Technical & Reference Section > Tech and Restoration

Retaping crank axles

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SaMAlex:
Hey, YGT. Take good care of those cranks!!! Not many of them about, esp ones that arent broken. It'd be a shame to wreck a set trying to fix them.

The splines are slightly smaller OD and deeper than profile ones so there is even less wall thickness to play with. I think that will rule out re taping to a larger size, or even using a heli coil (what i was going to suggest). Just drill small, and take it easy. It should come out and you can always mod a new bolt to work after, maybe take down the threads a little so they screw into the damaged axle (Im assuming you dont wanna ride the PA cranks very hard anyway).

If not, you might have to look for a set of Boss cranks and nick the axle out of it.

Oh, btw, Ive got an unused Prince Albert crank arm sticker if you want a scan. I'll buy some re pro ones off you.

lazychubs:
use the hot water trick
that way ya dont get the discoloured cranks from a blow torch
boil ya kettle and pour over the arm
should tap off ok then
but wear gloves as ya could burn yaself

slurp:

--- Quote from: J.T.Racing on May 09, 2007, 08:22 PM ---what bob ans steve said. don't be impatient if you DIY. cobalt drill bits are the key to getting through hard shit.

--- End quote ---

remember to reduce your drill speed if using cobalt.much more effect than going hell for leather. :daumenhoch:

Donker:
you might be able to heli-coil the threads rather than tap/re-cut the threads.

basically heli-coils are shaped like little springs, usually stainless steel, which are inserted into the knackered thread. they allow you to use a smaller bolt/thread and are a good backup option if needed. google should clarify. :Great_Britain:

SaMAlex:

--- Quote from: Donker on May 10, 2007, 09:14 PM ---you might be able to heli-coil the threads rather than tap/re-cut the threads.

basically heli-coils are shaped like little springs, usually stainless steel, which are inserted into the knackered thread. they allow you to use a smaller bolt/thread and are a good backup option if needed. google should clarify. :Great_Britain:

--- End quote ---

Oh, nice one. I was thinking about heli-coiling at the same size as the old thead, for the old bolt, but that would mean drilling and taping a bit deeper for the heli-coil and there isnt much room to play with. Heli-coiling for a smaller bolt is a top idea.

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