Page 433
= eS
GENERAL
The car has disc brakes in front and drum brakes at rear,
The hydraulic footbrake acts on all four wheels. The
brake system is of the two-circuit type, which means
that the master cylinder controls the left front and right
rear wheels simultaneously with, but independently of,
the right front and left rear wheels, Consequently, if leak-
age occurs as a result of damage to the brake system,
braking effect will be lost only on one diagonal pair of
wheels, while remaining for the other pair. Leakage is re-
vealed both by excessive pedal travel and by a tendency
for the car to swerve towards the side at which brake
pressure remains on the front wheel when the brakes are
applied.
BRAKE SYSTEM, MODEL 1967 AND 1968
. Master cylinder with brake fluid container
. Hand brake lever
. Brake pedal
Wheel cylinders
Stop light contact
. Brake warning contact
. Adjustment screw, rear wheel brake
NOODON=
BRAKE SYSTEM, AS FROM MODEL 1969
7. Stoplight contact
8, Brake warning contact
9. Moving, piece, brake
3. Filter, vacuum servo warning contact
4, Handbrake lever 10. Adjusting screw, rear
5. Brake pedal brake
6. Wheel cylinders
1. Master cylinder with
brake fluid container
2. Vacuum servo
Febr 1977
The mechanical handbrake acts on the rear wheels. The
brake lever is located between the two front seats and the
braking effect is transmitted to the rear wheels by two
sealed Bowden cables. .
The footbrake system as from model 1969 is hydraulic
with vacuum servo. The vacuum servo cylinder is con-
nected to the suction line of the engine. When the brake
pedal is depressed, the vacuum servo cylinder is affected,
which in turn strengthens the pedal power and transmits
the movement to the master cylinder.
The car has a brake warning system which consists of a
mechanical contact above the brake pedal and a warning
light, located in the speedometer. The light begins to
glow when the brake pedal travel becomes too long, e.g.
at a leak in the brake system.
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Page 434
FUNCTION
When the brake pedal is depressed, the master cylinder
pistons apply a force to the brake fluid, which is trans-
mitted through brake pipes and hoses to the pistons of
the brake cylinders, causing the brake pads to contact
the brake dise and the brake linings the drums. The mas-
ter cylinder has two pistons which work simultaneously,
but independently, so that one acts on the left front and
right rear wheels while the other acts on the right front
and left rear wheels. Consequently, if leakage occurs in
one Circuit, the piston in the damaged circuit moves with-
out affecting the brake pads.
Every application of the brakes thus pumps a certain
amount of brake fluid out of the system, but as the upper
part of the brake cylinder forms two chambers separated
by a partition, the system can only be emptied as far as
the partition. The brake fluid remaining for the undam-
aged circuit is sufficient to allow the car to be driven safe-
ly to a garage to have the damage repaired. Since the two-
circuit brakes operate on the diagonal wheels, always
approx. half the braking effect remains at leakage in one
circuit. Furthermore, this affords greater safety when
steering the car, as one front wheel and one rear wheel
roll freely at the same time and are not locked.
MASTER CYLINDER
LHD up to and incl model 1970, RHD up to and incl
chassis No. 96722017570 and 95722006474.
The tandem master cylinder comprises a body housing, a
primary piston and a secondary piston, which are ac-
tuated by the push-rod from the brake pedal. The distance
between the pistons is Geterm f
a wire clamp. The secondary pis
and a secondary cup at front an
behind the primary cup 's¢ als ie et
prevents the cup from being extruded sor he feed -
in the piston flange. The primary cup of the primary prs-
ton also has a dished piston washer and a secondary, rear
a ®
hed piston washer, which
cup.
he spiral springs return the pistons to
in their initial position, the pistons ere retained by the
spring pressure and as a consequence the chemeins open
between the fluid container and the master cylinder.
When the brake pedal is depressed, the push-rod actuates
the primary piston, making the inlet channel between
fluid container and cylinder close, and the pressure in
front of the primary piston rise which in turn affects the
secondary piston making it move and in this way the
same overpressure is obtained in front of both pistons.
