Patent ID: 8561762

Claim:
A brake system comprising: a brake caliper housing comprising a bore and, first and second portions defining a rotor channel therebetween that receives an associated automotive wheel brake rotor; a first brake member that is: (1) for use in engaging a first side of the associated automotive wheel brake rotor; and, (2) attached to the first portion of the brake caliper housing; a second brake member that is: (1) for use in engaging a second side of the associated automotive wheel brake rotor; and, (2) attached to the second portion of the brake caliper housing; a brake piston that is slidably mounted within the bore and that comprises: (1) a metal core having an axial height H 1 and having an opening; and, (2) a phenolic outer layer that has an axial height H 2 that is at least 0.5H 1 and that is attached to the metal core; wherein: the metal core is formed substantially of steel; the phenolic outer layer of the brake piston is overmolded onto the metal core; the metal core has at least one surface variation that is either concave or convex with respect to surrounding outer surfaces of the metal core; and, the phenolic outer layer covers the surrounding outer surfaces and completely covers the surface variation, to improve retention of the phenolic outer layer to the metal core, such that no other material or part contacts the metal core at the surface variation; a hydraulic brake system that uses hydraulic fluid pressure to cause the brake piston to slide within the bore to cause the first and second brake members to engage the first and second sides of the associated automotive wheel brake rotor in response to the actuation of the hydraulic brake system; and an electric parking brake system comprising a spindle nut that is received within the opening in the metal core and a spindle operatively attached to the spindle nut, wherein the electric parking brake system uses an electric motor to cause the spindle to rotate within the spindle nut to cause the brake piston to slide within the bore to cause the first and second brake members to engage the first and second sides of the associated automotive wheel brake in response to the actuation of the electric parking brake.