Provided is a testing system for a drivetrain, the testing system capable of simulating the slip behavior of a tire. The method comprises steps of generating at least one parameter value representing the reflected energy, and regulating the interaction of said impact element with said tool at least partially based on said value or values to control the rise time andor length of said shock wave. A connecting washer is fit on the outer circumference of the lower neck of the connecting head. The outer rail assembly may include first and second outer rail members that are slidable relative to each other and one or more locking mechanisms that may be operable to selectively limit sliding or translation of the first and second outer rail members relative to each other. In one embodiment, the outer section has multiple handle members, such as foam inserts.