order to get its mass as low and central as possible (at a probable mini-

141

mum of 5kg, or 11Ib, it’s worth more than a passing thought), it will very likely end up in the cockpit. A sturdy fibreglass box with a positively locking lid does the job, and you can buy these, or carbon fibre ones if you’re feeling financially flush, from good motorsport accessory retailers. If the battery is not contained in a nonconducting box, make sure it is securely clamped, and that the terminals cannot come into contact with any conducting parts of the car under any conditions. It is a requirement to colour code the battery earth lead yellow if it is not ‘readily distinguishable’ otherwise. The best way to interpret this rule is to colour it yellow in any event, and that way you keep the scrutineers content (it is always good to keep scrutineers, or technical inspectors, on your side). Any and all wiring also needs to be held securely in place with P-clips and/or cable ties and saddles, and _ protected from the possibility of accidental damage which could cause short circuits at worst,

or the failure of one

or more

electrical

components. If you are competing in your road car, there probably isn’t much else you can do to your electrical system,

especially if the car doubles up for road use. But once it becomes a dedicated competition car, there are more things to be done, some mandatory, some just beneficial to performance. Depending on which category of sport you are entering, as mentioned in the section’ on fuel systems, you will very probably have to fit an external circuitbreaker switch, often also called a master

switch or a battery cut-out switch. Wired into the main battery earth lead, this switch must be capable of isolating every electrical system on the car with the exception of any electrically-operated fire extinguisher(s). Two types are available, depending on whether there is an alternator in the electrical system or not. The

switch must be located as defined in the rules, which on saloons is preferably at the lower part of the windscreen mounting on the driver’s side or below the rear

COMPETITION

142

screen, and on open cars near the lower main part of the roll-over hoop on the driver’s side or at the lower part of the front

screen

mounting.

You

are

also

required to identify the location of the master switch with the prescribed sticker (a red ‘spark’ on a white-edged blue triangle), as well as indicating the on and off positions; these stickers, and the master switches themselves, are obtainable from any good motorsports acces-

sory dealer. Remember that the car is also required to have an internal ignition switch that can be operated by the driver in the seated, belted-in position. When the time comes that what used to be the shopping car finally gets dedicated solely for motorsport use, you will start to look at the electrics as a source of excess functionality and weight. There is a general rule in the UK MSA’s ‘Blue Book’ that all cars except racecars (that is, open-wheel .single-seaters) must have a battery, a generator, a self-starter, and side, tail and brake lights, all of which

should be in working order. On a production car this leaves a lot of electri-

CAR PREPARATION

cally-powered apparatus that can be considered redundant. With care, patience, and your Haynes Manual to hand, and providing the rules for your chosen category

permit

it, you

can

now

attack the

wiring ‘harness’ (which resembles a snakes’ wedding at the best of times) and remove redundant wiring. Copper-cored cable is heavy stuff, and you can save quite a bit of weight doing this. You will also be able to save weight by removing the extraneous equipment that was powered by the surplus cable, so out with the electric windows, heated seats, and selfemptying

ashtrays.

Of course,

in some

categories of motorsport you could end up adding electrical components, such as additional lighting for rallying. In this case you will also need to make sure your alternator is up to the job of powering everything when all the auxiliary lighting is in use. On the topic of making electrical connections, it’s fairly obvious that to be reliable they must be of good quality, and resistant to the vibrations and other environmental factors encountered in a

An attack on the wiring loom of this modified production

VW Golf was imminent!

SYSTEMS

143

competition car. Until very recently most people, I think, would have said this meant making good soldered connections,

but

on

a recent

visit to a well-

known motorsport electronics firm that also manufactures wiring harnesses, I was informed that all their connections were nowadays Mind crimped. you, their crimping tools were calibrated against an internal standard to ensure consistency of crimping pressure, and their staff were skilled and experienced at their jobs. Nevertheless, the reasons behind the use of crimping against soldering were not just about productivity, but about joint reliability too. Soldered joints, it seems, can be brittle, and are liable to fracture when subjected to continuous vibration.

So you have to decide which you can do best — solder or crimp — before setting about making new connections. If you’re not sure, enlist the skills of an auto-elec-

trical

specialist.

When

engine management

we

looked

at

systems in Chapter 9

it was said that 90 per cent of reliability problems with EMSs were down _ to electrical connections,

and this serves

to

just how illustrate frequently poor connections are made. With a racecar that need only be fitted with the absolute minimum of electrical components, you can get to design and make your own wiring harness, and at its simplest — on a car with just a starter, a fuel pump, an ignition system, and one or two electrical instruments — it’s not a complex task. Just make sure everything is properly earthed, preferably with a separate earth for every item; and take care with the connections. Also use the right grade of cable to carry the current needed by each component — fuel pumps and ignition circuits can draw a fair bit of power. Make life easier on yourself by colour-coding the cables for each component, and keeping a wiring diagram with the colours written on it to help out later if you need to service or modify anything. If in doubt, seek specialist advice. Don’t forget to tape or wrap all the cables neatly together, and hold them securely

Top quality electrical connections and cables on an F3 engine.

to panels or bulkheads getting damaged. In some

categories

to prevent them it is permitted

to

use an external ‘slave’ battery source for starting, obviating the need for self-start capability on the car itself. This enables you to carry a small, light-weight battery in the car since it is not going to have to power the starter motor and turn the engine over; a very useful weight saving can thus be made, and you don’t need to find the space for a large capacity battery either. In fact in these cases it is not actually required to have an on-board starter motor, and the engine may be started with a remote ‘plug-in’ starter, which may be electrical or powered by compressed air. This also saves carrying the weight of the starter motor, and looks all very hitech. Frankly, the extra hassle probably isn’t worth the weight saving, but that’s just a personal view. Two basic wiring diagrams are shown for guidance, one for an on-board starter battery, the other for a remote or slave

144

COMPETITION

CAR PREPARATION

Wisin

To circuit shown in Figure 11-2

Spring loaded starter button

‘Master switch’

Solenoid

SYSTEMS

Figure 11-4 Slave battery system.

‘Jump plug’

A Spring loaded starter button

Solenoid

‘Slave’ battery

za

NB Earth to engine/chassis

starter battery. Make sure that you inspect the wiring frequently, checking for any signs of chafing, abrasion, or any other damage. If everything is held to the chassis at frequent intervals by cable ties there shouldn't be any problems. Ensure, too, that cables are not vulnerable to damage when removing and installing the engine or other major components.

Miscellaneous systems There are two further systems worthy of at least passing mention here, and significant care and attention at the preparation stage: the throttle linkage and the gear linkage. About the only regulatory requirement for the throttle mechanism is that it must be equipped with an external spring or springs capable of shutting off the throttle should any part of the linkage fail. This is a basic safety requirement as well as being good common sense. But the rules really should also cover the rest of the throttle mechanism, perhaps in particular the throttle cable, which if not of top quality and suitably routed can cause resistance

to movement,

and

cause

the

throttle to stick open — an obviously dangerous state, which at best is highly likely to cause unnecessary damage to your

competition

car

at some

point.

