Disc & Drum (rwd) Cadillac Brougham I

AUTO ADJUSTER (DRUM BRAKE)

Automatic adjusters operate only when brakes are applied as car is moving in reverse. The link, which holds top of actuating lever stationary, forces lever to pivot on secondary shoe. This pivoting action forces pawl downward against tooth on adjuster screw.

If the lining-to-drum clearance is correct, the downward movement will stop before adjusting screw is turned. If clearance is too wide, secondary shoe will move outward. This allows pawl to move down enough to turn adjuster screw one notch. This brings lining-to-drum clearance back to correct specifications.

If adjuster screw is frozen or clearance is too great, an override device will prevent adjuster movement. This will prevent biding of automatic adjuster linkage.

Note. Some models use an adjuster pawl with a separate blade to contact star wheel. This system does not use an override spring.

BRAKE BOOSTER

The Delco Moraine Tandem Diaphragm power brake unit is mounted on firewall and connected directly to brake pedal. A combination of vacuum and atmospheric pressure is used to provide power assist. Power cylinder houses power piston assembly, which contains primary and secondary diaphragms, pistons, floating control valve, reaction piston and disc.

DISC BRAKES

Caliper is a single casting with 1 large piston inboard of disc rotor. It is mounted on the steering knuckle or a support bracket attached to front suspension. Brake rotors are cast iron with ventilation fins separating the 2 braking surfaces. Some models use a groove machined in the braking surfaces to help control brake noise.

Disc brake pads are stamped steel with riveted linings. Most models use a wear sensor, a piece of spring steel riveted to the rear edge of inner or outer brake shoe. The sensor produces a high pitched squeal when lining needs replacement.

DRUM BRAKES

Brakes are hydraulic single anchor and use Bendix type shoes. Anchor pins for brake shoes are fixed to backing plate and are non-adjustable. Automatic system is made up of a link, actuating lever, pawl and pawl spring. Pawl spring is mounted on secondary brake shoe. System uses an override pivot plate and spring to protect against binding linkage.

Note. Some models use an adjuster pawl with a separate blade to contact star wheel. This system does not use the override spring.

MASTER CYLINDER

The Delco Quick Take-Up master cylinder is a 2 piece unit with cast aluminum master cylinder body and plastic fluid reservoir. It is designed for use with systems utilizing low drag calipers.

This master cylinder includes a quick take-up valve. This valve delivers a large volume of fluid, at low pressure, upon initial application of brakes. The fluid quickly displaces retracted calipers, placing brake linings in contact with brake rotors.

HYDRAULIC BRAKE BLEEDING

Hydraulic system bleeding is necessary any time air has been introduced into system. Bleed brakes at all 4 wheels if master cylinder lines have been disconnected or master cylinder has run dry.

Bleeding may be done either by using pressure bleeding equipment or by manually pumping brake pedal and using bleeder tubes.

SERVICING METERING VALVE

1. On disc brake equipped vehicles, the metering section of the combination valve must be deactivated before bleeding.
2. To hold the metering valve open to pressure bleed the front brakes, the valve stem must be pushed in or pulled out. Loosen front mounting bolt and install tool (J-23709) on the combination valve. Stem should be fully extended or depressed. (Scheme 2)

Deactivating Metering Valve for Bleeding (Typical). Scheme 2

BENCH BLEEDING MASTER CYLINDER

Note. Bleed tubes must have a residual pressure check valve installed to keep tubes from siphoning brake fluid.

Scheme 3

1. Clamp master cylinder in vise by mounting flange. Install and tighten threaded end of bleed tubes in outlet ports of master cylinder with opposite end of bleeder tube in reservoirs. Fill reservoirs with clean brake fluid so that bleed tube ends are submerged in brake fluid. (Scheme 3) (Scheme 3): Bleeding Master Cylinder With Bleeding Tubes Installed
2. Slowly compress and release piston assemblies until bubbles cease to appear in brake fluid. Remove tubes and plug master cylinder outlets to keep fluid from draining.

MANUAL BLEEDING

Note. Before bleeding system, exhaust all vacuum from power unit by depressing brake pedal several times. Bleed master cylinder if equipped with bleed screws, then bleed wheel cylinders or calipers in sequence.

1. Fill master cylinder. Install bleeder hose to first bleeder valve to be serviced. Bleeding sequence is RR, LR, RF, LF. Place other end of hose in clean glass jar partially filled with clean brake fluid so end of hose is submerged in fluid.
2. Depress brake pedal slowly through its full travel. Open bleeder valve 3/4-1 turn. Close bleeder valve. Release pedal. Repeat procedure until flow of fluid shows no signs of air bubbles.

