Differential Out of the Car

[kingo328]

I have a 2000 328i, sedan, auto trans, 116k miles.
I have had this clunk the the rear end since I bought it at 60k miles. At that time I suspected the differential so I took it to a gear and diff shop but they could not find a problem. I was hoping it would get worse so a shop can diagnose it but it hasnt.

I've had the car on jack stands for a week now, checking everything from the trans output flange to the rear hubs and all bearings, bushings, u-joints, guido, and flanges along the way. Subframe is solid (thank goodness). All bushings including suspension bushings, diff mount bushings and subframe bushings look good.

I've also had the car on ramps several times so I could watch the diff, suspension etc as my wife shifts from reverse to drive to reverse repeatedly with the engine running. Obviously I trust her with my life. The diff does not move around proving the bushings are good.

There are no unusual movements or noises except the clunk coming from the differential.

Now I have the diff out of the car and the rear cover off. The only play is between the ring gear and the input pinion gear. And the clunk (with the diff out of the car the clunk now sounds more like a clink) is audible when the input flange is moved back and forth. There is about 1/16" of play in the input shaft...maybe a little more. The side pinions are very tight on the side gears....you can feel the teeth meshing.

Anybody know what the clearance spec is between the input pinion and the ring gear?

[kingo328]

Well, I've taken the diff to 2 shops and they both say its good.

I have a new rear diff bushing to install but I cant get the old one out. I've tried using a ball joint service kit but it wont work due to lack of space.

Any tips/ideas?

[grandmaster]

Hi Kingo328,

Any luck with your car. We have the same problem with our 328CI with the steptronic and only 50k miles. We have had the entire rear of the car taken apart. Bushings are good. Diff mount is good. Put new trailing bushings in. Had the new output flange installed. Changed the transmission and diff fluid. Had the differential taken apart/inspected. Said it was fine (very minor play which was tightened). Had the transmission module memory cleared.

Is yours only clunking when coming to a stop and hitting the accelerator? Can you describe the symptoms?

Only things that are left for us are replacing the transmision, differential, new transmission module software etc. It's been very frustrating.