A good

quality throttle cable can also make a car easier to drive, offering better sensitivity and control. The amount of pedal travel and the stiffness of the throttle return springs are a matter of personal preference really, and can be adjusted to suit. It's a good idea to adjust the pedal height so that it is level with the brake pedal when the brakes are in use. This makes ‘heel and toe’ down shifts easier to accomplish. Another neat trick is to provide the throttle mechanism with a progressive opening characteristic, such that initial pedal movement causes slow throttle opening, whilst further pedal movement opens the throttle more rapidly. This is more suited, perhaps, to powerful competition cars, where sensitive throttle control is required, and a well set-up system incorporating this principle makes life a lot simpler. So called ‘fly by wire’ throttles used in the top formulae of motor racing can be programmed to act like this, but with a little ingenuity a mechanical ‘rising rate’ throttle linkage can be devised. The gear linkage is another mechanical system which can benefit from close attention during preparation, and can help to avoid missed gears and wasted

COMPETITION

146

CAR PREPARATION

Note the top quality gear linkage joints on this Mini gearshift.

runs or laps. The gear linkage needs to be made and routed so that the movement at the driver’s end of things — that is, at the gear lever — is faithfully transmit-

ted

to the

Sounds

gearbox

obvious,

at the

other

end.

doesn’t it? Yet there are

an awful lot of competition cars that seem to suffer from poorly put together or badly maintained gear linkages, to the extent that missed gears seem to be a way of life. In a lot of cases a modest investment in some good quality universal joints can cure most of the problems. The bolts holding the universal joints to the linkage shaft need to be good and tight, with no free play. The bearings that the linkage shaft slides in should not be at all tight, but they do need to be a reasonable fit to prevent undue free movement. Naturally the linkage shaft needs to

be robust enough so as not to flex, and above all no part of the linkage should come into contact with chassis rails, gearbox side-plates, or any other ancillary components during any part of the linkage’s movement. Speak to any gearbox specialist and they will tell you tales of how gear selection problems that had to be ‘down to faulty internal set-up during the rebuild’ actually turned out to be caused by the customer’s lack of attention to the gear linkage routing. In fairness, what looks like sufficient clearance in the raceshop can disappear when cars get loaded up with g-forces and engine torque, so allow more than enough clearance and you'll be OK. With both the gear linkage and the throttle systems, make sure you keep things clean and well lubricated.

Chapter 12

The ‘office’ THE ‘OFFICE’ OF your competition car is where you do all the really important work, so it pays to spend a decent amount of time sorting it out properly so that you can work effectively and safely. There are a number of aspects to be considered, so let’s look at safety first, and start with the seat(s). Seating The seat of a competition car serves two

purposes; first, it holds the driver securely in place; and secondly, it locates him or her in the optimum position to control the car. UK competition rules, recognising that not all cars competing are dedicated solely to that purpose, are surprisingly flexible about the required standard of seating; although the rules for specific categories can be more exacting, it is nevertheless possible to use standard production car seats in some forms of competition. However, you will not be able to drive at your best unless you are securely held in place, particularly laterally. A seat that locates your hips and body and stops it moving from side to side, as well as preferably holding you by your shoulders while leaving your arms free to operate the steering wheel, will enable you to retain much better control of your car. If the seat doesn’t stop you moving from side to side, then you will be hanging on to the steering wheel in order to hold yourself in place, and that tends to be at odds with precise, smooth steering in-put. So at some point a com-

petition seat has to be a good purchase for your production-based racer. A competition location.

seat

vastly

improves

driver

148

COMPETITION

CAR PREPARATION

The prices of competition seats vary enormously, from budget level to completely outrageous. But the well-known brand name budget to mid-range seats offer good value, and most (even the budget ones) are FIA-approved, so you can be sure of minimum safety standards being met. Materials range from steel and glass fibre reinforced plastic in the cheaper ones, to advanced composite mixes of carbon fibre and kevlar for ultimate strength and rigidity with light weight. Seat shape is constantly evolving, with seat backs having become longer in the recent past to add some protection against whiplash injury to the neck, and nowadays it is possible to get seats that incorporate varying degrees of lateral head protection too, all at not unreasonable cost. The necessary mounting frames are available for a wide range of vehicles. So whilst you may not have thought of the seat as a safety item, these days it assuredly is. Sports racing and racing cars tend to be much more basic on the seating front, though, and. in some cases you get to sit directly on whatever material the chassis is made from, be it aluminium

or carbon

composite, sometimes with no additional padding at all. Usually this isn’t nearly as uncomfortable as it sounds, providing your personal build, shape, and dimensions are compatible with those of the cockpit. In a single-seater in particular, you tend to sit low in the ‘tub’, and you are held securely in place by the chassis sides and the sloping bulkhead that usually covers the fuel cell compartment, but with your arms free enough to operate the steering wheel. If you are slim enough to rattle around in the tub, you can use various foam systems to create a rigid seat insert moulded or cut to your exact

shape, and there are also vacuum-

formed plastic bead-filled bag systems in which the shape, which is moulded around you by the beads, is then bonded with a resin to form a rigid seat insert. Rigid foams are far better than spongy foams because they provide the driver

with much more positive location. And it's not being soft to make sure you are comfortable.

Far from it, in fact. That cer-

tain Formula 1 teams should have constructed cars which, by virtue of cockpit dimensions or inadequate seating provision, were so painfully uncomfortable for the drivers that it impaired their driving and their concentration seems to me to be bordering on negligent. Either the designers, or the people who hired the over-large drivers after the design was fixed, should be shot — slowly! There is another aspect to seating which relates to chassis performance: the driver represents a significant mass, and therefore ideally needs to be located as low in the car as possible. This requirement can be at odds with clear forward visibility, so yet another compromise has to be struck, but try to get the seat as low as possible. One or two final thoughts on seating. The UK MSA has a rule, specific to singleseaters,

that

the

maximum

time

for

a

driver to get in or out of the vehicle should not exceed five seconds. Though this was clearly well intended, it raises two questions in my mind. First, why would anyone want to get in the car in five

seconds

or

less,

unless

they

were

very late for practice? And secondly, far more importantly, why should this rule only be applied to single-seaters? Perhaps the rule writers were under the impression that it takes longer to get out of a single-seater than anything else. Maybe it did when the rule was having principally driven

written, but single-seaters for the past 20 years I wouldn’t mind betting I could get out of one faster than most of the sports racers and saloons I have driven. I reckon the five-second rule ought to be applicable to any competition vehicle, but to be sensible it should refer only to getting out of the car, and from being fully belted in place, of course. That would be more in line with what

is desirable,

and

achievable

when

propelled, for example, by flame-induced adrenaline!

