Threads on a crank stripped when trying to remove
 

The threads on this crank just up and failed when I used a crank remover.

I need to get the crank off. Ruining the crank is fine (it is being replaced along with the bottom bracket). Any ideas? Somehow hack saw it? The crank puller no longer threads in.

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...if you have one, the most expeditious way to remove it is cutting it off with an angle grinder. You're not supposed to use them on soft aluminum, which tends to grab and fill up the grinding disc, but I've done a couple that way anyway...carefully.

Your best bet is to just cut the steel crank spindle with the grinder, if you can get clear access. Mask the bike with something in case you slip.

Put the nut back on, but not all the way on. Just enough to keep the arm from falling off when it comes loose. Then hop on the bike and start pedaling. When you feel a tiny little bit of play, back out the nut and remove the arm.

Easiest way is to leave the retaining nut off and ride around the block a few times until the arm loosens up on its own. Don't go too far, because once it comes loose you'll be walking back home. But this carries the risk of damaging the square taper where the crank mates with the BB spindle (you did say destructive removal was an option, though).

If you want to be sure to remove the crank in usable condition, a "pickle fork" (aka "ball joint separator"), Jacobs chuck remover wedges, and gear pullers offer safer, but perhaps more tedious, means of removing the arm.

Jacob's Chuck Wedges: http://www.bikeforums.net/bicycle-me...-stripped.html

Well you can remove the non-drive side crank arm and pull the crank with spindle attached. Open up a vise wide enough to not damage the bottom bracket cup and smack it out... that was a response on a recent thread.

John

And how do you remove the DS cup?

You don't. Just open the vise wide enough to not interfere with the cup. The jaws don't get tightened. I'd remove the chainrings.

Better yet, forget about removing the crank from the spindle and throw the whole thing away since the OP is going to replace everything. But I would want to salvage the BB.

John

...to do it that way, you need some luck and one of those skinny cup wrenches. It's worth trying, because for some odd reason some fixed cups are not in there tightly. As you are doubtless aware, a lot of them are frozen in place.

And you have actually seen this done?
I'm curious because I have no idea what you are talking about.

So where do you get an open ended "skinny" fixed cup wrench? How do you keep it from slipping?
What does the vise have to do with anything?

Now that I have thought about it. What I said was pretty stupid. I didn't check a headset wrench size, which is not the same, so your points are correct. Vise was just to punch out spindle. It is too much work than just riding it loose.

Carry on.

John

I had the same issue once and I rode around for a while without the nut but to no effect. As I recall, I ended up getting it off by hitting it with a hammer and punch from the backside of the crank spider. It took a while but it eventually came off.

...I don't know where I got it, but I have one. Some bikes have room enough (enough Q) that you can get a slim jawed Crescent in there. You can't keep it from slipping if the cup is stuck in there, as I stated.

I'd be much more apologetic if I hadn't done this a couple of times. It works much better if the stripped arm is the non drive side and the adjustable cup needs to come out, but it does work occasionally on the drive side cup.


I don't usually suggest stuff here that I haven't successfully done myself IRL.

Heat the hub area of the arm with a propane torch to about 275-300F. Check the temp with an infrared thermometer. Aluminum expands more than steel when heated. Whack the arm from the backside with a large drift or punch. If no joy, allow to cool, remove the chain rings to gain access, heat it again and use a ball joint separator fork (ebay, $12) between the backside of the crank and the fixed cup. Or put the nut back on halfway, heat the hub area again and ride it (careful not to burn your ankle).

Blow torch. Heat specifically the crank. The heat will make the crank expand and you should be able to remove it.

Go to Auto Zone. They have a loan a tool program and I'm sure they have something that will pull it. I also agree with others who said just to ride it until it loosens on it's own. Also, if that doesn't work, a short 2x4 and a big hammer from the other side will get that sucker off.

Try using a bearing/pulley puller, less than $20 from harbor freight.

+1

That's what I used to remove some stripped Lambert/Viscount arms.

http://www.os2.dhs.org/~john/gear-puller.jpg

It would be kind of hard to get a good straight pull on a 5-arm crank with a 2 or 3 arm puller unless the puller arms are specifically designed to be respaced.

I was able to drive a DS cup off using an old screwdriver as a punch. It doesn't take much room.

I got desperate on a Raleigh Gran Sport I'm working on. The crank puller would of costed me 40 bucks so I used the same method(gear puller). I got the crank off no problem however the claws wouldn't fit the non drive side. Luckily I was able to loosen the cup and pull the axle out of the bottom bracket. I then took the axle with its non drive side arm still attached obviously and safely secured it in a vice. Steal punched it with my hammer and it came out pretty easily.