1994 Buick Roadmaster Brake Service (ONLINE REPAIR MANUALS)

• After disassembling a power brake unit, soak all metal parts in solvent.
• Use only alcohol on parts containing rubber. After the parts have been thoroughly cleaned and rinsed in solvent, they should be rewashed in clean alcohol before assembling.
• Use compressed air to blow dirt and cleaning fluid from the recesses and internal passages.
• Always use ...

MASTER CYLINDER OVERHAUL

EXCEPT CORVETTE

Disassemble

Refer to Figs. and when performing the following procedures.

• Remove master cylinder from vehicle as follows:
• Disconnect and plug hydraulic lines.
• Remove two master cylinder attaching nuts, then the master cylinder.
• Remove reservoir cover and diaphragm. Discard old brake fluid in reservoir.
• Inspect cover and diaphragm. Replace if cut, cracked or deformed.
• Remove fluid level switch, if equipped.
• On models with compact master cylinder, remove proportioner valve assembly, Fig. .
• Depress primary piston and remove lock ring.
• Plug primary fl...

REMOVAL

• Remove caliper assembly from steering knuckle as described in "Caliper Removal" under "Caliper Service."
• Remove inboard shoe. Dislodge outboard shoe and position caliper on the front suspension so the brake hose will not support the weight of the caliper.
• Remove shoe support spring from piston.
• Remove two sleeves from inboard ears of the caliper.
• Remove four rubber bushings from the grooves in each of the caliper ears.

INSTALLATION

• Lubricate new sleeves, rubber bushings, bushing grooves and mounting bolt ends with Delco Silicone Lube or its equivalent.
• Install new bushings and sle...

AC-DELCO TANDEM DIAPHRAGM TYPE

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.

AC-DELCO SINGLE DIAPHRAGM TYPE

The AC-Delco power booster assembly, Fig. is located along the bulkhead in ...

This single piston sliding caliper assembly, Fig. , incorporates a one piece housing with the inboard side of the housing bored for the piston. A seal within the housing bore provides a hydraulic seal between the piston and housing wall.

A spring steel scraper (wear sensor) is incorporated on each inboard shoe. When the shoe lining has worn to within .030 inch of the shoe, the sensor scrapes the rotor and emits an audible high fre...

• Inspect components for damage and unusual wear. Replace as necessary.
• Inspect wheel cylinders. Boots which are torn, cut or heat damaged indicate need for wheel cylinder replacement. On type 1 brakes, remove wheel cylinder links. Fluid spill from boot center hole indicates cup leakage and need for wheel cylinder replacement. On type 2 brakes, use a small screwdriver to pry center hole of boot away from piston. If fluid spills from center hole, cup leakage is indicated and wheel cylinder should be replaced. On all types, light fluid coatings on piston within cylinder is considered norm...