DIY needed for diff front bushing

[M3GA]

I installed the rear two bolts first while supporting the diff with the floor jack, this provides additional support and alignment of the diff to assist the install of the front bolt. Then (as I stated above) I used a 2x4 (actually it was prob the 2x6 that the diff was resting on top of the floor jack) to very carefully position the diff in alignment with the front bolt to avoid cross threading. You can also slide in a crow-bar on the side if needed for additional alignment. This was VERY easy, and allowed me to carefully thread the bolt in by HAND to ensure I was not cross-threading. This is how I did it. I am sure there are many other successful ways to do this.

BTW: I've got some pic's showing the tool configuration for installing the front bushing. If it would help, PM your email and I'll send them to you.

PM for pics, truly appreciated!

[M3GA]

I removed the diff and used my RTAB tool to do the front bushing. I used a large socket to first pull the core of the old bushing out and then used a chisel and hammer to cut the metal ring around it and then hammered it out. I then used the rtab tool to push the new bushing in after leaving it in the freezer. I ended up bending the metal threaded rod on my tool, but I just got another one at ace hardware as it's a common size.

Overall, this was one of the more frustrating jobs that I've done on my car, but it made a huge difference once done so it was worth it.

Also, I'm impressed that your state inspection caught this, ours are not detailed at all.

Yeah was surprised they caught it too. It's probably been in rough shape for quite some time. Maybe they heard the M3 "shift" clunk and started seeing $$$. Though they did refer me to the dealership to use a "special" tool to do the job.

The inspection place was a tire shop, and maybe not equipped.

[M3GA]

Also when the diff is out thread the bolt in once to get a feel for the type of resistance, or lack thereof, that you should expect.

Good idea! Did you or anyone else use thread locker (blue) to avoid backing out? Advised or overkill?

[Rich022]

That rear diff bolt cross-threads so easy. And once it gets cross-threaded you're not getting it out. --at least i couldn't. Required a 4 ft cheater bar to break the bolt off. remove diff, drill out etc.. was an $$$$ mistake

[Rich022]

Blue lock tight on dff bolt: it wouldn't hurt. I usually use blue lock tight on almost everything but did not on the diff bolt as it's torqued to a crazy 146 ft/lbs.

[2004LSB]

Oh boy...this job! It was a PITA for sure!

As others have mentioned, you have to remove the rear diff completely from the subframe. If you have a helper, using a traditional hydraulic floor jack is manageable. If it is just you, I would strongly recommend using a transmission jack from Harbor Freight as the diff is heavy (I'm guessing close to 100 pounds?) and very awkwardly shaped. It can easily slip off the floor jack and create a huge crater in your floor; or worse yet, it can fall on you and cause serious injury.

To prevent stripping or rounding of the head of the front diff bolt, I ended up using an electric impact gun on full power with a small extension and flex joint. If you haven't removed it in a long time, there's a good chance the bolt is seized up and tight as hell. Just make sure the socket is fitted properly onto the bolt and give it full power.

The Bav Auto / Schwaben tool was garbage - - the cups were plenty strong, but the threaded rod was simply not strong enough to handle the pushing / pulling forces required to get the factory bushing out of the rear subframe. I used plenty of grease, hand tools, and took my time and it failed about 60% of the way through the extraction. Ended up renting the giant C clamp tool from O'Reily's and with an electric impact gun, that did the trick. If I remember correctly, even with the diff out of the rear subframe, once all the driving / receiving cups, bushing + driving tools were all lined up, space is pretty tight and doesn't leave much room for anything else.

While you're in there, now is a good time to replace all the seals on the diff, diff cover + rear bushings, and paper gasket (between diff cover and diff).

Also don't forget there is a very specific torquing sequence when you're ready to button everything back up. The whole car must be level. Per the TIS, here is the sequence:

1. secure prop shaft with three bolts to rear diff
2. insert front diff bolt, thread in but do not tighten down
3. insert rear diff bolts, thread in but do not tighten down
4. remove all supporting jacks, etc from the diff; now the diff is supported only by the three bolts.
5. tighten front diff bolt to spec
6. tighten rear diff bolts to spec.

For good measure, I would use blue loctite on all the bolts. Just a pinch is all you need.

Good luck!

[M3GA]

Thank you all for the advice, starting the job tmw

[Rich022]

Man, looks like the posters and myself, forgot to mention you need to heat the bushing/cup with a propane torch just hot enough which breaks the seal from the trailing arm. The schwaben tool then easily pulls the RTABs out.