1991 Cadillac Eldorado Brake Service (ONLINE REPAIR MANUALS)

DESCRIPTION

This unit utilizes a vacuum power chamber, consisting of a front and rear shell, housing divider, front and rear diaphragm, plate assemblies, hydraulic pushrod and a diaphragm return spring,Figs. and .

The unit operates in much the same manner as the single diaphragm unit described previously. The diaphragm and plate assemblies utilize the pressure differential between the engine intake manifold vacuum and atmospheric pressure to assist in braking.

TROUBLESHOOTING

Hard Pedal

• Internal vacuum leak.
• Faulty control valve.

Brakes Grab

• Faulty control valve...

This caliper, Figs. and , has a single bore and is mounted to the support bracket with two mounting bolts. Hydraulic pressure, created by applying force to the brake pedal, is converted by the caliper into friction. The hydraulic pressure is applied equally against the piston and the bottom of the caliper bore moving the piston outward and the housing inward, resulting in a clamping action on the brake rotor.

Rear ...

Servicing of disc brakes is extremely critical due to the close tolerances required in machining the brake disc to insure proper brake operation.

The maintenance of these close controls of the shape of the rubbing surfaces is necessary to prevent brake roughness. In addition, the surface finish must be non-directional and maintained at a micro inch finish. This close control of the rubbing surface finish is necessary to avoid pulls and erratic performance, and to promote long lining life and equal lining wear of both left and right brakes.

In light of the foregoing remarks, ref...

DUAL MASTER CYLINDER

Front & Rear Split System

When the brake pedal is depressed, both the primary (front brake) and the secondary (rear brake) master cylinder pistons are moved simultaneously to exert hydraulic fluid pressure on their respective systems,Figs. and .

If the rear (secondary) brake system fails, initial brake pedal movement will cause the unrestricted secondary piston to bottom in the master cylinder bore. Primary piston movement will displace hydraulic fluid in the primary section of the master cylinder to actuate the front brake system.

If the front (primary) brak...

• Grease or any other foreign material must be kept off the brake linings, caliper, surfaces of the disc and external surfaces of the hub, during service procedures. Handling the brake disc and caliper should be done in a way to avoid deformation of the disc and nicking or scratching brake linings.
• If inspection reveals rubber piston seals are worn or damaged, they should be replaced immediately.
• During removal and installation of a wheel assembly, exercise care so as not to interfer...

BLEEDING BRAKES

Manual Bleeding

Pressure bleeding is recommended for all hydraulic systems. However, if a pressure bleeder is unavailable, use the following procedure.Brake fluid damages painted surfaces. Immediately clean any spilled fluid.

• Remove vacuum reserve by pumping brakes several times with engine off.
• Fill master cylinder reservoir with clean brake fluid. Check fluid level often during bleeding procedure; do not let reservoir fall below half full.
• If necessary, bleed master cylinder as follows:
• Disconnect master cylinder forward brake line connection until fluid flows from re...