Mysterious clunk in the "new" steering on my 75

[Duc Hunter]

I've recently taken my 1975 911S apart for rust repairs. As part of putting it back together I installed a steering rack spacer kit to lift the rack up for bump steer correction. Now there is a clunk every revolution in the steering wheel moving left or right in a certain spot in the rotation. It sounded to me like it was the upper universal touching the body so I pulled the air conditioning blower out and pulled the plastic cover off the body only to discover that neither of the 2 universal joints up top are rubbing any part of the body. With everything apart now it seems like the clunk is above the upper universal in the dash.

My recollection is that after the upper universal the entire unit is enclosed? Nothing was taken out of the car above the bearing that is bolted to the smugglers box. That bearing is a Rennline item, and I replaced the rubber attachment to the rack itself.

Before I took everything in the frunk off to investigate, I thought the bump steer spacers were causing one of the universal joints up high to rub the body because they raised the steering rack a bit. But now I'm at a total loss as to what the issue is. Does anyone have any thoughts?

[PeteKz]

Does it only do it when the car is on the ground, or also when off the ground?

Possible bad bearing in the steering column? Possible bad U-joint? I would get someone else to turn the steering wheel while you look in the smugglers box and under the car.

Last resort: Remove the spacers and see if that fixes it.

[Otter74]

Does this only occur when the steering is under load, or does it also occur when the wheels are in the air?

[Duc Hunter]

Car is off the ground right now (still putting it back together). I am 90% sure it's above the upper universal. I will be back to the car tomorrow and will have some help checking. It is def above the smugglers box area. After removing the blower, and the plastic covers off the channel the steering shaft goes down, nothing is rubbing. Strange thing is there was no clunk before we took it apart, so I am not sure how a universal would die from just sitting in the car for a year. I will report back tomorrow after a little more investigation.

[75 911s]

Chris,

When you put the spacers in, did you loosen the universal? Maybe it's binding.

[stownsen914]

Agree it sounds like binding somewhere.

Any chance you have one of those solid replacements for the rubber donut connector between the steering shaft and the rack? If so, it may not like the rack spacers, as they change the steering shaft geometry, and some articulation needs to happen at the donut. The solid replacement that I’ve seen sold may not properly articulate.

[Duc Hunter]

Again, for everybody’s information, the issue is not below the uppermost universal. It appears the clunk is in exactly the same spot as the steering lock engagement. It clunks when I turn the wheel and the key is in the ignition, and when I remove the key, the exact spot, the steering clunk in it locks in. It’s almost like the locking pin is not fully retracting. Seems very strange since none of that mechanism was touched in the year. The car has been taken apart for bodywork. Does anyone have any thoughts

[Otter74]

I suspect that regardless of where it is along the steering assembly path, this appeared because of the geometry change brought about by adding the rack spacers. At this point I’d pull the steering column shroud or get your head under the dash to look at the steering column lock. You’ve added a part (the spacers) that changes the relationship of everything to each other, and this pretty clearly seems to be turning the problem on. If you feel like the extra work, you can do an A-B-A and take the rack spacers off again and see if it goes away. Sometimes problems lie in the parts themselves, sometimes in the process, and sometimes in the assembly.

[Duc Hunter]

Otter74....roger that.

I did back off both universals and tapped teh shaft farther down to "relieve" any pressure at the top. Next I guess it's get into the wheel lock mechanism and maybe lube it up or blow it out with air. The car has been int eh body shop for a year.....maybe dust and debris is int here mucking up the lock pin from retracting all the way.

When you get down to the end, it's always something. So close to being finished. POR....Push On regardless.

[Duc Hunter]

PROBLEM FIXED!!!

I started off today looking at the universal joints again, while manipulating the steering. The problem was solved by taking a pair of channel locks to the lower most end of the lower universal joint, and clamping the joint together. Doing this there was a pop and now there’s no more clunk.

When we removed the steering rack (a year ago) we had to unbolt the clamping bolt for that universal where it attaches to the rack, and even then it would not come apart. So we tapped a metal wedge in and opened the end up a little. What we didn’t realize until today was that opening that end up, also opened the end of the knuckle where it contacts the cross. Putting a big pair of channel locks on the outside of the knuckles and squeezing them together, popped one of the knuckles back into place properly on the cross. It was not off by even an eighth of an inch, but you could see a little daylight away from the seal, and you could wiggle the universal left and right ever so slightly. nice that was noticed it was obvious that it was the source of the clunk. Now that it’s clamped back together, there’s absolutely no clunk, which is wonderful news. .

Moral of the story is if you remove those joints and have to open the end, make sure you clamp them back together snuggly so that the cross is pressed properly into the end of the knuckles.

Thanks for all the support gang. Really appreciate it.