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Technical & Reference Section => Tech and Restoration => Topic started by: Clean on May 02, 2011, 05:05 PM

Title: How tight should Crank Arms be on Shaft?
Post by: Clean on May 02, 2011, 05:05 PM

Peeps,

A quick nOob question; should my Crank Arms fit easily onto the shaft, do they need a little "assistance" or do they need twatting on?   ???

Worried that if it is the latter I may have the wrong shaft for the arms.  :(

Are all OS Bits configured with a square, very slightly tapering, interface between the arm and shaft?  :-\

All input gratefully received.  :daumenhoch:

Thanks,

Clean.

Title: Re: How tight should Crank Arms be on Shaft?
Post by: HUTCHMAN on May 02, 2011, 05:12 PM

with a square taper,just place the crank arm onto the spindle then tighten the spindle nut/bolt till tight.

Title: Re: How tight should Crank Arms be on Shaft?
Post by: Clean on May 02, 2011, 05:31 PM

Quote from: HUTCHMAN on May 02, 2011, 05:12 PM

with a square taper,just place the crank arm onto the spindle then tighten the spindle nut/bolt till tight.

Tried that. Arms go on about 1/4 of the way then become immovable. Tried "encouraging" them with a knocking stick but got nervous so stopped.  ::)

Upon removing the arm I can see light scraping on the taper and square hole which, to me, suggests that there may be a mismatch?  :-\

Title: Re: How tight should Crank Arms be on Shaft?
Post by: HUTCHMAN on May 02, 2011, 05:40 PM

yes,tapers sound totally different.

Title: Re: How tight should Crank Arms be on Shaft?
Post by: Clean on May 02, 2011, 05:43 PM

Quote from: HUTCHMAN on May 02, 2011, 05:40 PM

yes,tapers sound totally different.

 :'(

Title: Re: How tight should Crank Arms be on Shaft?
Post by: Jon The Bassist on May 02, 2011, 05:53 PM

Not all 3-piece cranks used a square-taper spindle but a lot did, ie aluminium arms from SR. Sugino etc, as well as a few cro-mo ones ie Redline/Sugino 400s. Some do take a bit of work to get on. Are the surfaces clean? If it's a 3-piece cro-mo crank you might need a tiny bit of copperslip grease.

Title: Re: How tight should Crank Arms be on Shaft?
Post by: 58 delray on May 02, 2011, 07:34 PM

there are different size tapers from different manufacturers, it sounds like yours may not be compatable.
what make arms and bb spindle are you using?

Title: Re: How tight should Crank Arms be on Shaft?
Post by: Spen69 on May 02, 2011, 08:02 PM

Richard, YGPM.

The original BB and spindle is still here, I just bought you a new one to make sure it was all nice and shiny when I flogged it to you - should have just cleaned the original one :-\

Serves me right for trying to give you NOS when bad-ass used would have been fine :yahoo_silent:

Title: Re: How tight should Crank Arms be on Shaft?
Post by: Clean on May 02, 2011, 08:05 PM

Quote from: Spen69 on May 02, 2011, 08:02 PM

Richard, YGPM.

The original BB and spindle is still here, I just bought you a new one to make sure it was all nice and shiny when I flogged it to you - should have just cleaned the original one :-\

Serves me right for trying to give you NOS when bad-ass used would have been fine :yahoo_silent:

 :daumenhoch: