Front Disc Brakes

Front Disc Brake Caliper Assembly:

GENERAL INFORMATION
The front disc brake assembly used on this vehicle consists of the following components.

^ The driving hub and bearing assembly
^ Braking disc (rotor)
^ Caliper assembly
^ Shoes and linings

Disc Brake Caliper Mounting:

The floating double pin single piston Kelsey-Hayes Family Calipers, used on this vehicle are mounted directly to the steering knuckles and use no adapter. The caliper is mounted to the steering knuckle using bushings, sleeves and 2 through bolts which thread directly into the steering knuckle. Two machined abutments on the steering knuckle, position and align the caliper fore and aft. The guide pin bolts, sleeves and bushings control the side to side movement of the caliper. The piston seal, is designed to pull the piston back into the bore of the caliper when the brake pedal is released. This maintains the proper brake shoe to rotor clearance. Vehicles equipped with the Kelsey-Hayes double pin family caliper, have anti-rattle clips attached to the inner and outer brake shoe and lining assemblies. All of the braking force is taken up directly by the steering knuckle of the vehicle. The caliper is a one piece casting with the inboard side containing a single piston cylinder bore.

WARNING: THE PISTONS THAT ARE USED IN THE FRONT AND REAR DISC BRAKE CALIPER ASSEMBLIES ARE UNIQUE TO THE CALIPER THEY ARE USED IN. THE DIMENSIONS OF THESE PISTONS ARE DIFFERENT; DO NOT INTERCHANGE THE CALIPER PISTONS. IMPROPER USE COULD CAUSE A COMPLETE FAILURE OF THE BRAKE SYSTEM.

Fig. 2 Piston Seal Function:

The front disc brake caliper phenolic piston is 60 mm (2.36 inch) in diameter. A square cut rubber piston seal is located in a machined groove in the cylinder bore. This provides a hydraulic seal between the piston and the cylinder wall. A molded rubber dust boot is installed in a groove in the cylinder bore and the piston, keeping contamination from the cylinder wall and the piston. As 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 pistdn is 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. All these vehicles, are equipped with an audible wear indicator on the outboard pad of the front disc brake assemblies. This indicator when emitting a sound signals that brake lining may need inspection and/or replacement.