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Thread: Slipper Clutch and Friction Zone

  1. #31
    Dress for fall & avoid it AlanColes's Avatar
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    Quote Originally Posted by ncpbmw1953 View Post
    Alan, I said nothing about 'cold engine oil' vs 'engine oil at proper operating temps...' that is your reframing of the point I was making.

    What I did say was that on a COLD START at AMBIENT of maybe 66F and up you get the clunk IMMEDIATELY, before engine oil or transmission has changed appreciably, whereas as below that you don't get the clunk until the engine runs for a few minutes. This suggests the source of the major difference is more to do w/ expansion of the parts involved, versus 'acoustic dampening differences' from changes in the oil. You're comment seems to suggest when OIL temp is 62F, major dampening happens, whereas when OIL temp is 66F minimal dampening effects are happening. No way, no how! It's as you mentioned later, 'Spacing of parts, spin-down and spin-up times, etc., all change as the transmission heats up and when completely cold' is essentially what I said in other words, 'My sense is that as parts heat up tolerances are tighter such that one rotating part starts to get dragged into turning by another adjacent gear/part, and so this creates the clunk that worsens as the bike warms.'
    My misunderstanding/misreading. I was thinking that your clunk was like mine, most pronounced at cold startup (oil at ambient (60F-80F mostly) and not after the bike has been run for a while (oil at 180F-210F).
    Regards, Alan - President BMWONS - MOA Charter Club #097, BMWMOA/BMWRA/BMWONS/Airheads
    Current: '14 R1200RT / '06 Ducati ST3s / '91 R100GS / '86 R80RT / '75 R90S / '73 850 & '70 750 Commando Prev: '04 R1150RT / '81 Honda GL1100 / '77 Suzuki GS750 / '73 Norton 850 Commando

  2. #32
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Boy........these new bikes are com-pli-kated
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  3. #33
    Quote Originally Posted by ncpbmw1953 View Post
    Alan, I said nothing about 'cold engine oil' vs 'engine oil at proper operating temps...' that is your reframing of the point I was making.

    What I did say was that on a COLD START at AMBIENT of maybe 66F and up you get the clunk IMMEDIATELY, before engine oil or transmission has changed appreciably, whereas as below that you don't get the clunk until the engine runs for a few minutes. This suggests the source of the major difference is more to do w/ expansion of the parts involved, versus 'acoustic dampening differences' from changes in the oil. You're comment seems to suggest when OIL temp is 62F, major dampening happens, whereas when OIL temp is 66F minimal dampening effects are happening. No way, no how! It's as you mentioned later, 'Spacing of parts, spin-down and spin-up times, etc., all change as the transmission heats up and when completely cold' is essentially what I said in other words, 'My sense is that as parts heat up tolerances are tighter such that one rotating part starts to get dragged into turning by another adjacent gear/part, and so this creates the clunk that worsens as the bike warms.'
    BMW motorcycle transmissions clunk. They always have. Some less than others but they clunk. In 1977 I got off a Yamaha triple and onto an R60/5. The first time I shifted from 1st to 2nd I actually looked back and down to see what had broken and fallen off the bike.
    Paul Glaves - "Big Bend", Texas U.S.A
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  4. #34
    Quote Originally Posted by PGlaves View Post
    BMW motorcycle transmissions clunk. They always have. Some less than others but they clunk. In 1977 I got off a Yamaha triple and onto an R60/5. The first time I shifted from 1st to 2nd I actually looked back and down to see what had broken and fallen off the bike.
    Apparently BMW decided enough people found their proprietary clunk objectionable enough to make revisions for at least some 2017 water boxer designs. Good for them as there is nothing inherently pleasing about clunking transmissions, especially the N>1st gear clunk.

  5. #35
    Dress for fall & avoid it AlanColes's Avatar
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    Quote Originally Posted by ncpbmw1953 View Post
    ... people found their proprietary clunk objectionable ...
    While folks might like to categorize things this way, it is not the case. Nothing proprietary about it.

    Quote Originally Posted by ncpbmw1953 View Post
    ... Good for them as there is nothing inherently pleasing about clunking transmissions, especially the N>1st gear clunk.
    For/to you. But that isn't everyone.

    I have no such aversion to the relatively un-muffled sound of the BMW transmission, I actually prefer it's honesty.

