Brake System - General Information Land Rover Range Rover L322

SPECIFICATIONS

BRAKE HYDRAULIC FLUID

GENERAL SPECIFICATION

PRINCIPLE OF OPERATION

For a detailed description of the brake system, refer to the relevant Description and Operation information.

INSPECTION AND VERIFICATION

Visually examine the front and rear wheel and tire assemblies for damage such as uneven wear patterns, tread worn out or sidewall damage. Verify the tires are the same size, type and, where possible, same manufacturer. Replace the damaged wheel or excessively worn tire.

Wheels and tires must be cleared of any foreign matter and tire pressures adjusted to the correct specification.

If the tires exhibit uneven wear or feathering, the cause must be corrected. Check the steering and suspension components for damage or wear and, if necessary, check and adjust front wheel alignment.

VISUAL INSPECTION

Road Test

Carry out a road test to compare actual vehicle braking performance with the performance standards expected by the driver. The ability of the test driver to make valid comparisons and detect performance deficiencies will depend on experience.

The driver should have a thorough knowledge of brake system operation and accepted general performance guidelines to make good comparisons and detect performance concerns.

An experienced brake technician will always establish a route that will be used for all brake diagnosis road tests. The roads selected will be reasonably smooth and level. Gravel or bumpy roads are not suitable because the surface does not allow the tires to grip the road equally. Crowned roads should be avoided because of the large amount of weight shifted to the low set of wheels on this type of road. Once the route is established and consistently used, the road surface variable can be eliminated from the test results.

Before a road test, obtain a complete description of the customer concerns or suspected condition. From the description, the technician's experience will allow the technician to match possible causes with symptoms. Certain components will be tagged as possible suspects while others will be eliminated by the evidence. More importantly, the customer description can reveal unsafe conditions which should be checked or corrected before the road test. The description will also help form the basic approach to the road test by narrowing the concern to specific components, vehicle speed or conditions.

Begin the road test with a general brake performance check. Keeping the description of the concern in mind, test the brakes at different vehicle speeds using both light and heavy pedal pressure. To determine if the concern is in the front or rear braking system, use the brake pedal and then use the parking brake control. If the condition (pull, vibration, pulsation) occurs only with the parking brake, the concern is in the rear brake system.

If the concern becomes evident during this check, verify it fits the description given before the road test. If the concern is not evident, attempt to duplicate the condition using the information from the description.

If a concern exists, use the Symptom Chart in order to isolate it to a specific sub-system and condition description. From this description, a list of possible sources can be used to further narrow the cause to a specific component or condition.

SYMPTOM CHART

PINPOINT TEST A: BRAKES NOISY

PINPOINT TEST B: VIBRATION WHEN BRAKES ARE APPLIED

PINPOINT TEST C: THE BRAKES PULL OR DRIFT

PINPOINT TEST D: THE PEDAL FEELS SPONGY

PINPOINT TEST E: THE PEDAL GOES DOWN FAST

PINPOINT TEST F: THE PEDAL GOES DOWN SLOWLY

PINPOINT TEST G: EXCESSIVE BRAKE PEDAL EFFORT

PINPOINT TEST H: BRAKE LOCKUP DURING LIGHT BRAKE PEDAL FORCE

PINPOINT TEST I: BRAKES DRAG

PINPOINT TEST J: EXCESSIVE/ERRATIC BRAKE PEDAL TRAVEL

PINPOINT TEST K: SLOW OR INCOMPLETE BRAKE PEDAL RETURN

BRAKE BOOSTER

1. Check all hoses and connections. All unused vacuum connectors should be capped. Hoses and their connections should be correctly secured and in good condition with no holes and no collapsed areas. Inspect the valve on the brake booster for damage.
2. Check the hydraulic brake system for leaks or low fluid.
3. With the automatic transmission in PARK, stop the engine and apply the parking brake. Pump the brake pedal several times to exhaust all vacuum in the system. With the engine switched off and all vacuum in the system exhausted, apply the brake pedal and hold it down. 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 vacuum booster system is not functioning.
4. Remove the vacuum hose from the brake booster. Manifold vacuum should be available at the brake booster end of the hose with the engine at idle speed and the automatic transmission in PARK. Make sure that all unused vacuum outlets are correctly capped, hose connectors are correctly secured and vacuum hoses are in good condition. When it is established that manifold vacuum is available to the brake booster, connect the vacuum hose to the brake booster and repeat Step 3. If no downward movement of the brake pedal is felt, install a new brake booster.
5. Operate the engine for a minimum of 10 seconds at a fast idle. Stop the engine and allow the vehicle to stand for 10 minutes. Then, apply the brake pedal with approximately 89 N (20lb) of force. The pedal feel (brake application) should be the same as that noted with the engine running. If the brake pedal feels hard (no power assist), install a new valve and then repeat the test. If the brake pedal still feels hard, install a new brake booster. If the brake pedal movement feels spongy, bleed the brake system.

