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Thread: K75C's 1987 & 1988. City Case Plastic type? Clutch Parts replacement?

  1. #1
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    142

    K75C's 1987 & 1988. City Case Plastic type? Clutch Parts replacement?

    I probably need to improve my search methods since I could not find the answers in the forum.

    Two questions. I値l start with the easiest first.

    1) What type of plastic are K75 city cases made of? My wife works at a plastic store and has access to all types of adhesives. I need to know the type of plastic in order to get the proper adhesive for city case repair. Does anyone know? No need to waste research time on this as I have found suggestions as to what can be used for case repair purchased at the local home repair store. Just wondering if someone had this arcane knowledge.


    #2 my be unanswerable. Sort of like asking how good will the party be, before I decide to attend.

    2) I知 planning on doing a clutch spline lube.

    Chris Harris posted a 6-part tutorial on YouTube which is quite thorough. YouTube is so fantastic filled will folks sharing their knowledge. I would not be surprised to find a tutorial on how to perform self-surgery!

    I壇 like to have parts on hand before starting. I知 expecting to replace the friction plate, but have no idea of the typical life span of the Pressure Plate, Housing Cover, and Diaphragm Spring. One K75C has 61k and the other has 210k mileage. To my knowledge (2nd owner) neither has had those parts replaced. Clymer's suggests they be inspected for wear or damage and describes such. In your experience how often do those three parts need replacement? I知 a first-timer and have zero prior experience on this maintenance work.

    Many thanks and be well,
    Pete

  2. #2
    Quote Originally Posted by pjar View Post
    I probably need to improve my search methods since I could not find the answers in the forum.

    Two questions. I’ll start with the easiest first.

    1) What type of plastic are K75 city cases made of? My wife works at a plastic store and has access to all types of adhesives. I need to know the type of plastic in order to get the proper adhesive for city case repair. Does anyone know? No need to waste research time on this as I have found suggestions as to what can be used for case repair purchased at the local home repair store. Just wondering if someone had this arcane knowledge.


    #2 my be unanswerable. Sort of like asking how good will the party be, before I decide to attend.

    2) I’m planning on doing a clutch spline lube.

    Chris Harris posted a 6-part tutorial on YouTube which is quite thorough. YouTube is so fantastic filled will folks sharing their knowledge. I would not be surprised to find a tutorial on how to perform self-surgery!

    I’d like to have parts on hand before starting. I’m expecting to replace the friction plate, but have no idea of the typical life span of the Pressure Plate, Housing Cover, and Diaphragm Spring. One K75C has 61k and the other has 210k mileage. To my knowledge (2nd owner) neither has had those parts replaced. Clymer's suggests they be inspected for wear or damage and describes such. In your experience how often do those three parts need replacement? I’m a first-timer and have zero prior experience on this maintenance work.

    Many thanks and be well,
    Pete
    There are two schools of thought about clutch parts. One group says that it is smart to always replace the spring, pressure plate, clutch housing, and the clutch disk. Another school of thought is to take the things apart and examine the pressure plate and clutch housing for wear, hotspots, and flatness. If still sound then replace the disk and the spring. I do the latter. Others buy all 4 parts.
    Last edited by PGlaves; 05-02-2020 at 09:11 PM.
    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/

  3. #3
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    142
    Quote Originally Posted by PGlaves View Post
    There are two schools of thought about clutch parts. One group says that it is smart to always replace the spring, pressure plate, clutch housing, and the clutch disk. Another school of though is to take the things apart and examine the pressure plate and clutch housing for wear, hotspts, and flatness. If still sound then replace the disk and the spring. I do the latter. Others buy all 4 parts.

    Thanks Paul. That answer was helpful and what I was looking for. Good to see there are two schools of thought. Greg Harris that I mentioned was a BMW factory mechanic. In his video he also inspected and reused the parts.

    Thank you,
    Pete

  4. #4
    Registered User
    Join Date
    Nov 2009
    Location
    Phila
    Posts
    129

    Clutch experience 203,000 mile '85 K100RS

    At ~100,000 I did the sprag starter clutch replacement, checked my regular clutch friction disk and it was thick enough to put back in and lubed the clutch spline lightly and put in a rear main seal and new clutch bolts and big center nut. One day in, one day out.

    At 172,000 I changed the bull gear from 6 rivets to 12. This time I put a new clutch friction disk in but it still had life left with 6 new bolts and a new big nut. One and half days to get in, the same to get it back together.

    When you loosen the clutch PRE MARK each of the thee fixed pieces so you can bolt them together without lessening the factory balancing of those three.

    My experience with Bob's BMW is that anything you find you need after you open it up, you can have in a couple days, so don't go too crazy pre buying all kinds of parts.

    I am not a drag racing type rider or driver so my clutches last. I also know how to rev match as I shift up and down.

    My experience is not to worry about clutch spline lube until you need to take off the clutch housing. I did lube both ends of the drive shaft when I lubed the shaft though maybe every 30-40k miles. Too much grease in the clutch area hurts a lot.
    Last edited by 075038; 05-04-2020 at 12:32 AM.

  5. #5
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    142
    Quote Originally Posted by 075038 View Post
    At ~100,000 I did the sprag starter clutch replacement, checked my regular clutch friction disk and it was thick enough to put back in and lubed the clutch spline lightly and put in a rear main seal and new clutch bolts and big center nut. One day in, one day out.

    At 172,000 I changed the bull gear from 6 rivets to 12. This time I put a new clutch friction disk in but it still had life left with 6 new bolts and a new big nut. One and half days to get in, the same to get it back together.

    When you loosen the clutch PRE MARK each of the thee fixed pieces so you can bolt them together without lessening the factory balancing of those three.

    My experience with Bob's BMW is that anything you find you need after you open it up, you can have in a couple days, so don't go too crazy pre buying all kinds of parts.

    I am not a drag racing type rider or driver so my clutches last. I also now how to rev match as I shift up and down.

    My experience is not to worry about clutch spline lube until you need to take off the clutch housing. I did lube both ends of the drive shaft when I lubed the shaft though maybe every 30-40k miles. Too much grease in the clutch area hurts a lot.
    Thanks for the feedback 075038. Very helpful as we share a similar riding style.
    Be well,
    Pete

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