    BMW transmissions are known to last as long or longer than most.

    Perhaps haven't ridden many touring Harleys. Like BMWs, they will happily rack up hundreds of thousands of worry-free miles but the trannies have a very definite audible clunk to them. They are just doing their job with less muffling than other makes.

    No one is forced to buy one, but also, no one should really complain about something that has been a known fact for decades. Buy Honda and you'll know you've shifted gears when the gear-indicator confirms it - that's a gross exageration, but there is a real difference just like there is with the Boxer engine. I had a Gold Wing but perfer the BMW Boxer to the Honda Boxer. If a person doesn't like the basic characteristics of a specific vehicle why did they buy it in the first place? Well, sometimes it takes owning/riding several bikes until we identify what it is that we like the most and what we don't care for or want. There are plenty of choices out there and most all of them are very good bikes, just different approaches and flavours, which is absolutely great for all of us.
    Regards, Alan - President BMWONS - MOA Charter Club #097, BMWMOA/BMWRA/BMWONS/Airheads
    Current: '14 R1200RT / '06 Ducati ST3s / '91 R100GS / '86 R80RT / '75 R90S / '73 850 & '70 750 Commando Prev: '04 R1150RT / '81 Honda GL1100 / '77 Suzuki GS750 / '73 Norton 850 Commando

  6. #36
    not so retired henzilla's Avatar
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    Quote Originally Posted by PGlaves View Post
    BMW motorcycle transmissions clunk. They always have. Some less than others but they clunk. In 1977 I got off a Yamaha triple and onto an R60/5. The first time I shifted from 1st to 2nd I actually looked back and down to see what had broken and fallen off the bike.
    My first Oilhead ride had me a bit worried I broke H's bike

    I think the biggest clunk I have experienced is a K 1200 Wedge idling high at start up and nudging it into 1st....EVERYONE turns to look I mean CLUNK And it's a wet clutch as well.

    I have ridden several Wetheads and haven't thought about it at all.
    Steve Henson-Mod Team and club tire changer

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  7. #37

    Clunk or Hop, that is the question?

    As the bard from Avon once said, to be or not to be, that is the question! Well this this thread has drifted mightily to clunk or not to cluck, is that a question??? Lots of bikes clunk. Some more so and others less. Really I am much more concerned about how well they shift, and does the clunk cause a problem with shifting. Although we have danced around this but how the transmission is designed and built has a lot to do with it. All the bikes I have ridden, if you pull in the clutch, you still get the clunk so the clutch usually isn't the clunk culprit. That's my 2 cents.

    Now, as the OP, the real issue was the hopping problem directly related to clutch activation. IMO, this issue was resolved as a design issue known to BMW. Also, IMO, it is a potentially dangerous situation and worthy of a report to the NHTSA.
    Old But Not Dead
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  8. #38
    Registered User BernieEcht's Avatar
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    Shifting Issues on 2018

    Quote Originally Posted by chewbacca View Post
    I found the following in an MCN article directed at the wethead clutch:
    "they also have an unfortunate centrifugally energized
    pressure plate design that creates control difficulties during hard
    launches. Attempt a quick start on the new water-head, and its
    clutch will bounce in and out of engagement, making the bike
    hop instead of drive forward
    ."
    In another review of an RT there was this:
    "My only complaint is that, when using the clutch, I found its very narrow friction zone at the end of the lever’s throw difficult to manipulate. Slow speed maneuvering was met with a herky-jerkiness I hadn’t mastered by the end of our ride."
    http://www.motorcycle.com/manufacturer/ ... -ride.html

    The highlighted sections above seem to be describing exactly what I was experiencing.

