There's a Rattle in my SC - With video

[OsoMoore]

Its a beautiful day, but something is rattling in the rear right quarter of my SC! It sounds kind of like a golf ball on a tile floor. It can be easily triggered by bouncing the rear of the car while it is turned off and stationary.

I've recently replaced my engine and transmission mounts, and I don't see any movement at them. I'm about to take the wheel off and go underneath, although I suspect I won't be able to duplicate it with it raised off the suspension because I then can't bounce the car. A video is forthcoming shortly, once it finishes uploading.

All ideas are appreciated, thanks folks!

EDIT: Seems to be coming from the shock absorber, see post #4.

Here's a video!
https://youtu.be/qixT_5KuUpo

[pete3799]

Check your sway bar mount.

[OsoMoore]

I'm not especially familiar with sway bars (took it on and off two summers ago) but it looks good to me. No loose bolts, doesn't appear to be rubbing metal on metal. Seems identical on both sides.

I might be missing something on it, or maybe its something else?

[OsoMoore]

I put a jack under the end of the axel/strut so I could bounce it with the wheel removed. It sounds and feels very much like its coming from the upper part of the shock absorber. I can feel the "clank" when I touch it whilst it bounces.

I'll start some research, as I have no experience with shocks. I believe they were replaced about 15 years ago by the previous owner. Maybe something is loose?

The car rides straight and true with no hands on the wheel, and doesn't appear to sag or hang unevenly. No sign of oil dropping from the shock. The shock is green.

[OsoMoore]

I figured it out! Here's the good side - no noise here. With the weight on the wheels, the shock is totally compressed and the mount bolt's washer has no weight on the rubber donut. When the car comes off a bounce which removes weight from the wheels, the shock hangs from this bolt, cushioned by the rubber donut. Good donut means a quiet bounce.



On the clanking side, the donut has deteriorated. Now when I come off a bump, the shock's washer pulls against the mount point without any cushioning. Clank!



Now I need to figure out if I can just replace the donut, or if more is needed.

[OsoMoore]

I think they are this thing: Rear Shock Mount Ring 91133352100 - Genuine Porsche - 911-333-521-00 | Pelican Parts

But I'm not sure, those darn parts diagrams aren't especially clear. The ones in my car look a lot flatter - maybe they've just flattened with use?

UPDATE: For the record, Rear Shock Question - Gap Too Large? confirms that is the right replacement piece. Now I just need to find $144 of parts to make it to free shipping...