Firstly, use flyscreen mesh on the bottom of your chassis. That hole isnt just there to bring debris in, it also brings it out

Its most likely your gear meshing isnt aligned properly. Make sure you threadlock your engine mounts into the chassis plates so it doesnt move.

Also try running bigger pinion gears, a big jolt of acceleration could strip spurs. At least this way your accelleration is reduced and more top speed

i dont think they even make metal spurs for hpi on roads, they only make them for offroads