Range-Rover-Maunua-Brakes.pdf

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BRAKE SYSTEM - Description

reducing valve.

A brake failure switch incorporated in the master

cylinder will illuminate a panel warning light if a

failure occurs in either the primary or secondary

hydraulic circuits.

The brake fluid reservoir is divided, the front

section (section closest to the servo) feeds the

primary circuit and the rear section feeds the

secondary circuit. Under normal operating

conditions both the primary and secondary

hydraulic circuits operate simultaneously on brake

pedal application. In the event 01 a failure in the

primary circuit the secondary circuit will still

function and operate front and rear calipers.

Alternatively, if the secondary circuit fails, the

primary circuit will still function and operate the

upper pistons in the front calipers.

If the servo should fail, both hydraulic circuits will

still function but would require greater pedal

pressure.

The hand-operated parking brake is completely

independent of the hydraulic circuits.

Brake pad wear sensors are incorporated into the

front right and rear left hand side, inboard brake

pads. The sensors will illuminate a brake pad wear

warning light in the instrument binnacle, when pad

thickness has been reduced to approximately 3mm

(0.118 in).

The brake system fitted to Range Rovers is of the

I.H. split type.

Early 1987 Range Rover vehicles were fitted during

manufacture with an Automotive Products (AP)

master cylinder and servo assembly, together with

associated brake pipes and pedal box assembly.

The brake failure warning system on the AP type

master cylinder is a Pressure Differential Warning

Actuator (P.D.W.A.) switch, which is activated when

the shuttle valve moves along its bore due to

pressure differential in either the primary or

secondary circuits caused by fluid loss or seal

failure. The result of the shuttle valve movement is

to illuminate a brake failure warning light in the

instrument binnacle.

Later 1987 models are fitted with an uprated Lucas

Girting type LSC 115 servo and 25,4mm AS/AS

master cylinder plus associated brake pipes and

pedal box assembly.

The brake failure warning system on the Lucas

Girling type is a Fluid Level Warning Indicator

(F.L.W.I.) which is incorporated into the fluid

reservoir cap and is activated when fluid loss in the

reservoir is sufficient so that the float in the switch

drops and in turn illuminates a brake failure warning

light in the instrument binnacle.

NOTE: It should be noted that the two systems

are not interchangeable on a component by

component basis but must be changed as a

complete package, ie, servo, master cylinder,

brake pipes and pedal box.

CAUTION: THOROUGHLY CLEAN ALL BRAKE

CALIPERS, PIPES AND FD-HNCS BEFORE

COMMENCING WORK ON ANY PART OF THE

BRAKE SYSTEM. FAILURE TO DO SO COULD

CAUSE FOREIGN MATTER TO ENTER THE SYSTEM

AND CAUSE DAMAGE TO SEALS, AND PISTONS

WHICH WILL SERIOUSLY IMPAIR THE BRAKE

SYSTEM EFFICIENCY.

The AP system can be found on pages :

1-19 inclusive.

The Lucas Girling system can be found on pages :

31-42 inclusive.

To ensure the brake system efficiency is not

impaired the following warnings must be

adhered to:-

BRAKE SYSTEM - (Vehicles fitted with AP servo and

master cylinder)

WARNING:

Description

DO NOT use brake fluid previously bled from

the system.

The hydraulic braking system fitted to the Range

Rover is of the dual line type, incorporating primary

and secondary hydraulic circuits.

DO NOT use old or stored brake fluid.

‘.

ENSURE that only new fluid is used and that it is

taken from a sealed container:

NOTE: References made to primary and

secondary do not imply main service brakes or

emergency brakes but denote hydraulic line

identification.

‘.

DO NOT flush the brake system with any fluid

other than the recommended brake fluid. (See

Lubricants, Fluids and Capacities Section 09).

The brake pedal is connected to a vacuum-assisted

mechanical servo which in turn operates a tandem

master cylinder. The front disc brake calipers each

house four pistons, the upper pistons are fed by

the primary hydraulic circuit, the lower pistons by

the secondary hydraulic circuit. The rear disc brake

calipers each house two pistons and these are fed

by the secondary hydraulic circuit via a pressure

The brake system should be drained and flushed

at the recommended service intervals. (See

Maintenance Section 10).

.’

‘.’

_:. ., ‘:

REVISED: JULY 87

1987 RANCE

ROVER

PRIMARY HYDRAULIC CIRCUIT

,...._ \

El SECONDARY HYDRAULIC CIRCUIT

WARNING: Some components on the vehicle,

such as gaskets and friction surfaces (brake

linings, clutch discs or automatic transmission

brake bands), may contain asbestos. Inhaling

asbestos dust is dangerous to your health and

the following essential precautions must be

observed:-

Dust found on the vehicle or produced

during work on the vehicle should be

removed by vacuuming and not by blowing.

Dust waste should be dampened, placed in

a sealed container and marked to ensure

safe disposal.

