Originally Posted by slackinoff

Update on my rear diff modifications. I think I forgot to post my outcome. My rtr did not come shimmed at all on the rear diff bearings. (for the correct pinion to sun gear mesh). I am sure this is what caused the destruction. I originally thought it was the plastic bearing housings, (they were extremely loose, so I needed a new set) and opted to purchase the aluminum versions ($9 shipped on ebay). The aluminum ones are part # LOSA4454. See picture below. I also found an ebay a seller (rc-parts4you) selling the entire RTR rear diff (gearbox housings, diff, pinion and sun gears, bearings, ect assemble and ready to go for cheaper than buying the pinon and sun gear set. Well in my searching anyway. $30 shipped. (I bet one could find a much better deal on NOs pinion sun gear from the 2.0....I was in a hurry for my next race) I do hunt Ebay for nos from time to time, which is why I like buying the 1 - 2 generations older kits. It is kind of fun to hunt and find these NOS (new old stock) parts. Especially when they are so heavily discounted.

Then I picked up a shim kit. LOSA4452. I popped the new complete diff apart and tested afew combos on the shims. They give you 10 .10 and 10 .20 shims. I forget the combo, but everyone will be different. Just think about how it is effecting the mesh, putting shims on the sun gear side will space it out away from the pinion, and shims on the opposite of the sun gear side will tighten that mesh. It takes several attempts but it is worth it. You know when you get that perfect combo and it is smooth but solid feeling. Mine with no shims was smooth, but not solid feeling. You could tell there was excessive clearance.