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Thread: 2008 R1200GS Final drive oil leak

  1. #1
    Registered User
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    Feb 2015
    Odessa, FL

    2008 R1200GS Final drive oil leak

    Firstly, apologies for the length of this post. As the name of the thread suggests, I’m looking for some advice on what might be going on with the final drive on my ’08 R1200GS, which has only 30k miles on it.

    This started with what, to me, looked like evidence of a very slow leak from the outer (right hand) final drive seal. The evidence was the usual tell-tale black gunk that collects when oil and dirt mix and it was on the underside of the final drive housing, from the seal down. I did some online searching and found indication that failure of this seal can be caused by not riding the bike for some time. This seems a plausible explanation since the bike was garaged for about 4 – 5 months late last year. It was only in December that I managed to put some miles on it and then noticed the slight leak.

    Anyway, I took it in to the local dealer who, without really looking at it, confirmed that they would replace the outer seal only. They did this last weekend and that’s when the real trouble started. I went to collect the bike and they hadn’t quite finished up so had to wait. While waiting I saw a technician take the bike out, I assume for a test ride which lasted no more that 5 minutes. They said the bike was OK and I paid up ($120 all in) and headed home – which is only ¾ mile away. On arrival at home, I checked the final drive and there was oil dripping from the bottom of the housing (not the new seal) and seemed to be coming from between the brake disc and the housing itself. The oil had clearly sprayed on both the tire and the rim. See the pictures (sorry but couldn't get the the right way up!).


    I immediately returned the bike to the dealer who, because of the late hour said they would look into it the next week. Now, after having had the bike for a week they are telling me that the “large O-ring” has failed and needs replacing. I am assuming that the O-ring is the one in the following picture (courtesy gtrider_texas from a different thread).

    FC5B5AF9-A3B4-4644-B7C1-DC92A4417FA4 (2).jpg

    So my questions are:
    1. On the first seal replacement is there any need to pull the final drive apart and disturb the O-ring?
    2. If there was no reason to disturb this O-ring, what is the likelihood of this failing at the same time as the other seal? Could it have also “dried out” due to lack of riding? This doesn’t seem likely to me.
    3. If the final drive had been over-filled with oil after the first seal replacement, could that have blown out the O-ring?
    4. How difficult is it to over-fill the final drive?
    5. Has anyone experienced a failure of this O-ring while riding? It seems to me that this would be very dangerous given the volume and rate that the oil was coming out and ending up all over the side of the tire. Not to mention the likelihood of severe damage to the final drive as it ran dry.

    Thanks in advance for any help.


  2. #2
    Lost again Texpaul's Avatar
    Join Date
    Oct 2006
    San Antonio, Tx
    I have a 2005 GS so very similar to yours.
    You can replace the outer seal without disassembling the entire drive. You can also do it without disturbing the final drive oil, but don't know if that's how your dealer did it.
    You don't state your mileage but if not ridden often the oil ring could fail, especially if the final drive oil was changed. It can be VERY easy to overfill the final drive but wouldn't expect that at a dealership. However, note that the oil level in the final drives was deceased as a way to address seal issues so maybe somebody used the old level???
    I would also note that, though the picture is not that clear, you appear to have a cracked rotor carrier, though I can't see it clear enough to be certain.
    Paul Mulhern
    MOA# 56330
    The biggest mistake people make... is thinking they have time.

  3. #3
    ... cracked rotor carrier - there was a recall for that a few years ago. Went from aluminum to steel.
    2007 R1200RT

  4. #4
    Registered User jandhumphreyme's Avatar
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    Sep 2013
    Central Maine
    No there is no need to disturb the O-Ring when replacing the right hand shaft seal.

    My $.02 it is NOT the O-Ring in your picture, there is an O-ring just outside of the the left side shaft seal. To get at that you will most likely have to break open the final drive case, I've not done one. My 2011 is built slightly different, it will weep a bit in the spring but not so bad yet that I'm wanting to dig into it. You will have to remove the wheel flange to get a good look at it to determine course of action.

    I concur with TexPaul, it looks like the wheel flange is cracked.