BRAKE MASTER CYLINDER

Usually, the first and strongest indicator of anything wrong in the brake system is a feeling through the brake pedal. In diagnosing the condition of the brake master cylinder, check pedal feel as evidence of a brake concern. Check for brake warning lamp illumination and the brake fluid level in the brake master cylinder reservoir.

Normal Conditions

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

1. Modern brake systems are designed to produce a pedal effort that is not as hard as in the past. Complaints of light pedal efforts should be compared to the pedal efforts of another vehicle of the same model and year.
2. The fluid level will fall with brake pad wear.

Abnormal Conditions

Changes in the brake pedal feel or brake pedal travel are indicators that something could be wrong in the brake system. The diagnostic procedure and techniques use brake pedal feel, warning indicator illumination and low brake fluid level as indicators to diagnosing brake system concerns. The following conditions are considered abnormal and indicate that the brake master cylinder is in need of repair

Note. Prior to carrying out any diagnosis, make sure the brake system warning indicator is functional.

1. Brake pedal goes down fast. This could be caused by an external or internal leak.
2. Brake pedal goes down slowly. This could be caused by an internal or external leak.
3. Brake pedal is low or feels spongy. This condition may be caused by no fluid in the brake master cylinder, reservoir cap vent holes clogged or air in the hydraulic system.
4. Brake pedal effort is excessive. This may be caused by a bind or obstruction in the pedal/linkage, a faulty non-return valve, booster or insufficient booster vacuum.
5. Rear brakes lock up during light pedal force. This may be caused by damaged brake pads, a partially applied parking brake, a damaged ABS sensor or bearing failure.
6. Brake pedal effort erratic. This condition could be caused by the brake booster or incorrectly installed brake pads.
7. Brake warning indicator is on. This may be caused by low fluid level or float assembly damaged.

NON PRESSURE LEAKS

Any reduced fluid volume in the brake master cylinder reservoir may be caused by two types of none pressure external leaks.

Type 1: An external leak may occur at the brake master cylinder reservoir cap because of incorrect positioning of the gasket and cap. Reposition cap and gasket.

Type 2: An external leak may occur at the brake master cylinder reservoir mounting seals. Repair such a leak by installing new seals and make sure that the brake master cylinder reservoir retaining bolt is correctly installed.

FRONT BRAKE DISC RUNOUT CHECK - (VEHICLES WITHOUT: HIGH PERFORMANCE BRAKES)

Note. Some variation in the illustrations may occur, but the essential information is always correct.

Note. LH illustration shown, RH is similar.

Scheme 1

Scheme 2

1. Raise the front of the vehicle.
2. Remove the road wheel.
3. Release the brake caliper and tie aside.
4. At 4 points around disc, measure disc thickness using a micrometer; renew disc if less than service limit or if variation is exceeded: Disc thickness, NEW 30 mm, Service limit = 27 mm. Thickness variation maximum = 0.01.
5. Mount a Dial Test Indicator (DTI) to and secure to inboard side of hub using caliper assembly upper bolt hole
6. Position DTI probe 5 mm in from outer edge of disc.
7. Install spacer washers under the wheel nuts. Tighten the road wheel nuts to 140 Nm (103 Ib.ft).
8. Zero DTI and rotate road wheel one complete revolution to measure disc runout. Disc runout must not exceed 0.05 mm (0.002 in).
9. If disc runout is outside limits
10. Remove the wheel hub nuts. Remove the spacers.
11. Remove Allen screw securing brake disc to drive flange.
12. Remove the brake disc.
13. Ensure mating surfaces of disc and drive flange are clean.
14. Fit disc to flange, fit Allen screw and tighten to 16 Nm (12 lbf.ft.).
15. Install spacer washers under the wheel nuts. Tighten the road wheel nuts to 140 Nm (103 Ib.ft).
16. Check disc runout as detailed above.
17. If runout is still outside limits, renew disc and/or hub.
18. Remove the wheel hub nuts. Remove the spacers.
19. Remove the DTI.
20. Install the brake caliper and tighten the bolts. TORQUE: 275 Nm
21. Install the road wheel(s) and tighten nuts to 140Nm (103 lb-ft).
22. Depress brake pedal several times to set brake pads.
23. Lower the vehicle.

