Abstract: A vehicle disc brake assembly having a mechanical parking brake comprises: a piston carried by the brake assembly, the piston having a bore provided with an inner cone surface and an internal groove formed in an inner wall of the bore; an adjusting strut part disposed within the piston bore, the strut part having a flange configured to contact the inner cone surface; and a single, one-piece clutch spring carried by the strut part within the piston bore; wherein the clutch spring includes a main body having a plurality of legs extending therefrom, each of the legs including an outermost remote end configured to be received in the groove of the piston to secure the clutch spring within the piston and each of the legs configured to provide a spring force operative to bias the flange of the strut part against the inner cone surface of the piston.