Nissan PULSAR N13 Series / ASTRA LD Series. Instruction — part 43

Brakes

173

Inspect the handbrake cable for chafing or fraying.

(4) Seized handbrake cables: Renew the hand-

brake cables.

NOTE: Raise the vehicle and spin the
wheels one at a time to check for binding. If
the wheels are not binding, have an assistant
apply and release the brakes. Check if the
brakes release immediately. A clogged mas-
ter cylinder port will cause binding on the
two wheels fed by that particular circuit
from the master cylinder. Open the bleeder
valve on one of the offending wheels to check
if pressure build up is the cause of the
binding. A seized handbrake cable will usu-
ally cause binding on a rear wheel. Discon-
nect the handbrake cable and check if the
wheel will then turn freely.

LOW SPONGY BRAKE PEDAL

(1) Incorrectly adjusted brake shoes: Check and

adjust the brake shoes.

(2) Insufficient fluid in the system: Check for

leaks, replenish the fluid to the specified level and
bleed the hydraulic system.

(3) Air in the brake hydraulic system: Bleed the

hydraulic system.

(4) Master cylinder faulty: Repair or renew as

necessary.

NOTE: A spongy brake pedal in most cases
is caused by air in the hydraulic system. For
air to enter the system one or more of the
sealing rubbers or brake lines must be
sucking in air. Always rectify the cause of
the trouble before bleeding the hydraulic
system. Faulty components usually show up
as fluid leakage.

BRAKES LOCK ON APPLICATION

(1) Gummy linings or brake pads due to oil or

fluid contamination: Renew the linings or brake pads
and rectify the source of contamination.

(2) Scored or eccentric brake drum or warped

disc: Check and machine or renew the drum or disc as
necessary.

(3) Incorrect or distorted linings or disc pads:

Check and renew as necessary.

(4) Brake servo unit faulty: Repair or renew the

brake servo unit.

(5) Broken or stretched brake shoe return

springs: Check and renew the faulty brake springs.

(6) Faulty brake pressure proportioning valve:

Renew the brake pressure proportioning valve.

NOTE: If this condition arises, remove all
the wheels and check the condition of the
friction material for oil contamination and
excessive wear. Check the shoe return
springs for stretching by comparing their
free length with new springs. An eccentric-
brake drum or warped disc will be indicated
by pulsating of the brake pedal when the
brakes are lightly applied.

BRAKE PEDAL PULSATES

(1) Eccentric brake drums or warped disc: Check

and machine or renew the drum or disc as required.

(2) Loose or worn hub bearings: Renew the hub

bearings as necessary.

NOTE: Brake drums or discs that are run-
ning out must be machined. This job is best
entrusted to a brake specialist who will also
be able to determine if a new disc or drum
needs to be installed.

BRAKE FADE

(1) Incorrect shoe adjustment: Check and adjust

the shoe to drum clearance.

(2) Eccentric brake drum: Check and machine or

renew the brake drum.

Check the brake hoses for deterioration, chafing and

leaks.

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Brakes

(3) Linings saturated with hydraulic fluid: Re-

new the linings in sets.

(4) Incorrect linings installed: Check and install

the recommended linings in sets.

NOTE: In most cases brake fade is caused
by overuse of the footbrake, which in turn
causes a build up of heat at the friction
material and drums or disc. Once this
excessive build up of heat is allowed to
dissipate the brakes should again function
normally.

BRAKES OVERHEAT

(1) Incorrect shoe adjustment: Check and adjust

the shoe to drum clearance.

(2) Broken shoe return springs: Renew any

faulty springs.

(3) Faulty handbrake cables or incorrect adjust-

ment: Check and renew or adjust the cables.

(4) Frozen wheel cylinder or caliper pistons:

Overhaul the cylinders or calipers.

(5) Obstructed or damaged hydraulic hose or

line: Remove the obstruction or renew the hydraulic
hose or line.

(6) Obstructed master cylinder compensating

port: Clean the compensating port.

