Can anyone explain to me what a "bump steer" modification consist of. I´m really eager to learn!

Cheers Roger

 

In doing this mod, what are the possible downsides/side-effectrs that could occur?

Lovejoy

 

Roger,

This is bumpsteer as I undestand it.

Compression of the springs (eg fronts under braking) causes a deflection in the front geometry consisting of an increase in toe-out on both sides.

The opposite effect occurs in rebound (when the springs are elongated) resulting in an increase in toe-in.

When you corner, the outside wheel acquires toe-out and the inside wheel acquires toe-in.
Thus both wheels point towards the outside of the corner = understeer The faster you corner, the more you load the suspension and the more understeer you get.

Removal involves shimming the steering rack to lower the track rod inner ends bringing them closed to horizontal which has the effect of preventing the changes in suspension geometry.

Because changes in compression/rebound of springs do not affect toe-in/out in the same way, mid-corner bumps do not unsettle the car so much.
If I am wrong we will no doubt both be informed shortly !!

Regards

DJ


[This message has been edited by DocJock (edited 15 August 2000).]

 

Oh! and one more question! If you dont like the effect can you have it put back!! I only ask as I noticed the words 'shimming the steering rack' sounds kinda serious!!!

 

There seems to be two threads on this subject today.

On the other thread this useful URL was noted: