GPL Setup Guide
Intro & What The Settings Mean
 

 

Introduction

My aim is to show you the principle that I use to set up cars to start you. There are more comprehensive guides should you find that you want to learn more. There are links to those guides here. I have also been privalaged enough to be given permission to host all the tools that I use so that after reading this guide you can pick them up and get started.

If you want to get further more technical information please go to the Useful Information page for Links and books that may help you.

I will only be using imperial measurements as that is what I am used to using. If you are used to using metric units I am affraid that you will have to convert them.

I must also thank Bas Van Meurs creator of the Tyre Temps Utility for his help in writing this guide, and to Robin (Stirling Herbert) of the Tleague whose questions promted me to write this.

Basic Principles

Do not assume that any particular setup must be better than others.

Try several peoples setups to find ones that you can drive consistently.

There are different basic types of track that will require different styles of setup.

You can use a setup for one car to give you a base line for another car.

What The Settings Do

I use Setup Assistant 65 by Marko Rasanen and Mark Stone to make a lot of my adjustments, some I do within GPL so I will use SA65 through out for illustration.

Suspension

The settings are the same for front and rear of the car.

Tyre pressure

If the tyre pressure is too high you will have very high temperatures in the middle of the tyre, this will mean reduced grip as the main contact to the road is the centre of the tyre.

If the pressure is too low you will have high temperatures on the outsides of the tyre, again you will suffer from poor grip.

I find that for racing in the 67's 19 psi is about right and the 65's 20 psi is good. I do vary them if I need to. These pressures do make life difficult for the first lap or two.

Wheel Rate

This is the rate of the spring. Lower means a softer car which is good for slower twistier circuits. Higher means a stiffer car which is good for fast circuits. Wheel rates will be higher at the rear because of the weight of the engine.

Bump and Rebound Rate

This is how much the damper controls the movement of the spring. An undamped spring will oscillate like a ball on a hard floor. The damper slows the spring's movement and makes a smoother transition back to it's normal position after hitting a bump or landing from a jump. It will also affect the way the car behaves in a corner because of the body roll

The lower the rate the less "damping" which is better for tight twisty circuits. Higher rates are more suited to faster circuits.

Bump and rebound rates will be higher at the rear because the weight of the engine.

Camber

This is the angle of the wheel on the road. The left wheel in the diagram has negative camber and the right positive.

Bump Rubber

This stops the upward movement of the wheel. Flat circuits need only the minimum, circuits like Nurburgring will need more. The taller the rubber the softer it is.

Toe, Roll Bar & Ride Height

Toe In

The Toe is the angle of the wheel relative to the centre line of the car. The illustrations below show the effects on the wheels of Toe In and Toe Out when looking down on the vehicle. Negative numbers in the Toe In box will give you toe out and positive numbers will give you toe In.

Toe Out is required on the front wheels and Tie In at the rear. These angles provide a force that will help to keep the car stable in a straight line.

Roll Bar

The roll bar stops the body of the car twisting relative to the wheels during cornering or acceleration. I use higher settings for fast circuits and lower ones for slower and twistier circuits.

Static Ride Height

This is the height of the bottom of the car to the ground. If the car scrapes on the ground you will need to alter this setting.

Fuel, Brakes & Steering

Brake Bias

This sets the amount of braking force that goes to the front and rear wheels.

25 will give you 25% braking force to the front wheels and 75% force to the rear wheels

50 will give you 50% braking force to both front and rear wheels

75 will give you 75% force to the front wheels and 25% to the rear.

Steering Ratio

This is how sensitive the front wheels are to the amount of turn on the steering wheel. Higher numbers make the response less sensitive.

Fuel

This is the amount of fuel in the car.

Gearing

Here you set the ratio for each gear.

Diff Settings

Diff Ratio

This will set the range of speed that can be achieved by the car, increase the ratio to make the car go faster.

Power/Coast Angle

The power and coast angles set how fast the differential engages high numbers mean a fast engagement, low numbers a slower engagement.

Clutches

The number of clutches will also affect the rate of engagement of the Diff. More clutches means a softer engagement.

To how I set a car up.