(7) Blocked vent in the master cylinder reservoir

cap; Check and remove the obstruction in the vent.

(8) Overuse of footbrake: Revise driving habits.

NOTE: To check for brake binding raise the
vehicle and spin each wheel in turn by hand.
If it is found that one wheel cylinder or
caliper piston is sticking it is advisable to
overhaul all the wheel cylinders and calipers.

BRAKE FAILURE

(1) Faulty master cylinder: Remove and over-

haul the master cylinder.

(2) Loss of fluid due to a leaking wheel cylinder:

Overhaul or renew the wheel cylinders and bleed the
hydraulic system.

(3) Loss of fluid due to a leaking caliper: Over-

haul or renew the caliper assemblies and bleed the
hydraulic system.

(4) Loss of fluid due to a fractured pipe or faulty

union: Renew the faulty components as necessary and
bleed the hydraulic system.

(5) Air in the hydraulic system: Locate the

source of the air leak, rectify the problem and bleed
the hydraulic system.

(6) Water in the hydraulic fluid: Drain, flush,

refill and bleed the hydraulic system.

NOTE: To locate the source of a fluid leak,
fill the master cylinder reservoir with fluid
and check for obvious signs of external
leakage while an assistant pumps the brake
pedal.

Check the brake pipe unions for leaks.

BRAKE NOISE

(1) Brakes squeal on application: Glazed friction

material or missing or damaged disc pad anti-squeal
shims.

(2) Grinding noise on application: Friction ma-

terial worn out. Check the friction material and
discs/drums. Renew the brake pads/shoes and ma-
chine or renew the brake discs/drums as necessary.

Inspect the brake discs for scoring and wear.

2. DESCRIPTION

The brakes are operated by hydraulic pressure in

two independent circuits by means of a tandem dual
circuit master cylinder coupled to a brake servo unit
mounted on the bulkhead between the brake pedal
and master cylinder.

The brake circuits are split diagonally. The left

hand front and right hand rear brakes are connected
to the primary circuit, and the right hand front and
left hand rear brakes are connected to the secondary
circuit. Should a malfunction occur in one circuit, the
remaining circuit is capable of stopping the vehicle.

Brakes

175

A pressure proportioning valve is incorporated in

each circuit to prevent premature locking of the rear
wheels during severe braking.

The four wheel hydraulically operated brakes

utilize disc brakes on each front wheel and disc brakes
or leading and trailing drum brake shoes on each rear
wheel.

The front disc brakes comprise a disc attached to

the hub assembly and a caliper bolted to the steering
knuckle.

The rear disc brakes comprise a disc and hub

assembly attached to the rear stub axle and a caliper
and anchor plate bolted to the backing plate.

The front and rear calipers are of the sliding type.

As pad wear takes place, the caliper piston is allowed
to slide outwards through the seal to take up a new
position in the caliper bore. Elastic deformation of the
seal takes place when the brakes are applied, which
returns the piston slightly when the brakes are re-
leased. Thus a constant clearance is maintained
between the pads and the disc when the brakes are in
the off position.

The disc brakes do not require periodical adjust-

ment in service to compensate for pad wear as they
are self adjusting.

The leading and trailing shoe drum brakes on the

rear wheels use a double ended wheel cylinder to
operate both brake shoes at the top. The lower end of
each brake shoe abuts a fixed anchor point. The brake
shoes are automatically adjusted when the brakes are
operated.

The handbrake operates the rear brakes via a

cable arrangement.

3. MASTER CYLINDER

Special Equipment Required:

To Install New Seals — Suitable machined drift

TO REMOVE

(1) Depress the brake pedal several times to

deplete the vacuum from the system.

(2) Raise the bonnet and install covers to

both
the front mudguards. Cover the areas of paintwork
beneath the master cylinder with absorbent cloth.

(3) Disconnect the wiring from the pressure

sensing switch.

