Any ideas ... troubleshooting a clickety clunk

[Stroked & Blown]

Does it sound like marbles in an empty coffee can?
If so, don't drive it - have it towed to a Porsche mechanic or dealer.
That is the indication that the IMS is about to go. When the IMS goes, it can cause "catastrophic" engine failure.
Read up on IMS on this forum and at: http://www.lnengineering.com/ims.html

[eightsandaces]

IMO, the IMS would make the sound in neutral since it would still be spinning, then again it would be worse under a load for shizzle.

[jcb986]

The brake cable is tied back and if the tie breaks, it could come in contact with the wheel. Check the back side and see if it's hitting.

[eightsandaces]

Originally Posted by jcb986

The brake cable is tied back and if the tie breaks, it could come in contact with the wheel. Check the back side and see if it's hitting.

While you're there, look for any scoring on the discs where anything could be intermittently hanging up,check the CV joint too.

[extanker]

and check the axle shafts

[kpm]

And the mounting flanges on both sides.

[clueless1]

quick update ... it seems pretty intermittent ... there was no sound at all this morning (cold start followed by 10 min drive).

all very good ideas, but sure about the interaction of these noises with the clutch (eg why would a loose brake cable sound go away when I engaged the clutch?). Pretty sure its not IMS ... sound is way too slow when I am creeping along (like one click every 2 or 3 seconds). And its just not there at all at idle. My first initial impression (which might be quite wrong, I was in the drivers seat) was that the sound was coming from the right rear wheel well.

Was wondering about the tranny mount??? ... otherwise can't figure out what that could be if engaging the clutch (or coasting in neutral) takes the sound away?