crank bottoms out and is slightly loose on the spindle

stefano
stefano Posts: 254
edited May 2010 in Workshop
Hi i am replacing an old three peace BB with a 68 / 113 mm shimano JIS cartridge one. The right crank goes all the way through (bottoms out) but is slightly loose on the spindle ...will i solve the problem with longer BB lets say a 118 or 122 mm?

Comments

  • sungod
    sungod Posts: 17,413
    if the crank is worn so that it goes too far onto the spindle, then i don't think a longer bb will help...

    the key distance is how far from the spindle end the crank goes before seating, a longer spindle won't change that, the crank will still be going too far from the end - so the crank bolt is bottoming out on the spindle rather than pushing on the crank

    you could try a thin shim between crank and spindle, try an aluminium drink can, it's very thin and easy to cut accurately with scissors, if that's too thick try cooking foil
    my bike - faster than god's and twice as shiny
  • desweller
    desweller Posts: 5,175
    The bottom bracket you are using is a square taper unit. If the axle is the same length as the one it replaces, then I can only imagine that your crank is split if it's sitting on the cup. Got any pics?
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  • ynyswen24
    ynyswen24 Posts: 703
    What make of cranks?
  • stefano
    stefano Posts: 254
    It is a Gitane French bike from the late 60s or 70s and the old BB is Sugino Japanese Bottom Bracket, separate Spindle three pieces traditional Cup and Cone with longer right site (36 mm). On the cranks I can read "Maxy F3 forged 171 Japan" and they have three chainring bolts.

    The new BB is Shimano, cartridge, British threaded, 68 x 113.

    I have put back temporally the old BB with the original spindle and the crank fits perfectly, though is not so smooth and will have to be replaced.
  • sungod
    sungod Posts: 17,413
    might be worth asking on the http://www.gitaneusa.com/ forum
    my bike - faster than god's and twice as shiny
  • tatanab
    tatanab Posts: 1,283
    With the old BB in place, compare the length of axle spindle sticking outwith the length available on the Shimano part. This will show if the Shimano spindle is simply too short which is what I suspect.
  • ride_whenever
    ride_whenever Posts: 13,279
    aren't there two standards of the shape of square taper, JIS and something else...

    possibly try the other one?
    Neeermad
    Carbon 456
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  • ynyswen24
    ynyswen24 Posts: 703
    ride_whenever wrote:
    aren't there two standards of the shape of square taper, JIS and something else...

    possibly try the other one?

    No, it sounds like it's a JIS (japanese) taper bb thats needed, the other standard, ISO (Campag etc) would end up with the crank about 4mm further out.. might be worth trying an ISO bb if all else fails to get that 4mm

    I looked this up on Sheldon Brown - I couldn't remember which was which until I did.

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