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Final Drive Issue 2008 R1200RT

Looks like good progress so far.

Be interested to learn a couple things from your experiences as you progress
1) Do you have any ideas about why the inner bearing failed? Can you get any hints from its condition if its an assembly/spacing issue, bad part, etc etc?
2) What issues will (did) you run into rear fitment and reassembly especially in getting gear engagement correct.

Thanks for the update.

Oh- a suggestion if you add a vent. Do one with a permeable membrane of some type (eg goretex, teflon, etc) so you can gas exchange without getting water vapor or grit in. Not sure you need it at the correct 180 ml volume but it won't hurt. I think a lot of the reported blown seals actually result from dealer overfills- I've measured over 260 ml out from work not done by me - that's over the factory fill or refill amount and enough to cause a pressure increase inside a sealed unit.
 
My dealer performed a minor "final drive repair" by replacing bearing p/n 33117720235 and some seals (all warranty). Is that part on your list?
 
1) Do you have any ideas about why the inner bearing failed? Can you get any hints from its condition if its an assembly/spacing issue, bad part, etc etc?

I cut the bearing apart today to determine what had failed. The inner race of the bearing was trashed. Deep pits and washboard surface on the raceway of the inner race. There was still plenty of grease inside the bearing and the balls, bearing cage and outer race looked to be in good shape. I suspect the bearing was bad and maybe the inner race was below hardness specification?

I do not have it back together as new parts have yet to arrive. I plan to replace the failed bearing and all the seals on both sides of the FD. I am leaving the input shaft alone as it appear to be okay. As to fitment and engagement, I am hoping that if the replacement bearing is dimensionally the same as the failed bearing the engagement will be unchanged and no fussing with the shims will be needed since the input shaft is not being taken apart. I will of course check it with machinist bluing when reassembling.

I am looking into adding a vent that will provide some measure of moisture resistance. So far I've checked McMaster Carr but haven't found a vent that I'm satisfied with. If you have any suggestions I would be interested.

You may be right about the amount of oil in the FD. I put in .22l at last fluid change as my service manual stated. I have since learned that .18l is the correct amount.

Sailorlite; yes, that is the bearing that failed. It is shown in the lower right of the picture above. I ordered it from A&S Cycle for but received notice that it is on order from their supplier. I checked with the local bearing house but they were unable to match the part number marked on the bearing exactly. Dimensionally the bearing they showed in their system is the same but the price was only $10 less. I'll wait for the correct bearing from BMW. Hopefully it won't be another bad one.
 
It's good news that you were able to do this repair on your own. It will definitely be cheaper than the $700 it cost me. This is the exact same failure that I had. Interesting to say the least. If you need some closer pictures of the vent, just let me know, or it may be easier to just look at one at the dealer.
Good luck!
 
I cut the bearing apart today to determine what had failed. The inner race of the bearing was trashed. Deep pits and washboard surface on the raceway of the inner race. There was still plenty of grease inside the bearing and the balls, bearing cage and outer race looked to be in good shape. I suspect the bearing was bad and maybe the inner race was below hardness specification?

I do not have it back together as new parts have yet to arrive. I plan to replace the failed bearing and all the seals on both sides of the FD. I am leaving the input shaft alone as it appear to be okay. As to fitment and engagement, I am hoping that if the replacement bearing is dimensionally the same as the failed bearing the engagement will be unchanged and no fussing with the shims will be needed since the input shaft is not being taken apart. I will of course check it with machinist bluing when reassembling.

I am looking into adding a vent that will provide some measure of moisture resistance. So far I've checked McMaster Carr but haven't found a vent that I'm satisfied with. If you have any suggestions I would be interested.

You may be right about the amount of oil in the FD. I put in .22l at last fluid change as my service manual stated. I have since learned that .18l is the correct amount.

Sailorlite; yes, that is the bearing that failed. It is shown in the lower right of the picture above. I ordered it from A&S Cycle for but received notice that it is on order from their supplier. I checked with the local bearing house but they were unable to match the part number marked on the bearing exactly. Dimensionally the bearing they showed in their system is the same but the price was only $10 less. I'll wait for the correct bearing from BMW. Hopefully it won't be another bad one.

You might try calling Hermy's BMW in Port Clinton, Pa. 610-562-7303. They have had great success using after market bearings with zero failures. I'm sure they can ship one to you. I talked in great length with their service manager about this issue at the national this past week. He also said that the FD was redesigned for 2010 as that bearing now is no longer a sealed one but lubricated by the FD oil.
 
My '75 Airhead has the venthole...I've never had a problem with the FD since new (knock on wood).

What progress! A vent has been added for 2011. A drain plug was also added a few years earlier, right? Still no fill plug?

I would like to know what was wrong with the final drives before BMW decided to improve them.
 
What progress! A vent has been added for 2011. A drain plug was also added a few years earlier, right? Still no fill plug?

I would like to know what was wrong with the final drives before BMW decided to improve them.

Perhaps lighter and cheaper
 
What progress! A vent has been added for 2011. A drain plug was also added a few years earlier, right? Still no fill plug?

There has always been a drain plug. That was it's only purpose. It just wasn't always where you may have wanted it. It's original location doesn't bother me, any.

