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Thread: A Different Final Drive question

  1. #1
    papafoxtrot
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    A Different Final Drive question

    I've noticed that when I'm on & off the throttle at low speed (as when I'm leaving the parking lot at work) that as I add throttle again I'll get a clunk sound from the rear end of my '07 R1200R. Since this is my first modern shaft bike, I was wondering if this torque wrap up is normal or if this is a manifestation of impending final drive problems?

    I have an old Guzzi that "jacks" the rear end on take off, but doesn't clunk like my Beemer.

  2. #2
    Rally Rat
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    Perfectly normal.

    You need to be a bit more precise and gentle with a dry clutch. There's not much forgiveness as opposed to a wet clutch. Basically, it's either on or off and very little in-between.

    I find creeping along in traffic is probably the single most annoying manuever with a dry clutch but somehow you manage.

    Throttle management can help with this as well. Its all in how the power is managed that will determine how hard that final drive is hit. You'll get used to it, takes some practice but eventually it will become second nature.

  3. #3
    papafoxtrot
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    Now I'm Confused

    I don't understand why this is a clutch issue. Is it the clutch I'm actually hearing/feeling? It feels like it's further back than where the clutch lives. Can you explain a bit more? This is interesting.

  4. #4
    Focused kbasa's Avatar
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    It's pretty typical driveline lash. As you feed in throttle, you take all the slack out of the entire driveline between the clutch and the rear wheel.
    Dave Swider
    Marin County, CA

    Some bikes. Some with motors, some without.

  5. #5
    Kool Aid Dispenser! jimvonbaden's Avatar
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    Quote Originally Posted by KBasa View Post
    It's pretty typical driveline lash. As you feed in throttle, you take all the slack out of the entire driveline between the clutch and the rear wheel.
    Right, it happens will all bikes, but a chain drive bike often has a cush drive (rubber interface) that takes up the slack without the clunk.

    Nothing to worry about.

    Jim
    www.JVBProductions.com Now, all videos available via download or DVD, or USB for the Wethead.

  6. #6
    Registered User AntonLargiader's Avatar
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    Quote Originally Posted by papafoxtrot View Post
    I don't understand why this is a clutch issue. Is it the clutch I'm actually hearing/feeling? It feels like it's further back than where the clutch lives. Can you explain a bit more? This is interesting.
    A tiny bit is in the various splines, but most of it is in the transmission between the shift dogs. You might hear it from the final drive, but only about 1mm of the entire lash actually happens there.
    Anton Largiader 72724
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  7. #7
    I think some of the problem is caused by the fuel injection or engine control module. I bought my RT about 1 1/2 years ago after spending 10 1/2 years on a Honda ST1100. The Honda was of course carbuerated/shaft drive but the throttle had a very smooth rheostatic effect whereas on the BMW the throttle feels more like an on/off switch, especially when accelerating. Yes, you could get the ST to clank with sloppy throttle transitions but was a lot less sensitive than the BMW. It could also be the difference in design of the final drives. Honda uses 5 hard rubber "pucks" in assembly which may serve to absorb some of the slack when accelerating or decelerating.

    I'm sure there is no appreciable difference in driveline "slack" in the BMW vs. the ST but, while it's taken awhile, I now feel reasonably comfortable with a very deliberate transition from off-to on-throttle. I equate it to using a bit of pre-load on the shifter to smooth shifting. I maintain a bit of preload on the throttle before really getting on it.

    John

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