basically the holes in the ends of the sliders where the metal U-joint fits in are getting stretched and ovalized in a relatively short time. the shafts themselves seem to be holding up fine as i have only cracked one....its always the ends that give out.
Toys:
Slash with VXL
E-revo with MMM/Teckno Nue 1515/1yf running 4s and 5s