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Thread: Fork Seals - K100

  1. #1
    Carguz
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    Fork Seals - K100

    How tough a job is a fork seal replacement on an '85 K bike?

    Since, I'm painting, I have the fairing and everything else off the bike. Do I need special tools? Is it tough for a first time job? While I'm at it, I plan to replace pads. Any hints, tips, etc. much appreciated.

    Carlos

  2. #2
    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by Carguz View Post
    How tough a job is a fork seal replacement on an '85 K bike?

    Since, I'm painting, I have the fairing and everything else off the bike. Do I need special tools? Is it tough for a first time job? While I'm at it, I plan to replace pads. Any hints, tips, etc. much appreciated.

    Carlos
    Remove the axle and loosen the bolts going straight up into the bottom of the fork -AFTER - draining the fork oil.

    With the bike on the centerstand the fork sliders will pull straight down off the fork tubes and just clear the damping rods before the sliders hit the floor.

    I don't think that model has a snap ring above the seal but look carefully to make sure. If it does, remove the snap ring with snap ring pliers.

    Then use a wide bladed screw driver to carefully pry the seal out - be careful not to gouge the aluminum bore. Clean the recess thoroughly.

    Then drive the new seals into place. The factory tool is a seal driver with a shank that is the same size as the fork tube. Some folks have found white plastic pipe the right size and with a length of the pipe and a fitting have made their own.

    If you are careful you can drive the seal flush with a piece of wood on top of it and then seat the seal in the bottom of the recess with a large socket that just fits the outside diameter of the seal.

    They are actually quite easy to replace but just be careful prying and pounding.
    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
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  3. #3
    Carguz
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    Almost sounds like I can pull it off. The Clymer manual describes the whole fork disassembly process but it sounds like I just need to focus on the bottom leg of the forks. Any recommendations on the oil, type, quantity, etc.

    Are the pads easy enough?

  4. #4
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    k75S

    Paul;

    Is the procedure the same for a 93 K75S??

    I'm due for a change.

  5. #5
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    No. The newer forks (after 8/91) require that the seal come off the top of the fork tube. The forks have to come off the bike.
    Check your manual.


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  6. #6
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    Quote Originally Posted by 98lee View Post
    No. The newer forks (after 8/91) require that the seal come off the top of the fork tube. The forks have to come off the bike.
    Check your manual.


    That's What I thought and why I have putting the job off.

  7. #7
    Rally Rat
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    if you don't have a socket large enough go to a hardware store and get an "electrical" pipe coupler that is the right size, I bought my last summer for about $2 and then tapped it in w/ a block of wood and hammer.

  8. #8
    Registered User PHMARVIN's Avatar
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    Hi,
    It's no big deal to replace the fork seals on '92-later K75 bikes. Just remember you need to drain the oil, remove the nut at the bottom, then remove the entire fork tube and slider from the triple clamp. To install the new seal, you need to have the fork tube in the slider before you pound the seal into the slider. That's where the white tubing Paul mentioned comes into play.
    Ride Safe,
    Phil Marvin - El Paso, TX
    '94 K75A/3
    '95 K75RTP

  9. #9
    A bozo on the bus deilenberger's Avatar
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    I'll just comment a tiny bit - not to disagree with Paul, but I had way too much experience changing seals on my FYK..

    I found it was easier to remove the fork tubes from the triple tree, and work on getting the bolt in the bottom out with the fork slider clamped in a vice (with soft-jaws.) The bolt is typically drastically overtightened by dealership employees who look at the size of it and decide to really honk it down. Problem is - it's a soft, shallow head special bolt, so trying to get it out by pushing up on it (and the bike teetering around) while the forks are on the bike usually results in simply stripping the allen recess out of it. Luckily - since it's soft aluminum - it's very easy then to remove with a large drill (I used a 1/2" bit) and the stub left in the bottom of the slider will then come out with your fingers. If you clamp the slider in a vice, you can then use an allen-driver in a 3/8" ratchet wrench, and if Godzilla didn't get too carried away - you might get it out intact. You only have to loosen two bolts in the triple-tree to get a fork tube out. Loosen them, and turn the tube and pull down. Sometimes a tap on the top will help get it moving.

