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Thread: 2005 R1200RT Cracked Rear Wheel Flange at the Wheel Mounting Studs

  1. #1
    jay1622
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    2005 R1200RT Cracked Rear Wheel Flange at the Wheel Mounting Studs

    I dare ask, but can someone tell me what I'm looking at here?

    The bike has 40K miles on it, is on its third or fourth rear tire and has only seen the likes of properly calibrated torque wrenches throughout its life.

    A quick search revealed this happens to be common, which surprises the heck out of me seeing as to how catastrophic something like this can be... My rear wheel flange has 3! separate cracked stud areas.

    On a bike with this kind of mileage on it, is there a snowball's chance in you know where that I'll be able to get some help from BMW. Obviously, there's no way to prove the TLC this bike has received so I know there is a strong chance they will tell me to pack sand.

    I know what the service entails (Heating to 90-110 degrees C), but I don't have the puller for the job and I'm not the makeshift kind of tool guy. I'd JB Weld the thing, but what's to say it doesn't crack somewhere else.

    Worse case scenario, I'll pop the FD and drop it off at the local BMW shop and have them replace it.

    Any advice on dealing with the BMW folks and or doing the job myself is greatly appreciated.
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  2. #2
    jay1622
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    The second stud.
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  3. #3
    jay1622
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    The third stud
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  4. #4
    Registered User David13's Avatar
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    JBWeld would never hold that safely. You need it replaced. The replacement is a steel one, instead of aluminum.
    You can ask at your dealer, if you have one, one that you use regularly.
    The BMW salesman who works at the BMWHarley dealer in Maryland had to pay for his. But he got a discount on the parts, or something.
    I do believe there was a thread on advrider by a guy who replaced his.
    dc

  5. #5
    jay1622
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    A Conversation with Flange

    The Conversation...

    So I sat with my morning coffee in hand and stared at the left hand side of my wheel-less rear wheel flange. I asked it to explain to me where the stress points are when under load by way of acceleration, braking and so on. The flange explained, "When under load by way of acceleration, I'm very strong and I don't feel any exorbitant forces beyond what I was designed to handle." I asked it to explain. It told me to take a closer look at it. While doing so, it asked me to consider how much faster and stronger the bike brakes than it accelerates. I reminded Flange I've been riding it and its R1200 series brothers and sisters ever since they came off the lot and that I was quite familiar with its sick ability to stop. This being the case, Flange said, "BMW engineered me in reverse order; that is, placed the structural integrity aspect of my build with a lean towards acceleration forces instead of braking. Under acceleration forces, the energy is distributed from the hub to the wheel through the Flange. There is a significant amount of material (aluminum) between each of my five points from hub/splines portion of me to where the studs attach to the rear wheel.

    I told Flange that made plenty of sense; I could see this significant amount of material right there in front of me, but, I said, "The front wheel stops so much more of the bike than the rear, right? So why the issue then from braking?" The Flange came just short of laughing at me and told me to bring up any picture on the internet I could find of it and told me to envision it in motion. The Flange reminded me of the caliper's immense strength and what results in immense shear strength experienced between where the rear rotor attaches to the Flange and the very little material that attaches the rotor bolt holes to the rest of the Flange. "Remember," it said, "Even though the rear wheel is only stopping fifteen to thirty percent of the bike's weight, that it still translates to an enormous amount of force." "So," I asked, "where are the weakest points then as it relates to shearing against the Flange?" It smiled and said, "You're still looking at that picture and seeing me in motion, right?" I said, "yes, go ahead." Flange said, "Now picture the caliper applying pressure via the pads to the rotor. That braking energy is transferred to the tire, but before it gets there it has to travel through me and the wheel first. First and foremost, don't forget how heavy the bike is and the considerable momentum. If you take a close look at how I am constructed, my two weakest points are where the rotor mounting bolts attach to me and then, and even more so, to outer thread holes for the wheel studs" I couldn't believe my ears or my eyes. To sink the knife in the argument even further, Flange said, "Don't forget to consider how often you load those cases and take that great looking bride of yours along. All that weight makes me work that much harder."

    As I sipped my designer latte, I thanked Flange for miles of service, for not letting me down on the road and that it would need to be replaced with a thinner and stronger model; one that was better engineered based on lessons learned. Flange smiled and said it understood.

    I plan on taking the bike in the next week or so. I hope to get some help from the shop/BMW seeing as to how many of these have failed. Of course, my time is worth more so I may just order a new one and do the work myself. If you've gotten this far, I hope you enjoyed the read. Did it make sense? Let me know if not.

    Note... The following pic is the one I found online for reference purposes as indicated by my conversation with Flange.
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  6. #6
    Quote Originally Posted by jay1622 View Post
    A quick search revealed this happens to be common, which surprises the heck out of me seeing as to how catastrophic something like this can be... My rear wheel flange has 3! separate cracked stud areas.
    Yes, it could be quite catastrophic... but in practice it turns out not so much. My guess is that people tend catch it before anything bad happens. I found mine when changing the rear brake rotor. http://www.snafu.org/pics/r1200gs/2009/1125-rear-brake/

    FWIW the new flange is cheaper than an OEM rotor. Not that I used the very expensive OEM rotor. It's not that difficult to change if you feel up to doing the job yourself. When I did mine the replacement was still aluminum.

