Join Date: Feb 2006
Location: Indianapolis, IN
I'm not sure I'd trust JB Weld or silicone there. It's a pretty big hole. For that, I'd recommend splitting the cases and having a machine shop build it up with weld and then machine it to match the mating surfaces. Take a couple more pictures, but put a tape measure in there to give some scale. Take it around to some shops, tell them it's cast aluminum. Depending on cost, if you could get them to build it up with weld, you could file it down so that there's a 1/16" short of the mating surfaces. Then just fill it with silicone. That I would trust.
The good news is that it's not structural. A good welder could have that filled in under an hour. Drain the fluids, pull the rotor, and clean it really well. As long as they don't weld the cases together (which would be very easy to correct), it'd be good as new.
The bad news is that this is an indication that there could be more damage. Something like this could be from a crash or a really shitty mechanic. If it's a crash, I'd pull the spark plugs and have someone crank the engine while I watched the rotor. If that shaft is bent, you're f-ed.