RC Tuning – Bumpsteer

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 will experience Bumpsteer! This effect will cause the car to bounce back and forth through bumpy track sections instead of going straight!

Tuning with Bumpsteer

As a general rule, this should work for all cars (assuming you have 2deg of kickup):

• 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.

Again, this 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.