This article covers the key aspects of car suspension setup and tuning, depending on your suspension you can use this guide for road or race.
Suspension Setup – Spring Rates
Springs rates are increased for racing to stop weight transfer from front to rear and from left to right. By keeping the weight over all 4 tyres as consistent as possible allows all 4 tyres to grip more and therefore increase cornering speeds.
Suspension Setup – Ride Height
Generally speaking & up to a point, the lower the ride height, the less a car’s body will want to roll. As with uprated springs, by reducing the roll all 4 tyres can maintain maximum grip with the road. When lowering a car, the spring rates should be increased to compensate for the reduced travel in the suspension.
Weight distribution can be altered by changing the height of the suspension eg if the front is lower than the rear than there will be more weight over the front tyres than if the car was level.
Suspension Setup – Damping – Bump
Adjusting the bump of the suspension affects the rate at which the suspension compresses. if this setting is to rigid the car will bounce over bumps. Reduced bump resistance will make the car more comfortable. Too soft in bump will make the suspension bottom out of bumps.
When adjusting a damper you are seeking a compromise between compliance, so the tyre remains in maximum contact with the road/track at all times and control of the car’s body in direction changes (and for the road, preventing the suspension from bottoming out)
Suspension Setup – Rebound
The rate at which the suspension expands. The expansion stroke can be set much higher/stiffer than the bump stroke.
Suspension Setup – Camber
The degree by which the wheels point in at the top from the vertical. Increasing he degree of camber allows the tyres to be utilised more effectively. However increasing it too much will compromise the braking power of the tyres. The balance of the car can be altered by changing the degree of camber from the front wheels to the rear.
Suspension Setup – Toe
The degree by which the tyres point away from the straight ahead. Toe out on the front tyres reduces steering response but the tyres are less likely to lose grip through direction changes. Toe out on the rear wheels makes it easier to change direction but almost always introduces some oversteer. It can be said that adjusting the toe on the rear wheels has a greater effect on handling than adjusting the toe on the front wheels.
Suspension Setup – Anti Roll Bars
A bar which connects the suspension on the two sides of the car. When cornering the outside suspension will be compressed more than the inside. The anti roll bars are intended to reduce this effect ie try to make the two sides compress equally. A thick anti roll bar will be more effective at this than a thin anti roll bar.
As with spring rates, the flatter a car can corner, the better the grip on all 4 tyres and the higher the cornering speeds. In a straight line anti roll bars play no part at all as both sides of the car will be compressing by the same amount. Anti roll bars are purely a secondary measure in improving handling, the spring rate is the primary means by which to reduce body roll.
Fine tuning anti-roll bars can be used to adjust the handling balance of the car. Make the car oversteer or understeer. Increase the thickness of the rear antiroll bar makes the car want to oversteer more. Increase the stiffness of the front anti-roll bar promotes understeer,