If any cutting, drilling etc., is attempted on

materials containing asbestos the item

should be dampened and only hands tools

or low speed power tools used.

Work out of doors or in a well ventilated

area and wear a protective mask.

. . . .

; .i

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‘, ’

REVISED: JULY 87

BRAKE SYSTEM LAYOUT

‘(.

RRlB45E

HOSES

1. Front left hand flexible hoses.

2. Front right hand flexible hoses.

3. Intermediate flexible hose.

7. Feed to front right hand caliper.

8. Feed to rear left hand caliper.

9. Feed to rear right hand 5aliper.

10. Feed to two way connector.

11. Feed to intermediate hose.

12. Feed to pressure reducing valve.

13. Brake failure warning switch.

PIPES

,..;

4. Feed to front left hand hose connector.

5. Feed to front right hand hose connector.

‘.

‘.’ :.:.::.

6. Feed to front left hand caliper.

..I.:

.:.

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RANGE

“*’ ROVER

._ .’

BRAKES

Bleed

The hydraulic system comprises two completely

independent sections. The rear calipers and the

lower pistons in the front calipers form the

secondary section, while the upper pistons in the

front calipers form the primary section. The

following procedure covers bleeding the complete

system, but it is permissible to bleed one section

only if disconnections are limited to that section.

: .:.::::

‘.

Bleeding will be assisted if the engine is run or a

vacuum supply is connected to the servo.

‘.’

WARNING: IF THE ENGINE IS RUNNING DURING

THE BRAKE BLEEDING PROCESS ENSURE THAT

NEUTRAL GEAR IS SELECTED AND THAT THE

PARKING BRAKE IS APPLIED.

NOTE: When bleeding the system

commence with the caliper furthest from

the master cylinder and bleed from the

screw on the same side as the fluid inlet

pipes, then close the screw and bleed from

the screw on the opposite side of the same

caliper. Tighten the bleed screws to the

correct torque. (see section 06.Torque

values).

;’ ‘.

When bleeding any part of the secondary section,

almost full brake pedal travel is available. When

bleeding the primary section only, brake pedal

travel will be restricted to approximately half.

WARNING: Before commencing to bleed the

system it is necessary to loosen off the brake

failure warning switch to prevent the shuttle

valve damaging the switch unit.

Bleeding

,’ ;’

1. Fill the fluid reservoir with the correct fluid,

see IData Section’.

1. Disconnect the leads from the switch.

2. Unscrew the switch and insert the ‘C’ washer

between the switch and master cylinder before

depressing the brake pedal.

3. After completion of bleeding, remove the ‘Cl

washer and screw in the switch and tighten to

the correct torque (see section 06-Torque

values).

‘.

.:’ ,.,

NOTE: The correct fluid level must be

maintained throughout the procedure of

bleeding

2. Connect a bleed hose to the bleed screw on

the rear caliper furthest from the master

cylinder.

‘.

3. Submerge the free end of the bleed hose in a

container of clean brake fluid.

4. Loosen the bleed screw.

5. Operate the brake pedal -fully and allow to

return.

NOTE: Allow at least five seconds to elapse

with the foot right off the pedal to ensure

that the pistons fully return before

operating the pedal again.

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ROVER ls8’

6. Repeat 5 until fluid clear of air bubbles

appears in the container, then keeping the

pedal fully depressed, tighten the bleed screw.

7. Remove the bleed hose and replace the dust

cap on the bleed screw.

13.

Connect a bleed hose to the other screw on

the front caliper furthest from the master

cylinder.

Repeat 3 to 7 for the second secondary screw

on the front caliper.

Refit the front wheel.

Repeat 9 to 15 for the front caliper nearest the

master cylinder.

Remove the ‘C’ washer and tighten the PDWA

switch to the correct torque. (see section

06-Torque values).

14.

15.

16.

17.

BRAKE PRESSURE REDUCING VALVE

Remove and refit

Removing

1. Remove all dust, grime, etc., from the vicinity

of the pressure reducing valve fluid pipe

RR1646E

unions.

2. Disconnect the outlet fluid pipe from the

pressure reducing valve. Plug the pipe and

reducing valve port to prevent the ingress of

foreign matter.

3. Remove the valve from the three-way

connector and plug both openings.

4. Withdraw the pressure reducing valve from the

engine compartment.

Repeat 1 to 7 for the other rear caliper.

Remove the front wheel on the side furthest

from the master cylinder.

Connect a bleed hose to the primary bleed

screw on the front caliper furthest from the

master cylinder.

Connect a bleed hose to the secondary bleed

screw on the same side of the caliper as the

primary screw.

Repeat 3 to 7 for the front caliper, bleeding

from the two screws simultaneously.

10.

,,..;.

11.

12.

RRlO4TE

Refitting

5. Reverse the removal instructions.

6. Bleed the brake systems.

NOTE: The pressure reducing valve is not a

serviceable item, in the event of failure or

damage, a new unit must be fitted.

Continued

REVISED: DEC. 87

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