I fixed a similar situation on an engine case screw. I JB Welded the broken threaded piece back on, chased out the threads, then coated them with JB Weld and put in a Heli-Coil insert (I seriously doubt it will break in that location again). Welding is better if done properly, but strong enough is strong enough.

After that I'd highly recommend Don's TCI brake support, real nice.