How do I shim a loose crown race

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  • How do I shim a loose crown race
  • eulach
    Member

    I’ve got an old BMX fork (1″) and a new crown race (26.4) which is loose. After cleaning up the fork and original crown race, this also has play in it. So I need to some how make up the difference. But how do I do this? Any advice welcome.

    plus one
    Member

    Using a punch around bottom of steerer to create small raised nicks can work.

    Premier Icon Rubber_Buccaneer
    Subscriber

    I might try a bit of stud and bearing fit depending on how loose you are talking about

    Premier Icon Yak
    Subscriber
    jkomo
    Member

    Glue or epoxy resin?
    Or cut and squish it in a bit.

    otsdr
    Member

    Cut it.

    Unless it’s actually a race for balls & stuff, but in that case it will also put up a fair fight.

    qwerty
    Member

    Loctite retaining compound, there’s a few, maybe 660.

    eulach
    Member

    It’s old school and the bearings and races are separate so I don’t think cutting it will work. What would happen if I melted som electrical solder between fork an race?

    Premier Icon JoeG
    Subscriber

    See if you can find a bike shop that has one of these:

    Knurling Tool

    ctk
    Member

    Coke can shim worth trying before using solder.

    Premier Icon mick_r
    Subscriber

    I’ve done it before (the proper way).

    Build up the diameter with brass (brazing rod and gas torch). Then find someone with a decent size lathe. Hold steerer in the chuck and recut the seat. Silver solder would also work but runnier so harder to build up (and more expensive). I wouldn’t bother with soft solder.

    Loctite bearing retainer isn’t going to fix it a 1mm diameter difference.

    smiffy
    Member

    Just a thought, have you built it up and checked that there’s a problem when it’s pre-loaded? That play in the fork and original crown race might have always been there and nobody ever noticed until it was disassembled? Punch is a good shout otherwise but if used in anger the dimples might get hammered out in time.

    eulach
    Member

    Dutch courage – a bit of a heineken tin

    P.S. Thanks to all that gave advice.

    BITD ( which stands for ” back in the day !!!) , We sat them in car body filler.

    Lionheart
    Member

    The Locktite 660 will fill a surprising gap, spec is .5mm but we’ve seen more very successfully done but it’s expensive. I’d definitely try the coke can shim, you be amazed how well that has adequately bodged race cars, race bikes and even aeroplanes around the world.

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