E30 Zone

So I've been having this knocking sound when changing gear (mostly from 1st-2nd, or 2nd-3rd) also u can kinda hear the diff moving a little bit when coming off the power etc, at first this was barely noticeable, now as its getting worse decided to jack her up and take a look.

So first concern, the bolts that hold the diff straight up at the top at the back (the ones that are impossible to reach and cant be seen from underneath) one of those is missing and the other is about 1cm unscrewed. Tried tightening it but after half an hour of swearing and cursing the sucker wouldn't budge either way (can't be moving about too much then..?)

Does anyone know the part number for my missing bolt?

Second problem is that one of the driveshafts appears to be a cm or so further away from the diff than the other one, and has some green goop dripping off it, would this be diff fluid? See terrible pictures!

Thirdly seem to have a loose cable tied up to the speedo sensor on the diff? Guessing not important? Least of my concerns after this discovery anyway

Any help is very appreciated!

terrible closeup of leaky driveshaft/diff




and the mystery cable, so professionally tied on to the speedo sensor diff pluggy bit cable

I had a similar issue with mine, the best thing I can recommend is to drop the diff/beam down and take a look at the part that connects the diff and beam. I found on mine that the front two had worked loose and the rear part had nearly cracked through, couple more months and the diff would have been sat on the road.
The beam is strong but not designed to that the forces of the diff through less than 4 bolts, so I really would advise some caution here, I ended up welding 5mm plate across the back/top two holes.

Diff bolts are available to order from your dealer,they are an odd size/thread combination,so any old M12 bolt cut down to length from the hardware shop will not fit!

It does seem nessesary,particularly with a diff that has been swapped,to check these mounting bolts at least every 6 months.

As the hairy one says,once the diff starts waggling about,the mounting holes get damaged,leading to further problems quickly.

Gotcha. Don't drive, add bolts. Any ideas on the leak?

What may have happened is if the diff is moving about independently from the rear beam due to the mounting bolt issue, one of the output shafts might have worked is way part way out - the seal won't be seated properly as a result and you may be leaking some fluid. There might also be a chance that the output shaft seal will be chewed up.

As for the cables - difficult to tell from the pic, but they look like the cables for abs wheel sensors to me.

Knew I had a picture of the top of the beam somewhere, beware of this:




Top hole is cracked where the line runs around it and the bottom one was totally gone, hence the dark bit not having been skimmed with a grinder yet.

Woah nasty! Ok gotcha will drop the frame next weekend inspect the damage and see what that seal looks like. Sounds like a fun weekend. Cheers for the help