Bumpsteer

Bumpsteer is the car steering itself. As the suspension moves through its travel, the steering tie rod traces an arc that does not match the arc of the suspension arm, so the wheel's toe changes - and the car changes direction without you asking it to.

Every car has some. It becomes a problem when you lower the car, because lowering moves the suspension geometry away from the position it was designed to work in, and the mismatch between those two arcs gets worse.

Why it matters to a drift car

You are driving on the limit of rear grip with the front doing the work, often on a surface with real bumps in it. A front end that steers itself over every undulation is a front end you cannot trust, and the symptoms are the car darting, tramlining, or feeling nervous mid-corner when nothing you did should have changed anything.

It also undoes the precision you paid for in an angle kit. A kit that gives you beautifully adjustable geometry at static ride height is worth much less if the toe is swinging through suspension travel.

The fix

Roll centre adjusters, extended lower arms, or corrected tie rod ends - the components that restore the relationship between the steering arc and the suspension arc at your actual ride height. Most angle kits either include this correction or assume you have it, which is why the roll centre item sits next to the angle kit in the build order rather than after it.

Fit both in one go and you pay for one alignment instead of two.

How to check it yourself

With the car on the ground and the steering held straight, cycle one corner through its suspension travel and watch the toe. If the wheel steers as it moves, you have bumpsteer. On a lowered car with no correction fitted, assume you have some - the geometry has moved away from where it was designed to work.

Why it gets worse with stiffer suspension

Not because the springs cause it, but because a stiffer car rides over surface changes rather than absorbing them, so the suspension travel that produces the unwanted steering happens more abruptly. The same amount of geometric error feels much worse.

Where it sits relative to the angle kit

Alongside it, not after it. The roll centre and bumpsteer correction components are frequently part of the same kit or assumed by it, and they share the alignment that has to follow. Fitting the kit, aligning, then fitting correction means paying for two alignments.