[RC-Monster Mike]

Artur,

Are you stripping the output gear in the tranny or the spur gear? If the output gear is stripping on hard brakes, replace the idler gear and you should be ok. Over time, the idlers develop a sharp back side, which cuts the outpur gear on hard brakes. Look at the idlers and see if the back of the teeth are sharp. A single speed also helps a lot.