Cloud9...68

This is a strange one. I recently performed a major revamp of my track-focused 968's front and rear suspension - Racers Edge extended ball joint pins to raise the roll center, bump steer kit, Bruce Karger's roll center correction trailing arm attachment bar, followed by a corner balance and alignment. The car tracked beautifully, and I've done about four track sessions since I finished the work. On the way to the track (as soon as I pulled out of my garage) this past Saturday, I noticed I had to turn the wheel about 20 degrees clockwise to keep the car going straight. The cars wants to bear left, in other words. I hadn't noticed this behavior before, including on my return trip from my last track session. The track is about 20 miles from my house, and includes mostly straight, expressway driving, where a tilted steering wheel would be very noticeable.

So I turned around, pulled into may garage, and set the wheel straight ahead. I removed the cap for the centering hole on the steering rack, and saw that the centering hole was right smack dab in the middle of the opening. I inserted my tapered steering centering bolt to lock the wheel in the straight-ahead position, and set up my string measurement apparatus to measure the toe, and sure enough, it's toed in by 8.5 mm on the right, and it's toed out by 6 mm on the left, which explains why the car wants to turn left all the time.

The question I have is, what could have caused it to move so much, and apparently so suddenly? I checked everything on the front suspension and steering - the bolts holding the steering rack to the cross member are snug, there's no trace of damage to either of the tie rod shafts, the caster block bolts are snug, as is every other bolt holding every component in the front suspension. I haven't hit anything since I finished the suspension work (other than a cone or two at the track). I could adjust the tie rod ends to correct the toe, but before doing that, I'd like to understand what might have caused the toe to shift on both sides, in the same direction, by close to the same amount, in such a short time after having aligned the car. Theories? Thanks.

Droops83

How are your steering rack bushings? The right/passenger side bushing is designed to locate the steering rack from side to side---if its "shoulders" are worn or broken, the rack can move side to side, which can cause your symptom.

I use the stiffer aftermarket rack mounts (can't remember who makes them), but be advised that like all Delrin/plastic bushings they don't last as long as the stock rubber bushings and will need to be changed out every couple of years.

951and944S

Seems like rack bushings, agree but with engine dead, a hard yak on the wheel with no PS should reposition the rack for diagnosing purposes.

Can't recall to say 100% but I don't think the engine crossmember's 4 bolt holes are elongated, just round; but if it were loose, may be enough to cause a shift of the rack also.

Other than that..., maybe the steering shaft could have slipped a spline or two if you dont have the right shouldered pinch bolt...?

T

Cloud9...68

Chris,

I took an admittedly cursory look at the steering rack bushing (I have the solid one, on the left side only, the side that locates the rack to the crossmember - the right one is the stock rubber piece), and it appears to be OK, but I'll clean it up and take a closer look. I did give the rack a good yank it both directions, and couldn't get it to move.

T,

I checked the tightness of the crossmember's four bolts, and they are snug. I don't think it's the steering shaft, because the wheel points dead straight ahead when the rack's centering hole is in the center of its opening.

I also tugged on both tie rod shafts, and there is no perceptible play. The car tracks very well - there's no slop whatsoever in the steering.

GPA951s

You obviously were very detailed in your alignment. Have your ride heights changed at all? Just thinking out loud that maybe it settled on one side. (Not sure with your pins which way the wheel would go relative to bump-steer) - just throwing it out there.... One thing that helps out in these situations is after your alignment is complete, Go around the entire car and take a paint pen and mark all the bolts, Rack, castor bock, crossmember to frame Ect… This will give you a "visual" reference in case something shifts in the future.

Droops83

One other thing that can cause this is slipping caster eccentric lock nuts/bolts---put a wrench on the middle/adjuster part of the caster eccentric bolt and make sure it doesn't turn. Ditto for slipping caster blocks, but you said that you checked these. When one goes to all solid bushings and uses sticky tires on track, fasteners work their way loose, so a nut-and-bolt check of the suspension after every track event is necessary.

Also make sure that one of your camber eccentrics didn't slip, these loosen with track use. For my 951 with Ground Control coilovers, the eccentric adjustment between the strut and spindle is eliminated and the only the camber camber plate is used. Also make sure your camber plate didn't slip!

I mention these as a reminder because changing caster affects both camber and toe, and changing camber affects toe but not caster. So anything that would cause either caster or camber to change could theoretically cause your symptom (including ride height like GPA951s mentioned).

Good luck!

Cloud9...68

Thanks - can't think of any reason the ride height might have shifted - it has coilovers all around. Good idea of marking all the bolts with a paint pen - I've had the caster block bolts work their way loose in the past, so this was one of the first things I had suspected, but they are tight. I'l get under the car tonight and have my wife move the wheel left and right to see if I can see any sign of the rack moving relative to the cross member. But the fact that the steering doesn't feel loose at all (no "wandering", tramlining, etc,) makes me think the rack is OK.

