Racing setup

In motorsport, the racing setup or car setup is the set of adjustments made to the vehicle in order to optimize its behaviour (performance, handling, reliability, etc.) for specific conditions. Adjustments can occur in suspensions, brakes, transmission, and many others.

Aftermarket modifications and adjustments to affect handling

The following trends will apply in most cases, but there can be exceptions to some of these. Generally changes should be made one at a time, in small steps.

Component Reduce Under-steer Reduce Over-steer
Weight distribution centre of gravity towards rear centre of gravity towards front
Front shock absorber softer stiffer
Rear shock absorber stiffer softer
Front sway bar softer stiffer
Rear sway bar stiffer softer
Front tire selection1 larger contact area² smaller contact area
Rear tire selection smaller contact area larger contact area²
Front wheel rim width or diameter - will change the SHAPE but not area larger² smaller
Rear wheel rim width or diameter - will change SHAPE, but not area smaller larger²
Front tire pressure* lower pressure higher pressure
Rear tire pressure* higher pressure lower pressure
Front wheel camber increase negative camber reduce negative camber
Rear wheel camber reduce negative camber increase negative camber
Rear spoiler smaller larger
Front height (because these usually
  affect camber and roll resistance) 		lower front end raise front end
Rear height raise rear end lower rear end
Front toe in decrease increase
Rear toe in decrease increase
1) tire contact area can be increased by using wider tires, or tires with fewer grooves in the tread pattern. Of course fewer grooves has the opposite effect in wet weather or other poor road conditions.

2) These also improve road holding, under most conditions.

* Actually every tire has its "optimum" pressure at which it makes the most grip. Above this grip slowly drops and below this it drops quickly. Just keep this in mind so that if you find dropping pressure improves that end of the car or adding pressure lowers it.

In addition, lowering the centre of gravity will always help the handling (as well as reduce the chance of roll-over). This can be done to some extent by using plastic windows (or none) and light roof, hood (bonnet) and boot (trunk) lid materials, by reducing the ground clearance, etc. Increasing the track with "reversed" wheels will have a similar effect, but remember that the wider the car the less spare room it has on the road and the farther you may have to swerve to miss an obstacle. Stiffer springs and/or shocks, both front and rear, will generally improve handling, at the expense of comfort on small bumps. Performance suspension kits are available. Light alloy (mostly aluminium or magnesium) wheels improve handling and ride as well as appearance.

The car's roll centre is the other fundamental piece of the equation. Care must be taken to avoid lowering the centre of gravity past the car's roll centre. The distance between the car's centre of gravity and its roll centre is known as the roll couple, or the length that the car rolls around. Ideally, if the roll centre and the centre of gravity occupy the same space, the car should exhibit zero body roll.

Moment of inertia can be reduced by reducing weight, usually results from using lighter bumpers and wings (fenders), or none at all.

See also

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