Brake System-General Information: Other Ford Thunderbird XI

Brake System, Hydraulic

This vehicle is equipped with a brake pedal-actuated hydraulic dual brake system. The system consists of the following

1. front disc brake calipers. For additional information, refer to «DISC»(ref-220751) .
2. rear disc brake calipers. For additional information, refer to «DISC»(ref-220751) «DISC»(ref-220751) .
3. brake master cylinder. For additional information, refer to «DISC»(ref-220751) .
4. brake tubes and brake hoses

The Anti-Lock Brake System (ABS) is a four-wheel anti-lock control/traction control brake system. For additional information, refer to ANTI-LOCK CONTROL and ANTI-LOCK CONTROL-TRACTION CONTROL .

The dual ABS hydraulic system is diagonally split with the LH front and RH rear making up one circuit, and the RH front and LH rear making up the other circuit.

Master Cylinder, Dual

The brake master cylinder contains the following feature

1. a common plastic brake master cylinder reservoir and low fluid level indicator combined in one assembly.

Booster, Power Brake

The power brake booster is a vacuum-operated, dual diaphragm type and is equipped with a separately serviceable power brake booster check valve. For additional information, refer to DISC .

Brakes, Front Disc

The front disc brakes consist of the following features

1. a full-cast vented front brake disc
2. hydraulically-activated pin slider-type front disc brake caliper assemblies

Brakes, Rear Disc

The rear disc brakes consist of the following features

1. a full-cast vented rear brake disc
2. hydraulically-activated rear disc brake caliper assemblies with integral mechanically (cable) operated parking brake mechanisms

Brake System, Parking

The parking brake system consists of the following features

1. the system is cable-actuated and controlled by a hand-operated parking brake control
2. the parking brake control pulls a cable which actuates the rear disc brake calipers
3. the parking brake is self-adjusting

For additional information, refer to DISC .

Brake Tubing

If a section of the brake tubing becomes damaged, install a new section of tubing the same type, size, shape and length.

Brake Hose

Install a new flexible brake hose if it shows signs of softening, cracking or other damage.

Refer to INSTRUMENT CLUSTER for schematic and connector information.

Scheme 10

Material

MATERIAL SPECIFICATION

Brake Pads

Note. It is not required to install new brake pads if friction material properties are within guidelines. It is also not required to install new brake pads when the brake discs are machined.

1. Remove the brake pads. For additional information, refer to «DISC»(ref-220751) .
2. Inspect and measure the thickness of the brake pad friction material. Install new brake pads if the thickness of the friction material is less than 3.0 mm (0.118 inch). For additional information, refer to «DISC»(ref-220751) . Compare all four front or rear pads for uneven wear. Install new brake pads if the thickness of the friction material varies from pad to pad by more than 2.0 mm (0.079 inch). For additional information, refer to «DISC»(ref-220751) . Install new brake pads if there are missing chunks or cracks in the lining through to the backing plate. For additional information, refer to «DISC»(ref-220751) . If the friction material shows taper wear (i.e. the thickness varies by more than 3.0 mm [0.118 inch] in any direction) verify the caliper guide pins are functioning correctly. For additional information, refer to «BRAKE CALIPER GUIDE PINS»(ref-204551-S37071555852005111200000) .

Brake Discs

Note. It is generally not required to install new brake discs to address noise issues.

1. Remove the brake disc. For additional information, refer to «DISC»(ref-220751) .
2. Inspect the brake discs and measure the brake disc thickness in a minimum of 4 places around the circumference of the brake disc. Record the measurements. Install new brake discs if any thickness measurement is less than the minimum specification. For additional information, refer to «DISC»(ref-220751) . Install new brake discs if cracked. For additional information, refer to «DISC»(ref-220751) s. Machine the brake discs if the diagnosis has revealed vibration in the steering wheel, seat, or pedal while braking. Heavily scored brake discs, similar to that caused by pads worn down to the backing plate, should also be machined. In order to machine, discs must be above the minimum thickness to machine specification. For additional information, refer to «SPECIFICATIONS»(ref-204551-S07589788622005111200000) . For additional information, refer to «BRAKE DISC MACHINING»(ref-204551-S35448691402005111200000) .