THE @FEICE?

The traditional rigid polyurethane foam and tape clad seat insert.

Seat belts One of the most curious rules in the UK MSA ‘Blue Book’ is that a car need not necessarily be equipped with seat belts if an event is to be held solely on private property. We'll assume that this particular phrase is just an anomaly from a bygone era that hasn’t been picked up yet, because elsewhere the good book says that seat

belts

correctly

adjusted

should

at

be worn,

all

times

and

be

during

events, which makes a lot more sense. As

der straps, are obviously better than three-point, and the four-point is specified in a large variety of competition categories

from

circuit

racing

to

stage

rallying. The six-point harness, specified for single-seater and some sports racing applications, is the only one that holds you from all directions, and prevents you sliding forwards out of your seat Csubmarining’) in a frontal impact, though admittedly this is more likely with the reclined seating positions of single-seaters and sports racers. It also holds the fastening point over your pelvis, where it needs

with seating, the rules do allow for the use of production car seat belts in some forms of the sport by permitting what are called ‘three-point’ harnesses, meaning a belt with three anchor points on the chas-

to

sis, shell, or roll-over bar, restraining the driver with one diagonal shoulder strap

belts are tensioned the fastener may ride up onto the stomach or even the lower

be,

because

of the

tension

on

the

crutch straps — a four-point harness does not

have

these,

so

when

the

shoulder

and one lap strap. This may be the legal

chest. I don’t know about you, but I don’t

minimum

like the idea of the fastener being thumped into that particular area in an accident, and a six-point harness is my preferred option on any vehicle if it can be practically installed. It would appear that the world governing body of motorsport, the FIA, doesn’t

in some

categories,

but it isn’t

going to hold you in place adequately, even with your new wrap-around competition seat; and perhaps more to the point, it won’t restrain you as well in the event of certain types of accident. Four-point harnesses, with two shoul-

COMPETITION

150

CAR PREPARATION

necessarily agree with me on this one, since it has approved a number of fourpoint designs. However, that approval, it seems,

has

more

to do with

the recent

incorporation of 3in (75mm) wide webbing straps to replace the previously accepted standard of 2in (SOmm) width. This in itself is a sound move, giving 50 per cent greater area to spread the impact loads, and

it has spread from Formula

1

into some other categories. One driver I know who once endured a full frontal impact told me of the painful two-inch wide bruises caused by the shoulder The six-point harness place.

holds you

securely

in

straps of his harness;

wider

straps may

well have lessened the discomfort, even if

the bruises would have been an inch wider! One or two belt designs now even offer 4in (100mm) wide shoulder straps. But I still stand by my assertion that the six-point harness is the way to go, with 3in straps if available — providing, of course, that the seat and car structure will

enable its use. It’s your choice, but the cost of competition belts is not that great, and you will be able to drive better if you are held securely in place, so don’t think

this is just another case of preaching safety. The rule book also makes some very valid points about the upkeep and use of seat belts. Most importantly, belts need to be discarded once they have been involved in a serious accident. This may seem extravagant or, to the sceptical, a means of keeping the manufacturers in business, but the reality is that there is no means of assessing how much load has been put through the belts in an accident, and it is possible that if you rely on them a second time they may not restrain you — at all. The analogy with a crash helmet is valid: if it has suffered an impact, it should be replaced.

Similarly, if the belts

have visible damage, wear, or fraying, or have been subjected to oil or heat, once again they need discarding. If you are in any doubt, take them or return them to the manufacturer — they may at least be able to re-use the buckle and anchor points if the only problem is wear or superficial damage to the webbing straps, attaching new straps to the metal work for you. The manufacturers will supply fitting hints, but the ‘Blue Book’ makes mention of one key point, which is to ensure that

the anchor points to the rear of the seat are positioned so that the straps from the shoulders are as near horizontal as possible. Fire extinguishers In some categories of motorsport in the UK, fire extinguishers are mandatory, in

Urbs OPBICE:

others they are recommended, and in yet others they are not even mentioned in the rules; it all depends on the level of perceived risk. In autotests, for example, there is no mention in the rules about fire extinguishers on cars, though the event organisers are required to have one available at each test location. In hill-climbs and sprints the use of a 1.5kg extinguisher that can discharge into the cockpit and the engine compartment is only recommended.

Most

circuit

racing

cate-

gories specify at least a ‘medium’ size plumbed-in or hand-held system, whilst for stage rallying it is required to carry a ‘large’ size, plumbed-in extinguisher for under-bonnet

use,

and

a medium

size,

hand-held one for the driver and codriver’s compartment. Clearly, whatever category you compete in, you will have to consult the ‘Blue Book’ very carefully, and also the local and championship regulations too, before you spend any money. The rules governing acceptable extinguishants have been changing in the

151

recent past, with the banning or phasing out of halons, and in effect you can now only buy ozone friendly aqueous-based extinguishants. BCF, a popular halon in fire extinguishers, is already illegal in some

countries, and will be deleted as an

approved extinguishant by the MSA from 1 January

2000.

There

are two

principle

extinguishants now available: AFFF (Aqueous Film Forming Foam) and Zero 2000 (also a water-based foam). In most cases you will be able to satisfy the regulations by fitting a 2.25 litre AFFF or Zero 2000 type fire extinguisher, and in the case of stage rallying supplementing this with a small hand-held extinguisher. But check the rules for your series first. Whichever type of extinguisher you select,

there.

are

some

basic

rules

to

follow regarding their installation and use. The ‘Blue Book’ states that the preferred method of operation of an onboard

extinguisher

is electrical,

order to provide a power totally independent

of the car,

The fire extinguisher is located beneath the driver's legs in the Spyder Formula neat cable run to the extinguisher.

and

source

in

that is

electrical

Vee. Notice the

COMPETITION

152

CAR PREPARATION

e Hella

fh

Peston 790 my

|

Fesii2000

The ‘E’ sticker stands out on this Spyder.

extinguishers come with their own battery power-packs, which have in-built self-test capabilities to ensure the battery and wiring are satisfactory. Mechanicallyoperated extinguishers are activated by one or more pull cables, and during installation it is important to make sure that the cables are not kinked or bent so as to impair operation when needed. The extinguisher bottle itself must be securely located to the car with the fitting kit supplied. In both cases the system should have two triggering points, one of which the driver can operate from the normal seated position, and another that can be operated from outside the car should the driver be incapacitated. This latter point must be located adjacent to the electrical

only be ‘full’ or ‘empty’ anyway, so this should be easy to determine. And secondly, the device must be ‘armed’ and ready for use, with any ‘safety’ pins that prevent accidental discharge removed prior to the start of an event. As with any safety equipment, the choice of fire extinguisher system and the amount of cash you are prepared to spend on one is all about how much you value your own personal well-being, and that of your competition car. A sophisti-

master

in a category where it is not mandatory, that’s up to you too. You might attempt to assess the level of risk of a fire, for

cut-out

switch,

and

be

marked

with the regulation sticker which is a red-edged white circle, no less than 10cm (4in) in diameter, with a large red letter EOE