  7. #7
    Registered User David13's Avatar
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    That looks like an excellent job, Marchy. I think the adv thread heated the new one, which may have been the new steel one, at 325, but I don't recall for how long. I do recall it was some good time, not just a few minutes.
    I believe someone else posted with a puller they used to help with the removal. It also fit ok.
    I think the flange is $250 or so.
    dc

  8. #8
    Registered User lkchris's Avatar
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    If you'll check Realoem, you'll note there's a part number supercession for this part (although realoem seems to have the new number incorrect). It's a $265 part.

    I'd speculate the ears of the wheel carrier could easily be cracked by improper fixing of the brake rotor. Reprom says tighten all to 12 nm then tighten all to 30 nm. New screws every time, BTW, as they come with encapsulated thread sealant. These are, again, the rotor mounts, so careful or not tightening of wheel bolts probably doesn't affect these ears much.

    Replacement looks really simple, although Reprom doesn't have a procedure, and I'm not certain I'd fall on my sword with my dealer for $265. Looks like it just slides on/off and is held with a snap ring.
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    Last edited by lkchris; 02-19-2012 at 10:07 PM.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  9. #9
    Quote Originally Posted by lkchris View Post

    Replacement looks really simple, although Reprom doesn't have a procedure, and I'm not certain I'd fall on my sword with my dealer for $265. Looks like it just slides on/off and is held with a snap ring.
    I don't think so. Last I heard the wheel flange was an interference fit on the axle tube and the snap ring was merely insurance. That is, the flange piece is heated to some specified temperature - for example 80c or 100c, and then placed on the axle tube where it cools, shrinks, and grips. Tightly!
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  10. #10
    jay1622
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    I have the instructions and the access to the parts/tools. Everything else at this point is effort and maybe a couple of Ben Franklins. The rotor is still true and the brake pads look great. I'm guessing five new rotor to flange mounting bolts, the flange and the spacer should do it. I do hope; however, my local dealership will try to throw me a bone. I'll write back once I know more. Thanks for the responses and the detailed instructions.

  11. #11
    Registered User lkchris's Avatar
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    Quote Originally Posted by PGlaves View Post
    I don't think so. Last I heard the wheel flange was an interference fit on the axle tube and the snap ring was merely insurance. That is, the flange piece is heated to some specified temperature - for example 80c or 100c, and then placed on the axle tube where it cools, shrinks, and grips. Tightly!
    I'm sure this is correct if you've heard that and I'm consequently surprised I can't find a BMW procedure on my RepROM disc. Ought to be in group 33 I'd think.

    BTW, I checked mine on my '08 and it shows no cracks. Check with magnet shows it's nonferrous, too.

    Wonder if the new version is actually steel and if this changes the heating requirement.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  12. #12
    Registered User David13's Avatar
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    You have got to heat it to get it on and off. They are heating the new steel one. There has been more than one changed over at advrider. They heat the steel one. One says to 130 c, and another one says 35 minutes.
    dc

  13. #13
    jay1622
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    For those of you who have delt with dealers and BMW/NA... Should I address the three huge cracks where my wheel meets the flange (historically NOT covered) or the hairline crack where my rotor meets the flange, which is still factory installed (historically covered). Or does it even matter?

    2005 R1200RT with 41,XXX miles, second owner.

  14. #14
    jay1622
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    RT is at the dealer... Wainting for an answer.

  15. #15
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    You don't have to be a professional metallurgist to see that these problems are caused by the same basic issue that leads to cracking of the plastic fuel pump flanges on various models as reported by many owners.

    Someone ought to teach engineering 101 to the responsible Germans- namely that a screw thread is a levered wedge that exerts expansion pressure in whatever threaded bit is holding it. Therefore the receiver has to be strong enough to resist the force as installed plus whatever load increase it sees while in operation.

    Just as the plastic pump flange is the wrong material (a new part has a metal reinforcing ring). this lightweight aluminum bit is also the wrong material in addition to being too thin at a critical point. Luckily, the manner in which it cracks is unlikely to cause immediate and potentially catastrophic separation. The receiver just "pops" to relieve the stress and the crack can't propagate for any distance. Even if all bolt locations were to crack simultaneously, immediate wheel separation is not probable.

    In this case, they took the cheap and easy way out for the fix, apparently, with a steel part (both more ductile and stronger so unlikely to crack) rather than using a more expensive solution which could also have been a proper alloy forged aluminum piece.

    Germans do a pretty good job at a lot of stuff but the number of basic engineering goofs on R models demonstrates an organizational weakness at BMW- failure to do adequate team-based engineering reviews prior to approving bits for production. Too much reliance on what's drawable in a CAD system and not enough on human knowledge based review to ensure it will work and be durable.

    One has to wonder how many of this type of silly choice is buried in the design of new and untested models like the K1600.

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