Chris,

I did take a close look at the teflon (or is it delrin?) bushing after cleaning it up, and visually, it doesn't look damaged.

Thanks for all the ideas.

Jay Wellwood

Probably beyond stupid...but are your tires pressures correct?

divil

I don't see how any of these things would cause the car to pull to one side. I've had the camber adjustment drift during track sessions (always just after having the car at an alignment shop). It results in the steering wheel being off centre when the car is driving straight, but it doesn't make the car "want to turn left" as you're experiencing. The car always naturally tracks straight and forces the toe to even out on both sides - that's why the steering wheel is off centre.

I thought that the caster setting would be the only thing that would cause what you're seeing, but I could be wrong. If the caster setting has drifted, that would explain why you measured a toe difference, since the caster adjustment affects toe (and camber actually).

Droops83

A large difference in camber from side to side will absolutely cause a pull. Think about a bicycle or motorcycle tire---you can cause it to veer one way or the other by leaning instead of actually turning the handlebars. One a car, the pull would tend to be towards the side with more positive camber, but of course this also depends on the camber of the road. In my experience there has to be a rather large difference in camber side to side to cause a pull (say 0.5 degrees or more) to cause a noticeable drift to one side.

I do agree that a slipped caster adjustment is more likely to cause this, but hopefully we will soon find out what the actual problem is!

Cloud9...68

I found a major smoking gun - Chris was right! I had checked the snugness of all the bolts in the front suspension, and all appeared OK, but I didn't pay attention to the caster adjusting tabs. The one on the left side is correct - it's pointing to the outside of the car, giving maximum caster, but the one on the right was miles off - it was probably 160 degrees or so rotated to the inside, almost pointing toward the engine, which would give mimimum caster on that side. I was amazed how much the control arm moved while correcting the caster on the right side by turning the eccentric. I think this explains most of my problem - thanks to everyone who has responded.

But I'm still puzzled as to why the toe on both sides of my car was off, as it doesn't make sense to me how having the caster off on the right side could cause the left side to be toed out by 6 mm. I will torque every bolt on the suspension assembly, and will keep looking for anything else that may be off.

Oh, and I'm definitely guilty as charged as far as having solid/spherical bushings everywhere, and super-sticky tires (275/35-17 Maxxis RC-1's on 17 x 10.5" wheels all around). I will be more diligent about checking my bolt tightnesses in the future. I rotate my tires after every track session, so the bolts are very accessible. Plus, I have a lift in my garage, so I have no excuse...

Humboldtgrin

All the above. Plus make sure your struts don’t have play in them as well. Also could have anything come loose inside your steering rack? Tire pressure will cause a pull effect of course, and the rear suspension not aligned will cause steering issues. So check the rear bolts as well. Camber will effect toe but toe will not effect camber. Failing wheel bearings are also something to look for. But it seems Chris got you on the right track.

Cloud9...68

I will check the rear bolts as well, but don't expect to find anything. I checked the rear toe a couple of days ago, and it was fine. I very recently completely removed the rear suspension to install Bruce Karger's roll center correcting trailing arm attachment bar, and removed the front struts as part of the work I had done to the front suspension, so all the bolts holding these components on have very recently been torqued, but I will double check them all. I didn't touch the front control arm bushings, and the nut holding the eccentric bolt on the right side had worked its way loose, probably over an extended period of time. I will have my wife turn the wheel right and left while I'm under the car to see if there's any motion of the steering rack relative to the cross member, since I still can't explain why the toe is so far off on the left side, and haven't yet completely ruled out some motion of the steering rack. The front wheel bearings are new (came with the RE heavy duty billet hubs I recently installed). The rears, however, are original - amazing they aren't giving any signs of being worn out, but I'm sure they are near the end of their useful life. Both struts have very recently been rebuilt as well.

Thanks again for all the helpful suggestions - this is definitely my go-to forum for troubleshooting.

GPA951s

Glad You found the Issue... Remember that Paint Pen... It makes checking things Way Faster and Gives you that instant Visual as opposed to putting a wrench on everything, Plus you don't have to "remember" which way Tabs were clocked, Or If the spring perches twisted a bit, I have a lift as well and a Quick walk under the car will tell me if something moved with all the paint markings. It almost seems trivial... But it sure is handy if all of a sudden you're at the track and say... "You know.. Something seems off" Then you look at your Rear Camber bolt and see the mark has moved.. Now you can just re-align the marks at the track and be on your way.

Cloud9...68

Yes - thanks very much for the tip!