    When I checked my res level, a bunch of fluid came out indicating it was over filled. There was a thread on AdvRider that point to the tune of several pages. So I think we are getting at the heart of the matter. Whether the slipper function has anything to do with the issue is mute, it is becoming clear that the clutch unit on a GS probably has a mechanical problem in its design.
    When you reduced the amount of fluid in the clutch reservoir did that help with the clutch problems?
    My RT is a 2018 with around 1700 miles on the clock has a problem with up shifts.
    I have also experienced this engage-disengage symptom during faster take offs from stops.
    But my main problem is that as the motor heats up during a days ride, the shifting action gets worse.
    When cold I can shift from Neutral to First gear with no noise and no Lurch. When Hot, it makes a lot clunk and will jump a foot or so, unless I lock down the brakes. It is as if the clutch doesn’t completely separate.
    Also the warmer the motor/transmission gets the worse the shift action between Frist and Second gear is, using the clutch. The shifting is very “notchey”, like you can feel the engagement of the gear teeth in the foot pedal. A few times it got stuck in Neutral and I was not able to shift into Second without coming to a stop or using very excessive force.
    The bike does have the Gear Change Pro system and it works down shifting with no problems. Upshifting is another story. I gave up on that part. Up shifts make me look like it is my first time using a manual transmission.
    The bike has now 1750 miles and it starting doing something similar from Second to Third gear.
    I returned the bike to the dealer yesterday.
    PS: My HexHead with a 188,000+ miles shifts better.
    Bernie Echt
    2018 R1200RT-LC Alpenweiss, starting out fresh
    2007 R1200RT Double Silver sold (188702 Smiles), 2000 R11RT sold (105K)
    Bumbling BackRoad Riders™, MOA#92589, BMWNEF, BMW-RA, AMA

  9. #39
    Hi Bernie,
    Yes correcting the fluid level did help, but not a cure. I also have gear change pro but for me it has pros and cons. But I kinda like it. Like I said before, this IS a design and build fault and BMW knows it. They made fixes to the 2018 but not sure if they fixed it. For me just knowing about the issue has allowed me to compensate. It could get someone hurt, but since most guys just blow it off it will not really be fixed. Seen that happen before. Still a great bike.
    Old But Not Dead
    Semper Fi

  10. #40
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    2016 R1200GSW as well. N to 1 clunks once warm, pretty loudly, but usually slick right after cold start up. I sit in neutral most all the time now. Other than that, it works quite well. My 2001 R11S's trans is smoother, however. Gear Shift Pro takes getting used to, as it requires that you just keep the throttle ON through the shift. It's against decades of experience that has one want to do otherwise. But it is some slick piece of kit... as long as your do what it wants.
    Ride Safe, Ride Lots

  11. #41
    Registered User BernieEcht's Avatar
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    Quote Originally Posted by bikerfish1100 View Post
    2016 R1200GSW as well....... Gear Shift Pro takes getting used to, as it requires that you just keep the throttle ON through the shift. It's against decades of experience that has one want to do otherwise. But it is some slick piece of kit... as long as your do what it wants.
    Thanks for the reply.
    How far do you have the throttle open when you use Gear Shift Pro? Also what rpm’s?
    Downshifting works fine, no throttle.
    Bernie Echt
    2018 R1200RT-LC Alpenweiss, starting out fresh
    2007 R1200RT Double Silver sold (188702 Smiles), 2000 R11RT sold (105K)
    Bumbling BackRoad Riders™, MOA#92589, BMWNEF, BMW-RA, AMA

  12. #42
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    Quote Originally Posted by BernieEcht View Post
    Thanks for the reply.
    How far do you have the throttle open when you use Gear Shift Pro? Also what rpm’s?
    Downshifting works fine, no throttle.
    It actually seems to be a tad smoother on a harder acceleration than a gentler one. I'd say everything up to WFO is fine. (remember, this was originally designed as race technology used on the S100RR).
    Generally, I don't bother with GSP upshifts until i'm in 3rd to 4th zone.
    RPMs are... wherever.
    Ride Safe, Ride Lots

  13. #43
    Registered User BernieEcht's Avatar
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    Quote Originally Posted by bikerfish1100 View Post
    It actually seems to be a tad smoother on a harder acceleration than a gentler one. I'd say everything up to WFO is fine. (remember, this was originally designed as race technology used on the S100RR).
    Generally, I don't bother with GSP upshifts until i'm in 3rd to 4th zone.
    RPMs are... wherever.
    Thanks, I guess I will have to try it and get used to what the results are.
    Bernie Echt
    2018 R1200RT-LC Alpenweiss, starting out fresh
    2007 R1200RT Double Silver sold (188702 Smiles), 2000 R11RT sold (105K)
    Bumbling BackRoad Riders™, MOA#92589, BMWNEF, BMW-RA, AMA

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