A couple of blindingly obvious

points

should, perhaps, also be made. First, your

extinguisher should be full at the start of any event. Given that they are supposed to be total discharge devices, they should

cated,

and

hence

more

costly, system

is

more likely to prevent damage to your car in the unhappy event that a fire does occur,

but, at the other extreme,

obtain-

ing a system that complies with the minimum requirements is relatively cheap. It’s your choice. As for whether you fit one

example by looking at the size of your fuel tank, which in the case of a hillclimber might only be a gallon (4.5 litres), and tell yourself that the risk is low. But if you happened to see the fire that befell Jos Verstappen’s Benetton F1 car in 1994, when during a pitstop just a

THES OPREICE:

few litres of fuel spilled out of the refuelling hose and ignited, covering several members of the pit crew in flames, you begin to realise that it takes very little petrol to cause a potentially serious conflagration. Luckily nobody was seriously hurt in that incident because they were all wearing fire-resistant clothing, but it was a salutary lesson for anyone who witnessed it. Ergonomics According to my Concise Oxford English Dictionary, the definition of ergonomics is ‘the study of the efficiency of persons in their working environment’, but it has also been corrupted to mean ‘the efficient

layout

of a person’s

working

environ-

ment’. Whether the use of the term here is technically correct or not, I am using it in the corrupted sense. The key issue, in our context, is that a driver has to be sur-

rounded by the controls and equipment that are needed, in such a way that he or she can operate at maximum efficiency and can drive at their best for the duration of an event. Thus the ergonomics of a competition car are very specific to an individual driver, and very personal as a result. But little of what we are going to look at here is difficult to achieve; it just takes thought, time, and effort, like any other aspect of good preparation. I’ve already said what I think about senior professional race teams who have failed to make their drivers comfortable and at home in their racecars. We haven't got as much to lose as they had, but all the same, let’s not fall into the same trap. We've already been over the topic of seating insofar as it relates to secure restraint of the driver, but let us not miss

the crucial point about the positioning of the seat relative to the main controls. Clearly the fore and aft position and the height of the seat must enable the clutch pedal, if fitted, to be fully depressed without over-extending the appropriate leg or over-flexing the ankle. From there, the positions of the other pedals are more or

153

less dictated, and the travel of the throttle

pedal needs to be fixed so that full throttle can be comfortably obtained over a suitable movement distance. Keep in mind that the shorter the movement range, the more sensitive will be the throttle, which is possibly just as undesirable as a very long travel. Thus some experimentation may be necessary with this control. The brake pedal movement will be dictated by the mechanical and hydraulic components in the braking system, but actual pedal movement is considerably less than the other two pedals. It must be possible to exert a high level of force with the braking leg without deflecting the pedal or its mounting, or the seat or its mounting. Lateral pedal spacing should preferably allow the left foot a space to brace against beside the clutch pedal (not always possible in the narrow confines of a single-seater chassis). For right foot brakers the brake and throttle pedals need to be spaced so that you can accomplish the ‘heel and toe’ technique for carrying out smooth downshifts of gear, wherein the right foot blips the throttle whilst maintaining steady brake pressure during the downshift in order to synchronise engine and wheel speeds in the lower gear. Each driver does this in their own unique way according to preference and personal construction, so expect to have to experiment here too until it’s just right. The throttle pedal should also be set a little lower than the brake pedal (when both are in the ‘off position) so that when the brake pedal is depressed it is on a level with the throttle. Again, personal fine tuning may be needed here. For left foot brakers the brake pedal will be further towards the clutch pedal Gf the footwell allows). Back to the seating position again. Not

only has this to keep the driver low enough to maintain a low centre of gravity, and high enough that forward visibility is satisfactory, it also has to put the driver in the right position to operate the steering wheel. This can be accomplished

COMPETITION

154

CAR PREPARATION

Relative pedal positions are important.

via the angle of the seat back or rigid foam padding between the driver and the seat back, and/or the length and height of the steering column. Once again, the ideal distance from shoulder to steering wheel is a matter of personal preference, but don’t be fooled into thinking that the old-fashioned straight-arm position is correct — it usually isn’t. You get more control, siand more. effort available to. be applied to the steering, if the arms are bent at the elbows to a greater or lesser extent. Some Super Touring and NASCAR drivers

seem

to

take

this

to

extremes,

with the steering wheel almost touching their chests, but if that’s what works

for

them, who’s to argue? The wheel doesn’t want to be too high either — it should be possible to put a hand on the wheel at the twelve o’clock position without coming close to stretching. In events

where

drivers

share

a car,

such as endurance saloon or sports car races, or hill-climbs and sprints, getting a

good seating position can often mean compromising. But with individually sculpted rigid-foam seat inserts the seat to pedal distance at least can be arranged properly for each driver, even if the shoulder to steering wheel distance is slightly compromised. The gear-shift lever also needs to be carefully positioned, and although in some cars this may well be dictated by the position of the original lever, it is usually still possible to ‘fine tune’ it. Basically you want the lever to be reasonably close to the steering wheel so that whichever hand has to move to it to change gear, it doesn’t have to move far. The lever should ideally be in the same plane as the steering wheel, beside it and at a distance so that when the car is in the gear that puts the lever closest to the steering wheel, there is still room

for the relevant

hand to grip the wheel without the gear lever interfering with the steering. There should also be plenty of clearance

THEY OFFICE;

around the hand when gripping the gear lever, so that it doesn’t get interfered with by bodywork, a point of relevance to single-seaters and some sports racers with the shift linkage outboard of the driver. You also need to make sure that the driver cannot (unwittingly) interfere with the linkage in any way. Instruments and switches need to be placed where they are visible and reachable. It still surprises me that a lot of cars have switches that you cannot see when you get in the car. The regular driver may know where they are by feel, but isn’t it better to be able to see them and their labels clearly, so that in an emergency

situation

you

are

not

fum-

bling clumsily for the ignition cut-off switch? Likewise with instruments: if you can’t see the dials or display easily with just a flick of the eyes from the track, then they are superfluous and you might as well take them off and save the weight. Look at the positioning of the

ISS

displays of vital information on the cockpit views during Grands Prix these days. The really important information, like the so-called ‘shift lights’ that tell the driver he needs to change up a gear any moment

now,

are

not

only

bright,

but

virtually in the line of sight, making them highly visible. Mirrors, if required by your competition category, need to be mounted so that they give a good rearwards and rear three-quarter view. Different types of car have different needs here, and production-based cars have the benefit of door mirrors supplemented by the central rear view mirror if desired. Single-seaters, however, can only use side mirrors, and these somehow need to give the driver an adequate view, often past large rear tyres and rear wings. Larger mirrors might

create a bit of extra aerodynamic drag, but they offer better rearward visibility. They need to be mounted sturdily so that they do not vibrate. Naturally, they are

The gear lever is close to the steering wheel, and there is clearance for the hand in the cockpit side on this Formula Palmer Audi.

