Weird self-healing noise

[tubwreck]

My '88 911 was equipeed by the PO with 22mm "charley bars" from Wrightwood Racing. (These bars use solid bushings for the bar and spherical rod ends for the drop links.)

A month or so ago, I noticed the classic 'sway bar clunk' -- a kind of slapping clunk from the back when driving over minor surface irregularities. A quick peek revealed that the left side bushing block had pulled the nuts out of the stock bracket.

My local (excellent) shop welded on two new updated brackets and remounted the bar. After the repair, I noticed a similar - but different - clunk from the back of the car. It happened when driving over minor bumps at low to moderate speed, but unlike the sway bar clunk, it was hard to localize -- it sounds like its from the rear or right rear. (What it sounds like is that somebody left a 3/8" drive extension inside a body cavity, and it's just bouncing around.)

Anyway, about a week later I drove over a smallish pothole and heard what sounded like the usual little rocks bouncing off of the underside of the car, except that from that moment forward, the sound was gone. Totally, magically fixed.

Until this week, when it reappeared, exactly as before.

I've carefully checked the new swaybar mounts (OK), the swaybar bushings (OK), and the drop links (OK). There's no wheel play, and the shocks appear unremarkable.

The only thing that's slightly odd is that the sway bar is very, very close to the transmission carrier (like 2-3 mm). It looks like the transmission carrier is bolted directly to the transmission and attached to the unibody through some rubber mounts, so I'm wondering if, as the engine/transmission shifts on its mounts, the carrier is contacting the swaybar slightly.

I'm basically looking for other theories about what might be causing this noise.

[ben parrish]

I had a similar noise. Turned out to be a loose transmission mount. The transmission was "bouncing" when I hit some bumps. Tightened it down and it cured it. Hope it is something simple for you. My sway bar was also very close to the transmission mount.
Good luck

Ben