Front Disc Brakes

COMPONENTS
The front disc brake system is made up of the components listed below.
^ Hub And Bearing Assembly
^ Rotor
^ Piston Opposed Fixed Caliper Assembly
^ Shoes and Lining Assemblies Semi-Metallic
^ Steering Knuckle
These components are described in detail below.





Front Hub And Bearing Assembly
The Front Hub And Bearing Assembly is used to mount the braking disc to the vehicle. The braking disc is mounted to the front face of the hub assembly by the wheel mounting studs. The braking disc is retained to the hub by the front wheel and the wheel attaching nuts. Brake Caliper, the 4 piston opposed fixed caliper is comprised of the following. The caliper body is cast aluminum, and is 2 individual pieces which are held together by 4 attaching bolts. Each caliper half houses 2 pistons, of 38 and 42 mm. in size. The pistons are mounted in the caliper halves so the 38 mm piston is on the bottom with the 42 mm on top when the caliper is mounted on the vehicle. The 2 halves of the caliper are hydraulically connected by means of an external brake tube on the bottom of the caliper assembly. Each caliper half has an individual bleeder screw at the top of the caliper half and each side must be individually bled. The caliper bolts directly to the steering knuckle of the vehicle by means of 2 machined mounting bosses on the inboard caliper half.

Brake Shoes
Brake Shoes, the brake shoe lining material is a semi-metallic non asbestos formula. The brake lining material used has been specifically formulated to meet the braking requirements of this vehicle. When brake shoes are replaced, only brake shoes meeting the Original Equipment Manufacturer formulation should be used to maintain the original braking performance of this vehicle.

Rotor
Rotor, the purpose of the rotor is to slow down and stop the front wheels of the vehicle. This is accomplished by applying the brake shoes against the braking surfaces of the rotor. The rotor is made of iron and vented to help cool it during brake applications. Steering Knuckle, the steering knuckle is used as the mounting location for the caliper assembly and the hub and bearing assembly. The steering knuckle also reacts against the braking forces when stopping the vehicle.

Fig. 2 Piston Seal Function:

Square Cut Rubber Piston Seal
One square cut rubber piston seal is located in the machined seal groove of each piston bore. There are 4 piston bores 2 located in each half of the caliper assembly. This provides the hydraulic seal between the caliper pistons and the caliper assembly. The piston seal also provides a means of pulling the piston back into the piston bore of the caliper assembly. This will maintain the proper brake shoe to rotor clearance. The ability of the piston seals to pull the pistons back into the caliper bores is illustrated in. As the piston moves out of the caliper bore, as the brake pedal is applied the piston seal becomes distorted. When the brake pedal is released and hydraulic pressure removed from the piston, the piston seal returns to its original shape pulling the piston back into the caliper bore.

Molded Rubber Dust Boot
A molded rubber dust boot is installed in a groove of each caliper bore and piston. The purpose of this dust boot is to keep contamination from the wall of the caliper bore and piston. The dust boots mount in the caliper bore openings and in a groove of each piston. As brake lining wears, master cylinder reservoir brake fluid level will go down. If brake fluid has been added to the reservoir, reservoir overflow may occur when the pistons are pushed back into the new lining position. Overflowing can be avoided in this case by removing a small amount of fluid from the master cylinder reservoir.