heinrich

lug wrench? loose tools? battery hold-down or spare wheel hold-down?

bd0nalds0n

This afternoon I'm going to have a buddy take turns gunning it and slamming on the brakes as I'm alongside the car to see if I can get a better sense of whether it's left or right side, etc. I'm trying to think about how I can "ride along" without the risk of getting run over or flung from the car. I'd really like to be able to sit on top of the engine with the hood up, or stand on the nose where all those heat sinks are. Before anyone takes this too seriously and interjects with commensurately cautious remarks, I say this (wistfully) in jest.

Battery is secured, there's a subwoofer box where the spare used to be, no lug wrench, and 99% sure it's originating somewhere ahead of the front seats.

Gregg K

The only way I've ever fixed a problem like this, is to systematically go over everything I can find. And usually I don't find it right away. But get it in the air, and start looking around. I'd check for loose suspension first. Give the tranni mounts a look. It could be that the drivetrain is shifting somehow. I hate these things. But it would be even worse to discover it at speed.

Peter Thompson

I've also been experiencing this mysterious clunk during medium braking...
I haven't seen anything strange under the wheel, and it was just in for some major servicing, and they didn't mention anything odd.

Please do post when you find the answer. Inquiring minds want to....um...drink more beer.

Cheers,
Peter Thompson
1988 928S4 Auto

bd0nalds0n

Well, we had a diagnosis session this afternoon--my buddy alternating between gunning it and slamming on the brakes. Eventually, we settled on my laying on my stomach, with my head out the open passenger door, with a shoulder braced against the door jam so I wouldn't pop out under acceleration.

I take back what I said about it coming from the front, it's definitely coming from the rear.

Since the sound started about the same time as I installed the rear Ott droplinks, they need to come off.

Somehow I must've put 'em in wrong--although the instructions were very common sense (e.g., match the first one to the length of the OEM droplink, then install and adjust the 2nd one so that there is no preload; be sure that the nuts go on the inside to prevent a bolt-end from being near the tires.

The instructions were also specific that there wasn't much room between the springs and the droplinks, so maybe something's sort of tweaked. Or a problem with the sway bar mounting bushings.

So if any of you are experiencing this sort of issue, and have the Ott rear droplinks, you may want to check there first. If I can get under the car tomorrow, I'll take them off and see if that takes care of the problem.

Has anyone with the rear links encountered a problem where there was rubbing or a phenomenon where is sounds like something is bumping off/against a stop under acceleration?

bd0nalds0n

Okay, well, it's not the droplinks. I took them off completely and the noise doesn't go away.

I took off each rear tire and nosed around. I don't have a socket large enough to check the cv/hub nut, that's probably the next first step.

On my 944, I once had a problem with some sort of splined connector, which I think went on one end of the torque tube...it cracked and a piece broke off. It was a pretty cheap fix, as I recall. I'm assuming there's at least some sort of splined connector along the driveline?

What about creeping TT bearings? Except I don't have any sort of driveline vibration...

I think this is getting beyond the scope of what I'm comfortable with. Time for a call to the shop...

I just am fearful it really is something in the driveline, and the diagnosis and r/r is undoubtedly going to be pricey.

If it is something in the transmission, how much are used or rebuilt units?

Gregg K

I doubt it's inside the transmission. Highly unlikely. Could be tranny mounts though. You might check them to see if they're loose. CV joints? Did you mention that? There's another idea.
You'll find it. Good luck!

Thaddeus

I had a very similar experience with my 951 about a year ago. I thought the noise was in the front, felt like a clunk, sometimes the car shifted weirdly under braking. Checked everything in front I could think of and was imagining huge expenses. Then I went to the rear and checked everything also.

Turned out to be a bad shock absorber in the rear. I had mentally ruled it out because they were almost new: they were KYB's. I'll never buy a KYB again. Swapped out the shocks, noise and weirdness gone.

Good luck, hope it's something as simple...

Gretch

Glad to hear it was not the drop links. i have them installed and have had no such problems, and Gretch likes them a lot. noticable difference in the way she corners......"flatter" is the only word I can think of to describe it.

Hope you find your problem soon. Look at caliper bolts. Pull them off if you have to to do a good inspection.

bd0nalds0n

Well I don't know what the problem was, but somehow as soon as I made the appointment to take the car in--and it's a real pain in the *** b/c the shop is in Anaheim and I'm in San Diego--the noise went away.

How do the cars know? Although, normally the noises go away as soon as the mechanic gets in.

In any event, I'm gratified that the noise went away, let's hope it stays gone. I think that it was somehow suspension-settling related. The car had been up and down a lot lately.

Blown Beast

Spray WD-40 or equivalent into the rubber bushing of the rear lower control arm....this is the large donut looking bushing by the rear jacking point.

I have had this noise happen to me on a few 928's and this will fix it

mspiegle

Let me know if this fixes it. I have the exact same noise. I had a CV joint blow up on me, so I thought that was the problem... but still had noise after replacement.

rob rossitto

FWIW, I had the same EXACT symtoms on my 85S/ AT, persisted for nearly a year until a shop trashed my AT trying to replicate it...(but not until after I'd replaced the MMs, springs/shocks, steering rack, ball joints/a-arms and a bunch of other stuff)

when the AT was out for OH, I had them pull the "fine" TT, and the front bearings were GONE! (except for the dust/debris left)....there is a bolt/spline there too - and there are some other threads here about that fine setup also...

happy hunting!

bd0nalds0n

Rob:

I'm thinking you've hit the nail on the head.

How much are the bearings, and what's the time on the tranny and TT r/r? Anyone have ideas?

bd0nalds0n

So I have done some more research on this, esp. on the Pirtle site, which led me to the rear pinch collar (which is sometimes loose, causing symptoms such as I have). Turns out that there's some kind of rubber bushing that you can see near the pinch collar. My sense is that the bushing surrounds the rear TT bearings, and that this has "walked" off. Probably replacement time for the TT at $500 from 928Int'l, plus labor (can't see doing this myself; don't have a garage or the month it would take me to do it nights/weekends). Probably $1500, all said and done. Contemplating doing the Bilstein/Eibach switchover at the same time, sort of a WYAI excuse to do a fun upgrade while I'm doing an unfun maintenance item.