[Supershafts]

It's 2 teeth at a time, and usa standard doesn't have the same processes as Dana and other quality gear companies.

Now the other issues are possibly for some here.... Are we doing a break in on new gears or just running them ?
I know many people seem to believe break in isn't important, but it actually is very important. Especially if you have a quality gear where run in was done and your set up isn't dead on perfect with their run in pattern.
Now you're running a gear in a different area it has no heat cycling , there is no run in between them and they're seeing excessive loads cold put against them.......
Another thing to do is get the diff to temp before runs... I know people don't believe in that either but, it is important and it does help greatly.

Putting them (gears) together in bind is KILLING them, there will be deflection and now you have it where they will be forced to break since there is no room either way for deflection..............
That brings me to the pinion 1 tooth on larger ratios.... there is not 1 tooth engagement at a time.... On any ratio it is never one tooth engagement... as one begins, one is center, and one is leaving always having 2 teeth on eachother together, now they're being hammered between eachother......

What happens to hardened material being hammered and pressurized ???? it cracks.

You need to really understand whats happening, it's far more than depth and backlash. There are preloads that counter deflection and tooth pattern run off which is present in every diff.

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