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Rozboz
08-14-2010, 03:54 AM
recently the rear end of my car has developed some sort of banging noise or a knocking. it's worst going over undulations when accelerating. feels like a badly blown shock or seriously stuffed bushes. almost the same sensation as axle tramp. it's most prominent on the left hand side but i can definately feel it on both sides.

so far i have replaced the shocks with bilstein sports including new strut tops. new subframe mounts, sway bar bushes and links, dogbones, main diff mount and today i fitted new trailing arm bushes with no improvement. i've also double checked all the nuts and bolts to make sure they're tight.

does anyone have any other ideas as to what it might be? it's almost that bad that i don't want to drive the car as it feels like the rear end is about to fall out.

thanks
Binjammin
08-14-2010, 10:30 AM
Find a prybar. Put rear end in air on jackstands safely. Find diff, in the area where the front bolt goes through the subframe and into the diff. Pry between the subframe and the diff, trying to lift the diff. If you can move it more than like 1mm, you've probably broken the front diff bolt.
JdoggWaWe34
08-14-2010, 11:19 AM
Mines did this but it was my sway bars, they had snapped in half
M5ish
08-14-2010, 12:35 PM
WOW! You can snap a swaybar???!!!! Was it a solid or hollow one?
bmwwheelman
08-14-2010, 01:42 PM
It's probably the front diff mount. Mine is torn and keeps loosening the front bolt on the bracket to the diff. It's actually stripped the threads on half the bolt because of this.

And yes M5ish it is possible. I've seen it happen. I also have a friend with a miata that snapped the sway bar bushing bracket.
TWO TONE
08-14-2010, 05:11 PM
Check the driveshaft center bearing.
Rozboz
08-14-2010, 08:23 PM
the center bearing is new as well.

ok i'll have a look at the diff mount and bolt. is it a prick to change if it is broken?

thanks
Binjammin
08-14-2010, 09:49 PM
If the bolts broken off in the diff its usually easy to remove the broken part, but usually requires removing the diff, kind of a pain as its bulky and heavy.
Rozboz
08-15-2010, 01:45 AM
yeah i swapped mine out by myself. not in a hurry to do it again :(
stoney85
08-19-2010, 01:22 PM
crap, mine seems to be doing a similar noise lately, your description is exactly what i'm getting, yet to delve into it and check