What causes 'bump steer'?

..When your steering wheel turns every time you go over.. you guessed it, a bump? Just had all 4 of my wheels tracked, straightened, had new anti-roll bar link rods fitted- and still it happens. What is the best way to neutralise it?





It's a Merc Vito 109 CDI 2005. (rear wheel drive)





Thanks in advance|||To stop the problem you have to adjust the caster setting more positive. you may have made some suspension alterations that require a custom alignment.Bump steer is caused by loose front end parts or the steering being too easy. Positive caster will make it harder to steer and eliminate the problem.|||M4D_MIKE: http://en.wikipedia.org/wiki/Mercedes-Benz_Vito


Thanks again Mike T.

Report Abuse

|||When you say "turns" I'm not sure as to what extent you mean, as you will have your hands on the steering wheel, as the wheel goes over a bump you will receive a steering wheel deflection (normal) ,but only a minor amount, say for example with your hands at the ten to two position on the steering wheel, i would think they deflect to the five to three position, but as others may say at what speed do you hit these bumps at etc, and I say the same thing. Lets say a normal speed for example.





If the deflection is excessive then something more elusive is occurring


Does your car have power assisted steering, the reason I ask is that with the steering wheel stationary there is a "hold condition" within the hydraulic control /steering box.


I have had (in the past) /experienced similar effect on wheeled military vehicles namely the Saracen and the steering box that housed the "spool valve" had a weak anti torque spring which through steering "kickback" due to bumps etc would cause the hydraulic system to put a slight lock on (steering wheel excessively moved but only for a second a sort of steering wheel bounce).


With what you have had done, the only other thing I can think of is that is your steering rack secure/correctly mounted and mountings are tight.|||the vito is not rwd and every time you hit a bump the wheel looses traction and spins up when it lands you get a tug in that direction try driving to suit the road. look out for the bumps and drive to match. also have your shocks checked they are the principal cause of this problem|||You must have "wear/play" somewhere.


Have you tried jacking the front of the car up (block the back wheels)


Get one wheel off the ground, try rocking the wheel up %26amp; down and left %26amp; right, (ideally with a helper rocking) and you looking for worn parts.


Do this on both wheels.


Hopefully you feel or see a "worn" joint or unit.


Then replace if possible.|||All has to do with the original design steerring geometry. Some cars have great handling but if they go over a bad bump half way round a corner it can cause them to deviate off line. Not a problem as long as you know the car. Can be minimised by stiffer shockers. Not sure what all this %26amp;/hash/38/39 stuff refers to.