Suspension Adjustments for Handling

Written and conceived by Susquehanna MotorSports

Near neutral handling characteristics are usually required to provide high performance cars with the ability to win in competition. While most event sanctioning organizations and clubs limit the degree of modification allowed to your suspension, it is still possible to adjust the basic handling characteristics of your vehicle and still be legal for your class of competition.

Usually the tire and road wheel's modifications offer the greatest improvement and are the easiest to perform. Your tires are the most important performance components on your car. The traction which they provide allow your engine's horsepower to be turned into acceleration, your suspension's springs, shock absorbers and anti-sway bars to be turned into cornering force, and your brake system's calipers, pads and rotors to be turned into stopping power. Therefore, any modifications that allow the vehicle to exceed the abilities of your tires will not necessarily provide the faster lap times you desire.

Any changes made to the vehicle's suspension and braking systems must be done with care and understanding. Some of the recommended adjustments will affect the vehicle's cornering capability, while others will primarily affect the vehicle as it transitions from straight-line acceleration to braking and cornering; and others, such as spoilers and ground-effects, will only affect its high speed handling.

Change only one component at a time. If more than one component is changed at a time, you won't be able to determine which change caused the resulting effect. Plan to follow a series of deliberate planned changes. Measure the test results as accurately as possible. Keep records of each modification's test results.

Take your time to test-drive the modifications made to your car and evaluate its new handling characteristics. Begin with test speeds well below your vehicle's known safety levels - work up to its new limits carefully!

Any time you make additional modifications you should retest your car.

There are quite a numbers of suspension elements which can be considered for change. These are listed in the order in which they effect handling.

Tires | Road Wheels | Wheel Alignment | Anti-Sway Bars | Spring Rates | Shock Rates
Suspension Bushings | Brake Proportion | Weight Distribution | Aerodynamics

 

Element to Adjust - Tires
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Inflation Pressure Increase (2.5# Increments) Decrease (2.5# Increments)
Rear Inflation Pressure
Decrease (2.5# Increments)
Increase (2.5# Increments)
Front Tire Width Increase Width Decrease Width
Rear Tire Width
Decrease Width
Increase Width
Front Aspect Ratio Higher Ratio Lower Ratio
Rear Aspect Ratio
Lower Ratio
Higher Ratio
Front Tread Depth Decrease Depth Increase Depth
Rear Tread Depth
Increase Depth
Decrease Depth

Element to Adjust - Road Wheels
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Wheel Width Wider Narrower
Rear Wheel Width
Narrower
Wider
Front Wheel Weight Lighter Heavier
Rear Wheel Weight
Heavier
Lighter

Element to Adjust - Wheel Alignment
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Camber More Negative More Positive
Front Caster More Positive More Negative
Front Toe
Toward Toe-out
Toward Toe-in
Rear Camber More Positive More Negative
Rear Toe
Toward Toe-out
Toward Toe-in

Element to Adjust - Anti-Sway Bars
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Soften Stiffen
Rear
Stiffen
Soften

Element to Adjust - Spring Rates
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Soften Stiffen
Rear
Stiffen
Soften

Element to Adjust - Shocks
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Soften Stiffen
Rear
Stiffen
Soften

Element to Adjust - Suspension Bushings
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Stiffen Soften
Rear
Soften
Stiffen

Element to Adjust - Brake Proportion
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Reduce Pressure Increase Pressure
Rear
Increase Pressure
Reduce Pressure
 

Element to Adjust - Weight Distribution
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Reduce Increase
Rear
Increase
Reduce

Element to Adjust - Aerodynamics
(Back to Index)


Adjustments and Modifications to Evaluate



To Reduce Understeer or Increase Oversteer



To Reduce Oversteer or Increase Understeer


Front Increase Downforce Reduce Downforce
Rear
Reduce Downforce
Increase Downforce

home