Abstract: There is disclosed a disc brake system incorporating a split calliper having a first calliper half integrally formed with a mounting plate for mounting the calliper on a vehicle. A second calliper half is fixedly and removably attached to the first calliper half in spaced apart relation to provide room for a rotor to be disposed between the calliper halves. The joiner plates permit adjustment of the distance between the calliper halves to accommodate rotors of different thickness. The split design provides a slimmer calliper profile permitting the use of larger diameter rotors in the same space. A splined rotor carrier permits mounting of the rotor on to a wheel hub housing having a corresponding spline. The disc brake system of the present invention is particularly useful in retrofitting existing vehicles, especially light armored vehicles (LAV's).