Brake Caliper

Inspect brake calipers for the following

1. Brake fluid leaks. For additional information, refer to «BRAKE SYSTEM LEAK CHECK»(ref-204551-S24548444472005111200000) .
2. Boots and seals for tears or cracks
3. Caliper piston for binding and corrosion
4. Guide pins for proper operation. For additional information, refer to «BRAKE CALIPER GUIDE PINS»(ref-204551-S37071555852005111200000) .

Brake Caliper Guide Pins

The guide pins should slide with a reasonable amount of hand force. If the brake pads show taper wear or the guide pins are difficult to move, then carry out the following steps.

Note. If a guide pin kit is not available, install a new caliper assembly.

1. Disassemble the guide pins. For additional information, refer to «DISC»(ref-220751) .
2. Use a wire brush, rolled up sandpaper or emery cloth to remove all corrosion and foreign material from the caliper guide pin bores. Clean remaining debris from bores with brake parts cleaner and compressed air.
3. Install new brake pads if the lining is not within specifications. For additional information, refer to «DISC»(ref-220751) .
4. Assemble the caliper guide pins using new caliper seals, boots and guide pins. Use an ample amount of grease to lubricate the bores and guide pins.

Brake Lines & Tubes

1. Double-wall steel tubing is used throughout the brake hydraulic system. All brake tube fittings must be correctly double flared to provide strong, leakproof connections. When bending tubing to fit the underbody or rear axle contours, be careful not to kink or crack the tube.
2. If a section of brake tube is damaged, the entire section must be installed new with a tube of the same type, size, shape and length.
3. When installing the hydraulic brake tubing, hoses, or connectors, tighten all connections to specifications. After installation, bleed the brake system. For additional information, refer to «BRAKE SYSTEM BLEEDING»(ref-204551-S21106890852005111200000) .
4. The wet appearance on the outer cover of rubber brake hoses is called "sweating." This is a normal condition for neoprene rayon braid hose and is not a sign of leakage or cause to install a new hose.

Install a new flexible brake hose if the hose shows signs of softening, cracking or other damage.

When installing a new brake hose, position the hose to avoid contact with other vehicle components.

Non-Pressure Leaks

Note. The wet appearance on the outer cover of rubber brake hoses is called "sweating." This is a normal condition for neoprene rayon braid hose. The sweating condition is not evidence of a brake fluid leak and will not result in a loss of pressure in the system.

The only part of the brake system that could have a brake fluid loss that does not appear when the system is under pressure is the brake master cylinder reservoir under the following conditions

1. Missing or poorly-fitted brake master cylinder filler cap
2. Punctured or otherwise damaged brake master cylinder reservoir
3. Missing or damaged brake master cylinder filler cap gasket
4. Missing, damaged or poorly-fitted sealing grommets between the brake master cylinder and the brake master cylinder reservoir

The brake master cylinder reservoir grommets are not seviceable. They are included with a new brake master cylinder reservoir.

Brake Master Cylinder - Normal Conditions

The following conditions are considered normal and are not indications that the brake master cylinder is in need of service.

Condition 1: During normal operation of the brake master cylinder, the fluid level in the brake master cylinder reservoir will rise during brake application and fall during release. The net fluid level (such as after brake application and release) will remain unchanged.

Condition 2: A trace of brake fluid will exist on the booster shell below the master cylinder mounting flange. This results from the normal lubricating action of the master cylinder bore and seal.

Condition 3: Fluid level will decrease with pad wear.

Brake Master Cylinder - Abnormal Conditions

Changes in brake pedal feel or travel are indicators that something could be wrong in the brake system. GO to SYMPTOM CHART for abnormal condition diagnosis.

Brake Booster

Inspect the brake booster for the following

1. Excessive corrosion or damage
2. Vacuum connections for leakage
3. Vacuum hoses for kinks or leakage
4. Brake booster check valve for correct operation

Changes in the brake pedal feel or travel are indicators that something could be wrong in the brake system. GO to SYMPTOM CHART for abnormal condition diagnosis.

