I have coilovers with tokico illuminas for my 71 Z. Will I need bump steer spacers, if I have 17 inch wheels? Thank you, TimsZ

The reason that shortening the strut/spring via the use of shorter springs or strut change causes an issue is that you alter the angular relationship between the control arm and the tie rod from the rack to the wheel hub.

Generally speaking, stock, the front control arm is at a approx 10-15deg angle to the ground as viewed from the front (wheel side lower of course) and the tie rod end follows the same angle. When you shorten the strut, however done, the control arm generally ends up more parallel to the ground. To compensate, you need to put in a spacer to restore the strut to stock length to get your steering geometry back when going over bump (control arm moves up, tie rod does not, result is some steering input you don't want... Overly simplified, its a 3D problem, but I hope you get the gist)

So, after you change out your strut assembly and get the car on the ground and settled (move car back and forth and steer L and R) just look at the control arm. If its more or less parallel with the ground, put the spacer in. If its still angled nicely like stock, don't bother.

In any event, on a street driven car you'll likely never feel the difference either way....

Edited April 3, 201313 yr by zKars

That's great info. Thank's so much, TimsZ