Rear main seal

[fig]

Question, I've just replaced the rear main seal on my 73 R75/5. I've also replaced the oil pump seal, I'll be putting on the flywheel next. Max BMW suggested keeping the seal and flywheel dry so the seal would bed in. Up to this point I've read to use oil or even grease on the surfaces that make contact. The seal is the new type made with Teflon. The seal I replaced was also the new type and was in the bike about 7 years, it leaked soon after it was installed. Not a lot but the shelf was always wet. When I removed the flywheel I noticed it had been rubbing the seal which obviously wasn't installed deep enough, it was proud of the case about 2mm. This time I pressed the seal in all the way and it's flush with the case. What's the consensus about lubricating the seal, oil or no oil?

Thanks in advance
DF

[dougie]

I replaced mine a couple of years ago with the new style seal (no spring) purchased from Motobins.
There website has some "tips and tricks". For the new style seal they say to soak it in oil for two hours.
That's what I did. No leaks. I put it in flush.

[Kurt in S.A.]

Snowbum covers the seal here about 1/3 of the way down:

http://bmwmotorcycletech.info/flywheelr ... arning.htm

It's probably PTFE, part number 11-11-1-338-342. He suggests that the old ways of soaking the seal are unnecessary but does recommend a slight amount of oil to ease the installation...he has other suggestions for installation

Kurt in S.A.

[fig]

Yes I have that seal part number ending in 342. Actually I just saw the service bulletin, dated 1988, on Max BMW's site and among other things it said... "this new seal will seat in rapidly if installed dry". I think I'll try it dry then. I guess my previous seal leaked because it wasn't installed flush and rubbed the flywheel and was somehow compromised. I'll give this a shot and see what happens.

Thanks
DF

[ME 109]

I've used the new type seal with a little oil.
I've also found once before that it wasn't the seal, it was the (in my case) the guide ring which runs in the seal that was worn.

There was also a time when the leak was not the rms, it was a cracked oil pump cover.