well i just checked the gear's and i need new 1 ....

do they go fast? sence i got this used... i just orderd 2 set's for the frount and rear .. so im going to put new gear in the frount and rear..lol....and how do you know if you shim it right? and dose and 1 know if the stock esc will take the orion baja motor? thanks for all your help.