clutch lever grommet leak

[CaptainSlow]

I was poking around the R65 a week or so ago and found this leak - it seems to be coming from the clutch operating lever grommet. Is it something to be concerned about? I'm not sure if there should be any oil on the other side of this grommet at all - is it just a water seal to keep the environment out of the tranny?



The more I look at this bike the more it seems to need a full stripdown!

Thanks as always

[Bob_Roller]

The rubber boot is to keep dirt from getting into the throwout bearing .

Just farther forward, there is a seal that prevents gear oil from coming out of the transmission, where the pushrod shaft enters it .

That seal may be worn and allowing oil into the throwout bearing area .

[georgesgiralt]

Hello !
The spring clutch actuator is normally dry. It is sealed from the gearbox oil by a lip seal concealed into the gearbox's input shaft (at the rear of the shaft) and from the outer pollution by the rubber boot you looked at.
IMHO, the lip seal is at fault. It is tiny and IMHO impossible to change without opening the box....  It is cheap, though.
Sorry to say that.

[CaptainSlow]

Thanks for the prompt replies - very helpful as always, thanks guys.

If its a tranny out job, then I'll leave it as is for now. There are so many jobs to do already that I need to get those sorted out first   Thanks for clarifying the problem though, its on the to-do list now  [smiley=thumbsup.gif]

[Luca]

Sorry to bring up an old thread, but I've just had the transmission pulled back for a spline lube.  I cleaned out the clutch arm bearing and throwout bearing while I was at it.  On my 82LS, which I'm pretty sure is unmolested, there is no seal to be found.  From the outside in the parts are: Clutch arm, boot, spring, throwout piston, throwout bearing, bearing race on clutch rod.

Furthermore, there is a groove machined in the rear central bore (through which the clutch rod passes) of the transmission, presumably to allow gear oil to lubricate the bearing.

Any thoughts?

[georgesgiralt]

Hello !
Actually there is a slip ring. but it sits on the input shaft of the gearbox, is very small and as it is into the tranny, very difficult to see from outside and impossible to change without opening the box.

[Luca]

wouldn't that seal be to keep the oil from coming out of the input shaft, not the back of the transmission?  I can't think of a good reason to have that groove in the throwout bore other than lubrication.

Part of my thought is influenced by Snowbum: Inspect the bearing, and if it looks bad, replace it.  Grease it with a good grease (Do NOT use moly).    While the bearing is theoretically lubricated by oil from the transmission, that is not hardly so for some miles after initial assembly....so use a quite soft & mild grease, non-moly.

[georgesgiralt]

Well, the shaft is sealed in the housing, housing which has a little hole just enough to pass the clutch push rod.
So if oil has to come from the tranny to go to the rear of the push rod, it has to leak behind the bearing, and through the push rod hole. As it is unlikely there is high pressure at this point, I doubt it.
But I can/may be absolutely wrong ;-) It has happened before, and not only once ;-)

[nhmaf]

The throwout bearing is lubricated by the small amount of gearbox oil that is supposed to migrate out along the pushrod as it goes in and out of the gearbox.   Generally - at least on the older models, there is a small FELT "washer" or "seal" if you will that goes into the hole and through which the pushrod passes into the gearbox housing.  The felt ring is supposed to keep the amount of oil coming out of the gearbox to a minimum, but doesn't prevent some oil film from coming out.   At one point I think that BMW changed that felt ring out, but I'd need to look at the fiche.   It is possible that you need a felt ring in there, as they do eventually disintegrate, and/or you may have a crack in the rubber boot.   Additionally, if your battery ground bolt (the hollow bolt which also retains the speedometer cable on the driveshaft side of the transmission) is plugged up, this might be causing the transmission to pressurize as it heats up, and forceing more oil out through the very weak (comparatively) felt ring seal/washer,thingie..

[Luca]

Georges, the bearing is of the "loose" variety.  It's not pressed or sealed.  Sounds like nhmaf is confirming my earlier thoughts.

nhmaf, I cleaned out the speedo bolt about a year ago, but I suppose I could check it again.  Boot seemed OK, but I put some silicone around both ends of it for the meantime.  No sign of the felt, but I couldn't look into the transmission.  The boot wasn't really full of oil either.  Perhaps my "ride it like I stole it" highway speeds are pushing a lot of oil back there.

Well, thank's for the input.  And CaptainSlow, you could replace the boot on your leaking transmission in pretty quick time.

[georgesgiralt]

Hello ,
I won't fight on this, but when I dismantled the bike to change the clutch, the push rod was awfully dry. This was on an Apr 82 bike (so no felt but with the slip ring on the input shaft).
It may explain why the latest plastic piston holding the pus rod bearing get stuck as it warms a lot and seize in the tube due to expansion...
I had bought one but decided not to mount it because I was worried...

[Luca]

FYI

Some of the plastic throwout pistons are oversized.  When they get hot, they bind in the throwout bore.  Chucking it in a lathe or drill press and gently sanding it will remedy the problem.  Snowbum (www.bmwmotorcycletech.info) has the measurements listed somewhere in his tomes.

The pushrod does not receive much lubrication, but it also does not receive much use.  That's one good reason to not sit at a stoplight with your transmission in gear.

[nhmaf]

It is also important to make sure that you do lube the bearing with gearbox oil or a very LIGHT wheel bearing type grease when reassembling.

[Ed Miller]

FYI

  That's one good reason to not sit at a stoplight with your transmission in gear.

Isn't the other reason that you will drill a hole in your pressure plate?

[tvrla]

A bunch of changes happened in 1981, and I believe that's when the felt disappeared and the seal on the front of the input shaft appeared. I think that there's a small hole in the input shaft, possibly under a gear bushing, and the slight bit of oil that gets in there is what enters the throw out area.

That plastic piston is kind of a pain - I had the problem of it sticking and carefully sanded it down. Didn't have the lathe back then so did it by hand.