Freshly installed Z3 rack not returning to center/bump steer issues

[Sagaris]

My initial test drive of my now Z3 rack swapped car was great except I have some bump steer and the rack doesn't return to center.

I searched and found a few threads that sound like a similar issue, none of which show any resolution to the problem.

1) http://www.e30tech.com/forum/showthread.php?t=109119

2) http://forums.eurocca.net/showthread...ering-problems

3) http://www.r3vlimited.com/board/show...turn+center%22

4) http://e30tech.com/forum/showthread.php?t=83378

5) http://forums.eurocca.net/showthread...ack-Conversion

6) http://forums.bimmerforums.com/forum....php?t=1200770

Background info:

1998 2.8 Z3 rack w/ 120k miles
1991 325i airbag equipped car
new E30 tie rods
e30tech alum. rack spacers installed above the rack
power steering working, filled with Lucas ATF fluid
alignment set to slight toe-in visually
had to get a used steering u-joint because the splines were bad on my original one



Problem:
I got my steering rack installed (not as easy of a task as I would have thought, but im sure if I ever do it again it will be a breeze). I topped off the res. and gave the car a few cycles back and forth with the steering while the engine was running (car off the ground). One observation is that after the first couple steering cycles the steering resistance increased. It still feels like a reasonable amount of resistance, but I thought it would behave the exact opposite and operate with increased resistance until the air bled out, then suddenly have less resistance once all the air was out. I got the car back on the ground and could feel the power assist working nicely. While driving the car it does not want to return to center. If I am making a right turn from a stop, as soon as i begin accelerating the car will just want to turn tighter to the right, rather than straighten out. Hitting bumps causes the steering wheel to turn one way or the other.

Initial thoughts:
I don't believe it to be an alignment problem: I went back home and noticed the toe was out just a bit, I turned it to toe in a tad and could feel that the alignment was set to toe-in on the next test drive, but the problem persists and do not believe a proper alignment ( will get one in the spring, car will be parked for the winter) will resolve the bump steer/ return to center issue.

I don't believe it to be related to the suspension or steering geometry:The suspension was completely refreshed a year ago and the car has driven absolutely perfect, stable, no noises, great steering return before the swap. Someone else with a Z3 rack and the same suspension setup does not have any issues, many other people have swapped the rack successfully using the same spacers in the same position, same tie rods etc.

I feel the steering joint (old flex disk) might contribute to the vague on-center feel, but not the root cause of my problems : link 6 up above mentions a little about this. I got a used steering joint because I ruined the splines on my original one. This used joint looked to be in comparable shape to the original and the u-joint is free of slop. The steering joint is not on any funky angles and I do not notice any binding in the joint or flex disk while turning the wheels back and forth. I would still like to get a fresh flex disk in there to be sure.

Something hydraulic related? I am thinking this is most likely it I am certainly getting power assist. Everything feels nice and smooth and I can turn the wheels with minimal effort with one hand while at a stop. I am not too familiar with the voodoo that goes on inside the steering rack, the valving and such. It is as if the rack is receiving pressure to both sides of the rack simultaneously. To me it seems that if I was running manual steering and had problems returning to center, that it would be an alignment issue, but this feels like the rack is receiving hydraulic assist and every little bump in the road is amplified by the assist. It sucks to think about buying a bad rack and installing it :( but its a junkyard rack so its entirely possible. I am hoping that since the rack has not been used for at least 6 months (had plastic plugs in the pressure hose fittings to keep dirt and moisture out) that anything hydro related will sort itself out with the exposure to the fluid and that with a little time, that things will be working normal inside if they arent currently doing so.


Rack preload/lash adjustment? Maybe a little bit I suspect that loosening the lash adjustment on the bottom of the rack would be my first step. It seems that if its too tight that it would not return to center, but that does not explain the bump-steer behavior.

Sorry for the long-winded post. I am hoping that someone has had this issue and knows the solution and that hopefully this thread can be helpful for someone down the road with a similar issue (once resolved).

[taiden]

What method are you using for measuring toe at the front? Eyes cannot see 1/32" of toe at each wheel

http://www.youtube.com/watch?v=sZoL1gaWedA

http://www.youtube.com/watch?v=gjcP07VKVZM

Also, be aware of Occam's razor

[Jafxod]

Get an alignment. At highways speed a tiny fraction of an inch can be everything.

[Sagaris]

Yes, obviously a proper alignment is in store, but I have enough experience to understand what toe-out feels like compared to toe-in. I have done a little bit more digging and am thinking that fluid is leaking past the seals on the spool valve, or that the torsion bar on the steering shaft may be broken. I have always had good luck with Lucas power steering stop-leak and will be giving that a try tonight. The next step will be the alignment (which is only going to help very slightly). I am thinking a rebuilt rack may be in store if the Lucas doesn't help.