Note. Check fluid level in master cylinder frequently during bleeding to insure air does not enter system.

PRESSURE BLEEDING

Note. Before bleeding system, exhaust all vacuum from power unit by depressing brake pedal several times. Bleed master cylinder if equipped with bleed screws, then bleed wheel cylinders or calipers in sequence.

1. Clean master cylinder cap and surrounding area, then remove cap. With pressure tank at least 1/3 full, connect to master cylinder using adapters. (Scheme 4) Attach bleeder hose to first bleeder valve to be serviced. Bleeding sequence is RR, LR, RF, LF. Place other end of hose in clean glass jar partially filled with clean brake fluid so end of hose is submerged in fluid.
2. Open release valve on pressure bleeder. Unscrew valve 3/4-1 turn noting fluid flow. When fluid flowing from cylinder to cup is free of bubbles, close bleeder valve securely. Bleed remaining cylinders in correct sequence and in same manner. Remove tool from combination valve.

Pressure Bleeder Installation (Typical). Scheme 4

BLEEDING PRESSURES

PRESSURE BLEEDING SPECIFICATIONS

BLEEDING SEQUENCE

BLEEDING SEQUENCE

DISC BRAKE

Disc brakes are self-adjusting. Caliper piston seals are designed to retract pistons just enough to allow brake lining to lightly brush disc without any drag. Sliding caliper design compensates for any lining wear.

DRUM BRAKE SHOE

Note. Adjustment should only be required after relining or replacing shoes, or if length of adjusting screw is changed.

Scheme 5

1. Raise vehicle and remove wheels and drums. Check to make certain that parking brake cable and linkage, including levers on rear secondary shoes, are free. Measure brake drum inside diameter using inside caliper portion of tool (J-21177).
2. Adjust brake shoes to dimension obtained on outside caliper portion of tool (J-21177). (Scheme 5) Check brake fluid level in both master cylinder reservoirs. Add fluid if necessary. Adjust parking brake. (Scheme 5): Adjusting Brake Shoe Clearance (Through Backing Plate)
3. Install drums and wheel. Tighten wheel mounting nuts. Lower vehicle. Drive car alternately forward and backward, applying brakes moderately in each direction.

FRONT WHEEL BEARING

1. Install wheel on vehicle. Remove dust cap and cotter pin. Tighten spindle nut to 12 ft. lbs. (16 N.m) while spinning wheel by hand. Back off nut until just loose, then tighten by hand until snug.
2. Back off enough to insert new cotter pin (about 1/2 hex flat or 1/12 turn). Adjustment should provide .001-.005" (.03-.13 mm) end play. Install dust cap.

Check

Push rod height check is necessary if master cylinder and power unit were separated. Push rod is replaced with a new one. Push rod is transferred from one unit to another. If push rod misadjustment is diagnosed as braking problem.

Adjustment

1. Remove power unit from vehicle and place power head assembly in padded vise with front housing up. Remove front housing seal.
2. Insert push rod (flat end first) into piston rod retainer. Depress rod with 40-50 lbs. force to ensure it is seated. Place "Go/No-Go" gauge (J-22647) over push rod. Make sure gauge does not contact studs. (Scheme 6)
3. "Go" or short tab on gauge should just clear push rod; "No-Go" or long tab on gauge should contact push rod. If push rod is too long or too short, an adjustable push rod must be used. Adjust new push rod to correct height using "Go/No-Go" gauge.

Push Rod Gauging Method with "Go/No-Go" Gauge J-22647. Scheme 6

PARKING BRAKE

Note. When rear drum brakes are serviced, the parking brake linkage cable at the equalizer must always be readjusted to prevent possible burn out of rear brakes.

1. Lubricate parking brake linkage at equalizer and cable stud, and ensure free movement of cables. Apply parking brake pedal exactly 3 clicks.
2. Raise and support vehicle. Tighten adjuster until the right rear wheel can just be turned rearward with two hands but cannot be turned forward.
3. Release parking brake. Wheels should turn freely in either direction without drag.

Lateral Runout

Adjust wheel bearings until all end play is eliminated. Attach a dial indicator to front suspension so pointer contacts face of rotor about 1 inch from edge. Set gauge to zero, then turn rotor through one complete revolution. (Scheme 7) Check gauge reading with specifications for maximum runout.

Checking Rotor Lateral Runout. Scheme 7

Parallelism

Check thickness of rotor at 4 or more points around edge of rotor. Make all measurements the same distance from edge. If thickness varies more than specified, refinish or replace rotor.