Now brake fluid is forced out through the brake lines to
the wheel cylinders and puts the brakes into action.
If a leakage occurs in the brake circuit served by the pri-
mary piston, the spring is compressed until the primary
piston contacts the secondary piston. Then the latter can
work normally.
At a leakage in the secondary piston circuit, the secon-
dary piston is pressed forward by the primary piston and
the spring, until the secondary piston strikes the bottom
of the cylinder. Then, brake fluid can be pressed out into
the undamaged circuit.
the initial position.
LHD as from model 1971, RHD as from chassis No.
96722017571 and 95722006474.
The pistons are equipped with three seals on each, and
the distance between the pistons is determined bya
spiral spring and a screw.
Nit ar
MASTER CYLINDER, SECTIONED, UP TO AND INCL. MODEL 1968
500—2
March 1979
Page 435
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MASTER CYLINDER, SECTIONED, LHD MODEL 1969-1970,
RHD MODEL 1969 - CH. No, 96722017570, 95722006474
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MASTER CYLINDER LHD AS FROM MODEL 1971
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March 1979
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500—3
Page 436
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$7076
MASTERCYLINDER , AS FROM CHASSIS NO.
96722017571 AND 95722006475 RHD
FRONT WHEEL BRAKE
The front wheels are equipped with disc brakes with only
one cylinder.
The principal parts of this brake are the support bracket,
brake body assembly, cylinder body and friction pad as-
semblies.
The support bracket, which is bolted to the steering
knuckle housing, keeps the brake in place and transmits
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S$ 1060
FRONT AXLE ASSEMBLY WITH DISC BRAKE
3. Brake housing
1. Brake disc
4. Brake pads
2. Whee! hub
the braking forces to the knuckle housing.
The brake body assembly is fitted to the support bracket
by means of a hinge pin and a friction unit. It is thus mov-
able in relation to the support bracket, the torsional cen-
tre being provided by the hinge pin.
The brake cylinder has an outer wiper seal, which pre-
vents the entry of dust, and an inner fluid seal.
The friction pad assemblies consist of frictional material
which is glued to a pressure plate. The friction pads are
wedge-shaped in order to compensate for the irregular
wear which occurs on account of the movement taking
place around the hinge pin. The outer friction pad is
mounted in the brake body assembly whereas the inner
pad rests against the brake piston and is held in position
by the support bracket and the brake body assembly.
The hydraulic pressure is built up in the master cylinder
and is transmitted to the brake cylinder. The pressure ac-
tuates the brake piston, causing this to move outwards
and press the friction pad against the brake disc. The mov-
able brake unit is then influenced, so that the outer fric-
tion pad is also pressed against the brake disc,
When the piston is being pressed outwards in the cylinder,
@ certain resilience occurs in the piston seal which sur-
rounds the piston. This springiness is sufficient to pull
the piston back when the hydraulic pressure decreases,
thus providing a clearance between the friction pad and
the disc. The outer friction pad is moved back on account
of the movement of the brake body assembly in relation
to the support bracket. Wear on the brake linings is com-
pensated for automatically, as the brake piston moves
outwards by means of the seal.
March 1979
Page 437
Braking position
THE BRAKE PISTON IS RETURNED TO REST BY THE
ACTION OF THE PISTON SEAL
The effect of this combination of the simple brake cylin-
der and the movable brake unit is that both friction pads
are pressed together with a torsional movement which
tends to give irregular wear on the friction pads. This
wear is made up for by the fact that the pads are wedge-
shaped. As the friction pads get worn, the brake body as-
sembly turns around the hinge pin, thus causing the angle
of wear to be continuously changed. When the linings
have become so worn as to necessitate changing the fric-
tion pads, the angle has become so small that the lining
is practically parallel with the pressure plate.
RS
Bera
SSS
NEW AND WORN PADS
1. New pads
2. Worn pads
March 1979
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REAR WHEEL BRAKES AND HANDBRAKE
The rear wheel brakes have one wheel cylinder mounted
in the backplate. The cylinder is fitted with two pistons,
each of which acts on one brake shoe. The brake shoes
are manually adjustable.
