What is Bumpsteer?
Bumpsteer gets its name from just that – undesirable steering while going through bumps.
A good way to check this is to set your race-ready car on a completely flat surface (race ready meaning with the battery installed) and slowly press down on the front of the car. Does the angle of the front tires switch from toe-straight to toe-in or out? If so, then you have Bumpsteer!
Bumpsteer will cause the car to bounce back and forth through bumpy sections of the track instead of going straight!
Bumpsteer can be changed by adding spacers under the link that connects to the steering arm. As a general rule:
• 0deg of caster, add a .100″ spacer under the front ball stud on both steering knuckles.
• 2deg of caster, add a .060″ spacer under the front ball stud on both steering knuckles.
• 4deg of caster, add a .030″ spacer under the front ball stud on both steering knuckles.
This also depends on the suspension geometry of your vehicle. You may have to experiment to get the desired effect you need. You should change the Bumpsteer EVERY time you change your caster.
If you change your car’s Camber Link Locations, Toe or Kickup, you will need to recheck your Bumpsteer settings.
See also: Active Toe, Toe In/Toe Out
Tuning with Bumpsteer
Less Bumpsteer
• Increases toe-in when compressed
• Less steering
• More stability
More Bumpsteer
• Increases toe-out when compressed
• More aggressive
• Less stable
Back to the RC Suspension Tuning Guide.