156

COMPETITION

only any good if the driver actually uses them! You may have seen photos of World Rally Cars competing on events in hot countries like Kenya and Indonesia that show periscope-like ducts protruding out of the roof line. Once again these not only serve to upset the aerodynamicists whose carefully-designed rear aerofoil is now totally compromised, but they are also to do with cooling — driver and codriver cooling. In other categories, driver cooling

ducts

are

a

little

more

subtle,

often taking the form of small ducts ahead of the lower line of the windscreen. It obviously makes sense in the more gruelling types of events to try to keep the driver cool. Not only will he or she be more comfortable, but they will perform better for longer. Instruments

As well as making

CAR PREPARATION

space, and how much information is needed and can usefully be presented to and processed by a driver. On the last point, the amount

of information that can

be taken in must depend on the type of event, and even the nature of the course

being driven on. I wonder if a Top Fuel drag racer has time to look at anything at all during a sub-five second quarter-mile pass, whereas a driver cruising at 200mph plus down the Mulsanne Straight at Le Mans has, relatively speaking, enough time to download the data-logging system, study it on a laptop, pour a cup of coffee and unwrap his sandwiches. Relatively speaking... So what information do you need? How about engine rpm, oil pressure, and water temperature

as the minimum,

with

fuel pressure on a fuel-injected car being a necessary addition? Better than that, how about rpm, plus visual alarms (flash-

sure

the instruments

you use are visible, as discussed above, you first need to decide what instruments you want to install. There are various constraints on this decision, such as cost,

ing lights) in the event other parameters fall limits? You might even counter altogether with lights. After all, the only

that any of the outside pre-set replace the rev illuminated shift reason that the

‘Old-fashioned’ analogue instruments still have a big following for their ‘at a glance’ clarity.

THE @REICE

driver monitors the engine parameters is to ensure they are normal, and to take appropriate action if they become abnormal. You might say that it’s sometimes useful to have the full display of engine parameters available — when warming up the engine, for example — and I wouldn’t argue, but once out on the track the driver will rarely have time to study gauges too closely, so why not make life simple and just inform him or her when something is not right? It's a moot point, and anyway, it may well be cheaper if you're on a tight budget to buy old-fashioned analogue display gauges for the engine parameters. There are so many

options available now in the instrumentation market that the choice is pretty bewildering. Electronic instrumentation is able to log all kinds of parameters, whether for display or for data gathering and later analysis (we'll discuss this in Chapter 14). Your budget will decide for you what you can afford, and after all, we did manage with

basic gauges for quite a while before the electronic revolution hit motorsport. Communications If Formula 1 drivers have radios linking them to their race teams back in the pits, how come they still use pit-boards hung out each time they pass the pits? Can it

Sy

be that the radios are less than reliable? Actually we can be pretty sure that they are not a wholly reliable communications medium. We’ve probably all seen some of the more public communications mix-ups in Grands Prix when a driver has come into the pits unexpectedly, or conversely hasn’t come in when he’s supposed to have done. In most cases the blame could probably be laid at the feet of the people involved — which is, after all, where most communications difficulties spring from — although signal problems and noise (electronic and acoustic) can’t help either. If you do plan to use a radio to communicate with your pit crew, assuming

your category permits it, make

sure that you work out as foolproof a method as possible for getting the most vital information across. And back it up with a clear, simple message on a pitboard! In-car communications between a rally driver and the co-driver have to be absolutely clear, and there are a number of radio kits on the market to facilitate this. Things have come on a bit since the days when plastic funnels and a piece of tubing were apparently used to amplify the co-driver’s instructions and transmit them to the driver’s ear! Naturally, the coded language that co-drivers use must be understood by the driver too.

Chapter 13

Bodywork and aerodynamics SO JUST WHAT is bodywork for? In the case of either the production-based car or the purpose-built competition car it can form part of the structure, but it is for the most part there to cover the inner workings, to provide the styling that is the identity of the particular make and model, and to create a more or less efficient aerodynamic outer wrapper. In the

case of many sports racing and singleseater racing cars the bodywork does not serve any structural purpose at all, and though this might not be quite so efficient from the point of view of utilising any mass for more than one purpose, it does provide more flexibility when developing the outer aerodynamic package. _ Let’s look a bit more closely at the functions of the bodywork, and _ the requirements that spring from these. As we said, there are elements of the bodywork that can form a part of the primary structure as well as aerodynamic wrapping. You could say that the structural engineer’s job is to meet the strength and stiffness requirements within the constraints imposed by the aerodynamicist — this is certainly the emphasis in those top professional racecar manufacturers at the front of the grid in Formula 1, for example. The bodywork must also cover and contain all those components that are not required to be left out in the cold, so to speak (the wheels in the case of singleseaters), which means pretty well all the other components. It must also protect

and cover, to the extent permitted or required by the regulations, the occupant(s) of the car. It provides somewhere to put the competition numbers for identification by officials and timekeepers. It provides valuable real estate to put sponsors advertisements and logos on. And it enables the designer to make a car look good, through styling of the basic shape and by the application of paint in an attractive colour scheme. The UK MSA requires all cars to have bodywork, a complete floor of ‘adequate strength’,

a minimum

cockpit

width

of

81cm (31.9in) in the case of non singleseaters, and mudguards covering the whole wheel width over a specified 120° arc; it also requires that they only have spoilers or aerofoils fitted if the car is a single-seater, or where they are specifically permitted by the rules of a given category or by virtue of FIA homologation on a particular vehicle model. So, given these functions and restrictions, what can be done to try to improve matters relating to bodywork? Well, where permitted you can seek to save some weight. For example, in some modified production categories it is permitted to change the bonnet, doors, and boot lid for ones made in a different material, which enables the use of fibre-reinforced plastic replacements which are usually considerably lighter than the original steel items. Naturally cost comes into this, and glass fibre replacements will be cheaper than carbon fibre ones, although if you

BODYWORK

AND AERODYNAMICS

are prepared to make your own the investment in carbon fibre panels will be more about time than all that much hard cash. Any body panels, whether original or replacement, need to be adequately strong and stiff to put up with the use to which they'll be subjected, and capable of lasting for whatever your budget defines as a reasonable length of time whilst still looking good. This is to ignore potential crash damage, which shortens ‘the life of body panels pretty rapidly, although repairs can often be effected. The material they are made of, and how much of it they are made of, will govern the durability of body panels. For example, very light bodywork can be made from a couple of plies of carbon fibre in a resin matrix,

but this material tends to

shatter into pieces in an accident. If this is an acceptable price for the ultimate in lightweight bodywork, then fine. However, if carbon is combined with glass fibre, or with kevlar — which was designed originally for ballistic protective gear such as bullet-proof clothing — then a lightweight but more durable composite results, which gives bodywork panels a much longer life and greater resistance to the knocks of everyday life on a racetrack. A couple of references to making the bodywork look smart have been made already. This is important for a number of reasons. First, you will be able to have pride in your car. Secondly, scrutineers look suspiciously at scruffy cars, and not without good reason, because if a competitor doesn’t care about his car’s outward appearance, then you have to ask

yourself whether he cares about it’s general upkeep and it’s integrity under the skin. And thirdly, if you are looking for sponsorship, potential investors are far more likely to back a smart-looking car that people will notice, thus drawing attention to their company name or logo. And if you are already fortunate enough to be sponsored, you owe it to your sponsor(s) to keep the car looking smart.

