Any of the possibilities could have caused the failure, but its about more that a year and half before the failure since the installation. AS I'm out of town now, and according to my mechanic, he said that looking at the cross-section of the bar, 2 different shear marks, meaning that an earlier hairline crack/fracture might have been the start of the failure and was at the thread end. Anyway its been welded back and going into the car.
