This one is for you, future scrub.
Briefly, removing the exhaust was easy, removing the drive shaft less so (I think I may have dinged up the centering bush trying to pull it off of the shaft), but all in all very straightforward. This is what my old giubo looked like:
Yep, time for a replace! (Incidentally, the clonk that used to accompany engaging the throttle is gone now that a good giubo's in place.)
Anyway, getting all that stuff off was trivial compared to this challenge:
This big fat nut is countersunk in the output flange and has a two inch shaft poking out of it. Haynes doesn't mention this, but I guarantee your 30mm socket will not fit on this monstrosity. I wasted two weeks trying sockets from Sears, Vans, Autozone, Harbor Fright, anything I could think of, until I found the answer on another BMW forum. The tool you're looking for is the
Gear Wrench 30mm Deep Socket, part number 80826, available at Advance Auto Parts. Ten bucks. Maybe someone else has something like it, I don't know. But I can't tell you the joy in my heart when I seated that socket and popped that nut off.
Flange removed, I could access the driveshaft seal and the shift selector seal. The driveshaft seal came out easily with a seal puller but be gentle because the tranny casing is easily gouged. AMHIK. The shift selector shaft seal, on the other hand, is &#@*^! difficult to remove while the tranny's in the car. Even after removing the shifter deck, you still only have two spots on the seal where you can exert leverage, the tunnel is too narrow for both hands to work, and no seal puller is small enough to fit in there anyway. I pulled on it for hours with picks, X-Acto blades (which did help to remove rubber from the seal), pipes, propane torches, anything I could fit in there. I stopped short of trying the Dremel on it, because one slip and you're buying a five-speed conversion.
This is the tool that finally pulled it out, ground out of a longish screwdriver:
Another insanely difficult task is removing the centering bush from the driveshaft. In what I can only describe as 'dry British humor', Haynes advises packing the cavity with grease and tapping a 14mm dowel in to force the bushing out. Hilarious. You might as well mail a formal invitation to the bushing for all the good that did. No, this was a Dremel job. Took a lot of grinding, but I got it out with only cosmetic damage to the driveshaft.
I replaced the broken nylon shift bushings with these spendy brass BMP ones, but I'll tell you it's still got a lot of side-to-side play. You might want to replace the entire shifter for only slightly more money. I also didn't replace the rubber/aluminum mount blocks that hold the shift deck in place, which I regret now.
Reassembly, as Haynes notes dryly, is the reverse of removal. It's a bear to get a torque wrench on the inboard giubo nuts, so I just tightened them as hard as I could with the spanner. The biggest challenge I had was getting the driveshaft to be perfectly parallel. I don't know if it was vertically parallel before disassembly, but I couldn't restore it to parallel afterward. I can't drop the transmission any lower on its mounts and I can't raise the center bearing; are there any other adjustment points? In any case, I don't detect the vibration or drumming that is supposedly symptomatic of a misaligned shaft, so I'm going with it. I do notice what appears to be premature wear on the new giubo; something to keep a close eye on.
All of this adventure kept my car on jackstands for four weeks. That part was ridiculous. Not ridiculous, though: I replaced my seals and they are holding. If I can do it, you can.