    I'd still suggest ordering:

    - 2 of the special bolts. They're on realOEM or Max's for a part#. Having them on hand invokes Eilenberger's Law of Spares - and you won't need them. Not having them handy means you WILL need them.
    - 2 of the crush washers that are under each bolt. They are undoubtably mushed beyond reuse - even if you can reuse the bolts.

    And I'd suggest not draining the oil using the drain bolt because it likes to strip out of the fork leg. If it's not leaking - LEAVE IT ALONE - never touch it or loosen it. The oil will come out just fine when you remove the bottom bolt that holds the slider on.

    The seal on an '85 has no snap ring above it - it's simply a press fit into the top of the fork slider. Find a socket that is larger than the seal to use when tapping the new one in. The old one can be pried out with a screwdriver - try not to bugger up (tech-term) the slider where it seats. There are special seal-puller tools that would make this easier, but for a one-time job, it's questionable if it's worth buying one.
    Last edited by deilenberger; 03-04-2009 at 02:15 AM. Reason: Additional info.
    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

  10. #10
    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by scbmwrider View Post
    Paul;

    Is the procedure the same for a 93 K75S??

    I'm due for a change.
    1992 and later (model year) bikes have the Showa forks instead of the Marzochi (sp?) forks on the earlier ones. The Showa forks have a bushings internal to the sliders and external to the fork tubes that inhibit the removal of the slider from the fork tube.

    They do come apart if jerked on slide hammer fashion, but then tricky technique and special tools are needed to put it back together. So aftermarket manuals advise to get the seal out and slide it up off the fork tube. Then a 2 foot (or so) plastic pipe with an ID to match the fork seal OD is used to drive the new seal.

    I suppose the Showa forks are theoretically "better" what with bushings and everything - but they were a huge leap backwards as far as maintainability is concerned.
    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://www.bigbend.net/users/glaves

  11. #11
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    K Bike Fork Seal Replacement

    Dear Fellow K Bike Owners:

    I have replaced the Fork Seals on my 88 K 75 and always removed the plugs on the top of the fork tubes before pulling off the legs. In that way, the spring pressure is removed. You will have to pull the top plugs anyway in order to put fork oil back into the forks.

    Also, you may see a lot of sludge in the bottom of the fork legs. I always clean that gunk out before reinstallation.

    Steve Littlefield

  12. #12
    Route 66 Missouri gstom's Avatar
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    Snap ring

    I have a 1988 K100LT. I have removed the slider from the fork leg. The seal is held in with a snap ring that is simply a wire in a groove. There are no s" in which to place a snap ring pliers. How is the best way to remove this ring? I can't get in behind it to pry it out and I am leary of using too much force. Any tips?

  13. #13
    Benchwrenching PGlaves's Avatar
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    I had the best luck with a tool from the hardware store called a "cotter pin puller".

    I can best describe it as looking like a screwdriver handle with a round shank that has a pointed end, with about the bottom 3/4 inch bent over to a right angle.

    Then a small thin screw driver to pry one tip of the ring away from the tube wall allows the tip of the puller to go in, and then with a small pry you can walk the ring out.
    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://www.bigbend.net/users/glaves

  14. #14
    Route 66 Missouri gstom's Avatar
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    Thanks, Paul. I was going in that direction with my latest attempt, but the only similar tool I had in the box was a pick with a 90 degree tip. It did not have the horsepower to lift the rig from the groove. I am headed out to get the tool you suggest. I have been adding tools to my set for over 30 years, but it always seems you need another one.

  15. #15
    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by GSTom View Post
    Thanks, Paul. I was going in that direction with my latest attempt, but the only similar tool I had in the box was a pick with a 90 degree tip. It did not have the horsepower to lift the rig from the groove. I am headed out to get the tool you suggest. I have been adding tools to my set for over 30 years, but it always seems you need another one.
    My little 90 degree machinist's pick didn't have the horsepower either. It was after I broke the end off of it that I went to the store and bought the cotter pin puller.
    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://www.bigbend.net/users/glaves

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