Third Major Blue Ox Casualty

It is hard to tell what actually happened without looking at pictures of the failure. But maybe if you receive enough guesses you can piece things together of why this is happening. I would start by looking at the failure site it self. Does the metal have very small grain structure indicating work hardening of the metal. This would indicate to me maybe some excess clearance in the load path of the bar to the frame of the car so each time you start or brake excessive handling loads are applied. Like if you were water skiing and there was slack in the line and the boat driver goes full throttle it would put way more stress on your shoulders than if there was no slack in the line. Handling loads from a tow motor on an aircraft for example can be 10 times as much as it sees in normal fight operations. This repeated applied load can work harden the metal and eventually lead to failure. the 4 in piece that was pulled from the frame leads me to believe that this is the failure mechanism. My friend had 2 failures like this with his Blue Ox. Hope this helps you find the cause.