Bicycle Mechanics - Broken Expander Bolt

I am trying to remove a Syncros quill stem and the allen bolt was not getting a good grasp. Upon examination, I noticed that the bolt has a crack across the top and was flexing open abit when the torque was applied. Anyone have any idea how to remove this bolt short of drilling it out?



edit: I can't spell

Can you get the next-size-up allen wrench to fit in the bolt?

The bolt is a 6mm. I tried to use a 1/4" allen but the split still opens a bit and the wrench will spin.

You may have to JB Weld a cheap allen wrench into the head of the bolt. Let it set for 24 hrs, then remove and replace.

If you can find them at a local machine supply shop, get a left handed drill bit. Use that to drill a hole in the center of the bit. Sometimes these bind a bit, or just the friction is enough to move a stubborn bolt.
http://www.mytoolstore.com/hanson/hanson.html {LGT: left handed drills**
Last resort would be to drill a hole, approx 1/2" deep in the center of bolt and turn in a screw-extractor, or even a left-handed tap. Then use a tap wrench, and care, to loosen the bolt.

These are techniques that are easier if you can mount the bike in some sort of vise, otherwise you might get unlucky and break the tap.


-a

along the lines of this question, where can one get a replacement bolt, and what measurement(s) does one have to make to get the appropriate size?

Take the bolt to a good hardware store and match it up.

Demon and amacks, thanks for the input. I think I will try the JB weld simply because I don't have a drill. I don't mind replacing the bolt, but I would rather not spend the $$ on a drill just for this.