[bagheera223]

OK - I have a possible cause for the sound - I have it on my SVX and also recognized it on my garaged (slipped timing belt) WRX. The WRX had this issue before my SVX (bought SVX because of timing belt issue above).

The sound is very possibly from a rear axle that is pulling out of the rear diff and causing a chattering sound as the circlip gives way and lets the axle start to pull loose - the teeth on the axle are hitting the diff gears incorrectly as it pulls out and makes the sound. Does it get worse with more weight in rear - then this is definitely the issue, IMHO. If it happens too much, the gears go on the axle and/or the diff (I had to replace both on the WRX).

Why does this happen? A) car has been lowered (like WRX), and axle is dropping down to mate with the diff - the greater the angle, the more likley this will happen. B) Springs are weak, can't hold up load C) too much weight in back (or a combination of any of these).

I hate these crappy R160 diffs! The R180 apparently doesn't have this issue.

So - in the interim, go to autozone or wherever and get some coil spring helpers and that will get you by (maybe). Also, keep weight out of the trunk and avoid anyone in the back seat (especially larger types).

I would think if you put the spring helpers in and tried the bounce in park deal it would either go away (the sound) or be much less. Let me know.