FRONT BRAKE DISC RUNOUT CHECK (VEHICLES WITH: HIGH PERFORMANCE BRAKES)

Note. Some variation in the illustrations may occur, but the essential information is always correct.

Note. LH illustration shown, RH is similar.

Scheme 3

1. Raise the front of the vehicle.
2. Remove the road wheel.
3. Release the brake caliper and tie aside.
4. At 4 points around disc, measure disc thickness using a micrometer; renew disc if less than service limit or if variation is exceeded: Disc thickness, NEW 34 mm, Service limit 31 mm. Thickness variation maximum = 0.01 mm
5. Mount a Dial Test Indicator (DTI) to and secure to inboard side of hub using caliper assembly upper bolt hole
6. Position DTI probe 5 mm in from outer edge of disc.
7. Install spacer washers under the wheel nuts. Tighten the road wheel nuts to 140 Nm (103 Ib.ft).
8. Zero DTI and rotate road wheel one complete revolution to measure disc runout. Disc runout must not exceed 0.05 mm (0.002 in).
9. If disc runout is outside limits
10. Remove the wheel hub nuts. Remove the spacers.
11. Remove Allen screw securing brake disc to drive flange.
12. Remove the brake disc.
13. Ensure mating surfaces of disc and drive flange are clean.
14. Fit disc to flange, fit Allen screw and tighten to 16 Nm (12 lbf.ft.).
15. Install spacer washers under the wheel nuts. Tighten the road wheel nuts to 140 Nm (103 Ib.ft).
16. Check disc runout as detailed above.
17. If runout is still outside limits, renew disc and/or hub.
18. Remove the wheel hub nuts. Remove the spacers.
19. Remove the DTI.
20. Install the brake caliper and tighten the bolts to 275 Nm (203 lb.ft)
21. Install the road wheel(s) and tighten nuts to 140Nm (103 lb-ft).
22. Depress brake pedal several times to set brake pads.
23. Lower the vehicle.

REAR BRAKE DISC RUNOUT CHECK

Note. Some variation in the illustrations may occur, but the essential information is always correct.

Note. RH illustration shown, LH is similar.

Note. It is not necessary to carry out the parking brake shoe 'bedding-in procedure' if the rear brake discs or parking brake shoes have been removed for access to other components.

Scheme 4

Scheme 5

1. Enter the parking brake into the service mode. Turn the ignition on. Apply, and hold, the footbrake. Apply, and hold, the parking brake switch to the RELEASE position. Turn the ignition off. Release the footbrake. Release the parking brake switch.
2. Raise rear of vehicle.
3. Remove road wheel.
4. RH side rear only: Disconnect the brake pad wear indicator sensor lead.
5. Remove 2 bolts securing brake caliper to hub. Release caliper from hub and tie aside.
6. At 4 points around the disc, measure disc thickness using a micrometer; renew disc if less than service limit or if variation is exceeded: Disc thickness, NEW = 20 mm Service limit = 18 mm. Thickness variation maximum = 0.01 mm.
7. Mount a Dial Test Indicator (DTI) to and secure to inboard side of hub using caliper assembly upper bolt hole.
8. Position DTI probe 5 mm in from outer edge of disc.
9. Tighten the wheel nuts to 140 Nm (103 lb.ft). Install spacer washers under the wheel nuts.
10. Zero DTI and rotate wheel one complete revolution to measure disc runout. Disc runout must not exceed 0.09 mm (0.003 in).
11. If disc runout is outside limits
12. Remove the wheel hub nuts. Remove the spacer washers.
13. Remove Allen screw securing brake disc to drive flange.
14. Remove brake disc.
15. Ensure mating surfaces of disc and drive flange are clean.
16. Fit disc to flange, fit Allen screw and tighten to 16 Nm (12 lbf.ft).
17. Tighten the wheel nuts to 140 Nm (103 lb.ft). Install spacer washers under the wheel nuts.
18. Check disc runout as detailed above.
19. If runout is still outside limits, renew disc and/or hub.
20. Remove the wheel hub nuts. Remove the spacer washers.
21. Remove the DTI.
22. Install the brake caliper anchor bolts Tighten the bolts to 115 Nm (85 lb.ft).
23. Tighten the wheel nuts to 140 Nm (103 lb.ft).
24. Depress brake pedal several times to set brake pads.
25. Remove stands and lower vehicle.

