check oil FIAT 500 1966 1.G Owner's Guide

A tolerance of —10'.+ 15' is permitted providing
that the value is the same for both rear wheels. It is
important that both rear wheels are set to the same
angle otherwise uneven tyre wear and adverse handl-
ing conditions will result. When the wheel is parallel to
the centre line of the vehicle the pin of bracket
C.696/3 will be .216 inch apart from the pin of the
front suspension swinging arm.
7 Release the swinging arm outer support to body
mounting screws and position arm in such a way as to
obtain the condition as described in Number 6 above.
After the adjustment has been completed tighten
the outer support mounting screws to a torque wrench
setting of 28.9 to 36.2 Ib/ft. Also tighten the two
swinging arm pin nuts C (see FIG 7 : 7) to a torque
wrench setting of 43.4 to 50.6 Ib/ft. Take off the gauge
C.696 w i t h bracket and support C.696/3, and repeat
the check and adjustment operations on the other
wheel. Care must be taken to ensure that bracket
C.696/3 is reversed from the position previously used.
New 500 type 500D, 110F and 110L sedan and
station wagon:
After the rear suspension has been replaced, check
and, if necessary adjust the rear wheel geometry.
1 Inflate the tyres to the normal operating pressures.
2 Lower the car body so that the rear wheels are set at
90 deg. to the floor. This condition is obtained when
the lowermost portion of the sump is 6.61 inches from
the floor level for the new 500D model or the centre
rear bracket for jacking up the rear of t h e vehicle
8.9 inches from the floor level for the 500 Station
Wagon.
3 With the vehicle set to the above conditions check the
wheel geometry. The wheel plane must converge w i t h
the centre line of the vehicle by an angle of 0 deg. 10'
(—10', +15') toeing in at the front.
4 The wheel plane must be 22.343 ± .059 inches from
the centre line of the vehicle for the 500D model.
Whereas for the 500 Station Wagon the distance must
be 22.264 ± .059 inches.
5 To adjust the rear wheel toe-in adjust the positions of
the mounting screws A and B as shown in FIG 7:7.
86
7:7 Modifications
The new 500 Sedan (110F) and late 500 Station
Wagon are fitted with modified wheels side flexible
joints and rear control arm as shown in FIG 7:13.
Together w i t h these modifications a new design rear
coil spring has been fitted details of which are given in
Technical Data.
7 : 8 Fault diagnosis
(a) Irregular or abnormal tyre wear
1 Incorrect tyre pressure
2 Wheels out of balance
3 Wheels off centre
4 Misadjusted brakes
5 Weak or broken coil springs
6 Excessive load
7 Incorrect wheel alignment
(b) Sag on one wheel
1 Incorrect tyre pressure
2 Weak or broken coil spring
3 Wear of shock absorber causing poor dampening
action
(c) Squeaks, thumps or rattles
1 Wheels out of balance
2 Wheels off centre
3 Misadjusted brakes
4 Weak or broken coil springs or spring seats dislodged
5 Wear of shock absorbers causing poor dampening
action
6 Worn rubber bushings in control arms
7 Poor lubrication of wheel bearings
(d) Pull to one side
1 Incorrect tyre pressure
2 Misadjusted brakes
3 Distorted suspension arm

2 Check that the surface of the pin that is in contact with
the camber and castor adjuster shims does not show
any signs of indentation or roughness which could
affect the accuracy of adjustment on reassembly. If
there are any signs of rust or small markings these
should be smoothed out using a file.
3 Inspect the condition of the half arm bushes, the inner
surface of which must not show signs of seizure and
the clearance of the bush to pin must not be greater
than .01 57 inch. Upon initial assembly the fit clearance
is .00059 to .0059 inch. Ensure t h a t the rubber parts
of the bush are not torn, cracked or show signs of
weakness which, if evident, must be renewed.
4 Use Fiat tool A.66058 or a suitably sized drift for
refitting the rubber bushes into the swinging arms.
