Rear End 'clunk'

[onthecut]

Hello all.

Earlier in the year I replaced the rear arm bearings (GSF kit). Ever since, and therefore presumably related, I've had a rattle / clunking noise from the rear end. It's most noticeable with the car lightly laden and occurs when going over bumps and irregularities. It shouldn't be the arms themselves as I did the bearing change in good time and there was no wear to the arm metal. I've been under and rechecked the tightness of the roll bar bolts -- fine. In my own mind, it sounds like the cylinders rattling in the cage, but I fail to see how they can, under pressure. The push rods are properly located and clipped to the arms and I've got no leaks. It's not the exhaust or spare carrier, either.

One thing I did do, is jack the car under the towbar, which would leave the rear frame mountings stretched instead of compressed ---- do they tear ? Any suggestions most welcome.

Mike.

[noz]

Hi Mike,

A couple of suggestions:

Flat rear spheres. When the wheel is descending out of the wheel arch (body on way up relative to wheels) then the piston in the strut should follow the motion. However, if you have insufficient pressure in the rear spheres then there's no pressure to push the piston out to follow the strut. Clearly there was sufficient presure to lift the car beforehand but with no elasticity in the system the pressure disappears immediately the body rises under its own steam (ie when you go over a bump). When the body falls the gap between the strut and the piston closes rapidly until the two metal surfaces collide producing the 'clunk'.

Rear or middle Exhaust Box touching the body when you go over a bump.

I can't see how anything could 'tear' when unsupported so I would rule out that possibility.

Don't know if that helps.

Cheers

noz

[onthecut]

Hi Noz.

Thanks for your suggestions. The spheres are fairly new (6 months ish), but having read some of the other threads recently on sphere shelf life it's worth a look. Only thing that doesn't add up about the sphere theory is that I didn't have the symptom before the job. I suppose I could try changing the front and rear units around and see if the symptom moves. All part of the 'fun' of having an XM, I suppose !

Mike.