A piston (50), comprising: •a shaft side (52) with a first circumferential groove, said first circumferential groove (90) bounded by a continuous circumferential seal plateau (88), said seal plateau extending axially outward from said first circumferential groove, wherein a planar outboard surface (96) extends radially outboard from said seal plateau; •a clutch side (54) having two grooves alternating with two lands (102, 108); •an inner circumferential surface (56) having a seal groove (62) formed therein; and an outer circumferential surface (58) with a having a seal groove (76) formed therein, wherein the sides and surfaces form a ring shape.