DISC PAD INSPECTION

Inspect linings every 6,000 miles or 12 months, or whenever wheels are removed. Check both ends of inboard and outboard linings for wear. Replace any that are worn to within .032" (.81 mm) of rivets on either end of lining.

DRUM BRAKE CLEANING

Clean all parts except the brake lining and the brake drums with brake cleaning solvent. To remove brake fluid contamination, clean all parts except the brake lining with denatured alcohol. Contaminated brake lining must be replaced.

DRUM BRAKE INSPECTION

1. Pull back the wheel cylinder dust boots and check for evidence of leakage. If evidence of leakage is noted, the cylinder should be disassembled, inspected and overhauled.
2. Polish the brake support plate ledges with fine emery cloth and inspect them for grooves that could restrict shoe movement. If grooves exist after polishing, the support plate must be replaced. Inspect lining wear pattern. If wear across the width of the lining is uneven, the drums should be checked for distortion, the shoes for correct positioning, and the support plate for distortion.
3. Inspect all springs for evidence of overheating and fractures. Self-adjusting cables should be inspected for kinks, fraying, or elongation of the eyelet. Inspect adjuster screws for freedom of rotation, and adjuster lever for wear and distortion.
4. Replace defective brake parts.

Removal

1. Without disconnecting hydraulic lines, remove master cylinder from power unit and position to one side. On Delco-Moraine models equipped with pipe distribution and switch mounting bolt, remove bolt before moving master cylinder away from power unit. CAUTION: Do not bend or kink hydraulic lines.
2. Disconnect vacuum hose from check valve on front of power unit. Disconnect push rod from brake pedal. CAUTION: Do not force push rod to the side when disconnecting.
3. Remove nuts mounting power unit to firewall and remove power unit.

Installation

Reverse removal procedure and check stop light and cruise control (if equipped) switch adjustments.

DISC CALIPERS & PADS

Note. Relining should be done in complete sets only.

1. Remove and discard 2/3 of brake fluid in master cylinder reservoir to prevent overflow during servicing.
2. Raise vehicle and remove front wheels. Position a "C" clamp on caliper. Place solid side of clamp against inside of caliper and screw end of clamp against outboard shoe.
3. Tighten clamp until caliper moves away from vehicle. When caliper moves enough, push piston to bottom on its bore. This will allow shoes to back off from rotor surface.
4. Remove "C" clamp. Unbolt caliper from steering knuckle or support bracket. If removing caliper for overhaul, remove brake hose inlet fitting.
5. Remove caliper and support with a wire so brake hose will not be damaged. Remove shoes and shoe support spring from cavity in piston. Remove sleeves from inboard ears of caliper and rubber bushings from all caliper ears.

Scheme 8

1. Using silicone lubricant, coat and install new sleeves and rubber bushings in caliper ears. Attach shoe support spring to inboard shoe. Ensure that shoe is installed in caliper with wear sensor to rear of vehicle. Shoe should be flush against piston.
2. Position outboard shoe in caliper. Engage tab at bottom of shoe with caliper cutout and shoe ears with caliper ears at top of shoe. Place caliper over rotor, aligning caliper ears with mounting holes.
3. Start bolts or pins through inboard caliper ears and mounting bracket. Make sure bolts or pins pass under retaining ears of inboard shoes.
4. Push bolts or pins through caliper to engage hole in outboard shoe and ears of caliper. Thread bolts into mounting bracket and tighten to 38 ft. lbs. (51 N.m). Measure clearance between caliper housing and bracket stops. If necessary, file ends of bracket stops to provide proper clearance. (Scheme 8)
5. Install brake hose inlet fitting (if removed) and tighten bolt to 32 ft. lbs. (44 N.m). Add brake fluid to fill master cylinder to within 1/8" of top. Bleed brake system if necessary. Pump brake pedal to seat shoes against rotor.
6. Use pliers to clinch upper ears of outboard shoe against caliper. (Scheme 9) Make sure ears are flat against caliper with no clearance.

Clinching Tabs on Outboard Shoe. Scheme 9

DISC ROTOR

Raise and support vehicle. Remove wheel, then remove and support caliper. Remove grease cup, cotter pin and nut, then remove rotor. To install brake rotor, reverse removal procedure.

DRUM BRAKE SHOE & LINING REPLACEMENT

Note. Mark position of springs and star adjusters as they are removed, for installation in original position.

