Jeep Wrangler/YJ 1987-1995 Repair Guide



The front disc brake consists of 3 assemblies: the caliper assembly, the hub and rotor assembly, and the support and shield assembly.

The caliper is a single piston sliding type, of one piece casting construction with the inboard side containing the single piston, piston bore and the bleeder screw and fluid inlet holes. There are two brake pads within the caliper, positioned on either side of the rotor. The brake pads take the place of brake shoes on drum brakes and the rotor takes the place of brake drums. The pads themselves actually consist of two parts: the metal shoe and the composition lining which is bonded or riveted to the shoe.

The significant operating feature of the single piston caliper is that it is free to slide laterally on the anchor plate. The pressure applied to the piston is transmitted to the inboard brake pad, forcing the lining of the pad against the inboard rotor surface. The pressure applied to the inboard end or bottom of the piston bore forces the caliper to slide toward the inboard side. This inward movement of the caliper causes the outboard section of the caliper to apply pressure against the lining of the outboard pad, forcing the lining of the outboard pad, forcing the lining against the outboard surface of the rotor. As hydraulic pressure builds within the brake lines, due to the increased application of pressure at the brake pedal, the brake pad assemblies press against the rotor surfaces with increasing force, thus slowing the rotation of the rotor.