Upon reassembly it should be observed that the
tightening of the two swinging arms m o u n t i n g nuts 5
(see FIG 8 : 3) , must be carried out whilst keeping
the axis of the swinging arm and the pin hole for the
screws 7 on the same plane otherwise distortion can
occur.
8 : 5 Kingpin housing
1 To remove and replace the 'estendblocks' use Fiat
tool A.66056 as shown in FIG 8 : 8. Ensure t h a t the
'estendblocks' is not worn and that there are no signs
of seizure on its inner surface, or that the rubber has
hardened. Renew if necessary.
2 Check that the kingpin to bush clearance is not
greater than .0079 inch. The clearance when fitted
new is .00063 to .00213 inch. If the clearance is
excessive the t w o bushes must be renewed and also
the kingpin if excessive wear is evident. To remove and
refit the kingpin bushes use Fiat tool A.66016 and
after reassembly the bushes must be accurately
refaced using a reamer set to a diameter of .5912 to
.5922 inch. If considered necessary use Fiat Fixture
C.1004 to check that the kingpin housing has not been
distorted which, if evident, the housing must be
renewed.
3 Whilst the kingpin assembly is being inspected ensure
that the lubrication hole is free to allow the passage of
oil.
4 To prevent incorrect loading of the 'estendblocks' that
is press fitted into the kingpin housing, the housing
to swinging arm pin nut must be tightened with the
parts so arranged that the angle between the swinging
arm plane and the housing axis is approximately
95 deg. as shown in FIG 8:14.
8:6 Steering knuckle and wheel hub
Dismantling:
1 To remove the wheel hub cap use Fiat puller A.46023
as shown in FIG 8 : 9 .
2 Using a universal t w o leg puller or Fiat puller A.40005
together with items 1 and 9 remove the wheel hub/
drum assembly having first extracted the splitpin and
released the hub retaining nut (see FIG 8:10). Later
models have a staked nut w i t h no splitpin. The nut
should be freed with a punch and discarded.
3 Remove the outer roller bearing, the oil seal and the
inner roller bearing outer race from the drum and pull
out the steering knuckle inner roller bearing inner ring
using Fiat puller A.46000
F500PULLER
A.46023
FIG 8 : 9 Removing right front wheel hub cap by
remover A.46023
UNIVERSAL PULLER A. 40005/
FIG 8:10 Removing left front wheel brake drum by
puller A.40005
4 Release the t w o brake to steering knuckle mounting
nuts and remove the complete brake housing flange.
5 To remove the steering knuckle from the kingpin
housing, remove the 'estendblock' from the kingpin
housing using Fiat drift A.66056 or a suitably sized
drift as shown in FIG 8 : 8.
6 Using a suitably sized punch drive the lockpin from the
kingpin, remove the lower plug and slide off the
kingpin. The steering knuckle is then disengaged
together with the snap ring, two thrust washers and a
shoulder ring.
Inspection:
Thoroughly clean all parts and dry using a compressed
air jet and to inspect proceed as follows:
1 Check that the steering knuckle and steering arm show
91

8 : 7 Hydraulic damper:
Description:
The front and rear shock absorbers are of the telescopic
double acting type. Their dampening action takes place
directly on the suspension without the use of any
intermediate linkage. The shock absorber comprises a
cylindrical body formed by to coaxial tubes 14 and 15
(see FIG 8:11), the inner tube acting as the working
cylinder and the outer one as a casing. The fluid reservoir
being located between the two sections. A third outer
cylinder 13 shields the rod 2 from any road dirt.
On the top the cylinder body is enclosed by a bush 1 1 ,
oil seals 5 and 9 and a housing 4. The rod 2 slides through
the seals 5, the upper end is fixed into the vehicle body
floor and its lower end carries the piston 22 on which
rebound 26 and inlet valves 21 are arranged.