1. Release parking brake and loosen parking brake cable at equalizer. If necessary, back off brake adjustment before removing brake drums. Remove return springs. Remove brake shoe hold down springs and cups. Lift up on parking brake actuator lever and remove actuator link. Remove actuator lever and return spring.
2. Separate brake shoes from wheel cylinder connecting links. Remove parking brake strut and spring. Disconnect parking brake cable. Remove brake shoes, spring and adjusting screw from backing plate. Detach spring and screw from brake shoes. Remove parking brake lever from secondary shoe.

Exploded View of Rear Drum Brake Assembly. Scheme 10

1. Lubricate fulcrum end of parking brake lever and attach to secondary shoe. Connect adjusting screw spring, then place screw in position. Ensure that star is aligned with adjusting hole. Lubricate surfaces where shoe and parking brake cable contact backing plate. Position shoes and insert into wheel cylinder links.
2. Connect cable to parking brake lever and install strut and spring between lever and primary shoe. Install actuator, actuator return spring and actuating link. Replace brake drums and wheels. Adjust parking brake and brake shoes. Check for proper operation of brakes before moving vehicle.

Disconnect switch wire (if equipped) and all hydraulic lines. Remove cylinder mounting nuts and remove cylinder.

To install, reverse removal procedure. Tighten mounting nuts to 20 ft. lbs. (27 N.m). Fill master cylinder to proper level. Bleed brake system.

Remove brake shoes. Disconnect inlet tube line and remove 2 screws holding wheel cylinder to backing plate. Remove wheel cylinder.

To install, replace wheel cylinder in position and install screws. Tighten screws to 13 ft. lbs. (18 N.m). Connect inlet tube line and tighten line nut to 18 ft. lbs. (24 N.m).

Scheme 11

1. Remove pushrod boot, silencer, front housing seal, grommet and vacuum check valve.
2. Scribe a mark on front and rear housings for reassembly reference. Scribe and unstake staked tabs. Install booster in Holding Fixture (J-23456). (Scheme 11)
3. Tighten fixture handscrew just enough to allow for housing rotation. Turn fixture handle counter-clockwise until tabs on front housing are moved to unlocked position.
4. Remove power piston group, power piston return spring, and power piston bearing. Remove piston rod, reaction retainer and power head silencer.
5. Grasp assembly at outside edge of divider and diaphragms. Hold with pushrod down against a hard surface. Use a slight force or impact to dislodge diaphragm retainer.
6. Remove primary diaphragm, primary support plate, secondary power piston bearing, housing divider, secondary support plate and diaphragm and power piston assembly.

Cleaning & Inspection

Clean all plastic, metal and rubber parts in denatured alcohol. Blow out all passages, orifices and valve holes. Air dry all parts. Slight rust on housing may be cleaned with crocus or emery cloth. Do not reinstall any rubber parts with cuts, nicks or distortion. If in doubt, replace the part.

Note. Prior to installation of rubber, plastic, and metal friction parts, lubricate with silicone lube.

Scheme 12

Scheme 13

1. Place power piston on bench with push rod end up. Install Assembly Cone (J-28458) over push rod end of piston. Lubricate inside diameter of secondary diaphragm with silicon lubricant and fit in secondary support plate.
2. Install secondary diaphragm and support plate over power piston and push down until it bottoms. Lubricate inside diameter of secondary power piston bearing. Install bearing in housing divider with flat surface of bearing on the same side as 6 raised lugs on divider. (Scheme 12): Exploded View of Delco-Moraine Tandem Diaphragm Booster (Scheme 13): Installing Secondary Diaphragm & Support Plate
3. Hold divider so that formed flange faces up. Press divider down over assembly cone and onto power piston to rest against secondary diaphragm. Lubricate inside diameter of primary diaphragm and install in primary support plate. Remove assembly cone from power piston, place primary support plate and diaphragm assembly over power piston and push down until it bottoms.
4. Place diaphragm retainer over power piston and onto diaphragm. Install Assembly Cone (J-28458) over power piston onto diaphragm retainer and strike with hammer until retainer is locked on neck of power piston. Remove assembly cone.
5. Install reaction retainer, piston rod and power head silencer. Place primary power piston bearing in rear housing center hole. Lubricate with silicone lubricant on inner diameter. Install rear housing in Holding Fixture (J-23456). Attach power piston assembly to rear housing.
6. Install power piston return spring over reaction retainer. Install front housing and align scribe marks. Tighten fixture handscrew just enough to allow for housing rotation. Rotate housing until tabs are fully seated. Stake 2 housing tabs into sockets at 2 new locations 180° apart. Do not stake tabs that have previously been staked.
7. Lubricate inside and outside diameters of grommet and front housing seal. Install seal, grommet, vacuum check valve, silencer and push rod boot.