Parking Brake

Check the operation of the parking brake system with the vehicle on a hoist and the parking brake control fully released. Check for any damaged cables and install new components as necessary. Check the rear brake adjustment or carry out the brake system diagnosis. For additional information, refer to DISC .

1. Check the hydraulic brake system for leaks or insufficient fluid.
2. With the transmission in NEUTRAL, stop the engine and apply the parking brake control. Apply the brake pedal several times to exhaust all vacuum in the system.
3. Apply the brake pedal and hold it in the applied position. Start the engine. If the vacuum system is operating, the brake pedal will tend to move downward under constant foot pressure. If no motion is felt, the power brake booster system is not functioning. Continue the test with the following steps.
4. Remove the vacuum booster hose from the check valve connection. Manifold vacuum must be available at the check valve end of the vacuum booster hose with the engine at idle speed and the transmission in NEUTRAL. If the manifold vacuum is available to the power brake booster, connect the vacuum booster hose to the power brake booster check valve and repeat Steps 2 and 3 .
5. Check and if no downward movement of the brake pedal is felt, install a new power brake booster.
6. Operate the engine a minimum of 10 seconds at fast idle. Stop the engine, and let the vehicle stand for 10 minutes. Then apply the brake pedal with approximately 89 N (20 lbs) of force. The brake pedal feel should be the same as that noted with the engine operating. If the brake pedal feels hard (no power assist), install a new check valve and retest. If the brake pedal feels spongy, bleed the hydraulic system to remove air. For additional information, refer to «BRAKE SYSTEM BLEEDING»(ref-204551-S21106890852005111200000) .

Check Valve

The function of the power brake booster check valve is to allow manifold vacuum to enter the power brake booster and prevent the escape of vacuum in the event manifold vacuum is lost during sustained full throttle operation.

To test the function of the power brake booster check valve

1. Start and run the engine for at least 10 seconds.
2. Operate the brake pedal to check for power assist.
3. Disconnect the vacuum booster hose from the power brake booster. Do not remove the power brake booster check valve from the power brake booster.
4. There should be enough vacuum retained in the power brake booster for at least one more power assisted brake operation.

Compensator Port Check

The purpose of the compensator ports in the brake master cylinder is to supply any additional brake fluid required by the system due to brake pad wear and to allow brake fluid returning from the brake lines to the brake master cylinder to enter the brake master cylinder reservoir.

The returning brake fluid will cause a slight turbulence in the brake master cylinder reservoir. Turbulence seen in the brake master cylinder reservoir upon release of the brake pedal is normal and shows that the compensating ports are not plugged.

Scheme 11

MATERIAL SPECIFICATION CHART

Note. Read the entire operating manual and view the video shipped with the lathe before installing, operating, or repairing the lathe.

Note. If the thickness of the brake disc is less than the minimum thickness to machine specification, install a new brake disc. This will make sure that the brake disc will be above minimum thickness after machining.

Note. Do not machine new brake discs.

Note. Lateral runout and disc thickness variation measurements are not required because correct adjustment of the on-vehicle brake lathe will make sure that these dimensions are within specifications.

1. Position the brake caliper and brake caliper anchor bracket aside. For additional information, refer to «DISC»(ref-220751) .
2. For vehicles with a 2-piece brake disc and hub assembly: Mark the brake disc and the wheel stud for correct indexing during re-assembly. Remove the brake disc from the hub. CAUTION: Do not use an abrasive sanding disc since it will remove paint or other protective finishes from the wheel or metal from the mounting surfaces, adversely affecting corrosion protection and brake disc lateral runout. Remove corrosion from the wheel mounting surface, both disc mounting surfaces, and hub mounting surface. Align the match marks and install the brake disc on the hub.
3. Machine the brake disc using an on-car brake lathe. Install the hub adapter and silencer belt, if necessary. Install the cutting lathe. If the lathe is not self adjusting, adjust the lathe oscillation using a dial indicator. Total Indicated Reading (TIR) target is 0.000 mm (0.000 in), maximum is 0.08 mm (0.003 in). Center the cutting head, adjust the cutting bits, and install the chip deflector. NOTE: The depth of cut should be between 0.10 and 0.20 mm (0.004 and 0.008 in). Lighter cuts will cause the bit to heat up and wear faster. Heavier cuts will cause poor brake disc surface finish. Machine the brake disc. Remove the lathe and, if installed, the silencer belt. Remove the hub adapter.
4. Remove the metal shavings.
5. For vehicles with a 2-piece brake disc and hub assembly: Remove the brake disc from the hub. Remove metal shavings from the hub, the brake disc mounting surfaces and from the ABS sensors. Apply anti-seize lubricant to the hub mounting surface to prevent corrosion. Align the match marks and install the brake disc on the hub.
6. Install the brake caliper and brake caliper anchor bracket. For additional information, refer to «DISC»(ref-220751) .