The braking movement is transmitted by sealed Bowden
cables to levers for the rear wheel brake shoes.
S$ 712
REAR WHEEL BRAKE
1. Adjustment
2. Spring
3. Handbrake link
500—5
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vention
Page 438
SERVO UNIT
pedai. The cylinder is connected to
ifolc by means of a hose. The func-
Me System can be seen from the description be-
¥Vecuum cylinder which is ac-
The vacuum servo shall not be disassembled.
Initial position
When “off”, the return spring holds the valve piston and
the push-rod in the right hand end position in the guide
housing. In this position, the atmospheric air channel is
kept closed and the vacuum channel open.
The vacuum is equal on both sides of the diaphragm.
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37089
SERVO UNIT, INITIAL POSITION
Brake position
When pressing the brake pedal, the valve piston 's moved
to the left, the vacuum channel is closed and air of atmo-
spheric pressure flowes in on the right hand side of the
cal “=
membrane.
As vacuum prevails on the L.H. i of the diaphragm and
atmospheric pressure on the R.H. side an increased force
is obtained on the cylinder. The brake action can be in-
creased further by larger pressure on the pedal. Once the
pedal pressure ceases, the return spring forces the valve
piston back. The vacuum channel opens, and the atmo-
spheric air channel closes. The vacuum servo returns to
its “off” position.
pal ah occur in the power brake unit, the brake
system of the car will function without servo effect. The
servo cylinder will in that case serve only as a lengthened
push-rod. In the latter case is, of course, a larger pedal
pressure required.
$7090
SERVO UNIT, BRAKE POSITION
Febr 1977
J
Page 439
BRAKE SHOES
REMOVAL OF BRAKE DRUM FOR INSPECTION OF
BRAKE LINING, REAR WHEEL
Remove the cotter pin and the shaft nut.
Jack up the car.
Remove the wheel.
Release the handbrake and adjust the rear brake shoes
with the adjusting screw.
5, Remove the brake drum, using puller 78 40 028.
Pops
WHEEL PULLER 78 40 028
Febr 1977
6. Examine the linings on all
. An exchange system is operative for complet
shoes. If they are worn to
a thickness of 0.1 in. (2.5 mm), OF unevenly worn, OF
covered with grease, new linings must be fitted. On
rear linings. It may then be sufficient to change the
two rear linings only.
e brake
shoes with fitted automatic adjustment device. Re-
placement of linings thus calls for exchange of the
entire brake shoe.
If linings only are replaced, they must be ground ina
special machine to a radius of about 0.010—0.012 in.
(0.25—0.30 mm) less than that of the drum in order
to ensure perfect contact. The ends of the linings must
not be chamfered; the edge should be left as sharp as
possible.
NOTE
Never fit new brake linings on one side only.
INSPECTION HOLE IN BRAKE DRUM
1. Inspection hole
511-1
Page 440
DISASSEMBLY
1. Use a piece of wire or a Clamp to keep the brake pis-
tons in the cylinder while carrying out this operation,
2. Remove the springs which hold the brake shoes against
the backplate.
REAR WHEEL BRAKES
1. Adjustment
2. Spring
3. Handbrake link
3. Lift the brake shoes off from the wheel cylinder and
handbrake levers, first at the top and then at the bot-
tom end.
REASSEMBLY
1. Hook on the springs between the shoes.
2. Locate the front shoe with the handbrake lever in the
oblong hole.
511-2
S714
FITTING THE HANDBRAKE LEVER
3. Lift the rear shoe with the handbrake lever into the
large hole, Make sure that the spring presses against
the lever as shown in the fig.
4. Remove the wire or clamp used to keep the brake pis-
tons in position,
5. Adjust the shoes to a position concentric with the
backplate. Refit the springs holding the shoes against
the backplate.
6. Refit the wheel hub and the wheel.
7. Adjust the brake shoes.
WARNING
Do not allow oil or grease to contaminate brake
linings or drums.
Febr 1977
a