Leading link for BMW airhead hack

Discussion in 'Hacks' started by androbus, Sep 16, 2012.

  1. bmwhacker

    bmwhacker Still on 3 wheels

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    WOW great work on the fork fabrication!!!!!!! Wish I had the skill / equipment to build something like that.


    No brake pressure loss that I've ever noticed. The Suzuki calipers are mounted underneath. The front end I have was modified by some dude in the Bay Area eons ago, so I was told. I wasn't too sure how it would work but no regrets.

    My front end has got a little squirrly a couple times especially if there were irregularities in the road, but nothing memorable. I remember thinking: "note to self...don't go into bumpy unknown corners so hot".
    After a lot of miles with a conventional front end, and then on an Earls, I definately love the Earls. A lot less work and no front dive under heavy braking. I have Progressive shocks in the front, set on the lower end. It is somewhat harsh on rough roads but is stable.


    [​IMG]

    [​IMG]

    I dissected the bike last winter for a new clutch assembly / rear main / head rebuild / timing chain.
    Now my final drive / wheel hub splines are getting worn, so that's next. Those things happen when you work a rig as hard as we do!:lol3
    The original builder hacked off the additional support member midway up the fork. I've bolted in another axle shaft in the rear swingarm mount to help reinforce things. I need to weld in another brace (someday) like the OP has on his.
    #21
  2. MotoJ

    MotoJ Mobtown Hacker

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    BMWHacker,

    Do you have any close-up shots of the caliper mounts? Did you just weld tabs to the bottom of the swingarm?
    I'm trying to decide the best way to hang my calipers- fixed to the swingarm, or floating brackets on the axle, with brake stays, like Prutser's bike.

    I'm kinda worried welding on the swingarm might create a stress riser. I suppose if I keep all the welds parallel with the arm that would help eliminate that. Somewhere in Hacks I saw a photo of leading links on a K bike broken right above a weld made perpendicular to the downtubes.

    Am I being a worrywart?
    #22
  3. bmwhacker

    bmwhacker Still on 3 wheels

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    Photo was taken early on before I mounted the Lester Wheels....tabs welded into place.
    The front end had some serious welding / modifications before coming to me. All the welds looked good though.
    I was real cautious riding for the first few thousand miles but all is well after 3 years of hard use.

    [​IMG]


    As found:
    [​IMG]
    #23
  4. Boxer Metal

    Boxer Metal Mad Scientist

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    If the /2 was designed for sidecar use how can that be true? The answer is - it works just fine.
    #24
  5. Boxer Metal

    Boxer Metal Mad Scientist

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    Here is my /2 leading link on a /6 frame.

    [​IMG]

    [​IMG]
    #25
  6. villageidiot

    villageidiot Long timer

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    In making a leading link fork for a bmw, how much further forward does the axle center move?

    I know the idea is to reduce trail, so the wheel needs to go forward, is there an exact amount, or is it something like "just move it forward an inch"
    #26
  7. Boxer Metal

    Boxer Metal Mad Scientist

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    From 0-2" max.
    #27
  8. MotoJ

    MotoJ Mobtown Hacker

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    I don't know what the wall thicknesses are for each or tensile strength ratings, etc., but I have held both a Unit set (with shocks and calipers) and an old Earles forks set (shocks only), and the Earles were heavier. Might not mean anything, but they are beefier than they look like in photos...
    #28
  9. Prutser

    Prutser Long timer

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    Nice bike !!

    Don't you mind that the front wil lift when you use the brake ?
    #29
  10. Boxer Metal

    Boxer Metal Mad Scientist

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    Thanks. No I don't mind. It seems like the front end lifting is putting more pressure on the front tire vs, having a floating caliper which just skids under hard braking.
    #30
  11. Prutser

    Prutser Long timer

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    Personally I do like the bike not to change geometry that much when braking in corners. But its all really personal !

    I'm using the leading link fork in a 69S frame like a standard one from those days.
    [​IMG]
    #31
  12. Boxer Metal

    Boxer Metal Mad Scientist

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    That is very cool looking.
    #32
  13. Prutser

    Prutser Long timer

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    Thank you.
    #33
  14. MotoJ

    MotoJ Mobtown Hacker

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    Very cool Prutser! Will that be a solo bike? I can see why you wouldn't want the front lift on a solo. On a sidecar rig probably not as noticeable.

    Do you build those shocks yourself or does someone make them for you?
    #34
  15. NitroMax

    NitroMax Been here awhile

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    Good looking bike and fork Prutser !
    #35
  16. Prutser

    Prutser Long timer

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    It wil not be used as a solo. Only with a side car:clap
    #36
  17. Boxer Metal

    Boxer Metal Mad Scientist

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    IS the frame and gas tank before 1939 BMW?
    #37
  18. Prutser

    Prutser Long timer

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    The tank is a Russian copy (I think) but I could fit the knee pads and logo's from a R32.
    I brazed some petcock treaded pipes and extra fuel line connections into the tank.
    And made a space for the R100R electric stuff under in the tank.

    At first it didn't fit on the 69s frame. Thought the frame is from 1956( but i need to check that)

    But this is not helpful info about a leading link :lol3
    #38