Brake disk assembly

An annular-shaped disk half (50) of a split friction disk assembly for a disk brake system. The disk half (50) includes a friction surface (56) and a non-friction surface (58). The friction surface (56) is at an axial end of the disk half (50). The non-friction surface (58) is at an axial end of the disk half (50) on a side opposite of the friction surface (56). The non-friction surface (58) includes a contact surface (60A) and a non-contact surface (62). The non-contact surface (62) is recessed from the contact surface (60A).