OK I have looked into the cause of this on a mates Mayhem. It appears that if you have the shocks on the inboard most hole on the lower A arm and the lowest outside hole on the tower then it is possibly to get to much suspension travel. Now this allows to much movement in the CVA joint allowing the shaft to rub on the hub, heat up and then crack/chip.

A fix we thought of would be to fit Hyper 7 Uni shafts, thus eliminating the travel limitations. Or just restrict your droop a bit more.