I've just replaced the bearings on my '82 RS, (apart from the ratios I believe they are virtually identical to all intents and purposes) while only one was knackered, the front output shaft race, it seemed silly not to change the others as well. Likewise the seals: input, output, gearchange shaft and there's a little one at the back end of the input shaft for the clutch pushrod. And the gasket for the cover. I got a new bellows for the output flange simply because it would be a bugger to replace if it gave up in the near future. Oh, the books say to replace the bolts for the output flange, but Steptoe, and I think others as well, say they always reuse the originals. If you get new bolts then make certain they are of the correct length, if you use the ones intended for use with locking washers then they will be too long and will chew up your output seal. And before you put the box back put a bit of lubricant on the clutch splines, you don't often have the opportunity to do it this easily.
The manuals all tell you to measure and calculate the thickness of the shims you need to give the correct end-float on the shafts and bearings, as I didn't have to change any of the shafts then there was no need to change the shims because the new bearings were identical to the old ones. Having said that I did check them because I had access to all the necessary tools and to the shimming plate because I joined the BMW Club, and it was so good to have all the proper tools for the job. You will also need a torque wrench as well as the usual assortment of spanners, a depth micrometer is ideal but calipers will do, with care. A very useful guide was
Jörgs Motorcyle Pages, see
http://jhau.maliwi.de/mot/gearbox.html Incidentally, a small point, but the angle iron he uses to mount the gearbox on is very useful, bit I was a bit dissapointed to find that the dimensions he gives for one of the holes is out by a millimetre or two- just enought to make it awkward to get a socket to one of the bolts (the gearchange mechanism bracket if I remember correctly) so check the measurements from your gearbox before you start drilling. Having said that it's still well worth having and the rest of his instructions are very helpful. You can borrow mine if you like.
I didn't find the job too tricky, just be careful to label (or measure) the shims behind the bearings in the end cover as you take them out, keep everything clean, and take lots of pictures as you go along, you may well be so glad to have done so if you are unsure of how things ought to go back.
I'll dig out the invoices for the bits and post them for you tomorrow, they are in the workshop somewhere.
