knocking from rear - *NOW WITH PICS*

[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?

[M5pilot]

Sounds like diff bush , I have the same problem but its not that bad yet.

It can be done DIY.

[ivqii]

My local yokel charged me Ԛ£40 for part and labour-hardly worth diy at that price

[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?

[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.

[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?

[hammoj28]

Think mine needs this doing.

[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.

[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

[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 ;-/ )

[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

[Brianmoooore]

Link doesn't work!

[minime1275]

Thanks.

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

[deano325t]

this helped me.

http://www.e30zone.co.uk/modules.php?na ... opic&t=677

Dean