A fill plug got added about 4 years ago when they moved the location of the drain plug.
 
Nice teardown FlyingW. I have been trying to get my hands on an R12 final dive for years w/o success to practice a rebuild. If you have assembly shots, please post.

Did you buy a special tool to seat the seal or will you wing it? I think I'd figure a way to do it w/o spending $75 for the tool but w/o seeing the task it is hard to say.

You said you plan to use the gear compound for the spacing. What pattern are you looking for? Direct centered contact of the teeth? I'm wondering since some items I've worked on specify a specific pattern, not centered (boat motors, etc.).

Why not use plastigage to set the clearance?

Please let us know how it all goes. I hope you get good life from it.

I'm encouraged that at least if I have this issue on mine I can deal with it in my own shop at a fraction of the price. Even if I only get 30k on a rebuild, that would be OK.
 
Nice teardown FlyingW. I have been trying to get my hands on an R12 final dive for years w/o success to practice a rebuild. If you have assembly shots, please post.

Did you buy a special tool to seat the seal or will you wing it? I think I'd figure a way to do it w/o spending $75 for the tool but w/o seeing the task it is hard to say.

You said you plan to use the gear compound for the spacing. What pattern are you looking for? Direct centered contact of the teeth? I'm wondering since some items I've worked on specify a specific pattern, not centered (boat motors, etc.).

Why not use plastigage to set the clearance?

Please let us know how it all goes. I hope you get good life from it.

I'm encouraged that at least if I have this issue on mine I can deal with it in my own shop at a fraction of the price. Even if I only get 30k on a rebuild, that would be OK.

I won't buy any special tools for this project. Before I became a mechanical engineer I was a machinist. I have access to a full machine shop and can make any tools I need as I go. I also have an electronic version of the service manual that details the re-assembly process and checking the engagement of the drive gears. I didn't think of plastigage frankly, but I suppose that might work. The service manual describes using bluing and the desired contact pattern.

I'll let you know how it goes when the parts arrive.
 
I have the BMW DVD service manual but didn't know it had rebuild instructions. Thanks for that. I'm an 'amateur' machinist and can make just about anything I need, also. A metal lathe would be nice to have, but I haven't got that serious yet!

I wish I lived closer, I'd love to hang around your shop for a day.
 
Success! Rebuilt '08 RT final drive......

Well I got my FD back together and it is working fine. All the racket I was hearing has disappeared. Rode 850 miles over the weekend and the FD worked flawlessly. I spent about 8 hours making tools and another 8 or so for tear down and re-assembly. Only hitch was that I ruined the main seal by over pressing it into the bearing housing. Thanks to Pandora European Motorcycles of Chattanooga TN I was able to get another one overnight. All total it cost $270 for the parts. I passed on installing a vent as I didn't find one that I liked. We'll see how long the bearing lasts this time. If I have to rebuild the FD again it will be no big deal.
 
Great news. I hope I don't have to follow in your footsteps!

What tools did you need to make? Can you post some pics of them?
 
That's great news and a LOT cheaper than the route I took. I don't have the tooling or shop available to do this type of work. I'm told that the new Final Drive I now have, has a different bearing. Evidently it is no longer a sealed bearing which allows it to be lubricated with the drive oil. We will see how it goes. I've got two years to drive the wheels off this thing to see if it lasts.
 
Evidently it is no longer a sealed bearing which allows it to be lubricated with the drive oil. We will see how it goes. I've got two years to drive the wheels off this thing to see if it lasts.

Eh? Unless the FD design has changed the big bearing is on the dry side of an oil seal. Sealed or unsealed, it isn't in the drive gear oil.
 
Eh? Unless the FD design has changed the big bearing is on the dry side of an oil seal. Sealed or unsealed, it isn't in the drive gear oil.

Absolutely correct. There's a great big seal between the bearing and the oil in the FD. I'm curious too.....what did they change?

Here's a picture of some of the tools I made....sorry about the poor quality. I also made a nice puller for the wheel mount hub.
 

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Can you elaborate on the use. What's the upper right one for? The upper left one for pressing in the seal? If you care to elaborate, I'm all ears. Too bad you didn't take more photos (or maybe you did) cause it would be a cool tech section write up.
 
Can you elaborate on the use. What's the upper right one for? The upper left one for pressing in the seal? If you care to elaborate, I'm all ears. Too bad you didn't take more photos (or maybe you did) cause it would be a cool tech section write up.

The upper right tool's purpose is to securely hold the FD so it can be mounted in a bench vise. This is really nice as the FD's shape is kind of rolly polly on the bench. The upper left one is used interchangeably with the lower left tool to press the crown wheel into the bearing housing. The other use for this tool is to press the wheel mount flange onto the spline crown wheel shaft. The small aluminum drift in the middle is to GENTLY seat the main seal behind the crown wheel bearing (as I stated before....I ruined the first seal by over pressing it in with an arbor press...totally not necessary).

Yes, I should have taken more pictures. The one's I did take where not detailed enough to clearly describe the rebuild process. I was stressing to get the motorcycle back together in time for a planned trip. Suffice it to say this is not rocket science. I now have 1600 miles on the FD and it's working fine. With a little thought and the right skills these FD's can be repaired without costly visits to the local dealer.
 
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