Disassembly

1. Clean exterior of caliper with denatured alcohol and place on a clean work surface. Remove brake shoe and discard copper gasket. Drain fluid from caliper. WARNING: DO NOT attempt to catch or protect piston with fingers while applying compressed air. Injury may result. Always use eye protection when performing this step.
2. Using clean shop towels to pad interior of caliper, apply just enough clean compressed air to caliper inlet so piston will ease out of bore.
3. Using a screwdriver, pry boot out of caliper. Pry piston and seal from caliper using a piece of wood or plastic. DO NOT use a metal tool as bore may be damaged requiring caliper replacement. Remove bleeder valve from caliper.

Scheme 14

1. Replace boot, piston seal, rubber bushings and sleeves each time caliper is overhauled.
2. Clean all parts in denatured alcohol. Dry parts using clean dry compressed air. Lubricated shop air will ruin rubber parts upon contact at reassembly.
3. Check mounting bolts for corrosion, breaks in plating or other damage. Replace bolts if damaged in any way. DO NOT attempt to wire brush or clean them.
4. Check outside diameter of piston for scoring, nicks, corrosion, or worn and damaged plating. If surface defects are visible, replace piston. DO NOT attempt to refinish with abrasives.
5. Check piston bore in caliper for scratches or other damage. Minor scratches or corrosion may be polished clean with crocus or emery cloth. Thoroughly clean bore after polishing. Replace caliper if corrosion is not easily cleaned.

Reassembly

1. Lubricate bore in caliper and new piston seal with clean brake fluid. Position seal in caliper bore groove. Lubricate piston with clean brake fluid. Assemble new boot into groove in piston with fold facing open end of piston.
2. Insert piston into caliper bore using care not to unseat seal. Do not force piston to bottom of bore. Position outer diameter of boot in caliper counterbore. Seat boot using dust boot installer.
3. Check boot installation to make sure retaining ring moulded into boot is not bent and that boot is installed completely below caliper face. Install brake hose, using a new copper gasket.

Note. After caliper has been overhauled and installed, it must be bled.

See DRUM BRAKE SHOE & LINING REPLACEMENT under REMOVAL & INSTALLATION.

1. Remove reservoir cover and diaphragm. Discard any brake fluid in reservoir. Depress primary piston and remove lock ring. Apply compressed air at forward brake line hole while plugging rear hole. Pistons will be forced out of bore.
2. Remove spring retainer and seals from secondary piston. Discard seals. Clamp master cylinder in vise by mounting ear and pry off reservoir.
3. Do not attempt to remove take-up valve from master cylinder as it is not serviceable. Remove reservoir grommets and discard.

Exploded View of Quick Take-Up Master Cylinder. Scheme 15

Inspection

Inspect cylinder bore for scoring or corrosion. If signs of corrosion are evident, master cylinder must be replaced. Under no circumstances should abrasive materials be used on cylinder bore.

1. Lubricate new reservoir grommets with silicone brake lube and press into master cylinder. Make sure grommets are properly seated. Lay reservoir on flat, hard surface.
2. Rock master cylinder body onto reservoir until completely seated. Lubricate new piston seals and install on secondary piston, with lip of seals towards ends of piston. Install spring retainer.
3. Install secondary piston spring and secondary piston assembly in master cylinder. Lubricate primary piston seals with clean brake fluid.
4. Install primary piston in master cylinder. Depress piston and install lock ring. Fit diaphragm in reservoir cover and install cover.

With wheel cylinder removed from vehicle, remove rubber boots from ends of cylinder. Remove piston, piston return spring, cups and bleeder screw. Inspect cylinder bore for scoring or corrosion. Replace wheel cylinder if corrosion cannot be removed with crocus cloth or if bore is scored. Rinse with brake fluid.

Exploded View of the Wheel Cylinder Assembly. Scheme 16

Install bleeder screw. Lubricate cylinder bore with brake fluid and install piston cup in 1 end of cylinder with lip toward center and install piston with flat side toward cup. Install rubber boot into end of cylinder. Install spring and expander assembly into opposite end. Install remaining cup, piston and rubber boot.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

WHEEL LUG NUT TORQUE SPECIFICATIONS

DISC & DRUM BRAKE SPECIFICATIONS

BRAKE SPECIFICATIONS

See also:
• DRUM BRAKE SHOE & LINING REPLACEMENT