bumpsteer and e36 rack spacer location

[Sagaris]

Everything I have read says to put the rack spacers on top, but taking a look at the geometry yesterday, the tie-rods would be more parallel to the control arms (on my car at least) if the spacers were put on bottom. I am going to change it up and put my rack spacers on bottom and see what happens.

[Hellabad]

Sooooo I think I MAY have put the spacers under the rack and read on e30tech that thjis can lead to bumpsteer

You need to take up some slack in the fitment, and under the rack is the best place for spacers. The geometry is best when the rack is close to the oilpan. (this has nothing to do with the oilpan, but you can't go higher because it's in the way)

What is bumpsteer?
if I need to change the spacer location can I get away with moving the spacers and keeping my alignment?

Probably not. Just moving spacers from one side to the other tweaks the to-in enough that you should recheck it. DO NOT PAY ANYBODY TO CHECK IT.

Buy a set of "toe-plates" and do it yourself.

http://www.amazon.com/Longacre-Toe-P.../dp/B000VAOHB2

[AndrewBird]

It is when the suspension and steering follow different arcs during suspension travel which will cause your car to turn just a bit when you hit a bump.

Not quite. Bumpsteer is a change in tow as the suspension compresses and decompresses. It doesn't make your car turn right or left, but it can make it feel "twitchy" and less stable in certain circumstances. On the street, I don't think most people would notice a difference. It is caused by the tie rod and the control arm having different pivot points (following different arcs as Sagaris put it). Ideally, they should be the same, but pretty much every car ever made has some bumpsteer in it. It's kind of hard to get rid of from a design standpoint.

This website has some good info:

http://acceleratingperformance.blogspot.com/2009/01/bump-steer-bump-stops.html

[Sagaris]

It is when the suspension and steering follow different arcs during suspension travel which will cause your car to turn just a bit when you hit a bump.

Good:

http://www.miracerros.com/mustang/t_animated_bumpsteer_0.gif

Bump steer:

http://www.miracerros.com/mustang/t_animated_bumpsteer_1.gif

[bastianshaw]

Sooooo I think I MAY have put the spacers under the rack and read on e30tech that thjis can lead to bumpsteer

What is bumpsteer?
if I need to change the spacer location can I get away with moving the spacers and keeping my alignment?