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Thread: 92 K75S Forks

  1. #1
    rcbimmer 67972's Avatar
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    92 K75S Forks

    I just rebuilt the forks and added a set of Progressive fork springs. I added 11 oz of 10 wt fork oil, same amount as I removed. Now the front suspension is stiff as can be to point that the bike just has no give at all. I know it should be some what stiff for the first 600 miles or so. Can anyone please give me some advice. Thanks.
    Robert Cantrell
    Spring Hill, Fl
    92 BMW K75S 73 BMW R60/5
    13 Victory Cross Country Tour

  2. #2
    Benchwrenching PGlaves's Avatar
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    If the volume of the springs installed is greater than the volume of the springs removed, then the specified quantity of oil will be higher in the fork legs, leaving a smaller air column above the oil, which will stiffen the suspension. BUT, I'm not at all sure this is your problem.

    Your problem sounds a lot more like fork stiction which may be caused by a misalignment of the fork sliders. This is easy to do when installing the integral fork brace on K75s.

    What I would do - with the wheel on and properly tightened - is loosen all four capscrews that attach the two fork legs to the aluminum brace. Then with the fork brace loose bounce the front end a few times. Then carefully retighten the fork brace.

    If that doesn't cure it then here is a test to see if the oil volume is the culprit. At the top of the fork, remove the 8mm capscrews in the "fill" holes, and gently - so as to not squirt an oil mess out the hole - bounce the front end. If the stiffness goes away then too much oil is the culprit. If not ...

    If these two things don't identify and cure the problem something is wrong inside the fork assembly. You said "rebuild" and without knowing what you mean specifically by that, I can only guess what might be wrong, but a misassembled valve could do 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://www.bigbend.net/users/glaves

  3. #3
    rcbimmer 67972's Avatar
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    Thanks Paul I will try what you recommend this weekend. By rebuild I meant that I took the forks apart and replaced the fork seals and dust covers. I put the oil level according to the instructions that came with the springs. The amount of oil is still the same as what I removed. I'll post back this weekend after trying what you said. Thanks again.
    Robert Cantrell
    Spring Hill, Fl
    92 BMW K75S 73 BMW R60/5
    13 Victory Cross Country Tour

  4. #4
    Benchwrenching PGlaves's Avatar
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    I left off a step in the earlier post. Loosen the brace and loosen the pinch bolts at the axle on the right side of the bike. Then bounce the front several times. Then tighten the brace. Then tighten the pinch bolts.
    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

  5. #5
    Italo Train k75s's Avatar
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    Quote Originally Posted by 67972 View Post
    I just rebuilt the forks and added a set of Progressive fork springs.
    I would like to do some maintenance to my forks also. What exactly did you order from Progressive? Do they have springs specifically for the K75S?
    Thanks in advance for any help.
    92 K75s (never sell), 97 F650st (sold), 04 R1100s (now owned by a deer), and about 10 others

  6. #6
    rcbimmer 67972's Avatar
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    Quote Originally Posted by k75s View Post
    I would like to do some maintenance to my forks also. What exactly did you order from Progressive? Do they have springs specifically for the K75S?
    Thanks in advance for any help.
    I found mine on ebay, just do a search for a K75S. They were fork springs I then ordered the seals and dust boots from my dealer.
    Robert Cantrell
    Spring Hill, Fl
    92 BMW K75S 73 BMW R60/5
    13 Victory Cross Country Tour

  7. #7
    3 Red Bricks
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    Robert,

    Did you get the 11-1509 springs or the 11-1126 springs?


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  8. #8
    rcbimmer 67972's Avatar
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    Quote Originally Posted by 98lee View Post
    Robert,

    Did you get the 11-1509 springs or the 11-1126 springs?


    The box says its a 11-509. What is the difference?
    Robert Cantrell
    Spring Hill, Fl
    92 BMW K75S 73 BMW R60/5
    13 Victory Cross Country Tour

  9. #9
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    11-1509 is for the '92-'95 Showa forks.

    11-1126 is for the earlier forks.

    If you have the forks that do not have the large rubber dust covers over the seals, you have the Showa forks and you have the correct springs.


    Your vin# is higher than 153330, right?



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  10. #10
    rcbimmer 67972's Avatar
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    Quote Originally Posted by 98lee View Post
    11-1509 is for the '92-'95 Showa forks.

    11-1126 is for the earlier forks.

    If you have the forks that do not have the large rubber dust covers over the seals, you have the Showa forks and you have the correct springs.


    Your vin# is higher than 153330, right?



    Checked the VIN number and yes it is higher then 153330. But I do have the dust covers over the seals. I have owned the bike since new so nothing has been changed until I added the springs.
    Robert Cantrell
    Spring Hill, Fl
    92 BMW K75S 73 BMW R60/5
    13 Victory Cross Country Tour

  11. #11
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    Quote Originally Posted by 67972 View Post
    But I do have the dust covers over the seals.
    No, I meant the early LARGE rubber dust boots like these:

    P1000567.jpg

    You should have the later flat ones that look like a regular seal. That changed in 9/91 (before your bike was built) when they went to the Showa forks (which your bike has).


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  12. #12
    rcbimmer 67972's Avatar
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    Lee you are correct. I have the other seals not the large ones like in your picture.
    Robert Cantrell
    Spring Hill, Fl
    92 BMW K75S 73 BMW R60/5
    13 Victory Cross Country Tour

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