Agreed. Sounds like you are over-tightening your diffs. I made the same mistake when I first built my DB-01.
I not only crushed the diff nut retainer. I also flattened the stock diff balls making my diffs very gritty..
I have since learned to set the correct tension for each diff and haven't had any problems since. I'm still racing with the same diff parts for the past 2 years