The fact that I am getting power assist and there are no leaks suggests that the seals in the pressurized portion of the rack are good and that the problem is relating to the control of the pressure (the spool valve)

[Wh33lhop]

Strange. My first thought is if you space the rack down you are actually increasing bump steer, but this clearly sounds like you have more of an issue. I would try an alignment (you'd be surprised) and then a rebuilt rack.

[Sagaris]

The only rack spacer setup I ever read about for the rack swap is with the spacers on top. I will take a second look at the tie-rod angles and determine if moving the spacers to the bottom would be beneficial.

[Wh33lhop]

It may very well preserve geometry if you have the spacers at the top. I did as well and am not experiencing excessive bump steer. It was just a thought--I would guess your problem lies elsewhere.

[taiden]

Does the car exhibit the same symptoms with the power steering disabled?
Is the alignment spot on?

Again, Occam's razor. Live by it

[Sagaris]

Does the car exhibit the same symptoms with the power steering disabled?
Is the alignment spot on?

Again, Occam's razor. Live by it

I cant remember if the power steering belt runs the water pump or alternator, but if it doesn't then i will remove the belt real quick to give that a try after an alignment and before buying a new rack.

[ZM Blue Devil]

did you use drop hats?

[Sagaris]

Yes I have drop hats, had the thick washers in the correct place , had the steering lockup on me completely while entering the freeway. Took all that nonsense apart, ground off the oblong portion down, and haven't had an issue in the 8k miles since.

http://www.r3vlimited.com/board/showthread.php?p=2053394

I appreciate the suggestion.

[taiden]

I cant remember if the power steering belt runs the water pump or alternator, but if it doesn't then i will remove the belt real quick to give that a try after an alignment and before buying a new rack.

If it does run the alternator, you can still remove it to test for a little.

Fun fact, the Civic VX from back in the day would disable the alternator under certain cruise conditions to reduce parasitic drag. It would turn it back on when battery voltage dropped below a certain level.

[Sagaris]

Update: Lucas power steering stop-leak made an appreciable difference!

After sitting for about 48 hours after the initial test drive I took the car out for another test drive to see if there was any difference since the steering rack had a chance to marinate in the fresh ATF. There was no difference. I drained out the PS reservoir and added Lucas power steering stop leak which I have had excellent instant results with in many other cars in eliminating pump noises, improving weak power assist, and smoothing out rough spots. I went out on yet another test drive and it was much improved.

The steering now slowly returns to center under most situations as opposed to before where it would not return to center at all and would keep turning if I didnt pull it back to center. I am thinking that my theory about the spool valve may have been correct. There is still a small amount of tram-lining/bump steer which is now to the level that I could anticipate being due to the bad alignment. I fully expect the problem to be cured with a new flex disk and a proper alignment.

I didnt feel comfortable going over 35 mph the way the car was behaving on the first test drive but now I feel good enough to take it on the freeway to get it to winter storage.

I will update more after an alignment is performed.

[Sagaris]

I took the car out for another drive (20 mile drive to winter storage location) and the steering was all over the place again. I white-knuckled it, got on the freeway, then got immediately off the freeway :finger:, SCREW THAT! way too unsafe for the freeway. So I took side streets and within 5 minutes the rack just completely snugged up and felt perfectly normal, even with the alignment out of whack. The Lucas seemed to be effective again at swelling whatever seal inside the rack was causing the crazy steering. It felt that way for the remainder of the 20 mile drive and it was fine to take it up to 70 mph.

So the rack itself is the problem. I hate knowing that the Lucas made it feel pretty good on the previous drive, then it went back to being nuts for the first couple miles of the most recent drive, and now feels perfectly fine. I would hate for something to give out at speed so I will be swapping in a rebuilt rack.

Also, everything I read has said to put the spacers above the rack. I took a look at the steering tie rod in comparison to the control arm and it looks like the steering geometry would be much better with the spacers on bottom. I will be changing it out and possibly taking before and after pictures.

[Sagaris]

Steering feels 100% perfect now.
The Lucas stop-leak has done its work, I still want to replace the rack with a rebuilt unit, though it has moved down the list of priorities.

The unstable feeling was probably 65% steering rack seals (fixed by Lucas)
35% bump steer from having the rack spacers installed on the top of the rack.
see my other post here:

http://www.r3vlimited.com/board/showpost.php?p=2917821&postcount=8

Moving the spacers to the bottom of the rack made things feel perfect.
My backwoods alignment job tracks perfectly, steering wheel is <5 degrees from center, and the car is perfectly stable on the freeway like an e30 should be.