    Good luck, couple of Youtube video's out there showing how to take apart the gear case, not extremely difficult if you patient and think through your steps. Simple tools needed as well. Please report back on what you want to do, pictures too.
    So often times it happens that we live our lives in chains
    And we never even know we have the key

  5. #5
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    Feb 2015
    Odessa, FL
    Thanks to all for the replies. Regarding the oil leak, my understanding is that a "seal" or oil ring provides a seal between parts that move relative to each other, while something like an O-ring or gasket provides a seal between parts that are stationary relative to each other. I have a hard time understanding how an O-ring would "dry out", either due to time alone or under-utilization. Instead, in my experience, O-rings fail because of bad installation (trapped) or excessive fluid pressure. I guess it just seems too coincidental to me that I take it in to have the outer seal replaced and then some other seal/O-ring fails catastrophically. With respect to which O-ring it is, I'm afraid I'm only going by what I'm being told by the dealer and I don't know what they mean by the "large O-ring". They still have the bike - waiting for the part. It's only been 9 days now!! I will report back on what they do and what their final verdict is on the cause of the leak.

    Regarding the crack in the rotor flange, please can you somehow indicate where/what you are seeing on the photos. Please also note that the photos of the inside of the final drive that show the O-ring are not of my bike (they are reproduced courtesy of gtrider_texas from a different post).


  6. #6
    Registered User jandhumphreyme's Avatar
    Join Date
    Sep 2013
    Central Maine
    Looking at the photo's up close, I was mistaken, what looks like a crack is merely a seam.

    Good luck with your repair, please do report back what the final resolution is and cost.
    So often times it happens that we live our lives in chains
    And we never even know we have the key

  7. #7

    I've got the tools to rebuild the final drive. I live in the Twin Cities.


    I wouldn't trust too many BMW mechanics with a final drive. As a former mechanic and engineer, some of them are good, and some are hacks. I doubt your large O'ring is leaking. First and foremost, remove the rear wheel and make sure the mechanic didn't just spill oil on the left case when filling the drive unit. You may be seeing spills, loose fill plug, or loose sensor. Check the obvious first.

    Wipe the entire area really good, and then inspect after riding for about 10 minutes. Is the wheel being sprayed with gear oil?

    On a 2008 R1200, the wheel carrier (left-side) seal is situated inside of the big sealed bearing. Therefore, in order to fix the seal, the wheel flange must be pulled off. Then the 10 quantity M8x1.25 T40 Torx bolts must all be removed. Then, with a bit of effort, you can pull the entire axle out. You can actually remove the bolts without taking off the wheel carrier, but if the seal is leaking, you will eventually need to pull the wheel carrier to remove the axle from the left case.

    I have made about a dozen special tools to rebuild the final drive. It's not rocket science, but it's definitely not a job for the average BMW rider. The trick is to never put any undo stresses on the bearings when assembling the bearings. I've watched YouTube videos. Most of the guys do an OK job, but I've watched them do a few assembly "no-no's".

    A lot of dealers will just sell you the 2010 - 2012 final drive. They are a bit better because they moved the big bearing into the fluid. It's no longer a 6013-2RS bearing (rubber sealed).

    The 6013 bearing may be bad. At a minimum, you will need a new big bearing and a new seal. For drives with over 85,000 miles, I'd just replace all the bearings, seals, and O-rings (about $500 in parts). The other option is to buy a new and improved final drive (BMW P/N 33 11 7 726 889). A friendly dealer might sell you one for $1,900 dollars. The list is about $2,400 dollars.

    If you junk the final drive, send it to me. I'll pay for you $25 for shipping and give you $40 for the drive. I like taking them apart and inspecting for damage.

    Last edited by FinalDriver777; 11-06-2019 at 03:03 AM.

  8. #8
    Registered User GTRider's Avatar
    Join Date
    Apr 2006
    Nibley, UT USA
    Quote Originally Posted by mjs1200 View Post
    I have a hard time understanding how an O-ring would "dry out", either due to time alone or under-utilization. Instead, in my experience, O-rings fail because of bad installation (trapped) or excessive fluid pressure.
    O-ring failure can also be attributed to heat, which tends to dry out the rubber and induce cracking and eventual failure. This was the root of the problem with brick-k bikes, where a lot of perfectly good rear main seals were replaced when the real problem was the buna-n o-ring that BMW used on the clutch shaft. The real fix was to replace the buna-n o-ring with a Viton o-ring, which has a higher heat tolerance. I think BMW eventually started shipping Viton rings through the parts channel, but I’ve continued to source mine in the aftermarket. O-rings take a “set” in use so should always be replaced once disturbed, but it sounds like there should have been no need to disturb the ring to replace the outer seal—I certainly haven’t had to when replacing the one on my K13GT.

    Good luck, hope your dealer gets this handled for you.

    1983 R80ST — 1984 R80 G/S-PD — 2004 K1200GT w/Hannigan S/C — 2010 K1300GT — 2018 R1200GS
    BMWMOA#52184, AMA#271542, IBA#138

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