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Thread: BMW Design Flaws

  1. #1
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    BMW Design Flaws

    I posted this question awhile back on another BMW forum. I want to offer participants the following short You Tube video from Chris Harris, owner of Affordable Beemer Services in Manchester, NH. in order to solicit reactions.

    Chris has my 2004 R1150 RT and will be installing a modified (non OEM) clutch plate, machined by Bruno Sax in Canada. The bike has 15 K, and exhibits no current transmission input spline - clutch plate issues. The tape speaks for Chris' perspectives on past BMW design and production problems, and their unwillingness to remediate them. The other design issues Chris has with many Oil Heads - not covered in his video - are Final Drive and servo-assisted brake problems.

    The fact that Chris has my bike for an expensive repair attests to my own belief in his judgement and mechanical work, and my wish not to experience a subsequent mechanical failure while touring that I would prefer to have addressed beforehand:

    http://www.youtube.com/watch?v=Jx3e...eature=youtu.be

  2. #2
    Registered User WalterK75's Avatar
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    Clicked on link to video. Message was "This video does not exist" Can you verify and post another link or video title?
    Walter

    G. K. Chesterton wrote - "The traveller sees what he sees, the tourist sees what he came to see."

  3. #3
    Registered User lkchris's Avatar
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    If he were an engineer, he'd have a better job.
    Kent Christensen
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    '12 R1200RT, '02 R1100S, '84 R80G/S

  4. #4
    aapasquale
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    very interesting video

    sometimes people have the job they have because they like what they are doing----the video on YouTube is entitled "BMW service-clutch/transmission spline failure explained--it's very informative--Chris' delivery is straightforward and edgy, but he does know these machines and the fact that he takes the time to put forward these videos is a real plus to the BMW community

  5. #5
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    BMW Design Flaws


  6. #6
    Curmudgeon nrpetersen's Avatar
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    I strongly disagree with Chris's analysis. R bike spline failure is caused by radial misalignment between the engine crankshaft axis and the transmission axis. Adding another 20% to the spline length won't significantly change the spline life if there is radial misalignment.

    I stripped out the splines many years ago @ ~20K miles in my R90/6. Even now at 50 K miles, in neutral, with the transmission-engine bolts loosened, I can feel micro-motion between these elements whenever the clutch is let out. I have to frequently lube these splines.

    My R1100RT doesn't do this. On dis-assembly @ 24K miles, the splines were perfect. Both bikes are driven the same way.

    The surge has nothing to do with spline life. My R1100 surged mightily until I cleaned and matched the throttle bodies and balanced the throttle stops vs the BBS screw openings.

    Think of a spline as an internal/external gear set with a 1:1 ratio. In our case it runs with minimum/no lubrication. If there is near perfect alignment, no problem as there is no relative motion. If there is radial misalignment, the spline drags the clutch disk around the flywheel every engine revolution and the result is fretting and spline teeth erosion. That's the red stuff you can see in the pictures. This radially loads the rear crankshaft main bearing too, and wear on this should always be checked on disassembly with any spline strip-out. If the rear main bearing becomes loose, the piston rod forces will hammer the spline, further hastening the spline failure.

    Why does this happen pretty much only in oilheads? I think it is because of the clutch housing design with the starter opening making it much less rigid. Possibly it is also caused by an assembly technique that compounds the alignment problem.
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

  7. #7
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    I have been riding some sort of motorcycle since I was twelve. I have been and still am a member of owner groups of various brands and models. One common denominator in all these groups is, that there are a number of owners who know the technical ups and downs of their bikes much better than those who made them and they also are convinced that the engineers who work for the manufacturers are all idots and nincompoops.

  8. #8
    JohnWC
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    I watched the video. I have to say I don't know if he would be the first person I would hand my bike to. Seemed kind of obnoxious. And for a guy who makes his living working on BMWs, he sure seems to feel they can't do anything right.
    I love the fact that you have to pre-pay him $600 for a clutch disc that you are not allowed to see. Trade secrets and all. And you might have to wait 6 months to get it, too. It's apparently being" modified" by the typical guy working out of his small shop/ garage making aftermarket parts. I didn't hear any mention of a warranty for that $600 clutch disc, either.
    Maybe this guy knows clutches. He's certainly done more of them than me. But comparing the pictures he is showing us, I didn't actually see a lot of difference in the clean, unused area near the transmission housing between the wonderful airhead spline system, and the rotten oilhead system. Plus the oilhead clutch disc is countersunk in more than the airhead, making it sit about on the full spline length. I also debate that the disc moves like a quarter of an inch when you pull the clutch lever in. I believe it is a very slight amount, negating the need for a much longer input shaft. I love his mention that you are an idiot if you are not racing the engine most of the time. If I wanted a crotch rocket, I'd buy one. His whole theory of "loading-unloading" wearing out the splines seems very suspect. I think that's what the spline system is supposed to take care of, and be designed to withstand. Overall, I am still of the feeling that if you keep the splines lubed, they will last a long time. Finally, I find it very hard to accept that you could wear out the splines in 7000 miles, as he states, even if you tried to.
    BMW makes mistakes, I don't always defend them. But in this case I find it a bit difficult to believe that a lot of well paid German engineers didn't take a very close look at this whole spline situation. If the bikes were constantly failing, it would be quickly known all around the world. Sales would plummet. That's not how BMW sold something like 100,000 machines last year.
    Last edited by JConway607; 02-22-2013 at 04:58 PM.

