Originally Posted by
SlowerOne
Due respect, this isn't quite accurate...
The diff works by ensuring there is no slip between the balls and the rings. Things only wear is there is some differential movement between them, so if there is no slipping there is no wear. If your theory holds, the wear rates would be different, and the balls would be out after just a couple of runs.
The hardness of the balls exceeds that rings, which we see as grooves worn into the rings, not flats worn onto the balls. Truth is, the balls are dependent on the grade used, and that the general grade used has a tolerance of about 0.0001" - there's more flex in the plates than that.
Scottrix and Slapmaster have the recipe we all find gives the smoothest diff for the longest time
Well I'm right and I'll stick to it. Take a pizza cutter wheel and cut some slices. The wheel didn't slip yet the contact pressure between the wheel edge and the pizza was great enough to indent and slice the pizza. Since the pizza is being moved by the slicing wheel it can be assumed that wear will happen to the slicing wheel. Yes this is an example of extremely hard and soft materials, but to some degree the softer diff-ring will yield to the harder diff balls at every pass and create wear. The same approch to pizza slicers is how the Chunnel and many other tunnels were bored through hard rock. This is why a diff with minimal slipping will still create a indentation where the balls were running. As long as there are one or two off sized balls, the contact pressure will increase for those balls and increase the wear to the diff ring.
The harder your diff balls and tighter the grade tollerance the less worry about wear. Some racers like me, just run the diff rings for months and months since the secret I found in a smooth diff is, high quality balls, good thrust bearing and cone washers.