[red99z]

If both wheels are off the ground and you spin one wheel, then the other wheel should spin in the other direction. If it does not then your spider gears were either installed incorrectly or they're broken. If your motor never actually moved the car (i.e. gravity moved it for you) then you may not have any gears in there at all.

Also, they are correct... if you have the wrong axle, then that could be it too. Make sure your axle retaining flange is on too. If its not then your axle can slide out causing your axle to become disconnected from the gears. this can also cause your axle and wheel to totally come out of the differental, your car will then be a three wheel cobra. becareful out there.