The bottom of the shock absorber is closed by a plug
35 with a threaded shank 36 for the shock absorber to be
mounted onto the suspension unit. The cylinder 15 and
carrier plug 32 is mounted with a compensation valve
30 and a compression valve 33. The piston is provided
with two rows of orifices. The internal row is blanked
underneath by the rebound valve which operates
downwards. The external row is blanked by the inlet
valve which opens upwards. Hydraulic shock absorbers
fitted since March 1959 are provided w i t h a vapour
pocket bleeder from the cylinder exterior. The bleeder
device comprises a capillary
hole 12 interconnecting the
inner cylinder 15 with the upper chamber 10 and also a
passage tube 16 from the upper chamber to the fluid
reservoir. Any vapour pockets in the pressure cylinder
are excluded past the capillary hole 12 into the chamber
10 from which they flow downwards during shock
absorber operation through the passage 16 in a light
fluid stream and up to the top of the reservoir with the
reservoir fluid.
Dismantling and inspection:
Normally during service if a shock absorber becomes
weak in operation then a new unit should be fitted.
Should however, it be necessary for the original unit to
be overhauled proceed as follows:
1 Thoroughly clean the outer casing in petrol and blow
dry using a compressed air jet.
2 Firmly clamp the lower shank of the shock absorber
in a vice and telescope upwards the outer casing and
using Fiat wrench A.56024 unscrew the upper
threaded ring 3 (see FIG 8:11).
3 Remove the shock absorber from the vice and carefully
remove the inner cylinder 15 using a screwdriver
inserted in the cylinder bottom chamfer and remove
the lower plug 32 which carries the compression and
compensation valves.
4 Push the rod i n t o the cylinder 15 and clamp the upper
shank in a vice. Unscrew the plug 29, and carefully
remove the piston 22 together with the inlet and
rebound valves. Withdraw the rod 2 from the cylinder
15 and remove the seal gasket, the housing, and
threaded ring. Thoroughly wash all parts in petrol and
carefully blow dry using a c
ompressed air jet. The
following parts should be inspected as follows.
Check that the inlet, rebound and compensation valve
discs are not deformed or show signs of cracking.
F50093 Inspect the surfaces of the piston, the seal ring and the
compression valve to ensure that they are smooth and
hydraulic fluid tight. Check that the rebound and
compression valve springs and upper seal gasket
springs are not broken or weak. Carefully inspect the
t w o seal gaskets for damage or wear and it is recom-
mended that they are renewed upon reassembly.
Check that the rod and the cylinders show no sign of
deformation and that the air pocket evacuating
passage is not blocked. Also check that the capillary
hole 12 is not blocked. Any parts which show signs
of wear or damage must be renewed.
Reassembly:
Reassembly of the shock absorber is the reverse
procedure to dismantling. Special care must be taken
when refilling the shock absorber w i t h Fiat SA1 oil
otherwise its operating characteristics will be altered.
The hydraulic fluid capacity for the front shock
absorbers is .112 imperial quarts.
The hydraulic capacity for the rear shock absorbers is
.088 imperial quarts. Only Fiat—SA1 oil must be
used.
To insert the components into the shock absorber
body proceed as follows:
1 Mount the piston on the rod, and insert the piston and
rod assembly into the cylinder 15 (see FIG 8:11).
2 Push the piston against the bush 11 and then very
carefully pour the correct amount of hydraulic fluid
up to about j inch from the edge.
3 Press f i t t h e plug 32 and pour the remaining fluid into
the casing 14.
4 Insert the cylinder 15 into the casing 14 and tighten
the upper threaded ring 3.
8 :8 Front suspension assembly and installation
1 Attach Fiat fixture A.66061 to the springs as shown
in FIG 8:12 and load it using the centre screw on the
fixture until the index 'Nuova 500' appears below
the crossbeam lower edge. It is in this position the
spring attains the full static load setting as on the FIG 8:13 Installing right front wheel hub cap by tool
A.66059TOOL
A.66059

VERTICAL LINE DB
S
EB
OIL SUMPF
GF
FIG 8:16 Castor, camber angles
6 Insert the swinging arm pin onto the two studs that
are welded to the body sides so as to support the
front suspension and wheel assembly.
