Retaping crank axles

[YGT]

anyone done this?
I have a set of cranks which the bolt has snapped in the axle due to way too much locktite ..... anyone ever tried to fix something like this?

[dj_benice]

tap and dye set stylee?  re-did the threads on a stem I had that was buggered turned out okay as I got away with re-tapping and just cleaning out threads at the size they where, if they are proper boogered you will need to re-cut to a slightly larger set, as long as there is enough meat there you should be o.k. 

[SteveG]

The axles are normally hardened so tapping them (other than cleaning the thread up) will be a problem.
If you heat it up with a blowtorch the loctite will soften, you will then need to used an easy out to get the broken bit out. You might be able to tap it round with a center punch if its near the top.

[TwoBobRob]

Yeah, I've done an axle.  Quite tough as they and the bolts are hardened.  But definately do-able.  Try a high quality easyout or other removal system first. Often once drilled, they relax/collapse just enough that they will wind back out.  If you have access a pillar drill then don't worry, get drilling!  Its likely the tap will end up chasing out the original thread and then you're good to go.  Be sure to find out precisely what pitch you need   you can get away with a very slightly larger drill bit than the one used in the factory and this will aid your thread chasing. Proceed with caution.

For your info, there are varying grades of threadlock - you will find one designed for frequent loosening/tightening. That's the kid for next time  

[TwoBobRob]

Note to self;   learn to type faster............................ 

[SteveG]

Sorry 
I hadn't thought about the bolt being hard as well so it might be a bit more tricky. The first Maxi cross axle I had had nuts on it. The threads on it got damaged so the only thing I could do was buy a new one, at least with the bolts there is a chance to fix it.

[jT Racing]

what bob ans steve said. don't be impatient if you DIY. cobalt drill bits are the key to getting through hard shit.

[jT Racing]

what sort of cranks?

[YGT]

prince albert , very first gens

[YGT]

thanks fo rthe help guys, I will look into the suggestions mentioned.
even getting the axle off the arms gonna be tricky .... i will let you know.

Mark

[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]

what bob ans steve said. don't be impatient if you DIY. cobalt drill bits are the key to getting through hard shit.

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

[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.

[SaMAlex]

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.

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.