MM/Feigao cogging

I've been running my truggy since I converted it and I've been having a problem with stripping spurs. At first I thought that it was due to the chassis flex; although I didn't know how this could be since my motor mount is mounted to the center diff mount.

Today, while I was playing around with the Muggy with my son driving his Monster GT (brushless of course), I nailed the throttle from a dead stop and it cogged so violently that it stripped the spur gear. I've never had that happen before, but then again, I've never nailed it from a dead stop either. I'm running with no punch control, lowest timing, and high start power.

I also have to say that I'm running way over geared. I think I'm over geared anyway. I still have the stock Muggy tires on it running 14/46 gearing, which is what I was running in my buggy, so I figure I must be over geared.

Anyway, has anyone else experienced anything like this. Could it be due to the over gearing? That's the only thing that I can figure because when I stipped the other spurs, the truck was too far away to see or hear if it was cogging.