7 Reconnect the kingpin housing to the spring eye by
inserting the bolt and tightening the self-locking nut
to a torque wrench setting of 28.9 Ib/ft. It is important
that during this operation the spring is always kept
in the 'set' position by fixture A.66061 so as to
ensure correct assembly and prevent excessive strain
on the 'estendblocks'.
8 Slide off the swinging arm and insert the spacers and
shims S (see FIG 8:16) onto the studs ensuring
that the resulting thickness is the same as was found
during dismantling. Reattach the swinging arm.
Screw on the nuts securing the pin to the body and
tighten to a torque wrench setting of 28.9 Ib/ft.
9 Refit the shock absorber securing it to the kingpin
housing and to the body inserting the plain washer
between the rubber pad and the toothed washer.
10 Carefully remove Fiat fixture A.66061, connect the
steering rods, hydraulic brake pipes and refit wheels.
Remove the wooden plug from the brake fluid tank
inlet opening. Carefully raise the vehicle using a
garage hydraulic jack, remove the axle stands and
lower slowly to the ground.
11 When both left- and righthand suspension units have
been refitted to the vehicle the front end steering
geometry must be checked and adjusted.
8:9 Steering geometry
Checking of the front wheel geometry is necessary
95
F500
if either excessive tyre wear or irregular steering per-
formance is noticed or if the front suspension assembly
has been dismantled for repair. The values for the front
end setting under a normal static load normally con-
sidered to comprise four passengers should be as
follows:
Camber angle — 1 d e g . ± 20'
Castor angle — 9 deg.± 1 deg.
The camber angle shown in FIG 8:14 and the castor
angle shown in FIG 8 : 1 6 adjustments are performed by
inserting shims S (see FIG 8 : 1 6 ) between the swinging
arm pin and the spacers on the studs that are welded to
the body at points D and E (see FIG 8:16). Shims .0197
inch thick are supplied in service to enable the castor and
camber angles to be adjusted.
It is suggested that the castor and camber angles are
checked at the local agents as specialised equipment is
necessary for completion of these checks.
Adjustment of castor angle:
Slacken the t w o nuts securing the swinging arm pin
to the body and proceed as follows:
1 If the castor angle requires to be increased (see FIG
8:16) move the shims S from the rear screw E to the
front screw D.
2 If the castor angle requires to be reduced (see FIG
8:16) move the shims from the front screw D to the
rear screw E.
Adjustment of camber angle:
Slacken the t w o nuts securing the swinging arm pin DE
A
C

RIGHT HAND TIE ROD
RELAY LEVER SUPPORTINTERMEDIATE TIE ROD!
STEERING BOX!
LEFT HAND TIE ROD
FIG 9 :1 Steering box, idler member and steering linkage arrangement on vehicle
FIG 9 : 2 Securing steering wheel mounting nut
Key
to Fig 9:2(Tightening torque: 29 to 36 Ib ft)
9 : 4 Steering box dismantling and reassembly
1 Remove the steering gear housing cover complete
with the adjusting screw and locking nut and drain the
oil from the unit.
2 Using Fiat puller A.4005.1.5 or a universal t w o leg
puller remove the pitman arm.
3 Remove the cotter pin from the lower thrust bearing
adjusting nut and unscrew this nut.
4 Remove the sealing ring at the sector shaft lower end
and using Fiat tool A.8065 loosen the eccentric bush
adjuster plate bolt and remove both the bolt and the
adjusting plate. Also remove the upper sealing ring.
98
5 Lift out the sector together with the upper thrust
washer and shims.
6 Remove the steering worm screw by pulling out from
below. The two bearing inner rings will remain on the
worm screw whilst the lower bearing outer ring will
remain in the housing.
7 Remove the oil seal using Fiat tool A.10110 followed
by the worm screw upper bearing outer ring using
Fiat tool A.66040 or a suitably sized drift.
Inspection:
1 Carefully inspect the sector teeth and the worm screw
threads to see that there are no signs of seizure,
indentations or scoring. Check that the contact faces
indicate that meshing between the two parts is taking
place at the centre.
