Abstract: A piston for an automatic transmission includes a cylindrical portion formed of a steel material and an elastomer bonded thereto. The elastomer includes an ethylene-acrylic polymer, a filler, and a hexamethylene diamine curing agent. The elastomer is compression or injection molded to the metal cylindrical portion. During the molding step, the elastomer is cured and achieves a cross-link density, strength, and other physical properties sufficient for use in an automatic transmission. Thus, the piston is formed without a post curing step. The piston provides a lower wear rate and a higher life expectancy than pistons formed with a post curing step.