  9. #9
    Registered User rxcrider's Avatar
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    I'm curious about the spline engagement issue Chris has shown. The M97 gearbox combined with a clutch from 2004 in my 1995 R110RS showed nearly full spline engagement based on the wear on the clutch hub.



    I do believe that low RPM riding may aggravate the issue, but the fact that he makes no mention of misalignment as a possible factor is unfortunate. When the day comes that I have to replace the input shaft on my bike, alignment and runout are the first things I'm checking.

  10. #10
    Curmudgeon nrpetersen's Avatar
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    Quote Originally Posted by rxcrider View Post
    When the day comes that I have to replace the input shaft on my bike, alignment and runout are the first things I'm checking.
    And the crankshaft rear main bearing clearance in all directions.
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

  11. #11
    Alps Adventurer GlobalRider's Avatar
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    Quote Originally Posted by Muchogum View Post
    The tape speaks for Chris' perspectives on past BMW design and production problems, and their unwillingness to remediate them.
    I'm still waiting for these so-called design flaws to materialize, both on my airheads and oilheads.

    I have yet to have any clutch issues and that is with far more shifts in a day than 99.9% of users see.

    And I have yet to find any metallic fuzz on my final drive magnetic drain plug.

    And I have yet to have an OEM fuel line quick-disconnect fail.

    Dumb luck, I guess.

  12. #12
    Day Dreaming ... happy wanderer's Avatar
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    I'm not a mechanical engineer but I would prefer to see the entire length of my input shaft splines fully engaged with the entire length of my clutch disc splines just because that makes total sense to me. I also think radial play or excess runout would be a very bad thing here before winding everyone up on that one again. We've been down this road an awful lot in this forum already.

    I don't know why he is making such a big deal about the modified clutch in this video and claiming he will not divulge anything about the design etc.. Just hamming it up for the camera I guess because the disc is made by Bruno's machine and repair in Canada and it's all been posted right here on SmugMug:
    http://affordable-beemers.smugmug.co...6756&k=GfTqZHD

    Might be better to just order one directly from Bruno! His expert skills in machined repairs of all sorts for BMW bikes are no secret in the Airhead community. Bruno rocks.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  13. #13
    Lucky motorradmike's Avatar
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    That video was a bit difficult to watch, it could have been a lot shorter for one thing.

    I agree that the reduced engagement is a design error, mis-alignment may be the biggest problem on some bikes but the engagement is wrong too.
    We'll never know how the mistake got by everybody and who got fired.

    I don't think the modified clutch boss is worth a patent.
    Nano bots depositing metal on the old splines to return the engagement to new however, is worth a patent.
    I've said too much but I trust you guys.
    Mike Marr
    1978 Yamaha XS750 (Needs rings), 1996 BMW R1100RS, 2004 Honda CRF230F

  14. #14
    Registered User rxcrider's Avatar
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    Quote Originally Posted by Happy Wanderer View Post
    I'm not a mechanical engineer but I would prefer to see the entire length of my input shaft splines fully engaged with the entire length of my clutch disc splines just because that makes total sense to me. I also think radial play or excess runout would be a very bad thing here before winding everyone up on that one again. We've been down this road an awful lot in this forum already.

    I don't know why he is making such a big deal about the modified clutch in this video and claiming he will not divulge anything about the design etc.. Just hamming it up for the camera I guess because the disc is made by Bruno's machine and repair in Canada and it's all been posted right here on SmugMug:
    http://affordable-beemers.smugmug.co...6756&k=GfTqZHD

    Might be better to just order one directly from Bruno! His expert skills in machined repairs of all sorts for BMW bikes are no secret in the Airhead community. Bruno rocks.
    Thanks for the link - just the stock hub remounted with a spacer to push it back


  15. #15
    Jammess jammess's Avatar
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    Jammess

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