(4) Disconnect the brake pipes from the master

cylinder and plug the outlets and pipes to prevent the
loss of fluid and the ingress of dirt.

(5) Remove the nuts retaining the master cylin-

der to the brake servo unit and remove the master
cylinder from the vehicle.

TO DISMANTLE

(1) Remove the master cylinder as previously

described.

(2) Remove the reservoir cap and diaphragm,

drain and discard the brake fluid from the reservoir.

(3) Carefully remove the reservoir from the

master cylinder by pulling it from the reservoir
retainers by hand. Remove and discard the retainers
from the master cylinder.

(4) Using internal snap ring pliers, remove the

snap ring from the primary reservoir port.

(5) Remove the fast fill valve assembly and the

O ring from the port. Remove and discard the valve
washer from the fast fill valve.

(6) Remove the proportioning valve plugs and

the O rings. Discard the O rings. Withdraw the springs
and valve plungers from the master cylinder. Remove
and discard the seals from the valve plungers.

(7) Remove the pressure sensing switch and

lever assembly from the master cylinder.

{8) Remove the cylinder end plug from the

master cylinder. Remove and discard the O ring from
the plug.

(9) Carefully tap the front of the master cylinder

vertically on a block of wood and remove the pressure
differential pistons from the master cylinder. Remove
and discard the O rings from the pistons.

(10) Push the primary piston forward in the

cylinder with a blunt rod and while holding the
pressure, remove the stop pin from the master cylin-
der.

(11) The primary piston may now be withdrawn

from the cylinder bore. The secondary piston, retainer
and spring can also be withdrawn by carefully tapping
the master cylinder on a block of wood.

(12) Prise the legs of the seal retainer upwards

and remove it from the primary piston. Remove the
seal and guide. Discard the seal and retainer.

NOTE: The secondary piston must no! be
dismantled by removing the screw. This
assembly has a factory preset length and the
screw must not be altered in service.

(13) Remove the main seal and the guide from

the front of the secondary piston. Stretch the rear seal
from the groove and remove it from the piston. Take

Installed view of the master cylinder and servo unit. Air

duct removed for clarity. 1.8 liter model.

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Brakes

care not to damage the piston surfaces where the inner
diameter of the piston seals locate.

(14) Remove the garter springs, back up rings,

seals and the retainer from the master cylinder, noting
the installed direction of the seals to aid assembly.

NOTE: It is important that care is taken not
to damage the bore surface or the seal
surfaces during removal of these parts. Note
the order and direction during removal,

(15) Remove the external O ring from the master

cylinder body.

TO CLEAN AND INSPECT

(1) Wash all components thoroughly in methyl-

ated spirits. Do not use petrol, kerosene or other
cleaning solvents.

(2) Check the master cylinder bore for wear,

scoring or pitting.

NOTE: Do not hone the master cylinder
bore. If the bore is pitted or worn, renew the
master cylinder as an assembly.

(3) Ensure that all the inlet and compensating

ports between the reservoir and the cylinder bore are
free of any obstructions.

(4) Discard all rubber parts and if applicable, the

piston assemblies.

NOTE: Where possible use a genuine major
repair kit which contains pre-assembled rub-
ber seals and pistons when overhauling a
master cylinder. The use of a major kit will
ensure a thorough overhaul and long service
from the unit.

TO ASSEMBLE

(1) Liberally coat the cylinder bore and all

internal parts with clean brake fluid.

NOTE: Install all parts supplied with the
repair kit.

(2) Install the seal retainer in the mouth of

the
master cylinder, small diameter first.

(3) Install the seal, in the direction rioted

on
removal, against the seal retainer, followed by the first
back up ring, large diameter first.

(4) Install the garter spring against the back up

ring. Insert a machined drift into the bore and lightly
push the garter spring into its locating groove.

(5) Install the remaining seal, in the

direction
noted on removal, against the garter spring already

PRIMARY PISTON SEAL

BACK UP RING

Dismantled view of the master cylinder.