Originally Posted by RedBullFiXX
I've seen the notchy diff, but the 2 cars I have, feel like a perfect ball diff, butter smooth, assembled per directions
Could be tolerance issues with some parts ?
The newer diffs seem to be tighter when new than they used to be with the bd5. I sand the back of the crown gear to the point where they look flat (the molding circles are still there though). Then assembled them. After a day of running mod, they smooth out, and all the notches go away. My dad's car, which he only runs 17.5 in, has a bit notchier feeling diffs.
Conversely, A friend of mine puts some whitening tooth paste inside and chucks it up on a drill to break the gears in, which helps them break in and become smooth. My only concern with that is the oring possibly getting fouled up.
On the Kyosho O Rings, they are not quite the exact same size and from experience make the diff not be as free. Personally, I run the stock O rings with Zero leakage. The only thing special I do is put a couple of drops of oil on the o rings and also soak the paper gasket with oil. I then crank it as hard as I can without using excessive force so as not to strip it. The diff comes out much freer this way.
If i would run the Kyosho o-rings, I would probably run slightly softer oil.