Manual

Note. When any part of the hydraulic system has been disconnected for repair or installation of new components, air can get into the system and cause spongy brake pedal action. This requires bleeding of the hydraulic system after it has been correctly connected. The hydraulic system can be bled manually or with pressure bleeding equipment.

Scheme 12

Scheme 13

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Scheme 15

Scheme 16

1. Clean all dirt from and remove the brake master cylinder filler cap and fill the brake master cylinder reservoir with the specified brake fluid.
2. Place a box end wrench on the RH rear bleeder screw. Attach a rubber drain tube to the RH rear bleeder screw and submerge the free end of the tube in a container partially filled with clean brake fluid.
3. Have an assistant hold firm pressure on the brake pedal.
4. Loosen the RH rear bleeder screw until a stream of brake fluid comes out. While the assistant maintains pressure on the brake pedal, tighten the RH rear bleeder screw. Repeat until clear, bubble-free fluid comes out. Refill the brake master cylinder reservoir as necessary.
5. Tighten the RH rear bleeder screw.
6. Repeat steps 3 , 4 and 5 for the LH rear bleeder screw.
7. Place a box end wrench on the RH front disc brake caliper bleeder screw. Attach a rubber drain tube to the RH front disc brake caliper bleeder screw, and submerge the free end of the tube in a container partially filled with clean brake fluid.
8. Have an assistant hold firm pressure on the brake pedal.
9. Loosen the RH front disc brake caliper bleeder screw until a stream of brake fluid comes out. While the assistant maintains pressure on the brake pedal, tighten the RH front disc brake caliper bleeder screw. Repeat until clear, bubble-free fluid comes out. Refill the brake master cylinder reservoir as necessary.
10. Tighten the RH front disc brake caliper bleeder screw. For additional information, refer to «SPECIFICATIONS»(ref-204551-S07589788622005111200000) .
11. Repeat Steps 8 , 9 and 10 for the LH front disc brake caliper bleeder screw.

Pressure

Scheme 17

Scheme 18

1. Clean all dirt from and remove the brake master cylinder filler cap and fill the brake master cylinder reservoir with the specified brake fluid.
2. Install the bleeder adapter to the brake master cylinder reservoir, and attach the bleeder tank hose to the fitting on the adapter.
3. Place a box end wrench on the RH rear bleeder screw. Attach a rubber drain tube to the RH rear bleeder screw, and submerge the free end of the tube in a container partially filled with clean brake fluid.
4. Open the valve on the bleeder tank.
5. Loosen the RH rear bleeder screw. Leave open until clear, bubble-free brake fluid flows, then tighten the RH rear bleeder screw and remove the rubber hose.
6. Continue bleeding the rear of the system, going in order from the LH rear bleeder screw to the RH front disc brake caliper bleeder screw ending with the LH front disc brake caliper bleeder screw.
7. Close the bleeder tank valve. Remove the tank hose from the adapter, and remove the adapter.

BRAKE SYSTEM LEAK CHECK

1. Make sure the brake master cylinder reservoir is full.
2. Apply the brakes several times and make sure the brake pedal feel is not spongy. If necessary, bleed the system. For additional information, refer to «BRAKE SYSTEM BLEEDING»(ref-204551-S21106890852005111200000) .
3. Verify that the reservoir level is dropping.
4. If the reservoir level is dropping, inspect the brake components, fittings and lines to locate the source of the leak.