How to Remove Understeer and Oversteer
UNDERSTEER
The first stage to check is if there is any friction or jamming of suspension components in the front suspension system as this can cause the front to jam and prevents the spring and damper from working.
CORNER ENTRY
The first question to ask now you have identified the understeer as occurring in corner entry is, are you entering the corner after being hard on the brakes?
If the answer is yes then you have two options to solve the understeer:
1) Increase front damper rebound stiffness. If you have high or low speed damper adjustment then increase the low speed rebound stiffness only.
2) Reduce the front brake bias.
If the answer is no then you must ask yourself another question, are you entering the corner at high speed or mid to low speed?
If the answer is high speed then one of the following options can be used to solve the understeer:
1) Reduce front ride height
2) Increase front aerodynamic downforce. If only the rear is adjustable then reduce rear downforce.
3) Check tire pressures to ensure that the tires are operating within recommended hot temperatures. Increase or decrease pressures accordingly.
4) Check tire temperatures and make sure that the temperatures are distributed by between 10 and 15 degrees Celsius between edges with the inside being the hottest.
If the inside is too hot then increase positive camber. If the outside is too hot then increase negative camber.
If the answer was mid to low speed then one of the following options can be used to solve the understeer:
1) Increase caster angle
2) Increase front toe out
3) Reduce front ride height
4) Check tire pressures to ensure that the tires are operating within recommended hot temperatures. Increase or decrease pressures accordingly.
5) Check tire temperatures and make sure that the temperatures are distributed by between 10 and 15 degrees Celsius between edges with the inside being the hottest. If the inside is too hot then increase positive camber. If the outside is too hot then increase negative camber.
MID CORNER
The first question to ask now that you have identified the understeer as occurring at the mid corner section is, does the car bottom out?
If the answer is yes then the below answers can solve the understeer:
1) Increase front coil spring rate. This can be achieved by installing stiffer springs or increasing pre-load.
If the answer is no then the next question to ask yourself is, does the front of the car roll excessively?
If the answer is no then the following solutions can be applied:
1) Soften front coil spring rate
2) Increase front damper rebound stiffness. Front compression stiffness can also be reduced slightly.
3) Reduce front ride height.
4) Soften front anti-roll bar stiffness.
5) Increase negative camber on the front wheels.
6) Lower front roll center or raise the rear roll center.
7) Check tire pressures to ensure that the tires are operating within recommended hot temperatures. Increase or decrease pressures accordingly.
8) Check tire temperatures and make sure that the temperatures are distributed by between 10 and 15 degrees Celsius between edges with the inside being the hottest.
If the inside is too hot then increase positive camber. If the outside is too hot then increase negative camber.
If the answer was yes then the following solutions can be applied:
1) Soften front anti-roll bar stiffness
2) Increase front damper compression stiffness. Increase low speed if you have a high or low speed option.
3) Increase front coil spring rate.
4) Make sure there is no excessive droop in the front suspension causing the inside front to lose traction.
5) Raise the front roll center.
OVERSTEER
The first stage to check is if there is any friction or jamming of suspension components in the rear suspension system as this can cause the front to jam and prevents the spring and damper from working.
CORNER ENTRY
With the oversteer identified as occurring in the corner entry section, the first question to ask yourself is, are you turning into the corner straight after being hard on the brakes?
If the answer is yes then one of the below options can be applied:
1) Slightly reduce rear damper rebound stiffness
2) Reduce rear brake bias
3) Check tire temperatures and make sure that the temperatures are distributed by between 10 and 15 degrees Celsius between edges with the inside being the hottest.
If the inside is too hot then increase positive camber. If the outside is too hot then increase negative camber.
If the answer is no then you must ask yourself another question, are you entering the corner at high speed or mid to low speed?
If the answer is high speed then the below areas can be applied to the car to solve the oversteer:
1) Increase rear aero downforce
2) Reduce rear ride height
3) Slightly increase rear toe in
If the answer is mid to low speed then another question must be asked, is the car lifting a wheel at the rear?
If the answer is yes then one of the below solutions can be applied:
1) Increase droop on the rear wheels to ensure that the tire stays in contact with the ground.
2) Lower the rear roll center.
3) Reduce the rear anti-roll bar stiffness
If the answer was no then the below solutions should be applied to your car:
1) Increase rear toe in
2) Reduce rear ride height
3) Reduce rear damper compression stiffness
4) Check tire pressures to ensure that the tires are operating within recommended hot temperatures. Increase or decrease pressures accordingly.
5) Check tire temperatures and make sure that the temperatures are distributed by between 10 and 15 degrees Celsius between edges with the inside being the hottest.
If the inside is too hot then increase positive camber. If the outside is too hot then increase negative camber.
MID CORNER
With the oversteer being identified as occurring in the mid corner section, the first question to ask yourself is, are you going through the corner at high speed or mid to low speed?
If the answer is high speed then one of the below solutions can be applied to reduce the oversteer:
1) Increase rear damper rebound stiffness
2) Increase rear aero downforce (this will sacrifice straight line speed)
3) Soften rear anti roll bar slightly
If your answer was mid to low speed then you must ask yourself another question, does the car bottom out?
If the answer is yes then you can apply one of the below options:
1) Increase rear coil spring rate.
2) Increase rear ride height
If the answer is no then you must ask yourself another question, does the rear of the car roll excessively?
If the answer is yes then one of the below options can be altered:
1) Increase rear coil spring rate.
2) Increase rear anti-roll bar stiffness
3) Raise rear roll center
If the answer once again is no, then the following solutions can be used to reduce oversteer:
1) Soften rear anti-roll bar stiffness
2) Soften rear coil spring rate
3) Reduce rear ride height
4) Lower rear roll center
5) Check tire pressures to ensure that the tires are operating within recommended hot temperatures. Increase or decrease pressures accordingly.
6) Check tire temperatures and make sure that the temperatures are distributed by between 10 and 15 degrees Celsius between edges with the inside being the hottest.
If the inside is too hot then increase positive camber. If the outside is too hot then increase negative camber.
CORNER EXIT
If you have oversteer occurring in the corner exit section then there are no questions to ask yourself and one of the following solutions can be applied to reduce the oversteer:
1) Reduce rear ride height
2) Soften rear coil spring rate to allow the rear to squat slightly more on initial power application
3) Reduce anti squat geometry to allow the rear to squat on power
4) Reduce rear damper compression stiffness
5) Ensure there is no excessive droop in the rear suspension causing the inside rear tire to lose traction.
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Source: https://suspensionsecrets.co.uk/how-to-remove-oversteer-and-understeer/
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