Originally Posted by JLock

Are you using Evolva clutchbell gears or Inferno GT clutchbell gears? Believe it or not, the pitch between the two type of clutchbell gears are slightly different and if you are using the Evolva clutchbell gears and Inferno GT spur gears, it could be one of your issues. Are your clutchbell gears old and knife-edged? If they have knife-edged and the mesh is off a little, torq or a flex in the chassis could cause enough separation in the mesh to possibly cause the stripping issue. Check your motor mount bolts to make sure your engine is secure to the mounts. Check the motor mount chassis screws as well. I have had issues with them vibrating out of one mount from the bottom thus causing the engine to shift and strip my spur gears.