The stock gears strip EASY. You really need to make sure you have them meshed just right.
CEN makes steel gears, but the problem is the only steel pinions they make are a 14t/17t combo, so your gearing will be taller. And if you use steel spurs with the stock alum pinions... bye bye pinions.
http://www.customrccars.com/product_...at=22&custom=0
http://www.customrccars.com/product_...at=22&custom=0
http://www.customrccars.com/product_...at=22&custom=0