Help removing cranks

[1id10t]

Hi

I bought an MTB off a friend some months ago and wanted to 'upgrade' the cranks. I was able to remove one crank arm (whatever they're called) but the one on which the sprockets are attached has a stripped thread. Therefore, the crank puller won't work. The axle on the bottom bracket is a square taper design. I have tried spraying WD40 into it, loosening the retaining bolt and then riding around hard (plenty of little hilly bits where I live) but it doesn't seem to be loosening in any way. I've read that you could hacksaw the cranks off but i'm a little hesitant in doing this. Not that I want to save the cranks (already have the new ones) but i'm not sure how to properly go about it; wouldn't want to be stuck with cranks i've sawn through but still can't remove. Anyone tried this and know it to work. Or does anyone have any other suggestions which may be tried and tested. I also wonder if anyone thinks this might work. I'd been thinking of maybe drilling holes inside the crank arm on all four sides beside the axle and then just sliding it off. BTW, I could take it to the LBS but i'm not keen on their pricing and service. Sorry for the long rant.
Cheers

 

[stevemtbsteve]

If you are not worried about losing the bottom bracket then you could hacksaw through the BB axel, thus removing the offending crank, and then remove the BB as you would normally, and then fit ur new BB and crank. lets face it square taper bb's are fairly cheap.

If not it is cutting the crank arm (not an easy task), or go for ur drilling idea, and let us know how u get on

 

[Born2bahick]

My thoughts are the same as Steve, Hacksaw the BB and replace or carefully dremel the crank arm itself, One other suggestion is to visit an auto parts store and pick up a gear puller of the correct size that wouldn't rely on the stripped threads to pull the crank! Good luck!

 

[dabac]

.. One other suggestion is to visit an auto parts store and pick up a gear puller of the correct size that wouldn't rely on the stripped threads to pull the crank! Good luck!

SInce it was on the drive side it can be hard to get a gear puller to grip properly, particularly if he's got a 5-bolt crank.

 

[dabac]

Hi

I bought an MTB off a friend some months ago and wanted to 'upgrade' the cranks. I was able to remove one crank arm (whatever they're called) but the one on which the sprockets are attached has a stripped thread. .. I've read that you could hacksaw the cranks off .

I'd go for cutting the crank off, it's should be aluminum (if it isn't a dirt-cheap bike) so a hacksaw will cut it easily. There shouldn't be any need to cut all the way down to the BB, and even if you do a few scratches wouldn't be critical. Lay the bike on its side and place the cut so that you remove a crescent shaped bit. You might have to trim away the arms carrying the sprockets to get access, but so be it, it's scrap anyway. I wouldn't try an angle grinder on this, 'cause aluminum is quite likely to smear the discs. If you can borrow a sawsall from someone you should be home free within minutes.

 

[1id10t]

Thanks for the suggestions guys. dabac, you must have been reading my mind about using an angle grinder. I had thought about it but will take your advice and will pass on using one. The crank arms are made of aluminum so I suspected they would be a little easier to cut; but not having cut aluminum before I didn't know what to expect.
Anyway, will try this weekend, hopefully, and will let you all know how it goes. Thanks again.

 

[dabac]

.. you must have been reading my mind about using an angle grinder. ..and will pass on using one.

Hi,

Don't worry about the angle grinder, they're built to be used and it's not like you're likely to damage it or anything. The discs are also very much expendable, so they're not really a concern either. But the wrong discs don't do well in soft materials, so you might as well use a hacksaw instead. If it had been the left arm you could have used used a sandpaper / emery disc and simply grind away material until the arm fell off, but given that you have the sprocket carrier to contend with sawing looks like your best option.

Good luck, and keep us posted!

Cheers,

dabac

 

[1id10t]

Okay, I opted for the hacksaw through the cranks method which took forever but eventually worked. Whoever fitted the cranks previously seems to have gotten carried away as the crank arm seemed to be so far onto the axle. Anyway, all is good. Thanks for everyone's help.