The Left front knuckle on my cen matrix tr arena has comepletly stripped out. This truck is less than 3 months old, and has seen minimal abuse. I find it quite disheartening that so many of the stock components of this truggy are of such low quality. Most drivers has upgraded to the cnc knuckles for this reason, but I think CEN should have made the stock knuckles able to hold up with the rest of the car. When I first got this truck I was so excited and felt that I had gotten a great deal. Now almost 3 months later I wish I gone with a different truck because of the high amount of factory parts failing.