Method of manufacturing an axially collapsible driveshaft

A method for manufacturing a driveshaft for use in a vehicle drive train system that is axially collapsible in the event of a collision to absorb energy. A workpiece, such as a hollow cylindrical tube, is deformed by hydroforming to provide an axial collapse initiation zone. The axial collapse initiation zone can be defined by a plurality of axially extending undulations or corrugations that are formed in a central portion of the tube. The axial collapse initiation zone is designed to accommodate the transmission of torque through the driveshaft without any deformation under normal operating conditions. However, if a relatively large axial force is applied to the front and rear end portions of the driveshaft, the axial collapse initiation zone is designed to allow relative axial movement to occur between the front and rear end portions of the driveshaft. Such collapsing functions to absorb energy during a collision, thereby providing additional safety to the occupants of the vehicle. If desired, the driveshaft can be hydroformed to include integral yoke portions on the ends thereof.