Clunk from rear of 991

[MagicRat]

This may be a very stupid question (if so, enjoy my foolishness), but I'm experiencing an occasional loud clunk from the back of my 991 GTS when I come down off a speed bump. My first thought was that it was the rear of the car bottoming out, but the sound sounds like it's coming from the top of the engine (almost like there's something banging around in the boot of the car, if it had a boot in the back, or on the back seat). If I go over the bumps slowly it doesn't happen, so it could be a case of 'doctor doctor it hurts when I do this / well, don't do that', but maybe my occasional desire to get across London at a reasonable speed has revealed something in the car that needs looking at.

Has anyone experienced this before? Does the sound of the back of a 911 touching down sound very different from the front lip scraping a bump, because of the extra weight? Should I just slow down over the bumps because I'm not driving a Boxster anymore?

Cheers!

[red997]

I get that too
only had it twice - once last night;
sounds like it's bottoming out to me.
it was at less than walking speed too !
Seems to be speed bump type dependent;
Frightened the st out of me when i first heard it.

[jezd]

My 991S used to do this too on the more severe supermarket speed bumps. Sounds unnerving but didn't seem to cause any harm and I couldn't find the source - didn't sound like it was bottoming out to me though.

[mollytherocker]

Maybe the bottoming out sound is coming through the piped symposer and so making it sound like its higher up?

[red997]

didn't know the 991 GT3 has a symposer...

[rosino]

Does it have PDCC ? Mine experienced that and it was a stone stuck in the active roll bar. Sometimes would be silent and some other times if the bar would stiffen then would sound awful.

Trip to the OPC who had had the same issue the week before allowed for a fix in 20'. The previous car had spent 2 days there before they figured it out.

[MagicRat]

That's what it was! Took it in this morning and they just called me.

Had a slightly mad morning getting there at 7am to locate a road bumpy enough to make the noise happen when I took the engineer out. Nothing worse than the old 'but it always does it at home!'