BRAKE SYSTEM BLEEDING (VEHICLES WITH: HIGH PERFORMANCE BRAKES)

Note. Bleeding of the complete brake system must be carried out using Land Rover approved diagnostic equipment. Where only the primary or secondary brake circuits have been disturbed in isolation, it should only be necessary to bleed that circuit. Partial bleeding of the hydraulic system is only permissible if a brake tube or hose has been disconnected with only minimal loss of fluid.

Note. Some variation in the illustrations may occur, but the essential information is always correct.

Scheme 6

Scheme 7

Scheme 8

Scheme 9

1. Raise and support the vehicle.
2. Check that the brake fluid lines are secure and that there are no signs of a brake fluid leak. If a brake fluid leak is detected, investigate and rectify the cause of the leak before bleeding the brakes.
3. Fill the brake fluid reservoir to the MAX mark. Disconnect the brake fluid reservoir electrical connector. Remove the brake fluid reservoir cap.
4. Conduct the bleed procedure with the engine running.
5. Connect the diagnostic tool to the vehicle, select diagnostic and proceed as directed for bleeding the brake system.
6. Starting at the brake caliper furthest away from the brake master cylinder, loosen the bleed screw by one-half to three-quarters of a turn.
7. Install the bleed tube to the brake caliper bleed screw and immerse the free end of the bleed tube in a bleed jar containing a small quantity of approved brake fluid. Hold the bleed container at least 300 mm above the Caliper that is being bled.
8. With assistance, depress the brake pedal steadily through to 2/3 of its full stroke.
9. With the brake pedal held down, close bleed screw and then return the brake pedal to 1/3 of its full stroke and hold.
10. Repeat steps 8 and 9, 28 times for the rear brake and 10 times for the front brake.
11. At the end of the bleed process, depress and hold the brake pedal down.
12. With the brake pedal fully depressed, tighten the bleed screw. Tighten the front caliper bleed screws to 19 Nm (14 lb.ft). Tighten the rear caliper bleed screws to 10 Nm (7 lb.ft).
13. Fill the brake fluid reservoir to the MAX mark.
14. Repeat the brake bleeding procedure for each front brake caliper, following the above sequence. If access is restricted to the front caliper outer bleed screws, rotate the road wheels to gain access. Tighten the bleed screws to 19 Nm (14 lb.ft).
15. Fill the brake fluid reservoir to the MAX mark.
16. Apply the brakes and check for leaks.
17. Install the brake fluid reservoir cap. Connect the brake fluid reservoir electrical connector.
18. On completion, road test the vehicle and check the brake pedal operation. The pedal travel should be short with a firm feel.

BRAKE SYSTEM BLEEDING

Note. Bleeding of the complete brake system must be carried out using Land Rover approved diagnostic equipment. Where only the primary or secondary brake circuits have been disturbed in isolation, it should only be necessary to bleed that circuit. Partial bleeding of the hydraulic system is only permissible if a brake tube or hose has been disconnected with only minimal loss of fluid.

Note. Some variation in the illustrations may occur, but the essential information is always correct.

