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Thread: Do not downshift..... do not

  1. #61
    K Bikes Complex by Choice cjack's Avatar
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    Quote Originally Posted by deilenberger View Post
    Yes it is fine - and I was sort of curious on a motorcycle transmission how you can shift it without ever downshifting.. is there some magic here I'm missing.. my motorcycle transmissions are sequential - 1-N-2-3-4-5-6, 6-5-4-3-2-N-1 Somehow I can't figure out how to get from 6th to 1st without downshifting (color me slow today.. )
    There was a BMW that had a neutral lever. Whatever gear to neutral. I forget which one.
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  2. #62
    Cannonball Rider #52 darrylri's Avatar
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    Quote Originally Posted by cjack View Post
    There was a BMW that had a neutral lever. Whatever gear to neutral. I forget which one.
    Hmmm, dunno about that, but the R12 (not R1200) and R17 had a "4 on the floor" H pattern shifter. Neutral always available.

    The earlier bikes had 3 speed linear shift transmissions. 1st and 3rd were constant mesh, but 2nd was what I've heard called a "crashbox" gear, where you actually push the gears into mesh. 2nd gear had dogs on both faces, and the shift lever actually pushed it into mesh with 1st or 3rd, as well. Besides the normal neutral between 1st and 2nd, if you shift carefully, there's a neutral between 2nd and 3rd.
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  3. #63
    Rally Rat torags's Avatar
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    I just filed a complaint with the NHTSA. To get it on record.

    Thanks for the suggestion.


  4. #64
    K Bikes Complex by Choice cjack's Avatar
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    Here is an interesting writeup on BMW transmissions. Interesting about using 90 weight only. No multigrade except in winter. I like the bit about o-rings to quiet the clunk.

    http://groups.google.com/group/rec.m...d8001a55ccb96#
    R1200GS LC Rallye
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  5. #65
    Kool Aid Dispenser! jimvonbaden's Avatar
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    Quote Originally Posted by PGlaves View Post
    A ball bearing is designed to take a given radial load - and in the case of a transmission the radial load is not huge, esentially created by the gear mesh in the transmission. I said "excess" radial load.

    I did not make my original comments up. I learned them from a good engineering book on driveline mechanics. Most row crop and hay farmers know fairly well what happens when driveline slop happens in splined connections.

    I suspect we will just need to agree to disagree on this one. I believe it - you don't.

    You also might or might not believe my understanding as to why a damaged driveshaft universal joint caused an output shaft bearing to fail too - but the lab that did the analysis said it was excessive radial force causing a lack of lubrication because the clearances closed up. And this on a bearing designed to take a given amount of radial load.

    We'll just have to disagree I guess.

    I get what you are saying there Paul. How is the BMW different from a car clutch with the shaft in a pilot bushing in the motor? Wouldn't the same thing happen in a car, and if so, wouldn't it happen in ANY dry clutch?

    Not trying to be argumentative, just understand how the BMW motorcycle is different?

    Jim
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  6. #66
    Quote Originally Posted by JimVonBaden1 View Post
    I get what you are saying there Paul. How is the BMW different from a car clutch with the shaft in a pilot bushing in the motor? Wouldn't the same thing happen in a car, and if so, wouldn't it happen in ANY dry clutch?

    Not trying to be argumentative, just understand how the BMW motorcycle is different?

    Jim
    Yes - in principle a badly worn spline in any dry clutch can off-center and impose loads on the transmission shaft bearing.

    Two differences that I know of: normally the transmission bearings are beefier (technical term for designed to take larger radial loads) and most can splines don't seem to have the habit of wearing like BMW motorcycle clutch splines do.

    I have no positive knowledge why that is - but the length of the spline is usually much longer - thus spreading the loading over a larger area.
    Paul Glaves - "Big Bend", Texas U.S.A
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  7. #67
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    Quote Originally Posted by PGlaves View Post
    Two differences that I know of: normally the transmission bearings are beefier (technical term for designed to take larger radial loads) and most can splines don't seem to have the habit of wearing like BMW motorcycle clutch splines do.

    I have no positive knowledge why that is - but the length of the spline is usually much longer - thus spreading the loading over a larger area.
    This is something I have often wondered about. I have owned a lot of manual transmission cars (from Honda to BMW to Porsche), and I NEVER remember seeing a requirement/need to lubricate transmission input shaft splines in between clutch replacements.

    "Why is that, Captain Ron?"
    Mike White
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  8. #68
    Kool Aid Dispenser! jimvonbaden's Avatar
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    Quote Originally Posted by PGlaves View Post
    Yes - in principle a badly worn spline in any dry clutch can off-center and impose loads on the transmission shaft bearing.

    Two differences that I know of: normally the transmission bearings are beefier (technical term for designed to take larger radial loads) and most can splines don't seem to have the habit of wearing like BMW motorcycle clutch splines do.

    I have no positive knowledge why that is - but the length of the spline is usually much longer - thus spreading the loading over a larger area.

    Is THAT what beefy means?

    Seriously, I often wondered why BMW didn't extend the length and add a pilot bushing. Any reason you can think of?

