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Thread: 'Faulty' Fork Seal Job on 1992 K75S from Dealer

  1. #1

    'Faulty' Fork Seal Job on 1992 K75S from Dealer

    Looking for some advice before I go back to the shop in the morning....

    In November I bought my 1992 K75S.

    I took it to the BMW Motorcycle dealer in Manhattan where they did oil change, flush brake fluid, flush coolant, flush transmission (i think) and most importantly: new fork seals.

    A couple of days later, another different motorcycle mechanic looked at the bike and told me i needed new fork seals. i just wrote him off as being not credible since i have just paid $400+ to have them replaced.

    Now another new mechanic, whom i trust a lot, told me again the fork seals are blown on the bike. this is less than 3 months and 400 miles from service date.

    my question is:

    what can go wrong with fork seals installation to cause this kind of problem? i.e. could there be some inherent problem with my bike that makes the fork seals problematic?

    any advice on how to approach this with original mechanic?

  2. #2
    Registered User dieselyoda's Avatar
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    That's odd. I think we need some other opinions here.

    I'm not a BMW mechanic but I have my buddies K75S in my shop to replace the fork seals. He swears they were done last season at the BMW dealer, but, they are leaking.

    After reading this, I wonder if I can do any better.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case, my baby, fast, fun)
    3xR90/6, two just sold, one for a sidecar. 1983 K100RS (Cafe now)
    Very Rough R80RT. 1987 K1100RS (freaking hooped I think)

  3. #3
    What do your eyes tell you? If they're leaking, tell the dealership about it. They will probably stand behind their work.

    There are a lot of reasons for fork seals to leak: pitted tubes, seals damaged during installation, too much air pressure buildup, grit between seal and tube, etc. Just tell them they're leaking (if they are).
    Anton Largiader 72724
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    Virginia Motorrad Werkstatt BMW motorcycle service and repair in central Virginia

  4. #4
    Nick Kennedy
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    I completely agree with Anton
    A Dealer is always a good place to take a leak.

  5. #5
    Registered User
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    Give the Dealer an Opportunity to Make it Right

    I agree with Anton also. If they aren't aware of the problem they can't fix it. As far as things that can cause fork seals to fail, anything that can impact exposed fork tubes (bugs, dirt, gravel). Check out the surface for anything including dings. Gaiters can help protect the tubes and the seals. I put some on my '87 K75 and never had an issue in 70K.
    Gary Phillips - #6322
    Wildland Firefighter, Retired, Riggins, ID
    Heartland Moto Locos BMW Riders
    '77 R100/7 Dirt Hack, '83 R80ST, '85 K100RS w/EML, '00 R1100RS

  6. #6
    Registered User dieselyoda's Avatar
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    Popped the fork seals tonight.

    I found something a bit interesting tonight. I don't know if it's a big deal but it is different than the forks I've done before.

    The seals get installed before the tubes according to the manual. You install the tubes, tighten the bolt at the bottom, install the springs then then install the "plug" at the top. Fill with oil, "Bob's your Uncle". The whole system is extended.

    On others I have done, tubes go in first without the springs, install the seals, fill with oil, extend the tubes, install springs and then the "plug" at the top.

    Lots of forks don't have the convenient fill bolt at the top of the "plug" like this BMW so you need to fill before complete assembly.

    Couple things come to mind, "ripping" the seal on tube install or too much air pressure when they heat up and are working.

    Just some thoughts about the OP's comments.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case, my baby, fast, fun)
    3xR90/6, two just sold, one for a sidecar. 1983 K100RS (Cafe now)
    Very Rough R80RT. 1987 K1100RS (freaking hooped I think)

  7. #7
    Still plays with trains. tinytrains's Avatar
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    I had leaky seals on my K75 because I waxed he fork tube. The wax built up in the seal and allowed oil out. I saw it my self.
    1988 K75 Low Seat
    2009 R1200R Roadster

  8. #8
    Quote Originally Posted by AntonLargiader View Post
    What do your eyes tell you? If they're leaking, tell the dealership about it. They will probably stand behind their work.
    My eyes tell me the seals are leaking but I am a novice to Motorcycles so I somewhat disregarded this evidence at first, since I just paid to have them fixed. I wasn't sure exactly how they should look, i thought perhaps a certain amount of oil on the tube was normal, but yeah, it looks like its leaking.

    Meanwhile, I took it back to the dealer this morning and it is my impression they are going to fix it under warranty (the original work was done on 11/20/2013 and approx 400 miles ago, the guy says the work has 2 year warranty)

    My biggest fear is that they will call me later this afternoon and say ' yeah the seals are leaking but it is because of XYZ and will cost $more to fix'

  9. #9
    Quote Originally Posted by 195709 View Post
    My biggest fear is that they will call me later this afternoon and say ' yeah the seals are leaking but it is because of XYZ and will cost $more to fix'
    If there are pits or scoring on the fork tubes this is a possibility. Do yourself a favor and have the shop install fork gaiters (boots) while putting it back together. The parts cost is a few bucks and the protection for the forks is more than well worth it.
    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/

  10. #10
    Rally Rat
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    The fork must be disassembled to install new seals so if there was tube pitting or another problem you should have heard about it the first time they did the work.

    The problem with fork gaiters is that you probably won't be able to see if the forks are leaking.

    If it's not too late, ask them to accurately measure the fork oil fluid that they remove during this repair so you can know if they're adding too much, which can cause the seals to fail.

  11. #11
    FUKENGRUVEN SURVIVOR akbeemer's Avatar
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    Quote Originally Posted by timtyler View Post
    The problem with fork gaiters is that you probably won't be able to see if the forks are leaking.
    Sure you can. There is a small hole in the gaiter that allows air in and out as the gaiter contracts and expands; it will also allow fluids to leave the gaiter. If the hole is properly positioned (low and to the rear of the fork) the fork oil will find its way out. Sure did on my GSPD. It is not also not a difficult job to loosen the bottom of the gaiter to take a look-see in there every now and then.
    Kevin Huddy
    Tm Pterodactyl MT Outpost

  12. #12
    Quote Originally Posted by timtyler View Post

    The problem with fork gaiters is that you probably won't be able to see if the forks are leaking.
    While it might not be immediately obvious, you can tell. If Kevin's answer isn't sufficient, it is very easy to periodically loosen a clamp and look.

    In 1986 I bought a K75. The dealer replaced a fork seal at the 600 miles service. Soon the other one began leaking so the dealer replaced that seal too. I replaced both seals again at the 6,000 mile service and installed fork gaiters. The seals I installed at 6,000 miles were still in the bike, not leaking, when the bike was wrecked at 370,000 miles, eighteen years later.

    So if periodically - say once a year - I have to loosen a couple of clamps, push up the boots and look for oil, the protection gained for the seals and the fork tubes is well worth it.
    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/

  13. #13
    13278
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    Fork seals on K75

    Anyone got suggestions or part #'s on fork gaiters that fit or look at least OK on K75's. I can't remember if any K75's or K100/1100's models came stock with fork covers.
    Charlie

  14. #14
    Rally Rat
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  15. #15
    The fork tubes are 42mm - so any 42 mm fork gaiters (boots) will work fine. I use hose clamps top and bottom.

    The bike really doesn't care if they are KawaYamaSusiHon or other brand. Try any good dirt bike supplier if your BMW dealer draws a blank. When I wanted some the BMW dealer parts guy knew exactly what I needed and went next door to the Yamaha shop to get them. Thanks, Mike!!
    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/

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