Noise from the rear centre of the vehicle!

[anonymous1]

Hi,

I was just wondering if anyone had any suggestions on what might be causing a noise at the rear centre of the vehicle. From what can make out, out itseems to be coming from the prop/diff area of the vehicle. Hard to describe the noice, kind of like a hollow clunk. It mainly happens when I pull off for the first time, but I can get it to repeatedly do it if I keep rolling back on forth with a little bit of speed. It also seems to happen when I lift of the accel after getting to about 20MPH or so. I had it in the shop the other day and they said without fully stripping the diff area t investigate (Obviously charging as they go), then they have no way of diagnosing.

Any suggestions on how I can further investigate myself are appreciated. I was wondering if it could be any of the links on the prop shaft, due to it being caused mainly by forward/backward movement?

Thanks in advance.

[AngryPopTart]

carrier bearing err I mean rubber guibo

[Jon K]

Center support bearing too

[Qube]

Guibo...

http://www.vertexauto.com/SQLCart/Images/Large/670.jpg

Or perhaps u-joint.

[billy]

you sure its the centre of the car the noise is coming from, the description could also be worn subframe mounts which tend to knock/bang on take off.

http://www.bmwe34.net/e34main/maintenance/suspension/subframebushing.htm

[anonymous1]

Hi,

Cheers for the input. I've recently had the rear trailing arm bushes replaced, so hoping one hasn't gone again already. A job I was aiming to do myself, until 16 years of rust decided otherwise and a carrier bolt snapped as I attempted to GENTLY ease it out. :D I've tested them by braking to see if the car moves to one side and this seems OK.

I had the car on ramps yesterday and a E34.535i.Sport kindly clutched it enough for the driveshaft to turn slightly while I was under the car. The noise seems to be coming from the rear where it bolts on to the diff. Can't see anything amiss, but don't know if the driveshaft will need to be removed to check it properly? Also not sure if the noise is actually coming from the diff itself, hard to pinpoint. (Especially when your wondering if the car will decide to roll of the ramps and introduce itself to you! :D )

[anonymous1]

Hi,

I still have not located the cause of this issue as yet, I have had it into a couple of garages and they seem to think there is nothing wrong and they cannot find anything unusual. (Although they haven't actually removed the driveshaft - so not sure if the could have checked it all in full).

I have checked the diff carrier and it seems to be fixed in place correctly, however, the mounting bushes on the frame look like they are in bad shape, so this is I am thinking is the possible culprit? I am also wondering if there is supposed to be natural play in the driveshaft, in the sense that I can rotate it either way about .5cm with engine off and then I get a light clunk sound coming from the gear box? (Sounds like gears might just be catching).

The guibo seems to be in perfect condition as far as I can tell.

The noise itself seems to be coming from the diff itself, I have changed the oil and this has not helped, although it did seem low from the amout that came out.

Is it easy to remove the driveshaft and diff to further check it is OK, I have a Bentley, so do can follow that. More concerned over pre-loading and if this is hard - taking into account limited tools and more enthusiam than knowlegde. :D

Thanks in advance and apologies if I ended up rambling there.

Thanks in advance.