Like a jerk I was rushing to replace my front brakes before a vacation next Saturday, and sure enough broke the top bolt holding the front caliper. Drilling it out looks next to impossible to due the lack of space - are there any other options?
Can you remove the caliper? If it sheared flush remove the pads then the caliper. This same thing happened to me a few weeks back. I drilled a hole all the way thru the bolt using a cobalt drill bit, then used a torch to heat it. The hole seemed to help get it hot all thru. For me multiple heat / cool cycles plus pentrsting fluid broke it loose. There was enough thread sticking out to turn it with a screw driver, then vice grips. Careful to not damage the threads drilling the hole.
removing the knuckle seems to be the way to go, since it offers the additional benefits of replacing the upper and lower control arm ball joints while the knuckle is removed. So it will be a little more work, but will result in better brakes and a better suspension as well.