2 Check the clearance between the eccentric bush 5
(see FIG 9 : 5) and the worm sector 11 which must not
exceed .0039 inch. These items have an initial
assembly clearance of .00 to .0016 inch. It should be
noted that if the eccentric bushing to sector shaft
clearance exceeds .0039 inch a new bushing should
be installed and its inner face reamed using Fiat
reamer U.0360.20.
3 Ensure that the worm screw is not distorted. The
permissible out of true is .0019 inch.
Adjustment:
1 If the backlash between the worm screw and the
sector is excessive it should be adjusted by first dis-
connecting the pitman arm and its relevant seal.
Remove the screw 7 (see FIG 9 : 5) fixing the abut-
ment plate 6. Rotate the eccentric bush 5 by the
adjustment plate and move the sector in towards the
worm screw. The adjustment plate should be secured
again using the second fixing hole.
Should the adjustment plate already be fixed in the
second hole remove the plate from the bush and
rotate one or more serrations and re-secure.

reassembling and during assembly liberally lubricated
using Fiat W90/M oil (SAE90 EP).
2 The pitman arm nut should be correctly positioned on
reassembly to the sector shaft and both are marked
with notches or a master tooth on the sector will mate
with a double tooth on the pitman arm which will
prevent incorrect reassembly.
3 The pitman arm nut must be tightened to a torque
wrench setting of 72 Ib/ft.
4 Fill the box up to the level and filler plug with SAE90 EP
gear oil.
Refitting the steering box:
To refit the steering box to the vehicle proceed as
follows:
1 Engage the w o r m screw f r o m the steering shaft by
gently manipulating the steering box.
2 Replace the steering box to body nuts and tighten to a
torque wrench setting of 14 to 18 Ib/ft.
3 Replace the t w o track rod pins in their seatings in the
pitman arm and tighten the self-locking nuts to a
torque wrench setting of 18 to 21 Ib/ft.
4 Replace the steering shaft to worm screw mounting
bolt, lock washer and nut.
9 :5 Relay lever and support
The steering idler arm is secured to the body by means
of a support bracket and a rubber bushed pivot bolt. This
is shown in FIG 9 : 7. When this unit is being serviced
the following points should be noted.
1 If there is excessive play between the pin and the
bushes the bushes must be renewed. Also check the
condition of the pin and if there are signs of excessive
wear it must be renewed.
2 To eliminate torsional stresses in the rubber bushes
during assembly the pin nut must be tightened to
torque wrench setting of 39 to 43 Ib/ft, once the
front wheel toe-in has been correctly adjusted w i t h the
wheels set in the straight ahead position.
3 The relay lever support to body mounting nuts must
be tightened to a torque wrench setting of 14 to 18
Ib/ft.
9 : 6 Steering rods (tie rods)
The steering rod is connected to the idler arm and the
drop arm by means of non-adjustable ball joints. The
track rods are connected to the right and left steering
arms by non-adjustable ball joints and comprise t w o
sleeves which are split and having internally threaded
ends. The ball joints are clamped to either end of the
sleeves. To facilitate adjustment one ball joint end has a
lefthand thread and the other a righthand thread.
Adjustment is made by loosening both the clamping bolts
and turning the central sleeve.
To remove the steering rods from the pitman arm, the
relay lever and knuckle arms Fiat pullers A.46006 and
A.6473 or universal ball joint removers should be used.
If excessive play is evident in the ball joint linkage or
the pin is damaged the complete ball joint assembly must
be renewed.
Upon reassembly the tie rod to ball pin knuckle arm
nuts must be tightened to a torque wrench setting of
18 to 21 Ib/ft.
F500101
FIG 9:7 Relay lever support section
FIG 9:8 Front wheel toe-in checking diagram
Key to Fig 9:8 A—B = 000 inch to .079 inch
It is important that all steering linkages are thoroughly
checked at regular intervals and if any parts are suspect
then they must be renewed.
