Bicycle Mechanics - Removing square taper cranks with damaged threads

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FlatMaster
05-15-09, 04:00 PM
Unfortunately, the threads on my drive side cranks are damaged. I'm looking for some other way to remove the cranks. I know that with skill and the right tools, I could file off the first few threads. However, I don't think I have the skill for this. THis is my idea.

Could one loosen the cup and lockring on the non-drive side as far as possible, then strike the spindle with a hammer? The fixed cup on the drive side would push the crank off of the spindle.

Any other ideas for removal of a crank with damaged threads? The crankset is being replaced with a sealed bottom bracket, so destructive removal is a possibility.


Al Criner
05-15-09, 05:09 PM
A gear puller from a auto parts store will pull them off.

FlatMaster
05-15-09, 05:33 PM
Never seen one of thoes. Might get one just to own another cool tool.


HillRider
05-15-09, 06:05 PM
Heat. Apply a torch or heat gun to the crank and then try to knock it off from the back using a heavy dowel or large diameter rod. Don't overdo it. You want to expand the crank, not melt it.

operator
05-15-09, 06:53 PM
Unfortunately, the threads on my drive side cranks are damaged. I'm looking for some other way to remove the cranks. I know that with skill and the right tools, I could file off the first few threads. However, I don't think I have the skill for this. THis is my idea.

Could one loosen the cup and lockring on the non-drive side as far as possible, then strike the spindle with a hammer? The fixed cup on the drive side would push the crank off of the spindle.

Any other ideas for removal of a crank with damaged threads? The crankset is being replaced with a sealed bottom bracket, so destructive removal is a possibility.

You have 3 options

1) Take it to a LBS with a wedge tool
2) Automotive puller
3) Grinder the crankarm in half

When you say the crankset is being replaced with a sealed bb, you didn't actually tell us if destructive removal of the crankset itself is acceptable or not. The BB can always be replaced if the crankarm extractor threads are damaged if you don't care about the crank itself.

sunburst
05-16-09, 01:13 AM
Here's what I did:
http://www.bikeforums.net/showthread.php?t=529885&highlight=stuck+cranks

There were people who disagreed with the approach (and most on this forum know more than me!), but it worked. It only took a couple of tries also, and not much heat.

griftereck
05-16-09, 04:58 AM
I use a cold chisel and a hammer to hit the back of the crank arm at the centre beside the axle.
it ussualy takes a couple of taps to pop the arm off.

I_bRAD
05-16-09, 05:56 AM
Could one loosen the cup and lockring on the non-drive side as far as possible, then strike the spindle with a hammer? The fixed cup on the drive side would push the crank off of the spindle.

Interesting idea. I'd remove the NDS cup entirely and be sure to properly support the BB shell before you get the hammer out.

JohnDThompson
05-16-09, 06:21 AM
If the threads aren't too badly damaged, you can clean them up with one of these (http://www.biketoolsetc.com/index.cgi?id=594510960559&d=single&c=Tools&sc=Crank&tc=Thread-Repair&item_id=BR-TC8):

http://www.biketoolsetc.com/Product_Images/BR-TC8.jpg

EatMyA**
05-16-09, 06:40 AM
crowbar

mmmdonuts
05-16-09, 06:41 AM
Remove the chainrings, unless you like scars.
Apply heat to the crankarm spider just around the spindle area.
Use 5/8 or bigger open ended wrench to pry it off from behind the crankarm. Between the back of the crank and the BB cup face. This is assuming you can fit the wrench back there.

curbtender
05-16-09, 06:52 AM
If the bike isn't too far dismanteled you can try riding around with the keeper bolt removed and see if that loosens it up.

Sturmcrow
05-16-09, 03:47 PM
When I was a kid and had never heard of a crank puller I used to just bash away at the crank with a hammer until it fell off. Sure it got marred, but I pulled that crank several times and it never broke.

Hopefully it broke later while the SOB that stole it was riding!