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2012 RT final drive - broken bit found


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I found this stuck to the magnet in the drain plug of my final drive. It's not mangled, so I suspect it broke off, got hit once (notice the swipe mark) and stuck to the magnet. There were no other bits on the magnet, just the usual slurry.


I'm not overly worried at this point (though I'm willing to get worried ), but would like to know what it is. Can anyone identify it?












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I don't know, but I'd certainly take your bike in and have the dealer document this, i.e., have a work order written up, dated etc., with mileage, so you have some record in case something goes amiss later (like past the warranty).

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Afternoon Tom


That piece doesn't look familiar. Seeing as it stuck to the magnet it didn't come from the aluminum part of the case & it is not round enough to be from a bearing race. I don't remember anything on the inside of the side cover looking like that either.


My guess is it got into the final drive during assembly (maybe a piece of broken tooling or something from the axle assembly line carrying equipment).


In any case it does look like it was hit so possibly came into contact with your ring or pinion gear.


You need to convince your dealer to at least remove the final drive side cover to inspect the insides or better yet install a new final drive for you.


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Hi D.R. -


I agree; it will go off to the dealer soon.


What it is, I cannot imagine. It looks very similar to a bearing retainer finger from an inexpensive ball bearing - the sort one might find in the bottom bracket of an old Schwinn that used the Ashtabula crank.


Sort of like this:



Though I'm sure the bearings in the FD are more like this (at least I hope they are!):










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Looks like a piece of ball bearing race cage to me. If so, The question is how did it break? You wont find any other pieces of it as it does look like a clean break to me and the ball should still be seated in the cage. The nick is probably from it hitting by a glance one of the gears. You seem to of gotten away lucky. Redline the sucker and get it fixed IMO.




My guess part 7..........

33 11 7 720 235 GROOVED BALL BEARING $110.68

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Looking at the photo in my response to D.R., I think you're right.


When I posted the photos I was thinking it looked like the finger retainer from a cheap bearing, but the corrugated retainer in the quality bearing looks a lot like my piece.



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Evening Tom


That all sounds plausible up until you realize the crown bearing on the 1200RT DOESN'T run in the gear oil chamber. That big crown bearing is isolated in it's own sealed off chamber lubricated with it's own grease (not the gear oil). No way for the bearing parts to get into the gear oil or on the magnet.


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D.R. -


Believe it or not, that makes me feel better; thanks muchly. The pinion bearing looks like a totally sealed unit, so it shouldn't be that, either. Am I correct in saying that?


I was sorely tempted to pull it apart and take a look for myself, but discretion seems the better idea.


I have an appointment at the dealer next Thursday (I have a sick puppy to care for and a gimpy kid who needs shuttling to physical therapy, so that's my first opening).


The dealer is good and the service manager wanted to see the bike and the part. So much so that I emailed him the pictures to ponder.


Until then, I'm on the KLR.


I'll report back.






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Take it to the dealer.

Take plenty of pics, document all.

Have them determine what it is and put that in writing

with an acknowledgement that it is/isn't related to internal

parts and integrity of the motor.


Document it is forwarded to BMW corp and document the response.


You will most likely never need that, but just in case...

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I got a call from the dealer's service representative.


They have no idea what the piece is or where it came from. The mechanic inspected the final drive and said it looks pristine. The piece was shown to the field service rep; he had no idea where it could have come from.


Unfortunately, I don't get my bike back yet as they found that the left grip heater doesn't work. I just thought it was normal that the left side didn't feel too warm because it's not insulated from the bar and because I keep an open hand on the clutch lever. Do you know that they have to remove the tank to replace the left hand heater? Apparently the heaters can be disconnected at the bar and replaced easily, but they have to remove the multi-function ring to get at the left one, and that requires removal of the tank to get at its connector. How Teutonic. I'm tempted to change my name to Smythe and pretend I'm British.



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It has 16,000 miles on it.


I know I'll get prodded a bit for this, but it's part and parcel of being anal...


If the rear wheel comes off the bike, the FD oil get's changed. A liter of the stuff ain't that expensive, makes about five oil changes, it takes but 10 minutes of actual work time, and given the BMW FD history gives me peace of mind.


I changed the FD oil at about 500 miles last December, then again at 6,000 miles or so, then again at about 10,000 and 14,500 miles.



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Well it certainly wouldn't get in during one of your fills but how sure are you it was really inside the FD rather than just recovered stuck to a plug fished out of an oil drain pan? Your included scale shows this thing to be over 1/2" wide and at the upper limit of what would fit through the drain hole and its a lot longer than that hole is wide....

