R100S: final drive oil coming out breather

 Hey folks,

I've got a '78 R100S that I've had for a month or two. I went out to
the BMW dealership to buy a few parts, and when I got there the final
drive had spit oil all over the rear wheel.

I've had this bike for a while, and I've never done anything with the
final drive oil, so I can't believe that it was over full. It wasn't a
particularly hot day -- we've had much hotter. It hasn't rained
recently. The bike has sat for a couple of weeks while I was out of
the country, but I had ridden it once since then with no problems.

The fellow at the parts counter said that something (a breather) in
the final drive might be blocked up, but I failed to take notes. I
figured I could just take the thing apart and it would be obvious what
needed to be done.

So, I've got the final drive off the bike, but the Clymer manual makes
the disassembly (and reassembly) of the final drive itself sound a bit
to complicated for me -- it requires special BMW tools I don't have.

Suggestions? I would love to fix this myself, but if I've got to take
it to a wrench I will.

Thanks,
Daniel

 
When this happened on my NightHawk I just replaced the breather
assembly (silver deal that sticks out of the top of the final drive).
Problem solved.
--
Rayvan

 
The oil is coming out of the breather for the rear drive, so it is not
that vent that is plugged.  I have heard that one problem that can
happen is for the seal between the rear drive and the drive shaft to
go bad.  gear lube from the drive shaft can then be pumped from the
shaft housing into the rear end should pressure build up in the shaft
housing.  It is my understanding that both the trans and shaft housing
are vented through a screw that holds the spedo cable to the trans.
That might be the breather the parts guy was talking about.  If it
were to plug up it would build pressure and force lube from the drive
shaft past the seal into the rear drive.  Shouldn't be any reason to
be taking gears apart.

Bruce