159

As an aside, have you ever noticed how the most competitive cars in any category

are usually the smartest

ones?

there can be exceptions,

but I think the

Certainly

general observation is valid, and that cannot be coincidence. Does it not reflect the attention to detail paid by the people who prepare the winning cars? So, bodywork needs to have adequate durability (and integrity, if structural), be lightweight wherever possible, must cover all the components that the rules require, and should preferably be smart in appearance.

But

as

previously

men-

tioned, it also constitutes the aerodynamic outer wrapper of the car, and it is in this area that some _ performanceinfluencing modifications can be made. There are two aspects of a competition car’s aerodynamics that are important: drag and lift or, preferably, downforce. Aerodynamic drag Clearly one of the basic functions that any bodywork fulfils is to reduce aerodynamic drag. If a car were to run without any bodywork fitted it would create huge amounts of drag. By making the shape smoother with carefully shaped body panels, air is encouraged to flow around and over the car’s surfaces with less disturbance, and this keeps drag down. Production car designers have done an excellent job in this respect since the days of the fuel crisis in the 1970s, and drag coefficients on very ordinary cars are significantly lower now than they were twenty or even just ten years ago. This is obviously a help to the production-based competition car, which is able to achieve a higher top speed for the same horsepower than its predecessors, and is also able to accelerate a little better at speeds where aerodynamic drag starts to get appreciable, which is to say at higher speeds. But if all modern production cars have low drag coefficients, what can be done to achieve any additional advantage? First, where does drag come from? It results from the fact that air is, in fluid

COMPETITION

160

CAR PREPARATION

dynamic terms, a dense and _ viscous medium, and trying to propel a body such as a car through it produces a force that tries to oppose the movement of the car. This force is aerodynamic drag, and you can feel how large its effects are if you put your arm out of a car travelling at even a low speed of, say, 20mph (32kph). The drag force tries to pull your arm backwards. At higher velocities the force is much greater, because it varies

Warwickshire, England, for an aerodynamic summary report. This information should be a criterion for your initial choice of car if you are going to enter a discipline where high average speeds are likely, because it is particularly relevant in those circumstances. In very simplistic terms, the absolute drag of a small, ‘slippery shaped’ coupé will be less than that of a big, boxy saloon, so if there’s a

with the square of the velocity, or v* in scientific notation. This means that at 40mph (64kph) the force is four times

ily lean towards the big, boxy saloon, go for the little curvy coupé. The size and basic shape of a vehicle, therefore, essentially establish the drag that a car creates. There isn’t a lot you can do about the size of a given vehicle, although lowering it on its suspension may actually decrease the effective frontal area. But you can make some modest improvements to its drag coefficient, if the rules in your category allow you any flexibility in this area. For a start, a front spoiler of the ‘airdam’ variety often reduces drag. It does this by cutting down the amount of air that flows beneath the car, meaning that there is less air to interfere with the aerodynamically ‘rough’ underside, which is generally full of cavities and _ protrusions. Significant percentage reductions in drag can be achieved in this way. Rear boot-

that at 20mph. The drag generated by a car at any given speed is directly proportional to its drag coefficient, or Cd value, which is a measure of the efficiency of its shape, if you

like;

and

also

to

its frontal

area,

which for inter-model comparisons can be very roughly estimated by multiplying the width by the height. The bigger the drag coefficient, the greater the drag will be; and the bigger the frontal area, the greater the drag will be. So for starters you should try to obtain data on these two values, which can often be gleaned from sales brochures, from one of the ref-

erence books listed in Appendix 4, or by paying a modest fee to the Motor Industry Research Association (MIRA), in The GT format produces sleek shapes.

choice, and other factors do not necessar-

BODYWORK

AND AERODYNAMICS

mounted spoilers can also help to reduce drag in some cases by helping to reduce the size of a car’s ‘wake’, that area of swirling, turbulent air which the car pulls along behind it. And given the adverse effect of the rough underside mentioned above, it makes sense to panel this in Gf you are allowed to) with light alloy, plywood, or lightweight composite sheet to make one flat surface, a move that will reduce drag in a lot of cases (it also helps to keep the cars components clean). Make sure, if you do this, that the resultant large, flat area is inclined slightly downwards at the front under all conditions, that is, it has a positive rake, so that

air does not pack underneath the front and lift the car at speed. This will help in another way, as will be discussed shortly. Then there is attention to small details. Make sure the body panels on your car fit together well, and there are no raised lips or unnecessarily large gaps between adjacent panels, and tape over gaps to seal them. Choose an ‘aerodynamically shaped’ pair of door mirrors over plain, flat ones. Remove extraneous projections such as radio or car phone aerials if you can — you are unlikely to listen to either whilst you are competing, although I have heard of the occasional eccentric who enjoys music while competing!

161

As discussed in previous chapters, examine the routes that the air is expected to flow along to get to, and especially from, the cooling matrices (water and oil) and see if there is anything you can do, within the framework of the regulations, to improve the situation. Relocation of the cooling matrices to areas where air can be more efficiently ducted to and from them will help to reduce drag, and probably improve cooling efficiency at the same time, enabling smaller cooling matrices to be used and thus reducing drag further, as well as possibly saving weight. With purpose-built competition cars, ranging from sports racers to singleseaters, one of the drag-causing elements at least may have been _ intrinsically improved, and that is the frontal area. Because of the no-compromise low centre of gravity approach adopted in the design of a genuine competition car, frontal area will most likely be smaller than a production-based car because of the much reduced height, although some competition cars are extremely wide. Cd values will depend very much on the car type, ranging from figures similar to those of production cars (0.35—-0.45 typically) for sleek sports racers, to more than double that for some single-seaters, with

The high downforce hill-climber is not a low drag car!

