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knocking from rear - *NOW WITH PICS*

Posted: Wed Apr 20, 2005 6:50 pm
by minime1275
There is a fairly loud clunking noise from the rear of the car if im not smooth with the throttle/gearchanges in first and second gear, or if I lift off the throttle sharply in 1st and 2nd. The clunk is fairly major and can be felt, but the car can be driven so that it doesnt happen (ie very gentle with throttle and gear changes in 1st and 2nd). I think someone suggested this could be worn rear diff bushes.

Can someone tell me if im looking at the right part - if I look under the car from the rear end, is the diff bush on the left hand side of the diff housing, near the exhaust (ie the one thats in a really obvious position on the bracket thing attached to the diff housing)? If it is the bush Im looking at, should it be donut shaped, cos mine is horseshoe shaped and looks like half of the rubber is missing at the bottom!

If this is the diff bush and it needs replacing, how difficult is replacement by a DIY mechanic and what would a garage charge to do it?

Posted: Wed Apr 20, 2005 7:50 pm
by M5pilot
Sounds like diff bush , I have the same problem but its not that bad yet.

It can be done DIY.

Posted: Wed Apr 20, 2005 7:58 pm
by ivqii
My local yokel charged me Ԛ£40 for part and labour-hardly worth diy at that price

Posted: Wed Apr 20, 2005 8:04 pm
by jamie325isport
would the rest of the mounts need doing? i.e engine, box and prop? just interested if that gone would make all the rest weak?

Posted: Wed Apr 20, 2005 10:32 pm
by minime1275
If Ԛ£40 is the going rate, I think I'll let somebody else get their hands dirty.

Jamie, I hope not. Engine mount bushes look healthy enough.

Posted: Wed Apr 20, 2005 10:43 pm
by jamie325isport
Can someone go through changing the diff mount. Ive kind of got it in my head as basically drain diff oil (needs replacing anyway). Then take off the back plate to the diff (providing all the nuts/bolts are accessable). Press the old mount out press in the new one!? Also are the back plates the same on all diffs?

Posted: Wed Apr 20, 2005 11:01 pm
by hammoj28
Think mine needs this doing.

Posted: Wed Apr 20, 2005 11:39 pm
by Martinaston
Sound's more like the rear bushes have dropped check this out,
http://www.bmwe30.net/cgi-bin/datacgi/d ... Section=05

it will show you what i'm talking about. If there's no gap (5 or 6mm) between the plate on the bottom and the axle carrier they have either been stretched (by jacking the car up by the axle carrier BIG NO NO. It's not a jacking point) or just worn due to hard driving and the centre shaft has seperated causing the outer to knock up and down.
With the rear diff bush if you take the bolt out and jack up the back slightly you can check the state of it.

Posted: Thu Apr 21, 2005 5:32 am
by Nic325i
I'd agree with the diff mount. My 325 sport had the same problem when I bought it. Got the diff mount replaced and haven't heard/felt the clunk since.

Nic

Posted: Thu Apr 21, 2005 8:32 am
by hoshy
Gonna sound like a twat suggesting this but have you checked the rear wheel nuts?

(sorry. but it's at least worth a look ;-/ )

Posted: Sun Apr 24, 2005 4:59 pm
by minime1275
Can anybody tell me if:
a) This is the diff housing bush (top left of pic);
b) Should it look like that or should it be round or donut shaped?
c) Could this be the cause of the knocking?

BTW, if the link below doesnt work, can you let me know.

http://community.webshots.com/scripts/e ... ity=uDLERr

Thanks, Neil

Posted: Sun Apr 24, 2005 7:33 pm
by Brianmoooore
Link doesn't work!

Posted: Sun Apr 24, 2005 7:47 pm
by minime1275
Thanks.

Any idea how I can display a pic saved on my computer?

Posted: Sun Apr 24, 2005 9:17 pm
by deano325t