ok guys, I'm a Buick guy and this is a chevy site. can't we all just get along??? graemlins/clonk.gif

I have a few questions:
his is what I have, a 71 a-body, and 71 z28 spindles. my car is originally a disc brake car. I plan on doing the tall spindle set up if you haven't already guessed it. I plan on buying the correct control arms, and having ball joints turned down. My question lies within the bumpsteer. I don't really have an definition of it, or how to fix it. I searched through the threads, and it seems some people just live with it, and otheres remedy the situation. how does one fix problem? can one just live with it and drive safely? I'd rather not have a car that steered by itself? does anybody make a kit that fixes it?

thanks guys, Joe.

PS. if it makes you feel better a good friend of mine has a chevelle...

It's not that bad, for a weekend cruiser you would probably never notice it. Mine is still wack and my suspension is about the tightest on an A body you will find anywhere, it still drives nice with the exception of BIG bumps. Correction depends on how much fab work you want to do and how much money you want to spend. Could be as detailed as relocating the stering box and idler arm or as simple as running shorter outer tie rods. I think MC&C is working on something right now.

To answer your question "what is bump steer" -- it is a change in wheel angle (toe-in or toe-out) as the wheel moves up and down. It is caused by the inboard pivot point of the lower control arm being out of line with the pivot point of the tie rod. In a typical Chevelle suspension, these two points are fairly close vertically. In my 911 however, it's whole different story. With a rack-n-pinion setup, and lowered a couple inches, it has a nasty bump steer because the pivot point is about an inch to high. Sometime I'll remount the rack to correct that, but I'm more fun with my Elky! I've owned both cars for quite awhile and never noticed any bump steer with the Chevy. I did, however really tighten up the suspension for better handling (less body roll) The geometry in the Chevy seems more forgiving. Maybe, because in 60's and 70's, they had to factor in more body roll? Just a thought..
-Bill

With the correct a-arms it will be just fine. My 66 with stock arms and tall spindles had about 1/2" toe-in/out difference through full travel and when I installed global west arms the difference was about 1/8".

Todd.

Just to clarify a small point, bump steer has nothing to do with tie rods being level or parallel which is how I read that. Bump steer is a difference in motion between the lower control arm and the tie rods assemblies. The outer tie rod could be 3" lower than the inner as long as the lower control arm followed that same geometry.

Simply switching upper control arms from stock to GW should not have had any affect except that you probably changed all the alignment settings during the swap and therefore helped to correct the problem. Caster has an impact on bump steer measurements, as does toe-in/toe-out.

Thanks for the replys guys. So Basically I have nothing to really worry about huh? Does this sound worse than it actually is? I was pretty worried about it.

Baer brakes makes a tie rod kit to fix bump steer. Has anyone reviewed this product yet?

Baer brakes makes a tie rod kit to fix bump steer. Has anyone reviewed this product yet?Their "bumpsteer eliminator" kits move the outer tie-rod end downward, which is the wrong direction when using tall-spindles on a Chevelle. They are already too low, and those would just make it WORSE.

Stock A body bumpsteer is really bad. Total toe change over 6" of travel on a dead stock A body with stock alignment specs is over an inch! I know this because I`ve measured it on a number of them. Most of this is due to the outter tie rod ends being about .625" too low (the tie rods are also the wrong length but that`s a secondary concern in this case). This puts the apex of the arc the tie rod end swings in and the apex of the arc the steering arm and spindle swings in (and which is eliptical BTW) way out of sync. As the arcs diverge the spindle turns. The B body or 2nd gen F body spindle steering arms are about .625" lower still which roughly doubles the already poor bumpsteer. They`re also longer which messes up the ackerman angle,slows the steering ratio and increases the size of your turning radius. Adding aftermarket arms like GW (or ours) can help it *a tiny bit* by adding more + caster. That`ll A) help the car track a bit straighter and B) raise the outter tie rod end maybe 1/4" which frankly is too little to do much good when it`s this far out of whack. This is all very simple geometry,no smoke and mirrors and quite easy to measure.
The typical aftermarket "fix" is to add huge swaybars,stiff spring and shocks to limit the total travel you typically use. Double the bumpsteer but halve the travel and although the rate of bumpsteer has doubled you can say "look no increase in *total* bumpsteer!". Kinda like going to the doctor complaining it hurts when you raise your arm above your head,so he ties a string between your wrist and belt so you can only lift your arm half way. Voila! You`re cured. Pay the nurse on your way out please. :clonk:

Have heart though,there`s a VERY EASY FIX! Just don`t put the wrong spindles on your car in the first place. ;) Today there are MUCH better solutions. Mark SC&C