COMPETITION

162

CAR PREPARATION

exposed wheels and drag-inducing high downforce aerofoils. But some of the same tweaks can be usefully employed on these types of competition car as well, including making sure body panels fit properly, a smooth under panel is installed, and the ducting to and from radiators is smooth, neat, and intelligently routed. The bodies of most sports racing and racing cars will probably already have come under the designer’s microscope and incorporate his or her ideas on trying to maintain low drag, at least to some extent. The majority, though, will not have been designed with the benefit of wind tunnel research, and even if the car has been wind tunnel tested, it may not have been refined too much as a result.

So how do you tell if one design of car is better than another in this respect? It’s not easy, but you can be reasonably sure that if the make. of car you want, or already own,

is or was

a front-runner in its cate-

gory then it won’t be any worse than the opposition. If, on the other hand, it looks like a shed,

and

it runs

around

at the

back of the pack, then maybe that tells you something. Such a car may possibly be purchased for a lot less than a frontrunner, and be ripe for the creation of your own design body kit. - But there are often far more tunes to be played when it comes to the aerodynamics of non-production based competition cars, again providing the rules allow some leeway, because you get to play with the balance between drag and downforce. Aerodynamic downforce Whilst drag is the part of the total aerodynamic force that acts against the forward motion of a car, there is another element

of the aerodynamic force which acts vertically, that is at right angles to drag. It can act upwards, in which case it is called positive lift, and it is that force which keeps aeroplanes in the air; or it can

act downwards,

called

negative

in which

case

lift, or in motor

it is

racing

parlance downforce. My previous book, Competition Car Downforce: A Practical Guide (G.T. Foulis, 1998) explains in far more detail than we have space for here how downforce

is created, and how it is

exploited by competition cars. Whether a car creates positive lift or downforce depends on how it is designed with respect to channelling airflow

over,

around,

and

under

it. Most

production cars actually create lift, which is why the steering tends to feel lighter at high speed than at low speed — the aerodynamic force actually lessens the weight of the car pressing on the ground. There are a few exceptions to this, such as the Escort RS Cosworth, with its front spoiler and large rear aerofoil, which creates a small amount of genuine downforce, but by and large it has been the very design work that went into creating low-drag shapes for production cars that means they generate lift. Basically, lessening drag has led to more curvy upper body shapes that bear some resemblance in side elevation to an aeroplane wing shape, which is to say, more curved on top than on the underside. This shape has the effect of making the airflow above move faster than the airflow below, which causes lower pressure above than below, and so a net upwards force — aerodynamic lift — results. For a competition car, lift is not really a good thing. It means that as speed rises, the effective weight acting on the tyres reduces,

which

means

in turn

that

the

available grip reduces, and that braking and cornering capabilities in particular are consequently reduced (acceleration is also potentially reduced, but only if there is enough torque available to spin the wheels in the higher gears and at the higher speeds where lift is sufficient to reduce grip). Conversely, if lift can be cancelled,

or even

reversed

and

turned

into downforce, then high-speed grip can be enhanced. There are arguments for and against the desirability of downforce existing in motorsport, and I don’t propose to go into them here. But the

BODYWORK

AND AERODYNAMICS

inescapable fact is that downforce, efficiently exploited, can increase the performance of your competition car. The phrase ‘efficiently exploited’ is central to the art and science of competition car aerodynamics, and it relates to the balance between drag and downforce. But Nature never offers something for nothing, and with additional downforce comes additional drag. The skill of the aerodynamicist is in getting the most downforce for the least drag. But as one wise motor racing engineer once said, all we can do is try to encourage the air to do what it really would prefer to do anyway. Top Formula 1 teams invest millions of pounds in computational fluid dynamics (CFD) software and sophisticated wind tunnels so that the odd percentage point gain can be eked out here and there to try to get ahead of the opposition, and all the time they are trying to get more downforce for less — or at least no more — drag. How do the rest of us hope to make improvements? By trying things, and testing and evaluating them on the track. Again, what you are permitted to do in this respect will be dependent on the rules you are compelled to run to, but I’m assuming that if you compete in, say, a restricted one-make series where wings and spoilers are not permitted, then you are either skipping this section, or just reading it for interest’s sake, in which event, thanks for staying with us! So let’s assume you run a productionbased competition car, and that you have determined to try to negate some of the naturally occurring lift, or even create some genuine downforce. What routes do you need to try? The first thing to keep in mind is that you really want to try to end up with a car that is aerodynamically balanced, which means ideally that you want the same split of downforce on the front and rear axles as the static front:rear weight distribution. This is a fairly simplistic approach, and anyway may not be achievable, but it’s a reasonable target to shoot for, because it

163

means that the cornering characteristics of your car will stay pretty constant whatever speed you are doing. So you need to create downforce at the front and at the rear. Generally it is easier to obtain downforce at the front of the car because the airflow at the front hasn’t yet been messed about by the rest of the car (to put it very non-technically). There are various styles and shapes of appendages that you could add at the front to negate some of the naturally occurring lift, and interestingly the airdam style of front spoiler mentioned earlier in the context of reducing drag can also help to reduce front end lift. The deeper the airdam, the greater will be the reduction in front end lift, and with luck you may even be able to create some actual downforce. But the most efficient set up, in lift cancellation versus drag reduction terms, is not necessarily with the deepest possible airdam, so some testing and evaluation on your particular car may be necessary. For still more improvements to front end aerodynamics we look next to the ‘splitter’, which in its simplest form is a horizontal flat extension projecting forwards at the bottom of the airdam. Look at Super Touring Cars in 1998/9 aerodynamic configuration for some well refined

airdam/splitter packages and you will get endless inspiration for a time-consuming but possibly very beneficial raceshop project. At the rear of the car, there

are

two

possible routes to cancelling some _ lift and maybe turning that into downforce, and as implied earlier, you may need a more radical device at the rear to balance the improvement at the front. The first is the conventional rear spoiler, which in its most basic guise, as used on NASCAR stock car racers, is a flat, nearly vertical

plate extending above the boot line. This shape can be refined with an angled, possibly curved fairing leading up to the trailing edge from the boot surface. The effect on the airflow is to create a higher pressure over the boot area, which

164

COMPETITION

CAR PREPARATION

|

Duncan Barnes’ Mini front spoiler was inspired by Super Touring Car designs.

Rear spoilers don't get any simpler than this, but they’re still effective.

