Wandering all over the road (bump steer?)

[Wishart]

More of a general question really, thankfully I havnt suffered from this in my last few dubs but my old bus did on occasion, take off into the centre of the road after a bump, and with the steering wheel going the other way :lol: :shock:

What causes bump-steer? Am I right in thinkin that it affects lowered vehicles more than standard height? What adjudstments would fix it?

I have plans for lowering the bus again, but just wondered about this potential issue.

 

[uber cool]

You will probably find a good explaination via a google search. It's to do with the arc the steering arm travels through whilst moving up and down due to normal suspension travel. As the suspension moves up so will the steering arm in an arc. It will have been designed so that the radius movement of the arm to hub remains the same. When we lower cars we move the hub up but leave the fixed point of the arm in the same place. Hence altering the relationship between steering arm and hub. Done to an extreme it can mean when the suspension is compressed the steering arm effectively becomes longer and hence pushes or pulls the wheel and has the effect of turning the wheel.
However I would suspect most buses just have a knackered centre pivot that's cause the bus to wander

 

[67 BAY]

Fit anti bump steer bushes,this puts the track rod ends under the steering arm rather than on top.This then levels the arms out rather than sloping up,which happens when you lower a bus,you will have to change to 2 adjustable track rods instead of having a fixed one.


Steve