9 : 7 Front wheel toe-in
To check and adjust the front wheel toe-in proceed as
follows:
1 Ensure that the tyres are inflated to the recommended
pressures. Ensure that the steering wheel is in its

FIG 10:1 Diagrammatic view of service and rear wheel parking brake system
Key to Fig 10:1 1 Bleeder connections 2 Brake fluid reservoir 3 Service brake pedal 4 Hand lever, mechanical
parking brake on rear wheels 5 Hand lever travel adjustment stretchers 6 Stop lamps 7 Mechanical brake operating lever,
controlled from lever 4 8 Shoe clearance self-adjusting device 9 Wheel cylinders 10 Master cylinder 11 Stoplight
pressure-operated switch
FIG 10:2 Left front wheel brake assembly (500 Sedan)
SHOE
RETURN
SPRINGSHOE MOUNTING
BRACKET SHOE
RETAINING
PLATE SHOES
DEVICESHOE
SELF-ADJUSTING
WHEEL CYLINDERSHOE RETURNSPRING
2 Check that the hydraulic flexible hoses are not con-
taminated with oil or grease which would destroy the
rubber.
3 Ensure that all pipeline fastening clips are secure
otherwise hydraulic line failure could occur due to
cracking caused by excessive vibration.
104
4 Carefully clean all connections and inspect for
hydraulic fluid leaks. Should any leaks be detected
then the connections should be tightened taking very
great care not to twist the pipes during this operation.
5 Ensure that the hydraulic fluid level in the reservoir is
correctly filled up to the top of the filter using Fiat
special 'Blue Label' brake fluid. Extra care must be
taken to ensure that no fluid is spilled over the body
paintwork, as this acts as a strong solvent.
6 Ensure that the play between the brake pedal pushrod
and the master cylinder plunger is .019 inch. This will
correspond to approximately .098 inch free pedal
travel.
Never use any fluid but the recommended hydraulic
fluid. Do not leave it in unsealed containers as it will
absorb moisture which can be dangerous. It is best to
discard fluid drained from the system or after a bleeding
operation. Observe absolute cleanliness when working
on all parts of the hydraulic system.
10:3 Front brakes
Front brake drum removal:
1 Remove the wheel trims and carefully slacken the road
wheel retaining bolts. Using a garage hydraulic jack
raise the front of the vehicle and place on firmly
based stands. Remove the road wheels.

2 Using Fiat puller A.46023 as shown in FIG 8 : 9
remove the wheel grease cap.
3 Using a universal t w o leg puller or Fiat puller A.40005
together w i t h items 1 and 9 remove the wheel hub/
drum assembly having first extracted the splitpin if
fitted and released the hub retaining nut (see FIG
8:10).
Dismantling brake unit:
1 Using a compressed air jet thoroughly clean all com-
ponents of the brake assembly.
2 Make a note of the location of the shoe return springs
and gently ease the shoes away from the brake
backplate (see FIG 10:2).
3 Disconnect the hydraulic line from the rear of t h e
wheel cylinder and remove the t w o cylinder retaining
bolts. Lift away the hydraulic cylinder.
Brake shoe lining:
Check the lining thickness and if found to be exces-
sively reduced service replacement shoes must be fitted.
The minimum allowable brake lining thickness is .059
inch.
Thoroughly check the linings for signs of oil or grease
which, if evident, the shoes must be renewed and the
drums and oil seals thoroughly inspected for the cause
of oil ingress and the cause remedied before reassembly.
Do not fit odd brake shoes and do not mix materials or
unbalanced braking will result.
Do not allow grease, oil or paint to contact the friction
linings.
Brake drums:
Whilst servicing the brakes, thoroughly inspect the
drums for scoring, ovality or distortion as well as inspect-
ing for minute hair line cracks. The drums may be refaced
by using a centre lathe and finally finishing by lapping
the drums to smooth out possible tool marks. The
maximum permissible oversize beyond the nominal drum
diameter of 6.702 to 6.712 inch is .039 inch. This limit
must never be exceeded otherwise the strength of the
drum will be impaired or a reduction in braking efficiency
caused by the increase of shoe expansion travel and the
consequent diminished contact pressure.