1. Raise and support the vehicle.
2. Check that the brake fluid lines are secure and that there are no signs of a brake fluid leak. If a brake fluid leak is detected, investigate and rectify the cause of the leak before bleeding the brakes.
3. Fill the brake fluid reservoir to the MAX mark. Disconnect the brake fluid reservoir electrical connector. Remove the brake fluid reservoir cap.
4. Conduct the bleed procedure with the engine running.
5. Connect the diagnostic tool to the vehicle, select diagnostic and proceed as directed for bleeding the brake system.
6. Starting at the brake caliper furthest away from the brake master cylinder, loosen the bleed screw by one-half to three-quarters of a turn.
7. Install the bleed tube to the brake caliper bleed screw and immerse the free end of the bleed tube in a bleed jar containing a small quantity of approved brake fluid. Hold the bleed container at least 300 mm above the Caliper that is being bled.
8. With assistance, depress the brake pedal steadily through to 2/3 of its full stroke.
9. With the brake pedal held down, close bleed screw and then return the brake pedal to 1/3 of its full stroke and hold.
10. Repeat steps 8 and 9, 28 times for the rear brake and 10 times for the front brake.
11. At the end of the bleed process, depress and hold the brake pedal down.
12. With the brake pedal fully depressed, tighten the bleed screw to 10 Nm (7 lb.ft).
13. Fill the brake fluid reservoir to the MAX mark.
14. Repeat the brake bleeding procedure for each brake caliper, following the above sequence.
15. Fill the brake fluid reservoir to the MAX mark.
16. Apply the brakes and check for leaks.
17. Install the brake fluid reservoir cap. Connect the brake fluid reservoir electrical connector.
18. On completion, road test the vehicle and check the brake pedal operation. The pedal travel should be short with a firm feel.

BRAKE SYSTEM PRESSURE BLEEDING

Note. Some variation in the illustrations may occur, but the essential information is always correct.

All vehicles

Scheme 10

1. Raise and support the vehicle.
2. Check that the brake fluid lines are secure and that there are no signs of a brake fluid leak. If a brake fluid leak is detected, investigate and rectify the cause of the leak before bleeding the brakes.
3. Fill the brake fluid reservoir to the MAX mark. Disconnect the brake fluid reservoir electrical connector. Remove the brake fluid reservoir cap.
4. Conduct the bleed procedure with the engine running.
5. Starting at the brake caliper furthest away from the brake master cylinder, loosen the bleed screw by one-half to three-quarters of a turn.
6. Install the bleed tube to the brake caliper bleed screw and immerse the free end of the bleed tube in a bleed jar containing a small quantity of approved brake fluid. Hold the bleed container at least 300 mm above the Caliper that is being bled.
7. With assistance, depress the brake pedal steadily through to 2/3 of its full stroke.
8. With the brake pedal held down, close bleed screw and then return the brake pedal to 1/3 of its full stroke and hold.
9. Repeat steps 7 and 8, 28 times for the rear brake and 10 times for the front brake.
10. At the end of the bleed process, depress and hold the brake pedal down.
11. With the brake pedal fully depressed, tighten the bleed screw. On vehicles with high performance brakes, tighten the front caliper bleed screw to 19 Nm (14 lb.ft). On vehicles with standard brakes, tighten the front caliper bleed screw to 10 Nm (7 lb.ft). Tighten the rear caliper bleed screws to 10 Nm (7 lb.ft).
12. Fill the brake fluid reservoir to the MAX mark.
13. Repeat the brake bleeding procedure for each brake caliper, following the above sequence.

Vehicles with supercharger

1. Repeat the brake bleeding procedure for each front brake caliper, following the above sequence. If access is restricted to the front caliper outer bleed screws, rotate the road wheels to gain access. Tighten the bleed screws to 19 Nm (14 lb.ft).

All vehicles

1. Fill the brake fluid reservoir to the MAX mark.
2. Apply the brakes and check for leaks.
3. Install the brake fluid reservoir cap. Connect the brake fluid reservoir electrical connector.
4. On completion, road test the vehicle and check the brake pedal operation. The pedal travel should be short with a firm feel.

COMPONENT BLEEDING (VEHICLES WITH: HIGH PERFORMANCE BRAKES)

Note. Bleeding of the complete brake system must be carried out using Land Rover approved diagnostic equipment. The following manual procedure covers bleeding the brake system for components down stream of the HCU, where only the primary or secondary brake circuits have been disturbed in isolation. Partial bleeding of the hydraulic system is only permissible if a brake tube or hose has been disconnected with only minimal loss of fluid.

