Leaking final drive "94 R1100RS

[eastbay]

I changed the final drive oil about a month ago with 80/90 GL5 gear oil. Last week I noticed gear oil on the rear wheel. It looked like it was leaking from the drain plug, so I got some new washers and replaced them. That did not stop the leak and after careful assessment it appears the oil is coming from the back of the final drive, between the drive and the rear rotor. Looking at the Max parts fiche it appears that it may be the gear housing o ring [33 11 1 241 257] that may be the issue. There doesn't seem to be any play in the rear wheel and besides some very fine black crud on the magnet, the oil looked clean with no metal shavings ;so I think the gears and bearings are ok. I am an intermediate mechanic but have not had to deal with a final drive . I'm hoping that whatever seal or o ring that may be causing the leaking is not too difficult to access and replace. Advice. ? The bike has about 70K mi. , I've only owned it about a year and have no idea if the drive has ever been apart.my manual is no help as it advises to leave the final drive to professionals.
Advice. ?

 

[eastbay]

I changed the final drive oil about a month ago with 80/90 GL5 gear oil. Last week I noticed gear oil on the rear wheel. It looked like it was leaking from the drain plug, so I got some new washers and replaced them. That did not stop the leak and after careful assessment it appears the oil is coming from the back of the final drive, between the drive and the rear rotor. Looking at the Max parts fiche it appears that it may be the gear housing o ring [33 11 1 241 257] that may be the issue. There doesn't seem to be any play in the rear wheel and besides some very fine black crud on the magnet, the oil looked clean with no metal shavings ;so I think the gears and bearings are ok. I am an intermediate mechanic but have not had to deal with a final drive . I'm hoping that whatever seal or o ring that may be causing the leaking is not too difficult to access and replace. Advice. ? The bike has about 70K mi. , I've only owned it about a year and have no idea if the drive has ever been apart.my manual is no help as it advises to leave the final drive to professionals.
Advice. ?

this is from an older post's reply:

I would definitely replace only the big seal. There isn't much labor in common between the two jobs; in fact the rear drive doesn't even need to come off for the big seal so there isn't any. Just last week I replaced the big seal on my R11RS at about 150,000 miles. Didn't even open the housing.

If the pinion seal does start to leak, which isn't unheard of, you probably want to have a dealer do the repair. The ring gear seal can be done without any special tools.

Is the "big seal " the o ring referenced in my original post? I'm glad to hear the rear drive may not need to come off.

 

[eastbay]

I found this,

https://advrider.com/f/threads/changing-the-final-drive-seal.359403/

so it's probably my differential output shaft seal. This seems to be the part number 33 12 7 663 482, ax has it for $46 + shipping, ouch, EME is $30, so I guess I'll order it.

 

[Omega Man]

There are some of the members that are real good at this kind of problem. You may need to wait a bit until they get on and see your post to help you out.
OM

 

[m_stock10506]

I changed the final drive oil about a month ago with 80/90 GL5 gear oil. Last week I noticed gear oil on the rear wheel. It looked like it was leaking from the drain plug, so I got some new washers and replaced them. That did not stop the leak and after careful assessment it appears the oil is coming from the back of the final drive, between the drive and the rear rotor. Looking at the Max parts fiche it appears that it may be the gear housing o ring [33 11 1 241 257] that may be the issue. There doesn't seem to be any play in the rear wheel and besides some very fine black crud on the magnet, the oil looked clean with no metal shavings ;so I think the gears and bearings are ok.......................
Advice. ?

It's possible that just changing that big seal will do the job. Typically, the seal starts leaking because the bearing starts moving around and displaces the seal. Maybe you'll be lucky. There are also o-rings at the hole where the ABS speed sensor goes through the FD housing. You might want to get them on hand, in case there is oil weeping from there. Or, just put two new o-rings in anyway. If it turns out to be the big bearing, it isn't a horrible job for a handy wrench.

 

[eastbay]

I found this,

https://advrider.com/f/threads/changing-the-final-drive-seal.359403/

so it's probably my differential output shaft seal. This seems to be the part number 33 12 7 663 482, ax has it for $46 + shipping, ouch, EME is $30, so I guess I'll order it.

For those who like closure, I replaced the seal yesterday. Not too difficult, but the seal was a bugger to get out. Had to get a screwdriver and pry from the inner part of the seal. The seal was pretty hard and there was some rust around the end beyond the seal which cleaned up with scotchbrite pad. Looks like it had been leaking for a long time, lots of tar- like sludge back there.
fingers crossed that that cures the issue , Thanks for the help.

 

[Omega Man]

Always good to read about how the effort worked out.

OM