A disk brake assembly (20; 50; 55; 60; 70; 75) comprising: a pressure plate coupled to a first rotor friction disk of a plurality of rotor friction disks; a plurality of stator friction disks located between the pressure plate and an end plate, wherein locations of the stator friction disks alternate with locations of the rotor friction disks, wherein at least one of the rotor friction disks and the stator friction disks is a split friction disk (90, 95) having an open cavity, and wherein at least one of the rotor friction disks and the stator friction disks is a solid friction disk (80, 85); and the end plate coupled to a second rotor friction disk of the plurality of rotor friction disks; characterised in that the split friction disk (90, 95) further comprises an annular-shaped disk half comprising: a friction surface; and a non-friction surface on a side opposite of the friction surface, the non-friction surface including: a first contact surface and a second contact surface; and a non-contact surface recessed from the contact surfaces (93A, 93B), wherein the non-friction surface and a surface of the fiction surface are non-parallel surfaces and the first and second contact surfaces (93A, 93B) are not parallel to the friction surface. a pressure plate coupled to a first rotor friction disk of a plurality of rotor friction disks; a plurality of stator friction disks located between the pressure plate and an end plate, wherein locations of the stator friction disks alternate with locations of the rotor friction disks, wherein at least one of the rotor friction disks and the stator friction disks is a split friction disk (90, 95) having an open cavity, and wherein at least one of the rotor friction disks and the stator friction disks is a solid friction disk (80, 85); and the end plate coupled to a second rotor friction disk of the plurality of rotor friction disks; characterised in that the split friction disk (90, 95) further comprises an annular-shaped disk half comprising: a friction surface; and a non-friction surface on a side opposite of the friction surface, the non-friction surface including: a first contact surface and a second contact surface; and a non-contact surface recessed from the contact surfaces (93A, 93B), wherein the non-friction surface and a surface of the fiction surface are non-parallel surfaces and the first and second contact surfaces (93A, 93B) are not parallel to the friction surface. a friction surface; and a non-friction surface on a side opposite of the friction surface, the non-friction surface including: a first contact surface and a second contact surface; and a non-contact surface recessed from the contact surfaces (93A, 93B), wherein the non-friction surface and a surface of the fiction surface are non-parallel surfaces and the first and second contact surfaces (93A, 93B) are not parallel to the friction surface. a first contact surface and a second contact surface; and a non-contact surface recessed from the contact surfaces (93A, 93B), wherein the non-friction surface and a surface of the fiction surface are non-parallel surfaces and the first and second contact surfaces (93A, 93B) are not parallel to the friction surface.