So, I got my diffs assembled. I used Traxxas heavy duty diff cups and diff gears w/I-bar, Traxxas diff fluids, acer racing ceramic bearings and RD logics aluminium diff cases. Now when I try rotating the diff from the input, it just gets stuck in one point, with some force it does rotate over the weird point but it makes quite much noise. I thought that this was caused by the RD logics diff cases but when I assembled it again with the stock diff cases the problem was still there. I found that it helped that I put shims on the pinion gear's shaft to pull it a little out from the diff case, but no big difference. It feels like in one point the pinion and ring gear don't mesh. Why? They are the same pinion and ring gears that were in my Revo when I bought it and then they worked well.