Crank keeps working lose!

Fatamorgana
Fatamorgana Posts: 257
edited May 2012 in MTB workshop & tech
I have a fairly simple crank set, a FSA CK-300 on a GT Avalanche.

Anyhow, it's a square tapered spindle that the left crank arm attaches to, you push it into place (hard) and then screw in an Allen bolt to hold it in place.
'Cept that ain't working as it comes lose every 100 miles or less.
I think the issue is that in the past owner (eBay) it's happened before and maybe the square-ness of the spindle is not so square.
Is there a reasonably simple fix or work-around to this as I am not keen to buying a new crank set?
Is it possible to file down the 4x sides to square them up again and if so do you have any suggestions?

Thanks

Comments

  • styxd
    styxd Posts: 3,234
    A coke can shim
    Threadlock on the bolt
  • oodboo
    oodboo Posts: 2,171
    I had the same problem on my cheapo unicycle. I got a mate to weld them in place and they've been fine since.
    I love horses, best of all the animals. I love horses, they're my friends.

    Strava
  • estampida
    estampida Posts: 1,008
    once the taper goes its not worth repairing

    new crank arm (ebay) or new bb / crank combo (get an isis 1 as they have a better interface) or exo......

    if you can get it to stay on good for you...... might cost a fortune to have it removed.........
  • The Rookie
    The Rookie Posts: 27,812
    The hardened steel axle won't be damaged, the alloy crank arm will be.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    styxd wrote:
    A coke can shim
    Threadlock on the bolt

    This.

    But try the tread lock first.

    This is mostly why other standards came about.

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