Cloud9...68

Well, I can't make heads or tails out of this thing. I spent the better part of the day 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 759947

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.

tamathumper

Does the sound of the power steering pump change when the binding occurs?

Is the binding *always* in exactly the same spot?

How many "binds" occur between center and full lock to the left (still assuming none to the right?)

I didn't see unequivocal answers in the thread.

Cloud9...68

Good questions. Here are my answers:

The sound of the power steering pump doesn't change as the wheel is turned. I'm pretty certain of this, because I was under the car watching the motion of the steering coupler and the tie rods while my wife was turning the wheel inside the car, so I'm pretty sure I would have noticed if the sound of the pump had changed.

I don't think the binding is always in exactly the same spot, but it's hard to tell, because it doesn't always do it. I noted the position of the coupler's pinch bolt nut at the moment my wife said she felt the binding, and I had her keep turning the wheel. When the nut came back around (so when the wheel made a full 360 degree revolution), it didn't bind again. About the most consistent thing I can point to is that the binding tends to happen at the moment when I first turn the steering wheel to the left, whether the car is pointed straight ahead, or has just completed a right turn. So it's as if there is some momentary initial resistance to left-hand turns, but it doesn't happen every single time.

The number of binds that happen from full right lock to full left lock is inconsistent - usually only one, but sometimes two, on rare occasions maybe three. Definitely none to the right, ever.

Cloud9...68

Travis from Rennbay (great guy, and I'd highly recommend Rennbay to anybody with a 944/986) had an interesting theory - he thinks one of the strut bearings, or front springs, may somehow be binding up as I turn the wheel, and then releasing. But I can't think of any way to test this besides taking it to someone who has a lift that lifts the car up by the tires, as I haven't been able to reproduce the problem in my garage. This is a dumb question, but under normal operation, what exactly is supposed to turn against what when you turn the wheel? The bottom of the strut is bolted to the spindle, which is rotated by the tie rod ends when the wheel is turned, and the top of the spring is pressed against the hat by the force of the spring, so I'm assuming the entire assembly is supposed to rotate via the upper strut bearing (I have Racers Edge camber plates, with solid upper strut bearings). Is this correct? Any idea what could cause this to bind? Thanks.

mbardeen

The entire strut rotates via the strut bearing. If they're new bearings, they shouldn't be binding... unless your alignment is way off.

Given your second to last post, I'm still thinking binding on the U-joint. Check the test procedure on the following link: http://my.cardone.com/techdocs/PT%2027-0007.pdf

Cloud9...68

Thanks for the document - I'll follow the procedure as soon as I can, but unfortunately, as I was working on the car last weekend, I injured my back (herniated disk - no fun), which I'll have to wait to heal before I can do anything more taxing than adding air to my tires. Hopefully in a few days. But I have to say, it seemed to be rotating very smoothly, with no hint of binding anywhere through its rotation, as I was watching it last weekend as my wife was turning the steering wheel with the full weight of the car in its tires.

tamathumper

The strut binding is a great idea, wouldn't have occurred to me, but you said it's binding when you're cornering which means all the weight is forward - do you have a way to add weight to your front end so you can do the test in your garage with the front suspension loaded? Sorry to hear about your back.

Cloud9...68

Thanks - the back is finally feeling better today. Hopefully I'll be able to get back to troubleshooting my car's various problems (a newly-discovered coolant leak in the vicinity of the water pump - gasp - is going to have to leap to the front of the priority list...) in a few days. Yes, the binding happens in corners, but if anything, it happens at a higher rate when turning the wheel to the left when the car is stationary. So movement/cornerning isn't a necessary condition for the binding, but weight on the wheels is. If mbardeen's link to the procedure for troubleshooting the steering coupler doesn't pinpoint the problem, I'm going to have to take it to someone with a lift that lifts the car by the wheels, so we can turn the steering wheel with the weight of the car on the tires while someone is watching everything from below for something unusual to happen at the exact moment the binding is felt.

MB968

If you have a tie rod end link puller (good investment), you can pull each tie rod and rotate the strut on it's bearing free of the steering rack/mechanism. You probably won't be able to easily load the tires, but you could see if it is smooth on its own. I'm not sure I see how this would manifest itself more on left hand rather than right hand turns, but it would be easy to at least check the unloaded condition.

Cloud9...68

MB,

I do have a tie rod puller, but with the particular shape of the tie rod ends of these cars, it's quite an ordeal to wedge the "teeth" of the puller between the tie rod end and the spindle. It tends to fall off half a dozen times before I can wedge it in there enough to survive the turning of the puller's driver. Maybe it's because I have a cheap-a$$ Harbor Freight puller...

But be that as it may, having weight on the front wheels seems to be an essential condition for the binding to happen. And even then it doesn't happen all the time, which is making this problem a bear to troubleshoot. I would be inclined to just ignore it once I'm sure it isn't a safety-related issue, but when I last went to the track, the instructor who drove it was quite concerned about it, to the point where I don't know if he'd let me back onto the track until I get this fixed.

mbardeen

Any word on this? I found the cause of my problem. Not the bearing, though it might fail at a later point, but a loose power steering pump.

How loose, you ask? The tensioner was hanging straight down when I pulled the belly pan off. Evidently I left the bolt a bit loose and wiggled it's way out. New bolt and problem solved.

Cloud9...68

Congrats on finding your problem. Yes, I can see how this could cause the power assist to come and go. I've checked mine, and it's tight. Plus, I don't think this would cause the steering to bind only in left-hand turns.

No progress on my problem. I was out of town for several days, so I haven't had much time to work on it. I'm going to have to get the car up on a lift, because I can't see anything obviously wrong poking around with the car on jack stands. Tie rods are tight, ball joints are new, steering coupler appears to be moving freely, steering rack bolts are tight, ride height is perfect, strut mounts appear to be OK, Also, it hardly did it when I drove it today - either that, or I'm just getting used to it.

Cloud9...68

Well, I have a possible clue on this mysterious problem. I left the front of the car elevated on jack stands Monday night and all day Tuesday as I was working on replacing the starter, which I completed last night (took two nights because I also replaced the bushing, which required removing the bellhousing window, etc.). I've only driven it about four miles since finishing the starter replacement, but so far, no sign of the binding, Typically, it does in by the second or third left-hand turn I make. So, I'm wondering if having the front suspension fully extended somehow "unbound" something. Of course, it may start doing it again soon, but having the weight off the front wheels for about a day does seem to have helped. Does this make any sense?

MB968

Did you move the steering while it was off the tires. I could see this allowing something to move to a new location that was stuck from rotation when loaded. Just a pretty WAG. Otherwise don't see how it could make any difference. But heah, if it works, go with it. You may want to put some of those air jacks under the front of the car, so when you put it in the garage you can put an air hose to it, and take the front off the ground.

Cloud9...68

Well, the improvement to my car's very bizarre condition was extremely short-lived. By the first left turn on the 4-mile drive home, it bound up. It's very annoying, but it doesn't really cause any problems. I need to take it to someone with a lift that lifts the car by the tires so we can look at the components of the suspension and steering as the problem is happening.