RE: Backwheels dont spin, any suggestions??
you will be at your LHS for your drive cup, just buy a bottle of diff fluid(5$).
take one between 10wt and 40wt. your preference, the more the number is high, the more it will ''lock'' your diff.
the more the number is high, the more chance you have to break another cup...
personnally, i run 30wt. frton and rear.