Can you tell us how much lower you went on the suspension, it doesn't sound like you are really dealing with a bump steer issue but something else not found yet. When you say the wheel is jerked out, under what circumstances, power on, decel, turns left right both, under braking? Have you checked the steering rack mounting bolts, it's something some forget but an easy fix for something that can cause a tremendous amount of why it drives differently. More info please

 

The wheel jerks when I hit bumps or dips in the road one one side of the car but not the other. Whether it jerks toward or away from that side depends on it if was a bump or a dip. Immediately after the bump/dip the wheel snaps back to center. The steering doesnt feel loose or sloppy though, very precise handling and great feeling of control as long as the road is perfect (a rare find in MI). To answer the questiob about the drop, the only thing lowering the car is the SVT kit which says 1 to 1.5 inches, though Id say its more like a 2 inch drop.

Under acceleration I get pulls to one side or the other if the wheel isnt straight or if the road isnt level or smooth. Otherwise it keeps true. I assume the above is just tq steer due to it being fwd with an open diff. This effect is significant but less dramatic than the bump steer effect.

Least prominent of all three would be brake steer. No pattern I can identify as to when it pulls and when it doesnt, or why it pulls one way vs another. My rear brakes are drums and are pretty rusty. Ive replaced the drums bearing shoes and hardware twice in 3 years and they just rust out so fast. Ive ignored it for a while since i have the MSS rear disc brake kit waiting to go on this summer, but Id always assumed the poor rear brakes were the cause of the sporadic brake steer issues.

All that being said, its certainly possible that what I percieve as three distinct issues all actually share a common cause, or at least a common contributor.

 

Do you have access to a bump steer gage? Although my suspension is heavily modified (added MKIII knuckles), I had to raise the rack 7/8 inch to zero out the bump steer. Yours won't be the same, but using a bump steer gage to find out what the suspension is doing under travel is the surest way to see what is happening.

Pappy

 

I had no idea such a thing existed, but that sounds really promising! Would any old alignment shop have one of these? Only performance/tuning shops?

 

Possibly a stabar issue since it is occurring under single-wheel road events, you said the stabar bushings are shot, and that the steering snaps back afterwards. Maybe some undesirable movement of the bar is exerting additional steering moment on the strut. The link geometry orientation probably isn't ideal under lowering, exacerbating the issue.

 

Hmm, could be. I may end up fast tracking my upcoming project which includes replacing both subframes as well as some odds and ends suspension items. I could replace the front bar bushings and steering rack bushings while im at it and see if that helps before taking it in for a bump steer assessment.

 

Sway bar bushings should have no effect on actual bump steer, but loose/bad rack bushings can. If either end of the rack is moving up or down under load, that changes the height of the inboard tie rod pick up point which changes the bump steer for that wheel. Bump steer is a function of the heights of the inner and outer tie rod pick up points and the length of the tie rods. If the steering is adjusted where the tie rods are not equal length, then that will also make the bump steer different for each of the drive wheels.

Pappy

 

Thanks for that input. I would probably be able to get a better idea of what's going on under there if I could get the car in the air (pull/push on the steering rack, etc). Between the SVT kit and the front SAP kit I can no longer drive my car onto my ramps or get the a floor jack to the torque mount on the front subframe to jack it up. Didn't think about that until it was too late, now I will need lowpro ramps and a lowpro jack (not cheap). Might just rent a bay for now to get this taken care of.

 

Before u go spending money on new ramps and jacks, a couple of pieces of 2x4 staggered and nailed together, build it three pieces high, place one in front of each front wheel, drive up the jack should be more than lower enough, lift up, put jack stands under and check out what's going one. Simple with some wood, hammer and nails she is up in the air.

 

All fixed. It was a front lca bushing that was completelt destroyed. The steering rack and its bushings were tip top. So much morr enjoyable to drive now!! Check out my album in my singature for pics if the job, also have info on it in my build thread.

 

Thats great you figured it out...

 

...and great that you came back and updated us with the solution! Thanks

 

I was surprised, I had more or less ruled out control arm or sway bar link or tie rod issues because I replaced all that stuff two years ago. The rear LCA bushings were also destroyed, annoying because I replaced those 2 yeara ago as well. Maybe a design or a geometry problem. Or a michigan pothole problem.