Simon.Gardiner wrote: BMW insist on a GL5-spec oil for the gearbox and bevel of the old air-head twins (eg my R100RT). I'm pretty sure there will be some bushes in there somewhere.
There is only one - the 1st gear pinion on the output shaft runs on a bronze sleeve.
The bearings are mainly 'C3' ball races (1 x 6403 & 4 x 6304), with a special roller bearing running on a steel 'top hat' on the front of the input shaft. the rest of the pinions are steel-on-steel.
I have rebuilt 27 of these boxes for 'UKGSer.com' members (I have a 1988 R100GS and used to have a 1988 R80RT).
I always use EP90 GL5 with these and haven't had any problems.
My avatar shows the late Len Rich in 1970 with the bike I now have - a 1958 Ariel VH