Note. Some variation in the illustrations may occur, but the essential information is always correct.

1. Raise and support the vehicle.
2. Check that the brake fluid lines are secure and that there are no signs of a brake fluid leak. If a brake fluid leak is detected, investigate and rectify the cause of the leak before bleeding the brakes.
3. Conduct the bleed procedure with the engine running.
4. Disconnect the brake fluid reservoir electrical connector. Remove the brake fluid reservoir cap. Fill the brake fluid reservoir to the MAX mark.
5. Install the bleed tube to the brake caliper bleed screw and immerse the free end of the bleed tube in a bleed jar containing a small quantity of approved brake fluid. Hold the bleed container at least 300 mm above the Caliper that is being bled.
6. If access is restricted to the front caliper outer bleed screws, rotate the road wheels to gain access. Loosen the bleed screw by one-half to three-quarters of a turn.
7. With assistance, depress the brake pedal steadily through to 2/3 of its full stroke.
8. With the brake pedal held down, close bleed screw and then return the brake pedal to 1/3 of its full stroke and hold.
9. Repeat steps 7 and 8, 28 times for the rear brake and 10 times for the front brake.
10. At the end of the bleed process, depress and hold the brake pedal down.
11. With the brake pedal fully depressed, tighten the bleed screw. Tighten the front caliper bleed screws to 19 Nm (14 lb.ft). Tighten the rear caliper bleed screws to 10 Nm (7 lb.ft).
12. Fill the brake fluid reservoir to the MAX mark.
13. Apply the brakes and check for leaks.
14. Install the brake fluid reservoir cap. Connect the brake fluid reservoir electrical connector.
15. On completion, road test the vehicle and check the brake pedal operation. The pedal travel should be short with a firm feel.

COMPONENT BLEEDING

Note. Bleeding of the complete brake system must be carried out using Land Rover approved diagnostic equipment. The following manual procedure covers bleeding the brake system for components down stream of the HCU, where only the primary or secondary brake circuits have been disturbed in isolation. Partial bleeding of the hydraulic system is only permissible if a brake tube or hose has been disconnected with only minimal loss of fluid.

Note. Some variation in the illustrations may occur, but the essential information is always correct.

1. Raise and support the vehicle.
2. Check that the brake fluid lines are secure and that there are no signs of a brake fluid leak. If a brake fluid leak is detected, investigate and rectify the cause of the leak before bleeding the brakes.
3. Pump the brake pedal until the brake vacuum assistance is exhausted.
4. Remove the brake fluid reservoir cap. Disconnect the brake fluid reservoir electrical connector. Fill the brake fluid reservoir to the MAX mark.
5. Install the bleed tube to the brake caliper bleed screw and immerse the free end of the bleed tube in a bleed jar containing a small quantity of approved brake fluid. Hold the bleed container at least 300 mm above the Caliper that is being bled.
6. Loosen the bleed screw by one-half turn to three-quarters of a turn.
7. With assistance, depress the brake pedal steadily through to 2/3 of its full stroke.
8. With the brake pedal held down, close bleed screw and then return the brake pedal to 1/3 of its full stroke and hold.
9. Repeat steps 7 and 8, 28 times for the rear brake and 10 times for the front brake.
10. At the end of the bleed process, depress and hold the brake pedal down.
11. With the brake pedal fully depressed, tighten the bleed screw. On vehicles with high performance brakes, tighten the front caliper bleed screw to 19 Nm (14 lb.ft). On vehicles with standard brakes, tighten the front caliper bleed screw to 10 Nm (7 lb.ft). Tighten the rear caliper bleed screws to 10 Nm (7 lb.ft).
12. Fill the brake fluid reservoir to the MAX mark.
13. Apply the brakes and check for leaks.
14. Install the brake fluid reservoir cap. Connect the brake fluid reservoir electrical connector.
15. On completion, road test the vehicle and check the brake pedal operation. The pedal travel should be short with a firm feel.

See also:
• Pinpoint Test A
• Pinpoint Test B
• Pinpoint Test C
• Pinpoint Test D
• Pinpoint Test E
• Pinpoint Test F
• Pinpoint Test G
• Pinpoint Test H
• Pinpoint Test I
• Pinpoint Test J
• Pinpoint Test K