BODYWORK

AND AERODYNAMICS

negates or reverses the natural lift force. However, the best appendage for creating downforce

is, of course, the inverted

aerofoil, or wing. If permitted, a wing will create its own downward force to improve rear-end grip, and if your category’s rules are particularly liberal you may even be allowed to adjust the angle of attack of the wing to change the car’s balance, since wings create more downforce the more steeply inclined to the airflow they are — up to the point that they stall, that is. When this happens, at somewhere between 15° and 20° angle to the airflow, depending on the installation and the efficiency of the wing profile, the downforce goes away but the drag remains, and possibly even increases. This will not help your car’s handling, or its times. Aerodynamics tend to be pretty tightly regulated on production-based competition car categories, Super Touring Cars or

World Rally Cars being good examples. But generally speaking, the sports racing and racing car categories, though having

165

their own particular restrictions, allow more freedom in the first place to try out downforce-inducing devices, and nowhere is this better exemplified than in Formula 1, where lots of inspirational ideas can be observed. F1 designers maintain that aerodynamics represents the most important single area of their cars’ performance that is under their control (tyres and engines are supplied to them, usually). As such, they spend vast amounts of time refining and chipping away to get a few small improvements each close season, in a constant battle of wits with the regulators, who are just as intent on preventing per-

formance escalation. Not only do we see changes in wing configuration, but also detail alterations to wing end-plates, sidepod shapes, and also underbody shapes too. Fl cars get a sizeable chunk of their overall downforce by exploiting the airflow that passes beneath the cars. They do this by stimulating the air to flow fast under the car, which maintains low pressure under the

Considerable thought and effort went into this Formula 750 diffuser.

COMPETITION

166

CAR PREPARATION

body. The driving force behind this fast, low pressure flow is the diffuser at the rear. This expanding duct (which is what it is) causes the air ahead of it to rush in and fill it as the car moves along at speed, and this is what creates the fastflowing, low pressure region underneath, which is concentrated just ahead of the diffuser. Interactions between the lower elements of the rear wing also help to suck air through the diffuser, which in turn adds to the effect and further increases downforce. So, suitably armed with this concept, a sports racing or racing car can usefully be modified with a smooth, flat underside as

previously mentioned, but with the addition of an upswept diffuser at the rear. This provides not only the low drag, clean flow alluded

to earlier, but also a

fast, low-pressure flow that creates downforce. No wonder, when Colin Chapman excitedly unveiled this ‘ground effect concept’ along with the Lotus 78 in 1977, that he stated that they had found ‘something for nothing’. This was something of an exaggeration in reality, but it reflected the efficiency of the principle.

Evaluating aerodynamics There are two basic ways of evaluating the aerodynamic performance of your competition car. One is to track-test it, and do the best you can to evaluate the influence of the aerodynamics using driver feel, timing, and data acquisition if fitted. The other is to hire some wind tunnel time. No, don’t laugh. It is possible to hire the full-scale wind tunnel at the Motor Industry Research Association (MIRA) at a price well short of exorbitant, for a couple of hours, or half a day even, and get some really useful, hard aerodynamic

data

on

drag,

lift, or downforce,

and the effects of changes to aerodynamic configuration. You can also use ‘flow visualisation methods’, using smoke plumes and wool tufts, to look at the details of airflow quality into and out of cooling ducts, or at any other point of special interest.

It’s a really useful exercise to carry out, and for roughly the cost of a set of new race tyres you can gain some invaluable information. What you need to do to maximise the benefit of your all-too-brief session, though, is to prepare thoroughly, so that you waste as little time as possible making changes, and spend as much time as possible obtaining data. So if you aim to measure, for example, the effects of changes of spoiler height or wing angle, then make sure you can change them quickly and easily, substituting wing nuts for nylocs and so forth beforehand. If you have to do a ‘with versus without’ test on a component, fit the thing before you go to the tunnel, and once you've tested ‘with’, take it off and test ‘without’ — it’s

usually a lot faster removing components than fitting them. If you want to use wool-tuft flow visualisation and take photos, stick roughly 3in (75mm) tufts of wool with masking tape not just around areas you are especially interested in, but all over the body. You'll kick yourself afterwards if you don’t do this, because it’s actually quite helpful to us amateurs to be able to envisage what the air is doing around our competition cars. The pros will tell you they don’t bother with this kids’ stuff any more, but don’t you believe them! They just do it on their computers instead. Smoke plume visualisation also helps to envisage what’s going on, and can tell you extremely useful things like whether or not air is actually flowing into that new

cooling

duct

you’ve

just incorpo-

rated. So wind tunnel time is amazingly valuable, and once you've tried it you’ll want to go back for more. But the cost would mount up pretty quickly, and having got some basic data and information on the scale of change to downforce and drag brought about by modifications and adjustments, you have the essentials anyway. Track-testing, on the other hand, is perhaps what really matters, because gains on the track are what you’re seek-

BODYWORK

AND AERODYNAMICS

167

MIRA’s wind tunnel can provide masses of data at reasonable cost. (Tracey Inglis)

ing after all. So having found some improvements in the wind tunnel you need to establish whether they make significant differences to your car’s performance and handling. However, you can also do some valuable aerodynamic testing on track, which is useful if wind tunnel time is not available to you. For example, the wool-tuft flow visualisation method can be done at a suitable venue where you can get a friend to drive another vehicle alongside your competi-

tion

car,

and

a second

friend

to

take

photographs. You don’t need to go fast, 30mph (S0kph) or so is fine. Take pic-

tures

at around

1/60

to 1/125

shutter

speed, providing your camera gives you that level of control. That way any tufts that are fluttering in turbulent air will show up as fan shaped blurs. If you use too fast a shutter speed, the fluttering will be ‘frozen’ in the photo, and you will not see it. Another method of visualising flow is to put drops of fluid (diesel oil is

Wool tuft photos can be taken from trackside. (Tracey Inglis)

168

COMPETITION

good), coloured with poster paint powder or food dye, on to areas of interest, and then drive the car. The fluid will

run out along the bodywork, leaving behind visible streak marks — which can also be photographed for a permanent record — that tell you what the airflow at the bodywork surfaces was doing. Testing against the clock is the only real way to evaluate the benefit or otherwise of aerodynamic (or any other) changes to the competition car, and by driving the car hard enough you will also be able to feel any changes to its handling characteristics. Top speeds can be assessed by remembering or logging rpm or speed maxima achieved on straights. Altogether, you can do a_- surprising amount of evaluation on your competition car’s aerodynamics, with or without the benefit of a wind tunnel. Making bodywork If you can shape sheet aluminium or layup glass-reinforced fibre, you can make your own body panels or aerodynamic appendages. Sheet aluminium lends itself to creating simple, single-curvature shapes, unless you are a craftsman with the equipment to put complex curvature Spoilers can be simple and effective.

CAR PREPARATION

into it. But even the most basic raceshop and modest skill of hand can be put to making simple spoilers and even aerofoils in aluminium. Glass-reinforced fibre moulding techniques can more easily be applied to making more complex shapes, though a fair degree of manual skill is needed at the ‘pattern’ making stage. The process usually goes in three stages: pattern, followed by mould, followed by moulding. Various levels of materials sophistication are available for use in the home raceshop, and if you can lay-up glass fibre in polyester resin, you can use these techniques to successfully lay-up carbon fibre or kevlar, in polyester resin or epoxy resin for improved strength and rigidity. There isn’t space here to go into all the practical details, but my next book ins'.this., ,