well i've shimmed my diff's and i gotta say WHAT a difference! they are silky smooth!
my diff's consist of RD logic's inner & outer case's, RobinsonRacing hardened ring & pinion and E-maxx spyder gear's.....
the shim's i ended up using were HPI Z892 and associated no.6373.
i needed to add 4 shim's on the bearing side opposite to the ring gear and the pinion needed a couple shim's as well.
thnx