Stripped thread in crank arm - scrap it or not?

[Richard]

In the process of removing the left hand crank arm I've managed to strip the thread used by the crank extractor. There doesn't seem to be an economically viable method of repairing it but it seems a shame to junk a perfectly good crankset for something so trivial. Opinions please as to whether I replace it or put it on and worry about future removal at a later date.

[random37]

Yeah, fill yer boots.

You can remove a crank just by unfastening it and riding around for a bit. Possibly for the last time though.

[Mick F]

Basically, if you never want to remove the crank again by using an extractor, then the crank can be left where it is with no problems.

However, if you do want to remove it - and you should do periodically to remove your BB to re-grease the threads, as we don't want any repetitions of seized BBs! - you will have to use some sort of puller/wedge and risk damaging it.

My advice it to leave well alone until you need to remove it, then scrap it.

[reohn2]

You could buy one of these, which is much cheaper than a new chainset:- http://www.screwfix.com/prods/48634/Van ... r%20Puller

[Edwards]

Why not just replace the LH crank not the crankset. SJS sell some.
I have tried legged pullers without much success. So came up with this.
Clamping the crank in a vice with the bike above then with a nut against the end of the axle to protect the thread. Then hit the nut with a hammer and drift. It helps if somebody else supports the rest of the bike. Provided the crank arm is well supported you should not get any problems.

[Gearoidmuar]

I've used this trick once.
Stripped thread left crank.

Take off nut.
I then took off chainset and unscrewed bottom bracket. This was in a onc-piece, not an ISIS type BB.
I can't remember if I used something between the left side and the crank (you will discover if you need to soon enough), but the BB pulled the axle out of the crank. It was surprisingly easy. I read it somewhere on line.

[lovetoridetwo]

Whichever alternative method to pull or push off you are going to use, first arrange it then get a heat gun on the crank around the crank pin( but not onto the end of the pin) if you can catch it right the heat will swell the alloy crank arm before the heat gets into the pin and will therefore loosen it, its all a matter of timing with the heat transfer.

[DurableAce]

I'd say it's heading for the recycling bin the next time you need to remove it. In my experience there isn't an effective repair. Cutting new threads doesn't work well enough in my opinion.

+1 for just getting a new crank arm. I got a new Ultegra crank arm for my 2003 bike only a few months ago.

[531colin]

I've used this trick once.
Stripped thread left crank.

Take off nut.
I then took off chainset and unscrewed bottom bracket. This was in a onc-piece, not an ISIS type BB.
I can't remember if I used something between the left side and the crank (you will discover if you need to soon enough), but the BB pulled the axle out of the crank. It was surprisingly easy. I read it somewhere on line.

+1 for this. If the BB is a shimano UN whatever, or similar Bb, the right hand BB cup will act as an extractor for the left crank. I think the left BB cup was all I used to push the crank off.

EDIT perhaps not with an aluminium frame, though.

[thirdcrank]

You could buy one of these, which is much cheaper than a new chainset:- http://www.screwfix.com/prods/48634/Van ... r%20Puller

I'm used to looking at stuff on a website then finding that ads for the product pop up all over - it even happens on SB now - presumably it's all done by cookies. I didn't open that link because I could see it was for a puller, but I've just had a Screwfix ad appear on another site and among the offerings was .... a three-leg reversible puller. Aarrgh. I'm getting paranoid. (Or perhaps I opened the link and forgot )

[mattsccm]

If you have a puller, 3 legs work well, then apart form the slight time delay, say 3 minutes not 3 then there is no reason why not to carry on as usual. A 3 legged puller works fine and leaves no damage.

[PW]

3 leg pullers are cheap on fleamarket tool stalls. Buy 2 with different length arms, then you can concoct a hybrid to get a good grip on the chainring spider. If you use heat apply it to the centre of the crank, not the ends, and expect to trash the B/B unit.

[mattsccm]

Don't heat it . It will just pop off.