What thread on a crank bolt?

craker
craker Posts: 1,739
edited December 2011 in Workshop
As someone suggested, bolting the splined bb tool can help free a recalcitrant cartridge bb.

It's square taper 68mm. I can't find a bolt to suit though - any idea? (The crank bolt being not long enough).

Thanks

Comments

  • Monty Dog
    Monty Dog Posts: 20,614
    Crank bolts for square taper BBs are usually standard 8mm.
    Make mine an Italian, with Campagnolo on the side..
  • buckmulligan
    buckmulligan Posts: 1,031
    Ahh yes, I did this a while ago, bolting the BB tool into the BB makes it so much easier. The bolt you want is an M8, but you need one with a 'fine' thread pitch (1.0mm) rather than the standard 'coarse' thread pitch (1.25mm), see here.

    I bought these and they were the perfect length for using with the park tools BB tool. You'll need a large washer to go between the head of the bolt and the tool though otherwise the head of the bolt won't sit nicely.
  • craker
    craker Posts: 1,739
    ^^ Thanks :-)
  • capt_slog
    capt_slog Posts: 3,974
    Is this to stop the splined BB tool from slipping out whilst you put pressure on it?

    I had problems with this so I used a G-clamp. One side of the G-clamp has a swivel pad, I put that side on the BB tool, and the other end of the clamp on the end of the opposite crank, and tightened it enough to hold the BB tool in place while applied the spanner.

    This certainly works on the drive side of the BB, because as you undo it, the tension on the clamp stays the same due to the crank following the BB out of the frame. (On the non-drive side, you would be inadvertently increasing the clamp tension unless the BB starts to 'give' as you undo the spline).


    The older I get, the better I was.

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