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Thread: '85 K100 clutch replacement

  1. #1
    '85 K100RS Brodiex's Avatar
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    '85 K100 clutch replacement

    Hey All,

    I put my '85 K100RS into the shop for a full service, new tire, splines, and brake rebuild...Since the bike is getting up there in miles (60K), they found some other stuff, including swingarm bearings, that need to be replaced - and they also mentioned that the clutch feels like it's within a few thousand miles of needing to be replaced as well...But I declined, due to lack of funds to pay the additional 500 bucks to replace it...

    Ideally, I would have liked to get it over with while the entire back end of the bike is still apart, to save on labor, but I just can't afford it right now - and the labor charge seems high, considering the swingarm job leaves the transmission housing sitting pretty for removal/reinstallation...But I have no knowlege with which to justify second-guessing the shop, and they have been treating me very well.

    Here are my questions:

    -What is the worst thing that can happen if they are right about the clutch? I don't want to carry on with a condition that could be dangerous

    -Is this procedure as difficult and time-consuming as Clymer's makes it out to be, or is there a how-to that simpifies it a little?

    -Has anyone ever had the clutch replaced on their pre-mid-nineties K-100 or K75?

    -Optional: any moral support that the longtime K owners can give would be much appreciated. I bought this bike last summer and I love it, but I'll feel a lot better taking a big hit on this service if I can be confident it will be the last of its kind for quite a while.

    Thanks!

  2. #2
    Don't forget your towel
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    I wonder how you can "feel" like the clutch is about to fail... seems to me it either slips or it doesn't. Not sure how one could measure the thickness ofthe disc without removing it either.

    A quick look at the Capital Cycle catalog tells me if you replaced EVERYTHING in the clutch package it would run you about $350.00 (USD) figure in some time to do the R&R and I can see where it could come out to the $500 quoted. That being said, there are a lot of high mileage Ks out there with the original clutch still in service- YMMV of course depending on how many times you've been to the dragstrip and maintained the clutch lever free play. The real wear item is the friction disc, it's about $100, do the rest of the parts really need replacing? I think that is a philosophical matter you'll need to decide for yourself. I put a new disc in this winter and kept the rest of the old parts on the bike as they looked to be a fine shape. The old disc was probably sevicable but I was replacing the output shaft seal so I thought I'd just do it while I was in there. I've done the same for a couple of my old airheads in the past without any problems. Your shop may not want to anything less than the whole project for warranty/liability issues. I do my own work so it's all on me....

    Sounds like the bike is back together? Ride it till something actually breaks, meanwhile invest the $500 you saved in some manuals and a few good tools and do the job yourself if/when the clutch decides to quit ( the two times I've had one fail on me it was a slow event, slippage at low temps or high load like accelerating hard up a hill).

    Steve

  3. #3
    A bozo on the bus deilenberger's Avatar
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    Re: '85 K100 clutch replacement

    Originally posted by Brickhead
    Hey All,

    I put my '85 K100RS into the shop for a full service, new tire, splines, and brake rebuild...Since the bike is getting up there in miles (60K), they found some other stuff, including swingarm bearings, that need to be replaced - and they also mentioned that the clutch feels like it's within a few thousand miles of needing to be replaced as well...But I declined, due to lack of funds to pay the additional 500 bucks to replace it...

    Ideally, I would have liked to get it over with while the entire back end of the bike is still apart, to save on labor, but I just can't afford it right now - and the labor charge seems high, considering the swingarm job leaves the transmission housing sitting pretty for removal/reinstallation...But I have no knowlege with which to justify second-guessing the shop, and they have been treating me very well.

    Here are my questions:

    1. -What is the worst thing that can happen if they are right about the clutch? I don't want to carry on with a condition that could be dangerous

    2. -Is this procedure as difficult and time-consuming as Clymer's makes it out to be, or is there a how-to that simpifies it a little?

    3. -Has anyone ever had the clutch replaced on their pre-mid-nineties K-100 or K75?

    4. -Optional: any moral support that the longtime K owners can give would be much appreciated. I bought this bike last summer and I love it, but I'll feel a lot better taking a big hit on this service if I can be confident it will be the last of its kind for quite a while.

    Thanks!
    OK.. first off - a question you didn't ask. How long do these clutches last?

    If they aren't abused - the life of the bike... figure 150-200k miles out of one easily.

    They look and "feel" like the disk needs replacing because the actual wear allowance is quite small and the rivet heads are close to the friction surface even when the disk is brand new.

    I rather question how they could "feel" the clutch is near the end of it's life. Normally a spline lube does not include disassembly of the clutch assembly, so a visible inspection of the wear isn't possible. If the clutch splines were worn - they should have reported that to you, and reported that the transmission splines were equally worn. They didn't - so I'm guessing they aren't.

    OK - your questions (I've added #'s to make it easier):

    1. Your bike stops moving forwards. That's about it. Nothing is gonna blow up.

    2. Dunno that it is shown as difficult. I can do a spline lube in about 90 minutes with a helper and the bike on a lift, and a complete clutch (with engine seals) in about 3 hours. I imagine the flat-rate book the dealer uses gives 4-5 hours labor for the job.. although they have all the special tools needed so it probably takes them LESS time than it does me.

    3. Sure. If the clutch gets oil soaked due to the transmission input seal going bad - you'll need a new disk. It is highly unlikely that you'll need anything else. A disk is less than $100.

    4. I suspect the shop is being over cautious (or is hungry for work, unlikely in the US this time of year). I'd ride the bike. The K's are known as the Maytags of motorcycles for a reason.

    Best,
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  4. #4
    '85 K100RS Brodiex's Avatar
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    Talking Thanks guys...

    Hey guys,

    Thanks for posting - it really helped to put my mind at ease...Later this afternoon, I got a call from the dealer to let me know the bike was about ready, and when I asked some more about the proposed clutch job, the guy said that they had measured the thickness of the friction disc and found it to be getting thin...

    But if they typically last over 100K, I'm not really sweating it...The bike had 2 owners before me, so I can't really speak for how well the clutch was treated, but it will be treated well by me for the rest of its life, and with any luck it will be a while before anything happens...

    PS - Don, after becoming an avid reader of your splines-related posts here and on IBMWR, I had both splines done, and adamantly insisted they used Honda Moly60, which I provided to them...I guess a certified BMW dealer doesn't have the stuff lying around...

  5. #5
    A bozo on the bus deilenberger's Avatar
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    Re: Thanks guys...

    Originally posted by Brickhead
    Hey guys,

    Thanks for posting - it really helped to put my mind at ease...Later this afternoon, I got a call from the dealer to let me know the bike was about ready, and when I asked some more about the proposed clutch job, the guy said that they had measured the thickness of the friction disc and found it to be getting thin...
    Getting thin is a relative term. I still can't understand how they measure the thickness without complete disassembly of the clutch - which they would have charged you for.. I think it's BS

    But if they typically last over 100K, I'm not really sweating it...The bike had 2 owners before me, so I can't really speak for how well the clutch was treated, but it will be treated well by me for the rest of its life, and with any luck it will be a while before anything happens...

    PS - Don, after becoming an avid reader of your splines-related posts here and on IBMWR, I had both splines done, and adamantly insisted they used Honda Moly60, which I provided to them...I guess a certified BMW dealer doesn't have the stuff lying around...
    Good! So far - with lots of people using the Moly60 - it has worked well. There have been a few failures caused by other reasons (the K75 bent intermediate housing) - but on bikes without alignment problems - it has worked great and is very long lasting. I wouldn't worry about the splines again for at least 3 years or 36k miles, whichever comes first.

    Best,
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

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