Vibration damping brake piston for a motor vehicle

A disc brake assembly for use in a motor vehicle, said disc brake assembly comprising:

• caliper means for straddling a rotor and supporting friction elements to be applied against opposite sides of said rotor, said caliper means having a first side forming a cylinder bore and a fluid channel in communication with said cylinder bore;
• a brake piston slidably mounted within said cylinder bore for axial displacement in response to fluid pressure communicated to said cylinder bore via said fluid channel, said brake piston comprising:
• a first piston member disposed within said cylinder bore and having a first end;
• a second piston member disposed within said cylinder bore and having a first and second end, said first end of said second piston member urging at least one of said friction elements against said rotor and said second end adjacent to said first end of said first piston member;
• and
• a compliant member disposed between said first end of said first piston member and said second end of said second piston member, whereby said compliant member is operative to isolate said first piston member and said brake caliper from vibrations of said second piston member during low to medium effort braking.

A brake piston apparatus for use in a disc brake caliper of a disc brake assembly in a motor vehicle, said brake piston apparatus comprising:

• a first piston member slidably disposed within a cylinder bore of said brake caliper, said first piston member having a hydraulic reaction face in communication with hydraulic fluid within said cylinder bore and a first groove circumferentially disposed in a first end opposite said hydraulic reaction face;
• a second piston member slidably disposed within said cylinder bore, said second piston member having a second groove circumferentially disposed in a second end adjacent to and axially aligned with said first end of said first piston member and an operating face opposite said second end for urging a friction element against a rotor;
• guide means slidably disposed within said first groove and said second groove for maintaining axial alignment of said first and second piston members within said cylinder bore;
• and
• a compliant member positioned between said first end of said first piston member and said second end of said second piston member, said compliant member being adapted to urge said first piston member into a spaced apart relationship from said second piston member, whereby said first piston member and said brake caliper are isolated from vibrations caused by surface variations in said rotor.