🔧 Bump Steer
Unwanted toe change that happens as the suspension moves up and down, caused by steering linkage geometry that doesn't match the suspension arc — makes a car wander over bumps.
What it actually does
Bump steer is unwanted steering that happens on its own when the suspension moves up and down, without you touching the wheel. It comes from the steering link and the suspension arm swinging on different arcs, and it makes a car dart unpredictably over bumps and on landings.
In practice
It is checked by lifting and lowering the suspension by hand with the steering held straight and watching whether the wheels turn. It is corrected with shims or spacers under the steering ball studs so the link swings on a matched arc.
Worth knowing
Bump steer often appears after a ride height change or a rebuild, so re-check it whenever you have altered suspension geometry. A car that suddenly darts on rough sections is worth checking here before you change tyres.