Cloud9...68

I already posted this on the 968-specific forum, but since the steering systems are similar on the 944's, I thought i'd open this up to a wider group:

It took me three tries to re-seal the steering rack on my '92 968 to get it to work (kept breaking the fragile teflon seals as I was jamming the tight-fighting sleeves back around them), but I finally got it together with no leaks, and the power assist is now working. But all is not yet quite well. When I turn the wheel to the right, it feels normal. But when I turn it to the left, I'm immediately met with some resistance, as if something is binding or sticking. Then once I turn past this sticking point, it feels fine, then sometimes sticks again, then feels normal again, as I keep turning left. It's definitely happening when turning the wheel to the left from a straight-ahead position, but I'm not as sure about the behavior if I turn it to the left after having just turned it to the right.

Any ideas on what could be causing the left-turn binding? Something inside the steering rack? Tie rod ends? Steering knuckle (although I don't see why a problem with the knuckle would be directional)? Thanks.

mytrplseven

I would recommend removing the tie rods, thereby isolating the steering rack from the rest of the suspension. Count the revolutions of the steering wheel before you do this to see how many turns lock-to-lock it takes so you won't go beyond it and damage the rack after you've disconnected the tie rods. Then turn the wheel the same amount to see if you can feel the binding. If you do, then it's in the rack. If not, then you may have bad ball joints or maybe tie rod ends.

Cloud9...68

Good suggestion - thanks. Although one challenge might be that I suspect the binding will be difficult to feel with the front wheels off the ground, but it's definitely worth checking.

cruise98

Did this just start after rebuilding the rack?

MAGK944

On the ground or off the ground it shouldn't matter, if there is binding inside the rack you will feel it regardless. I would first jack the front up with the wheels and tie rods attached and move the rack full movement using the road wheels, that should tell you something. Even with the tie rods disconnected it just tells you its not the tie rods, top mounts or bottom ball joints, you still have the intermediate steering shaft in the equation, they have been known to bind if the bearings are worn or if they are not fitted correctly. Common mistake to fit the steering shaft in wrong. There is a cut-out where the bolt should go but it will fit and bolt up without going into the cut-out and that will cause a bind. Kinda hard to see and it should only fit one way but you have to do it by feel as you can't really eyeball what your doing. Double check you have that correct, use a mirror & flashlight.

Cloud9...68

Cruise98,

Yes, the problem has only been since the rack rebuild. This is one of the most finicky, difficult things I've ever done on a car, and that includes the enginr rebuild and complete suspension overhaul I've just finished on my 968, so I'm highly suspicious that I did in fact make some sort of mistake that's responsible for the binding.

MAGK944,

Thanks for the info - After checking on the tie rod ends, I'll take a close look at the connections between the intermediate shafts and the rack mechanism, and maybe snap some pictures and ask you to confirm if I put them on correctly. I'll probably do this tomorrow night after work.

william_b_noble

you will get odd feel if you don' ttighten the bolt on the U joint at the input to the rack, that would be one place to look. also, did the rack move smoothly before you put it in - you shouldn't have had trouble with the seals so something is odd.

cruise98

Is the rack centered? There is the little inspection hole, and the dimple in the rack should be visible when the steering wheel and tires are pointed straight ahead. There is a Porsche tool for locking it straight ahead.

Rebuilding the rack is pain. BTDT.

Cloud9...68

William,

I was careful to make sure I tightened the u-joint bolt securely, but that's one of the first things I will definitely check. Yes, everything was smooth before I took the rack apart - as I said, this was one of the most challenging jobs I ever did on a car, so there's a high likelihood I messed something up, but I dread tearing into that thing again. I pray it's something external to the rack.

Cruise,

Yes, I centered the rack using the special tapered bolt that screws into the centering hole on the rack.

Cloud9...68

I can't make heads or tails out of this thing. I spent several hours troubleshooting it, and I got nothin'

I first lifted the front up in the air, and inspected everything. The tie rod ends look fine, and I checked to make sure they were tight (they were) before I re-attached them to the steering knuckles a few months ago. Likewise, the steering shaft's u-joint's pinch bolt is nice and tight (its a new, high quality toplock nut), and the steering shaft hasn't moved inside the u-joint's splines since I put the rack back on the car a few months ago.

