BMW r75/5 possible clutch slip problem

Discussion in 'Airheads' started by khale, Apr 23, 2012.

  1. khale

    khale ride dirty

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    I'm having a possible clutch issue that I need some help troubleshooting.

    When I first start the bike, I put the bike in first gear and released the clutch to get the bike going, it feels like the bike is not completely engaging in first gear. The acceleration of the bike is very, very slow, and it feels like the bike isn't fully catching first gear. This continues to happen moving to 2nd gear, and I can't really go past 2nd gear as the bike is barely breaking 40mph at this point. I have already adjusted the clutch cable on the handlebar and on the bottom of the bike to allow for more clutch engagement. I've read on a few forums this could either be the clutch plates that need to be resurfaced or a leaky transmission seal that's dripping oil on the clutch, causing it to slip. If I ride for about 15-20 minutes or so, the problem vanishes about 95% of the time.

    Any help is appreciated.:D
    #1
  2. Nolan Woodbury

    Nolan Woodbury Been here awhile

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    Worn clutches/clutch plates usually slip in top gear; when the load is greatest.

    Otherwise, sounds like the rear main seal is leaking engine oil. The problem 'clearing up' after time points to this as well. I've got one ('72 R75/5) down for the same reason. It needs to come apart-
    #2
  3. Mista Vern

    Mista Vern Knows all - tells some.

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    +1
    #3
  4. Wirespokes

    Wirespokes Beemerholics Anonymous

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    I'm thinking it might be a throw-out bearing problem. Something with the throw-out mechanism might be hanging up. It just doesn't sound like an oily or slipping clutch - not the normal symptoms.

    How much slack do you have at the lever?
    #4
  5. CurlyMike

    CurlyMike Formerly SaddleSoar

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    That was my first thought as well. Have had several where that little very expensive bearing is gone from wear or poor lubrication.
    #5
  6. khale

    khale ride dirty

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    The problem is very sporadic. For instance, I took my bike out yesterday to ride, no problems whatsoever.

    So the 2 possible causes are a rear main leaky seal and and throw out bearing gone bad? How heavy of a job is it to change either of these? I figure if I get into the clutch I might as well replace both.

    Good place to buy either part?
    #6
  7. blaine.hale

    blaine.hale Long timer

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    It's probably your four burner inner spinner after shafter.
    Yup. That's it.
    #7
  8. SJ BMW

    SJ BMW Adventurer

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    Just clear things up - rear main seal leaks do NOT get on the clutch, only a leaking transmission input seal will get on the clutch plate.

    Chris
    #8
  9. ignatz72

    ignatz72 call me iggy

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    Throwout bearing is a 1 beer job. Easy peasy.
    #9
  10. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Unless you've let it go far too long, then it becomes a kegger... :lol3
    #10
  11. patanga

    patanga BMWAirheadsDownunder

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    Either way it sounds like you make have to take the box out to confirm your diagnosis. If you fail to find a problem with your clutch then another often overlooked fault is the gearbox output yoke nut. These can come loose (rare but it happens) and will give you very similar symptoms. The output shaft to yoke is a tapered shaft (not splined) and relies on the nut tension (220 ft/lbs) to provide positive power transmission. If/when you take to box out, it is unlikely that you will be able to test this simply by hand, or visually. You will need to lock the yoke to stop it rotating (BMW special tool) and then use a socket and also hold the input shaft still (in gear) to test. If the nut is the culprit then you will be able to turn the yoke/input shaft (in gear) as the taper slips. The bad news is, if that's the case, then you may be up for a gearbox rebuild as the slippage usually causes fretting damage to the output shaft and yoke. In more extreme cases the shaft and yoke can become cold welded together. Slippage then stops but really yuk outcome. That can also make strip down more challenging. If you don't have the right tools or know how then make sure to have your local BM repairer test this for you prior to reassembly.

    ____________________
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    #11
  12. noman

    noman Long timer

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    " I have already adjusted the clutch cable on the handlebar and on the bottom of the bike"

    when sorting out a problem, i usually start at the beginning. how much play do you have at the clutch throwout lever? should be 2mm or so, at least it is on my r75/6.
    #12
  13. bmwhacker

    bmwhacker Still on 3 wheels

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    I experienced a similar symptom with my sidehack but also had a rear main seal leak. Pulled the gearbox and found a large chunk missing on each side. Don't know how long it ran this way. I ended up changing every componant in the clutch assembly.


    [​IMG]
    #13
  14. khale

    khale ride dirty

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    More symptoms:

    1. The bike has a horrible screeching noise when I'm at the end of the clutch lever to engage the gears. I'll try to post video if I can.
    2. The problem really shows up when I'm on an incline. If I first start the bike and have to go up a small hill, even if the grade is less than 5% I hear the awful screeching noise and the bike barely moves, as if the bike is not in gear
    #14
  15. patanga

    patanga BMWAirheadsDownunder

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    Why are you still riding it? You're only doing more damage....... If the adjustments are ok, then trailer the bike to a repairer to take the box out and look at the clutch, throw out, oil contamination AND the rear yoke nut. Remember there is a procedure involved in removing the clutch and for checking the output yoke.

    ____________________
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    Check us out on facebook at "BMW Airheads Downunder", (The Australia and New Zealand Airhead Community). "B.A.D" :wink:
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    #15
  16. Boxerworks

    Boxerworks g00b

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    Waiting for it to warm up could be a symtom of having too heavy a gear oil in the box. And that screech noise could be a worn clutch rod end...
    before you take it apart you could make sure you have the right oil in it. And you could pull the clutch pushrod out and check to see if the rod is worn funny at the end.
    Just a guess off the top of my head....
    Matt
    #16
  17. TheForefront

    TheForefront n00b

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    ::::BUMP::::

    Did you ever get this fixed? I'm having a very similar issue. Thanks!
    #17
  18. khale

    khale ride dirty

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    I did get the issue corrected. It was the original clutch (40 years old). I replaced the entire clutch and the problem is no more.
    #18