What effect does a "bump steer" condition have on a vehicle's steering response?

The concept of "bump steer" refers to a condition where the vehicle's toe angle (the angle at which the wheels point relative to the centerline of the vehicle) changes unexpectedly during suspension travel, particularly as the wheels respond to bumps in the road. This unintended change can occur because of the suspension geometry, which may not allow for the desired relationship between vertical wheel movement and steering response.

When a vehicle experiences bump steer, as one wheel travels upward (for example, over a bump), it can cause the toe angle to shift. This results in the vehicle steering itself in an unpredictable manner, which can lead to a disconcerting driving experience. The driver may feel that the vehicle is wandering or responding differently than expected, particularly during cornering or when hitting irregularities in the road surface. This negative effect on steering can compromise the precision of vehicle handling and diminish the driver's confidence while driving.

Overall, understanding bump steer is critical for assessing vehicle dynamics and ensuring proper vehicle alignment and handling characteristics.