No brake adjustment will be required on the new 500
Saloon models after the drum has been reassembled as
the self-adjusting device will accommodate for the shoe
position to the new drum diameter during the first
operation of the brake pedal.
Reassembly of front brakes:
This is the reverse procedure to dismantling. Ensure
that the pull-off springs are correctly fitted to the holes in
the webs of the brake shoes and that the shoes register
correctly in the slotted ends of the pistons and the
side
mounting plate.
Upon assembly of the hub and brake drum assembly
liberally pack the space between the two bearings w i t h
Fiat MR grease, and remount the hub according to the
instructions in Chapter 8.
F500
FIG 10:3 Section view of left side f r o n t brake assembly
(500 Station Wagon)
Key to Fig 10:3 1 Wheel cylinder 2 Shoe return spring
3 Adjusting cams 4 Shoe guide pin 5 Shoe with lining
6 Drum 7 Housing flange
BRAKE SHOE
ADJUSTING DEVICE
SHOE WEDGE
SELF
WHEEL CYLINDER
SHOE RETURN SPRING
PARKING BRAKE
SHOE CONTROL
RETURN SPRINGS
LEVER
SHOE LOCK PLATEBRAKE SHOES
SHOE RETURN SPRING
SHOE MOUNTING PLATE
FIG 1 0:4 Right rear wheel brake assembly (500 Sedan)
10:4 Rear brakes
Rear brake drum removal:
1 Remove the wheel trims and carefully slacken the road
wheel retaining bolts. Using a garage hydraulic jack
raise the rear of t h e vehicle and place on firmly based
stands. Remove the road wheels.
2 Remove the four drum to hub retaining bolts and
spring washers and carefully withdraw the drum from
the backplate assembly.
Dismantling brake unit:
1 Using a compressed air jet thoroughly clean all
components of the brake assembly.
105

10:9 Brake fluid reservoir
The reservoir is located in the front compartment to the
side of the fuel tank as shown in FIG 10:9. Should it be
necessary to detach the fluid outlet line from the reservoir
the outlet hole must be blanked off using a tapered
wooden peg of suitable length so that the cap may be
replaced to prevent the ingress of foreign matter into
the reservoir and the absorbtion of moisture, oil or petrol
vapours which would alter the properties of the hydraulic
fluid.
A special filter is fitted into the top of the reservoir
through which all fluid used for topping-up the reservoir
must pass to ensure utmost inner cleanliness of the
hydraulic system.
10:10 Bleeding the system
This is not a routine maintenance operation and is only
necessary if air has entered the hydraulic system because
parts have been dismantled or because the f l u i d level in
the reservoir has dropped so low that air has been drawn
into the main feed pipe to the master cylinders.
1 Fill the reservoir w i t h Fiat 'Blue Label' hydraulic fluid.
During the bleeding operation fluid will be used and
constant topping-up of the supply reservoir will be
needed. If this is not done it is possible for air to enter
the master cylinder main feed pipe which will nullify
the operation and necessitate a fresh start.
2 Attach a length of rubber or plastic tubing to the
bleeder screw on the rear wheel cylinder furthermost
from the master cylinder. Immerse the free end of the
tube in a small volume of hydraulic brake fluid in a
clean jar.
3 Open the bleed screw one turn and get a second
operator to press down slowly on the brake pedal. After
a full stroke let the pedal return without assistance,
pause a moment and repeat the d o w n stroke. At first
there will be air bubbles issuing from the bleed tube,
but when fluid alone is ejected, hold the pedal firmly
down on the floor panel and tighten the bleed screw.
Repeat this operation on the other rear brake and then
repeat the operation on the two front brakes.
4 On completion, top-up the fluid in the reservoir to the
correct level. Discard all dirty fluid. If fluid is perfectly
clean, let it stand for twenty four hours to become
clear of air bubbles before using it again.