    Jim
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  9. #69
    Loose Cannon flash412's Avatar
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    Quote Originally Posted by JimVonBaden1 View Post
    I often wondered why BMW didn't extend the length and add a pilot bushing. Any reason you can think of?
    Crappy engineering with the cost accountants controlling all the decisions. Same idea behind the "SEALED! Lifetime lubricated" differential fiasco. They saved the price of a pair of bolts for fill and drain (and machining operations to make the holes) and created a generation of BMW-Flamb?.
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  10. #70
    Rally Rat torags's Avatar
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    Quote Originally Posted by BeemerMike View Post
    This is something I have often wondered about. I have owned a lot of manual transmission cars (from Honda to BMW to Porsche), and I NEVER remember seeing a requirement/need to lubricate transmission input shaft splines in between clutch replacements.

    "Why is that, Captain Ron?"
    I'm with you. How do you lubricate an input shaft without having the lube spritz on within the clutch cavity onto the clutch?

  11. #71
    Quote Originally Posted by torags View Post
    I'm with you. How do you lubricate an input shaft without having the lube spritz on within the clutch cavity onto the clutch?
    The snide answer is, "by doing it properly." To be more specific, the front edge of the clutch hub is in line with the disk and lube can be flung from this location onto the friction surface. But the rear of the clutch hub extends back and is not in line with the friction surface, so lube flung from this location will not foul the disk.

    So to lubricate that spline you should first clean all traces of old lubricant, dust, and metal grindings off both the clutch hub splines and the input shaft splines. You should then apply a thin layer of lubricant so it completely covers the entire splined area of the INPUT SHAFT ONLY.

    If you do this any excess will be pushed back along the shaft by the rear of the hub and if flung is not in line with the disk. If you put lube on the splines in the hub any excess will be pushed forward out of the hub, and if flung it will contaminate the friction surface.

    If, after lubing the splines you (for whatever reason) slide it together and then again pull the transmission back, then you need to clean the lube that stuck in the hub out before you put the transmission back forward.

    If you use this procedure and avoid slathering a lot of excess lube on or in the splines, disk contamination will not be a problem.
    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/

  12. #72
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    Quote Originally Posted by torags View Post
    I'm with you. How do you lubricate an input shaft without having the lube spritz on within the clutch cavity onto the clutch?
    I believe the short answer (to supplement Paul's long answer) is "you separate the transmission from the engine the same as you would if you were replacing the clutch".
    Mike White
    MOA Life Time Member #57882
    '13 K1300S "30 Years", '95 R1100RS, '88 K75S, '97 Ducati 916, '95 Ducati 900SS CR. Gone, but not forgotten, '75 R90S

  13. #73
    Rally Rat torags's Avatar
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    Does that mean lubricating the shaft along the clutch plate travel? It is a dry clutch. The oil bathes are in the motor and the transmission and the cavity where the clutch is, is lube free - hence the term dry clutch. Or is the end of the thrust shaft lubed into the engine bearing.

    Enlighten me if I'm off base.

    Additionally that would have to be done on manufacture or any subsequent transmission removal, is that right?

    I don't know of any owner/maintenance lubrication means.

    Perhaps there are three reasons for the clutch spline to get cheesed. A sloppy engine bearing fit or a misaligned transmission. If yes, than responsibility for the condition lies with the last entity that assembled engine/trans, or extreme mileage (over 100K, but the plates would probably fail first)

  14. #74
    Focused kbasa's Avatar
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    Quote Originally Posted by torags View Post
    Does that mean lubricating the shaft along the clutch plate travel? It is a dry clutch. The oil bathes are in the motor and the transmission and the cavity where the clutch is, is lube free - hence the term dry clutch. Or is the end of the thrust shaft lubed into the engine bearing.

    Enlighten me if I'm off base.

    Additionally that would have to be done on manufacture or any subsequent transmission removal, is that right?

    I don't know of any owner/maintenance lubrication means.

    Perhaps there are three reasons for the clutch spline to get cheesed. A sloppy engine bearing fit or a misaligned transmission. If yes, than responsibility for the condition lies with the last entity that assembled engine/trans, or extreme mileage (over 100K, but the plates would probably fail first)
    For dry clutches, some lubrication on the input shaft helps the clutch plate slide back and forth more easily.

    Lubricant is typically a paste of some kind. I prefer Honda's Moly60. It's very thick and sticks well. Making sure the input spline is well lubed allows the clutch to move easily, but also provides some lubrication and prevents the clutch splines from chewing on the input spline when power is fed through it.

    I hope that's helpful. After you've lubed the input, you'll notice remarkably smooth and easy clutch and shift effort.
    Dave Swider
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  15. #75
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    Quote Originally Posted by torags View Post
    Does that mean lubricating the shaft along the clutch plate travel?
    I believe the answer is "yes". Paul?


    Quote Originally Posted by torags View Post
    Additionally that would have to be done on manufacture or any subsequent transmission removal, is that right?

    I don't know of any owner/maintenance lubrication means.
    See notes below.

    Quote Originally Posted by torags View Post
    Perhaps there are three reasons for the clutch spline to get cheesed. A sloppy engine bearing fit or a misaligned transmission. If yes, than responsibility for the condition lies with the last entity that assembled engine/trans, or extreme mileage (over 100K, but the plates would probably fail first)
    I believe you have correctly summarized the frustration many of us have with the (unspecified, but apparently necessary) periodic maintenance on a difficult-to-access part at intervals less than required for major repair (i.e., clutch replacement). We acknowledge and deal with it, even if we don't agree with or understand it.
    Mike White
    MOA Life Time Member #57882
    '13 K1300S "30 Years", '95 R1100RS, '88 K75S, '97 Ducati 916, '95 Ducati 900SS CR. Gone, but not forgotten, '75 R90S

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