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Thread: 82 clutch in an 1980 bike. Insufficent cable travel.

  1. #1
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    82 clutch in an 1980 bike. Insufficent cable travel.

    Hello to the group.

    In restoring my 1980 R100T, I removed the heavy flywheel and installed a newer style clutch.
    Unknown at the time, the newer clutch requires more travel to operate the clutch.

    So the investigation went like this.
    Original clutch, .040" travel on the pushrod.
    3/4" travel on the cable gives overall movement of .050"
    .010" for free play in the clutch setting, great.

    New clutch requires .090" to operate the clutch.
    At least .100" of travel is needed for proper adjustments.
    Double the travel, double the cable movement is needed with the old set up.
    Not possible......

    I am building a lever box to double the cable travel. The clutch cable will attach 1/2 way up a bearinged lever.
    The new outgoing cable will attach twice as far from centre, the result is double cable travel.
    3/4" cable travel becomes .100". The new clutch will work! Woohoo (I hope)

    Anyone with the same problem or has anyone worked out a better way to do this?

    George
    Vernon, BC, CA
    R100T #6170523

  2. #2
    Administrator 20774's Avatar
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    George -

    Welcome to the forum! My first question is are you changing the transmission, too? The newer style clutch, called the clutch carrier, was put first on the '81 models. They changed the transmission input shaft at the same time. There may have been changes to the clutch mechanism at the back of the transmission.

    So, you might have some incompatible parts issue going on.

    It sounds like you're putting together something that is called the EZ Clutch. It's designed to decrease the power needed to move the hand lever but the result is that the lever at the back of the transmission moves twice as far. In this set up, adjustment of the clutch has to be very close to ideal otherwise there won't be complete engagement/disengagement at the ends of travel.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    . AntonLargiader's Avatar
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    George,
    The problem is that you have the old transmission cover. The updated cover provides well over twice the displacement. I don't know if the old-style lever is even capable of moving enough to properly actuate the new clutch.
    Anton Largiader 72724
    largiader.com bmwra.org

  4. #4
    Registered User PAS's Avatar
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    George, you can't mix the parts between 1980 and newer without extensive replacement of all components involved.

  5. #5
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    Old bike, new clutch

    Quote Originally Posted by PAS View Post
    George, you can't mix the parts between 1980 and newer without extensive replacement of all components involved.
    Maybe the quote should be, you SHOULDN'T mix old and new parts.
    The newer far lighter clutch is in and staying, the bike performance increase is noticeable.
    The EZ clutch is for old clutches and creates 1/2 the clutch travel and 1/2 the force, wrong way for a new clutch, I need double the travel.
    A lever cable travel doubler is designed and test fit. It bolts on where the stock cable end mounted.
    There is plenty of lever movement to operate the newer clutch.
    The ACAD drawings went to the pattern cutter this morning. The bike will be back on the road soon.
    This is going to work.

    George

  6. #6
    Administrator 20774's Avatar
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    George -

    Enquiring minds want to know! Let us know how it goes.

    One thing I wonder about since it appears that you're using the original transmission from the 1980 bike. The trans input shaft is about 5mm longer than the 1981 and on transmissions due to the design of the new clutch carrier/flywheel. From what you've done so far, this 5mm doesn't pose any issues with operation? I would have thought this might be an issue. Also, do you have to change the clutch pushrod? If you're expecting increased movement of the pushrod, seems like it would virtually disappear inside the old transmission housing unless something longer is used. Anton mentioned a different rear cover...the area where the newer clutch rod and parts fits is probably redesigned to accommodate the extra movement. I've never seen the two setups side by side so I really don't know if these will be issues. But if you've already gone down this path, then as you said "this is going to work".

    I'm sure we'd like to see pictures when you're done.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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