A rotor hub includes a sheet metal cylinder including spline teeth including angularly spaced crests and valleys, a tube surrounding the cylinder, secured to the crests and supporting a rotor thereon, a hub secured to the cylinder and supported for rotation, a torque converter, and a flex plate secured to the hub and the torque converter.

A constant velocity drive shaft manufacturing method capable of manufacturing a constant velocity drive shaft among drive shafts with high efficiency and with stable and high accuracy. A method for manufacturing a constant velocity drive shaft by full enclosed die cold forging including a metal mold pair including an upper metal mold and a lower metal mold includes an annealing step of partially annealing a molding material at positions where a first large-diameter part and a second large-diameter part included in the constant velocity drive shaft are respectively molded, a cooling step of cooling the molding material partially annealed in the first step, and a molding step of molding in one step a first large-diameter part, a second large-diameter part, and a third large-diameter part in the molding material cooled in the second step by pressing with the metal mold pair and pressing from both directions of the molding material.