So I next turned the wheel side to side without the engine running, and it turns perfectly smoothly in both directions. I then fired up the engine, and turned the wheel side to side with the power steering engaged, and got the same good result.

I next placed a stack of rubber coated barbell plates under each front wheel, and placed a pair of tiles with a coat of heavy grease between them, on top of the plates, and lowered the car such that its full weight was resting on the tile/barbell plate stack. I fired up the engine, and turned the wheel side to side, and was able to feel a hint of the binding, proving that the full weight of the car needs to be on the front tires to produce the effect. So I asked my wife to get in the car and turn the wheel side to side, which I watched the motion of the u-joint. The u-joint seems to be moving smoothly. She noticed the binding at one point, and stopped turning the wheel as soon as she felt it, and I made a note of the position of the u-joint pinch bolt's nut. I asked her to keep turning the wheel to the left, but she never felt the binding again, even after the u-joint made a full 360 degree rotation.

So I lifted the car again, and removed the tiles, so the full weight of the car was resting on the rubberized barbell plates, to better simulate the friction of the tires against the road. I fired it up again, and turned the wheel from side to side, and this time wasn't able to feel a hint of the binding.

Finally, I pulled back the rubber boot, and took a look at the steering half-shaft connector to the rack. It looks fine, and I checked to make sure it was tight (I had a neighbor help me tighten it, so I know it was very tight when I put it back together), and it felt plenty tight. Here's a picture of this connector (not sure what's it's actually called):

Attachment 759948

So, I'm no closer to understanding what may be causing the weird binding sensation, but at least I'm reasonably confident there isn't a safety issue. I'm afraid it's something inside that wretched rack, but it that's the case, I think I'm just going to live with this minor annoyance until it starts happening on a more regular and predictable frequency.

william_b_noble

maybe it's not the rack - what you are describing sounds like ball joints or maybe the inner tie rod ends - can you check for play on those two items? I had the plastic in the inner tie rod ends turn to moosh and I had about 1/4 inch of play in each tie rod as a result.

Cloud9...68

As I said, I checked for play in the tie rod ends (and my neighbor also commented that they feel very tight), and the A-arms are brand new, heavy-duty Racers Edge units with the thicker ball joint pins, and of course the ball joints are new and, as you would expect, very tight.

It's not a looseness I'm feeling - it's a periodic binding, or resistance to turning the wheel, but only in the left direction. But it isn't consistent, in that it doesn't happen every time I turn the wheel, and I'm having trouble reproducing it with the wheels up on blocks (in my case rubberized barbell plates) in my garage.

Another way I could almost describe the sensation is that it's as if the power assist is momentarily cutting out. But that isn't quite accurate, because it actually feels like there is some sort of mechanical binding happening.

I dearly hope it isn't something inside the rack, because I'd just as soon break into my transaxle as I would tear into that nightmare again, but the steering was perfect before I took the rack apart to reseal it (which took me three tries to get it "right"), which is why I'm highly suspicious that's where the problem is.

cruise98

If the rack is nice and smooth, it could be the u-joints on the steering shaft. Just another possibility.

Cloud9...68

It would be great if it were one of the u-joints, as that would be a lot easier to fix than something inside the rack. But I carefully watched the lower u-joint as my wife was turning the wheel, and it seemed to be turning nice and smoothly. She did notice the bind at one point, so she stopped turning the wheel, and I noted the position of the u-joint's pinch bolt's nut. I asked her to keep turning the wheel, and when the nut came back around (so the shaft went through a full 360 degree rotation), it didn't bind again. The bottom line is that I have no idea how to check the health of a u-joint, short of something obviously visibly being out of whack. There isn't an inordinate amount of play in the steering, either.

I meant to take a look at the upper u-joint, but I hurt my back late yesterday, so I'm not going to be able to do that today, but I never touched the upper u-joint, so this strikes me as being a pretty unlikely culprit. This car, including the guts of the steering rack, was largely in boxes during the 2+ year track car conversion project, and if there's one thing I've learned, it's that if something worked perfectly before the project, and now there's something wrong with it, 99% chance the problem was caused by something I touched.

william_b_noble

I don't know what procedure you used to assemble the rack, but I can think of two places where something might have gone wrong - something got into the gear on the rack, or a burr on the bore - if it only happens in one place, I don't think the servovalve is a likely culprit.