Pretty hard to imagine a piece that size being held in place by the fairly weak magnet of the drain plug (though perhaps it might wedge into the hole) and suffer only that small amount of damage from gears. There is a lot of turbulence in that FD from fluid movement and splashing.

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The scale is a machinist's scale. The graduations are .1", so it is just over .3" long and about .15" wide; about half the size of your pinkie nail.


It came out of the final drive stuck to the magnet in the drain plug. It wasn't fished out of a drain pan.



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Racer7 -


My bad, actually. One of the most important things in any discussion is to define your terms. I should have noted it was a machinist's scale and what the graduations meant.



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Well its still big enough that is seems almost impossible for it to have gotten in there with new fluid (if, for example, it had come off a filling machine or beeen in the lube bottle prior to filling).

So that leaves something getting in prior to or during assembly.


I suspect the fact that is barely been dinged by a gear means it hasn't exacted any gear damage inside but at least it documented. Looks like the only way to figure out what would be to track back the procss at the factory.

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  • 5 weeks later...

The saga continues.


After the dealership inspected the drive and pronounced it worthy, it developed a slight leak, so back it went. They did a repair of some sort, and off I went. Now, the bike pretty much didn't go anywhere for a while as I was stuck at home with a new (and sick) puppy. I toodled around a bit and it seemed fine.


Last Sunday I resumed my normal activities and headed up north, taking Mil Portrero and Cerro Noroeste on my way to northern California. There have been times when I've had the RT hard over to the point where there really isn't a contact patch back there, and it slips a little when you do that. I noticed a bit of slipping in the back end, but I wasn't riding hard. Odd.


Stopped and looked to see what I could see, and the final drive was leaking some. The rim was splattered with oil and it there was oil on the side wall and on the tread just below the sidewall. Damn. I continued on, taking care the rest of the way, and rode around Sacramento for a week, getting back last night.


That brings us to this morning, when I took the bike in to the dealership. They were expecting me, as I sent a heated e-mail to them at midnight last Sunday. You shouldn't send e-mails when you're ticked....


They have had the bike apart all day and just called me. Apparently, it's been a long strange trip.


That piece I showed in the first post - there are more!


Here's where it gets strange, and where I'm out of my element as I've never been inside one of these drives. Hereafter I'm parroting what the Service Manger told me. This is a guy I've come to know and trust, at a dealer I feel is a good one. Of course, he's been a bystander to this and is passing along to me what the techs have told him, so if something was lost in the translation, well, it's lost.


At first they thought the bike had the final drive guts from an R1200R in it. Apparently, the final drive in the R1200R is different and has the caged bearings installed. They thought that for a couple of hours. It is the cage on the bearing that is apparently coming apart. Somehow, the bits just drop into the bottom and don't mess things up, except maybe the seal. Seems odd, but OK, whatever. They say the final drive works perfectly, it just that the bearing cage is falling apart. They see a perfect pair of gears, no shiny stuff in the oil, just the chunks from the bearing.


Since it didn't make sense that my RT would have an R1200R final in it from the factory and they know I didn't put it in there, they got a bit more curious and took a new RT off the show room floor and took it apart. Same set up. They did some more digging (seems they had a couple of people banging away at the keyboard on this one). Apparently, BMW has changed the final drive, this in-line change being effective about a year ago. They just kinda sorta didn't really tell anybody...


Though the final drive is fixable, they have started a PUMA to get authorization to install a complete new final drive. That's the good news. The bad news is that the only place one of these exists is in Germany, so it's at least a week away.


The good news is that I either need my bike Sunday to go back to Sacramento or I don't need it for over a week.


The bad news is I'll be riding my KLR to Sacramento Sunday.




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Camhead in STL
TThe bad news is that the only place one of these exists is in Germany, so it's at least a week away.


Someone owes you a loaner. PERIOD.

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They always give me a loaner if I ask for one. This time it's an F800S.


How do people ride them things? Seems like it would give you carpal tunnel issues unless you keep it over 70mph.


They did offer me a loaner with luggage, but I'd prefer not to ride a loaner except to get home.


The F800S goes back tomorrow.



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  • 3 weeks later...
Camhead in STL

they got a bit more curious and took a new RT off the show room floor and took it apart.




The bad news is that the only place one of these exists is in Germany, so it's at least a week away.

Did you see that contradiction right there? I did.
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If at some point you can get hold of the failed FD for some internal photos to post it would be much appreciated by others sure to have similar issues..


Just what is needed- another way for an FD to crap out from yet another design "improvement"......


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