[thstone]

+2 on heat and use the longest breaker bar you can come up with.

Get it as hot as you can - the remaining portion of the caliper bolt will start to glow red. I used a regular propane torch and you can get it hot enough with a little patience.

For a breaker bar, I use a 4-ft piece of 1" diameter Schedule K copper pipe with a 1/2" Craftsman 18" breaker bar slid into the end of the pipe.

Then crank on that beetch.

This is how I removed the exhaust bolts on my wife's BMW that broke off in a similar manner to your caliper bolts.