10:11 Hand parking brake
Normally with the new 500 Sedan model automatic
brake adjusting device, adjustment of the rear brakes
will take up excessive handbrake travel.
If there is excessive travel on the handbrake of the
Sedan model at any time, or in the case of Station Wagon
model even after the rear brakes have been manually
adjusted, suspect worn brake shoe linings or stretched
handbrake cables. Examine the linings and fit replace-
ment shoes if necessary. Check the action of the hand
parking brake again and if there is still too much travel
before the brakes are applied it is permissible to take up as
follows:
1 It is essential to ensure that the rear shoes are correctly
adjusted as described in Section 10:2.
2 Apply the hand parking brake lever until the pawl
engages with the ratchet at the second notch.
F500
FIG 10:11 An exploded view showing the components of
the tandem master cylinder
3 Jack up the rear of t h e vehicle and place on firmly
based stands.
4 Locate the cable adjusting nuts as shown in FIG
10:10 and adjust these until it is just possible to turn
the road wheels by heavy hand pressure. It is important
that both wheels offer the same resistance to turning
to obtain correctly balanced braking.
5 Return the lever to the OFF position and check that
both wheels are quite free to rotate. If a brake tends to
bind, remove the wheel and brake drum and check
the brake shoe pull-off spring is correctly fitted and
that the lever return spring and operating lever are
functioning correctly. Also check for suspected
seizure of the wheel cylinder. When the fault has
been rectified refit the drum. Readjust and recheck.
Removing the hand parking brake cable:
1 Chock the front wheels and release the handbrake.
Raise t h e rear of the vehicle and place on firmly based
stands.
2 Disconnect the cables from the operating levers on
each rear brake unit. Release each cable from its body
mounted bracket.
3 Inside the car, remove the rear seat and the seat belt
fitting from the floor. As necessary, remove the centre
console and the carpet to give access to the cover plate
on the centre tunnel and remove it.
4 Remove the handbrake lever assembly, detach the
cable compensator and pull the cables through the
holes in the box panel.
5 Reassembly is the reverse procedure to removal.
Ensure t h a t the cable is well lubricated and finally
readjust as previously described.
10:12 The dual circuit braking system
This is used on later model cars. A tandem master
cylinder provides t w o entirely separate hydraulic circuits,
one for the front and one for the rear brakes. The
components of the master cylinder are shown in the
exploded view of FIG 1 0 : 1 1 . The principle of operation is
quite straightforward and easy to understand.
169

When the pedal is applied, it moves the rear (primary)
piston to pressurise the front brakes through the rear port.
This, in turn, forces the front (secondary) piston down the
bore to pressurise the rear brake circuit through the front
port. In the event of a failure in the primary circuit, the
primary piston moves into direct contact with the second-
ary piston and full braking is still available on the rear
wheels. If a leak occurs in the rear circuit, the secondary
piston is moved to the end of the bore, sealing off the out-
let port and full braking pressure is applied to the t w o front
brakes.
With two fluid reservoirs connected to the inlets 3 and 5
the two circuits are fully independent.
The remaining components in the braking system are
similar to those used in the earlier single circuit layout.
10:13 Fault diagnosis
(a) 'Spongy' pedal
1 Leak in t h e system
2 Worn master cylinder
3 Leaking wheel cylinders
4 Air in the system
5 Gaps between shoes and underside of linings
110
(b) Excessive pedal movement
1 Check 1 and 4 in (a)
2 Excessive lining wear
3 Very low fluid level in supply reservoir
4 Too much free movement of pedal
(c) Brakes grab or pull to one side
1 Brake backplate loose
2 Scored, cracked or distorted drum
3 High spots on drum
4 Unbalanced shoe adjustment
5 Wet or oily linings
6 Worn or loose spring fixings
7 Front suspension or rear suspension anchorages
loose
8 Worn steering connections
9 Mixed linings of different grades
10 Uneven tyre pressure
11 Broken shoe return springs
12 Seized handbrake cable