cobalt

I recently observed a weird clunk in my 93 GTS. It appears to be coming from the front right. It happens occasionally without warning and it sounds as though something is binding and then letting go. I had the car put on a hunter alignment machine and a new alignment done. I trusted the shop that did it a number of years back only to find the numbers were all over the place. The new alignment made the car feel so much nicer, handles better and the rear end feels more planted.

The issue is still there and the mechanic who did the work checked out the entire front end with me and we can't find a thing wrong. Everything is perfect. Ball joints, tie rods, springs etc all as they should be with no evidence of binding or issues as far as we can tell.

Has anyone experienced something like this before?

kervracing446

May not be it, but check control arm ball joints. I had same issue last week on race car. Dust cap on lower control arm was gone and it would push through the bottom randomly making a pronounced clunk sound. Our guys missed it during track inspection so it's possible alignment was done and this was missed.

FredR

Unless the ball joint is separated it is difficult to tell if the upper and for that matter, the lower ball joints are shot and I doubt that a check at the alignment shop would do that if that is where you mechanic did the checking- that is not entirely clear from your post.

Unless the suspension has been gone through, by now most of it will be degraded to some extent and quite possibly shot in places on just about every 928 out there. Splitting the ball joints to exam them is a simple task and as with post No2, that is where I would start looking.

The lower ball joint is an easy/cheap replacement, the upper one mucho $$$'s I fear but our 928 vendors do refreshed ones even though Porsche will tell you they are not rebuidable.

cobalt

I will take a look at them again. Tried using a pry bar to see if there was any slop but didn't find any. The car has just 66k miles and everything looks like new and nothing sloppy in the drive. It must be we missed something but there is nothing consistent about when it happens.

He is a decent mechanic with an engineering background. He happens to have a new hunter alignment machine and an AWD mustang dyno. Nice young guy, did the work practically for free.

I will report back when I figure it out.

Thx

FredR

Anthony,

Mileage is almost irrelevant. Rubbers and plastics etc age harden and become brittle/crack. The ball spindle will doubtless be fine but the seat it sits in could well be an issue.

cobalt

I understand age creeps up. This is a car that has been garage kept all of its life so they do hold up better than a car that sits outside but no doubt time will eventually get to them. First thing I checked were the boots, everything seems as new. Very soft and pliable no signs of aging, hardening, cracking etc. Their is no slop that we could find. I am assuming I can check them as I would my old 944? See if the ball lifts out of the seat? If so that is not an issue either. Steering rack seems to be fine no leaks or slop.

The only thing that has any play in it appears to be the aftermarket sway bars I have. These were for sale back in 2006 or so here on rennlist. The other thought could be the GT sport springs I am using but they appear to be fine unless the spring is not sitting properly in the perch.

I am hoping not to have to start replacing unnecessary parts although everything else on the car except the coolant hoses is original. No doubt new parts wouldn't hurt but I want to isolate the problem first.

FredR

Being stored in a garage sure helps matters. Trouble with these sort of problems is that you just have to work your way through the various possibilities until you find the culprit.

Last year just by random inspection I found one of my inner tie rods had gone. No signs on the road that something was amiss but when I found it there was a surprising amount of play but only on one side- changed both and the lower lower ball joints anyway and fitted Delrin bushes in the steering rack.

Even now I have squeak in the front suspension over speed bumps- I suspect that is the upper A arm bushes. I also thought I could feel some play in the upper ball joint but when I checked it with the joint apart I could not feel anything. Either way refurbished arms will be going in during our next cooler season.

Rgds

Fred

Alan

You sure the mounts for the sway bar aren't damaged?

Alan

AO

Check wheel lugs too. We sometimes forget to torque them down.

After that I'd look at the caliper, ball joints, and all the other front-end joints including the one mentioned above.

cobalt

Alan,

That is what is puzzling me there is no apparent sign of damage anywhere. The car was fine up until a few weeks back when I heard it the first time pulling into my driveway. Never hit anything, roads here suck but nothing that should result in damage. When we checked everything it all appears correct.

Sometimes it makes the noise when making a left hand turn and others when I go over a crest but only occasionally and not all the time.

The lower mounts are fine the bushings appear to have some slop but nothing major. IIRC they were delrin supplied with the kit.

I am running out of things to look at.

The car has never handled or driven better which only makes it more confusing.

Wisconsin Joe

Can you 'feel' the clunk in any way?

Through the steering wheel?
In the seat?
Up from the floor through your feet?

Have you checked the torque on the bolts? There is a lot of force on those components. It's entirely possible for something to be just a little bit loose, not enough that you can move it with a pry bar, but enough to shift/slip when the force hits it.

Also, you mention a bit of slop in the sway bar.

That's interesting because I had a "strange clunk" in my front end. It turned out to be the sway bar. The end bolt on one side was either not torqued properly or had loosened up "just a bit."

I had pushed and pulled on the bar, unable to make it move. But when I did some other stuff that required pulling the sway bar, one side was not tight. Not loose enough to "wiggle", but not as tight as it should be.
After finishing the job and putting everything back together (with the right torque), the clunk was gone.

No clue if this has any relevance to your issue, but it's a thought.

cobalt

At this point any bit of advise is welcome. The sound occurs in varying degrees. The feel is dependent on how loud. When I do feel it it seems to be through the floor boards which makes me think sway bar but all the hardware checks out. I did not install the bars they were installed by Bob at Stable Energies back in 2006 he usually doesn't make mistakes. They have about 15k miles on them along with the springs and shocks.

I have no doubt when I find it I will be kicking myself for missing it or it will be unrelated to anything I am checking. For now I don't see anything that is obvious or of concern and I plan to drive it until I can get the sound to repeat itself.

I was hoping maybe this might be something others experienced more regularly but it appears to be unique or just in its early stages and is not apparent visually yet.

worf928

These---^

Lug nuts.
Caliper bolts.
Lower a-arm bolts.

Next, its much easier to check the various 'joints' when the suspension is loaded. Put it on a four-post or ramps, have someone cycle the steering wheel while you observe each joint's movement. (Some guidance for this in my inspection guide.)

cobalt

Yep all done as specified. All check out. It is the most frustrating thing.

Mrmerlin

drive it to the shop I will take a look 19038 Glenside pa