Gear oil leaks anybody??

Ive noticed gear oil leaking out of my rear swingarm boot(1990 R100GSPD) and suspect it is coming upstream from my output shaft-seal or vent hole(a little evidence present at seal driveshaft coupling). I went on a 1000mile ride this weekend and about 20cc worth pooled down into the rear lower boot. no noticeable loss of capacity in my final drive or gearbox. Would a new outputshaft seal remedy this? 40,000 miles. Any help greatly appreciated!!

Hmmm, I'm glad you metioned this. I have a '95 R100R which is mostly the same bike and I've not noticed anything in the boot since I've never opened the boot, but I do get a nice coating of gear oil all over the bottom of the final drive which based on a cursory inspection seemed to be coming through the seals around the output. But that cursory evidence didn't seem right for the amount outside. I'll give this a look before too long.

Ive noticed gear oil leaking out of my rear swingarm boot

Click to expand...

Maybe you have a split in the boot itself. How old is it? After all, it IS a rubber part. They generally split either on the accordian fold or directly adjacent to one of the clamps.

Oil Leak

Well the Delio is that the swingarm inside, the hollow core, should not be wet with lubricant. So the two swingarm boots should not have anything for them to permiate. I put that LUCAS OIL STABILIZER in with my gear oil about 30-40% and boy does it shift smoooth. You all should try it. Lucas also makes gear oil with a "Climbing Additive". Possibly too much oil makees it to the output bearing and finds its way through the seal, or the seal is just bad. Whats up with things going bad on these rides? They will run forever, but the maintinence is higher than normal. maybe thats why! My TDM 850 never needs this much maintinence.

I would agree with flash412. Those accordian boots don't last forever. My experience is a split on the bottom of the boot at the fold. Replacing this is NOT one of my favorite jobs.

Rear Boot

It looks to be in good condition, but thats not a super keen observation. I agree with you about that being a pain in the butt to do, i shoulda replaced it when i lubed those rear splines. Well there is an output shaft seal on its way and when i replace it ill post if any crazy stuff has been found. It says you need a special puller to get the speedo/output flange off of its press fit from the gear shaft but im hopin that a small flywheel puller will suffice.

When I had the symptoms you describe on my 1992 R100R it turned out to be a leaking transmission output shaft seal. I had to remove the trans. and send it out for repair. I took the oppertunity to lube all the splines that I could find and replace both boots.
Mike

Pulled the seal out.

Well. I weaseled the swingarm out with the wheel attached. Un bolted the driveshaft from the output flange. Used an impact to get the nut off. Used a flywheel puller to get the output flange off of the gear shaft and pulled out the seal with a pair of small channel locks. Tranny still on engine. Didnt even pull off the exhaust but might have to in order to install and realign the driveshaft to final drive. Oh yeah, i left the rear final drive atached to the swingarm. It really doesnt take very long just a little messy.

PIC

A Pic.

Was the area right at the output wet with oil?

I just changed my fifth gear to the taller one and I was dry at the back of the tranny but wet at the final drive end.

I built my own puller for the flange to prevent any chance of bending it. Changed all the tranny seals and bearings while I was there.

When you go to torque the flange bolts, I just used a 10 mm combination wrench and stuck a 3/8 torque wrench in the open end of the wrench. Had to do the calculations for torque, and used locktight.

My little brother had a shaft come loose on the freeway. wasn't fun from what he says.

Gear Oil Mystery

There were signs of gear oil around the base of the output seal recently. Last year when I lubed my driveshaft zerc on top at the out put, I noticed some gear oil in the folds of the boot. Thought it was strange but didnt do anything about it.
When I just pulled off the swingarm there was no real buildup of oil in the final drive seal area. This last trip, it poored out of somewhere and the levels in the final drive were still good. Inspecting the seal(out) it is no longer pliable and when stretched a little, it stays. Old rubber hardening type feel to it.

It sounds like you know your way inside of a Tranny. Any real Problems with yours? Ive heard of the output bearing going south but have heard no whining or whirring yet. Im wondering if it( fails due to people not lubing their rear splines in which the stiction would cause excess pressure to the output shaft then the bearing upon compressing the rear end of the suspension.) Thats my theory, no clue really! I just use that lucas oil stabilizer "with Climbing Action"and hope it gets up to those high bearings.

Todd

That seems to be a fair assessment to me. Inside the tranny is a wonderfull setup. A tad difficult to pull apart, but real basic and tidey inside, not like the case spliting hondas etc.

My tranny came off due to a rear oil leak on the engine. I figured to install the taller 5th gear to help the pathetic mileage I was getting.

When I had the tranny off I noticed that the output flange did not spin smoothly. It also was a difficult shift from 1st through 3rd. I found the front bearing of the output going south. The rear it looked to be changed already as it was a different brand (skf) dual rubber seal, and all the rest were FAG bearings.

While inside I found one of the case washers floating in the area of the bad bearing, hmm suspect. I probably will add some of that oil stabilizer as the output shaft rides higher in the case and is not dipping into the oil, which may be contributory to failure. I think that may be why the new double rubber sealed bearing upgrade, poor oil flow to rear bearing.

Your bike is this far apart, and the flange was probably the tougher part, all you really need to do is get a couple of soft wedges and a good heat gun and the cover pops right off. I have the Clymer book which is real helpfull.

I should be finishing mine up tonight, but have been procrastinating for awhile.

trans...

When you say that it didnt spin smoothly do you mean that it was notchy, like bearing notchiness? I just installed the seal and flange. It rotated without hangup or notchiness. It doesnt exactly freewheel when I turn it, requires a little force; then again the gear oil is cold I guess. Like when the engine is just started cold, on centerstand in neutral and the rear wheel spins from the grab of the cold gear oil. Least thats what im a reckoning. Theres not much to that seal really, the sealing lip is just a folded back thin piece of stiff rubber with a coating on it. It has a thin Labyrinth type surface to it.
I really didnt want to get into the Contents of it by removing the cover. I have no Special tools and no practical knowledge of these BMW transmissions. So until it goes south, im just gonna ride it and see what happens. If i see oodles of gear oil again, ill be sure to post the findings/results/Hypothesis of new problem- im sure the final drive by then..yadda yadda.
Thankyou for the great info. Im so glad that MOA has this forum. Best group Ive ever been a part of!!!!

Todd Z.