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A complete novice trying to solve oil leaking around transmission and paralever R100R


A complete novice trying to solve oil leaking around transmission and Paralever R100R

*UPDATE* Post 3

I've owned this 1993 R100R for quite a while, over 20 years now and have done most of what little maintenance that it's needed myself; engine trans, final drive oils every year, tires, brake fluid, etc. For a while I'd noticed slight wetness around a sensor plug under the transmission but never enough to drip. More recently (not long after I last changed fluids) I noticed drops of oil on the floor and in checking found oil at the outside bottom of both driveshaft boots. Today I decided to take a closer look. After removing the collector I had access to the sensor bolt figuring I'll have to order a new one but it wasn't very tight. It's threaded into the aluminum case so I wouldn't want to use much force but I was easily able to snug it up almost 1/4 turn so maybe that'll solve the oil in that area.

Next I loosen the front driveshaft boot and a bit of oil comes out maybe a thimble full but I don't believe there should be any.

Then I pull the rear boot and OMG probably 6 ounces of dark oil pours out! No wonder there were oil drops on the floor, there should not be oil in the paralever at all should there?

After cleaning up that mess I check FD and trans oil levels and they're right at the bottom of the threads.

So just sitting here trying to determine where all that oil came from, maybe it was me over filling the transmission over the years? The fact it is so dark is likely because I used to add Moly Gear-guard to the trans and FD with each oil change. Tom Cutter noticed that when he had the transmission out and said not to use moly so since then I haven't.
So some of that oil almost had to be from prior years. My fill procedure for the transmission was once up to the threads, give the bottle another good squeeze then quickly screw the plug in. Does the transmission vent or overflow to the paralever? If so my overfilling over the years could be my problem. Or is the only way oil could get in the paralever is past a leaking seal? For now the boots are pulled back so any residual oil can drip out.

I have since discovered that the transmission vents through the speedometer cable bolt, and there is no oil present there. Looks like the output seal is the culprit, now to find someone to change it......
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My Haynes gives oil quantities for driveshafts for all except R80GS, R80R, R100GS, and R100R. The paralever element is supposed to be dry inside...no fluid. I think the transmission vents like it always has, that is through the speedo cable bolt. Do you see a small hole in the middle of that bolt? If so, you might want to remove it and push something through it to be sure it is open. It doesn't vent into the paralever shaft. So, the fluid is coming from either the transmission rear seal or working forward from the final drive.

I don't think it's really necessary to do that final squeeze of oil for the transmission. If it's just up to the bottom of the fill hole, that's enough and the gears inside there will provide plenty of splash lubrication.

That other "sensor" was probably the neutral switch for the transmission. Hopefully snugging it up will stop that from leaking.
So far snugging up the neutral plug seems to have stopped the wetness from that area. For the other leak I took it to someone more familiar with Airheads and he replaced both the transmission rear seal (he thinks was the culprit) and since there anyway the seal to the final drive. When he ordered the seals from Bob's they said that the trans to driveshaft seal had been updated to a different one. The prior seal itself was an "update" from what was used originally and had proved problematic. (Maybe that was the problem with mine?) I've only been able to ride it one time since I got it back but so far no drips there.
Here are the parts that came out.

You can see where a section of the seal is damaged or melted, not sure if the damage was from him removing it or that was the problem all along.

Looking at the pictures I am guessing the damage to the seal is due to the mechanic removing it. it is very hard not to damage seals when removing them.

The leak could be from the seal and a new one could solve the problem. Seals do wear over time and can look fine at a glance.

Thanks for the write up and pictures. St.
Thanks Steve. One thing he mentioned was he felt the old seal didn't look like one that was designed for something like a spinning shaft, more like a moving shaft such as a shifter etc. He said he didn't know that for a fact but he's just never seen one used in an application like this. The new seal was completely different, it was to be heated to a certain temp, put over a form that came with it for a brief period, then installed. Anyway I hope it solves the leak.

Well, it is always possible a mistake was made at the assembly line, rare but it happens. Or, the previous owner to you changed the seal and used the wrong one. Frankly, I have no experience with this bike year and model, so I would know what the proper seal looks like. I would have to go with the new seal and instructions that came with it.

Also is possible BMW changed the seal sometime during the production run or later due to customer complaints. A BMW dealership would get notice and if it was a recall, they would change the seal. Perhaps the previous owner never got that notice or the dealership never got it.

Anyway, it looks like you are on the right path. I don't know what your weather is like but I have been chomping at the bit to ride. Too much salt on the roads here for me to ride my usual bike as I did a major restoration over the winter and it is now to pretty again.

I totaled my other bike I was going to ride this winter in October. So no riding until the roads dry and clear. St.
I've owned it since the late 1990's. Around 2016 at 29,000 miles Tom Cutter had the transmission out to install the circlip and I noticed it leaking a couple years later. (It has about 31K now). I have to believe Tom changed the seal in the process.

Well Tom knows his stuff, so I doubt it was an issue with his work. Perhaps the seal was changed in spec by BMW after he changed it, that does happen from time to time. St.