wheel FIAT 500 1961 1.G Repair Manual

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

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11
10
16,15
14 13
1265
FIG 11:5 Components of starter
Key to Fig 11:5 1 Drive end head 2 Head shield 3 Frame 4 Switch 5 Commutator cover band
6 and 7 Pin and spring for lever 8 8 Starting engagement lever 9 Head shield 10 and 11 Head fixing tie rods and tubes
12 Pinion, complete 13 Starting engagement spring 14 Drive unit sleeve and free wheel hub 15 Armature
16 Commutator end head
Testing field coils:
When tested w i t h an ohmmeter the reading should be
8+.1—.3 ohms. Failing an ohmmeter use a 12-volt
supply and connect it in series w i t h an ammeter across
the field terminal and the yoke or body. The meter should
read approximately 2 amps. If there is no reading the
field coil winding has a break in it. If the reading is much
more than 2 amps or the ohmmeter records at much less
than 8 ohms it shows that field coil insulation has broken
down. Renewal of the field coils is a specialist operation
best left to a service station.
The armature:
Apart from reconditioning the commutator, there is
little which can be done to the armature itself. Never try
to straighten a bent shaft and do not machine the arma-
ture core. Armature windings are tested w i t h equipment
normally not available to the car owner. The only check
for a suspected faulty armature which the owner can do
is to substitute an armature which is known to be
satisfactory.
Generator bearings:
1 Commutator end head bearings. Remove the ball-
bearing outer race stop bracket mounting screw and
nut, ease o u t t h e stop brackets and the ballbearings.
2 Fan end head bearing. Remove the ballbearing retainer
mounting screw nuts and ease o u t t h e retainers and
the seals. Using a suitably sized drift remove the ball-
bearing.
114Reassembly is the reverse procedure to dismantling
in both cases.
Reassembly and refitting the generator:
This is the reverse procedure to dismantling. The
following points should however be noted.
1 The commutator end head ballbearing outer race stop
bracket mounting screw nut must be tightened to a
torque wrench setting of .80 Ib ft.
2 The pulley and fan-to-generator armature shaft self-
locking nuts must be tightened to a torque wrench
setting of 14.5 Ib ft.
3 To assemble the commutator end bracket to the yoke,
partially withdraw the brushes and trap them in this
position by letting the springs bear on the sides of the
brushes. Fit the bracket to the armature shaft and when
it is about 1/2 inch from the yoke face, lift the springs
using a thin screwdriver or a piece of hooked wire and
this will let the brushes drop onto the commutator.
Check that the springs now bear correctly on the tops
of the brushes and push the bracket fully home.
4 Pack all ballbearings with Fiat Jota 3 grease or an
equivalent grade grease.
11:4 The starter motor
Operation:
When operating the starter hand lever through a
flexible coupling a lever is operated (see FIG 11:5)
which controls the pinion engagement with the flywheel.
As the lever completes its movement it closes the starter

switch contacts. The starter motor rotates driving the
engine through the pinion and ring gear. As soon as the
engine fires the starter hand lever must be released which
will open the starter switch contacts so stopping the
starter motor and the pinion will return under the action
of a spring to a neutral position.
Tests for a starter which does not operate:
Check the condition of the battery and particularly
the connections to the terminals and to earth. If the
battery is charged, switch on the lights and operate the
starter hand lever control. If the lights go dim but the
starter does not operate it shows that current is reaching
the starter motor. The probability is that the pinion of the
starter shaft is jammed in mesh due to dirty pinion splines
or a broken spring. To release the pinion engage a low
gear with the ignition switched off and rock the vehicle
backwards and forwards which should allow the pinion
to be disengaged from the flywheel ring gear. If it proves
impossible to free a jammed pinion the starter motor must
be removed for examination and repair.
If the lamps do not go dim, check the starter switch and
also check the connection between the battery and the
starter switch to ensure that they are tight and making
good electrical connection. If the starter motor still does
not work it should be removed from the power unit for
inspection.
Removing the starter:
To remove the starter motor from the power unit
proceed as follows:
1 Disconnect the positive terminal from the
battery post.
2 Release the hand lever control cable from the starter
motor engagement lever.
3 Disconnect the battery cable terminal from the starter
motor switch.
4 Remove the retaining nuts and washers holding the
starter motor to body to the transmission bellhousing
and gently ease backwards and lift away the starter
motor.
Examining the commutator and brush gear :
Refer to FIG 11:5 and remove the coverband 5. Hold
back each spring in turn and pull gently on the flexible
connection to the brush. If the brush does not move
freely remove it from its holder and polish the sides using
a fine file. Mark the brushes so that they will be replaced
in their original positions. If the brushes are so worn that
they no longer bear onto the commutator, or the brush
connector has become exposed on the running face, the
brushes must be renewed.
If the commutator is blackened it should be cleaned by
turning it against a petrol-moistened cloth. With the
brushes and commutator overhauled hold the body of the
starter motor in a vice and connect it with thick cables to a
12 volt battery. One cable should go to the starter
switch terminal and the other to the body of the starter.
The starter should run at high speed. If it does not, it
must be dismantled for further examination and testing.
F500115 Dismantling the starter:
To dismantle the starter proceed as follows:
1 Remove the coverband 5 (see FIG 11:5) and hold
back the brush springs and take out the brushes.
2 Remove the starter switch by releasing the t w o
mounting screws and lift away the switch.
3 Remove the commutator end head 16, slide off the
armature assembly from the drive unit and from the
pole shoes.
4 Release the engagement lever pin 6 and spring 7 from
the lever operating bracket on the drive end head. Lift
away the lever and withdraw the pinion assembly
complete which is shown in FIG 11:5.
Servicing the brushes
Test the brush springs with a balance, the correct
tension is 2.5 to 2.9 Ib. according to the wear of the
brushes. Fit a new spring if the tension is low.
The life of the brushes depends on the type of service
in which the vehicle is being used. In normal circum-
stances even when the starter is being used frequently,
the brushes should last more than 18,000 miles. If the
wear is found to be abnormal it will probably be found
that the commutator is either damaged or excessively
w o r n . Only Fiat replacement brushes must be used.
Testing the field coils:
Use a 12 volt bulb in one lead of a 12 volt battery.
Connect one lead to the brush connection joint to the coil
field and the other to the field coil current supply lead.
If the bulb does not light there is a break in the f i e l d coil
windings. This is not a complete test as it is still possible
for a coil to be earthed. Check this by moving the lead
from the brush connection and holding it on a clean
metal
surface on the yoke or body. If the bulb lights it shows
that the field coils are earthed.
The only sure way of curing faulty field coils is to take
the starter motor to a service station.
Examining the armature:
The armature shaft may be bent due to the starter
being operated whilst the engine is operating. Do not try
to straighten a bent shaft or machine the armature core to
obtain the correct clearance.
If the commutator is damaged or any wires or segments
have lifted from it, the assembly will have to be renewed.
Starter bearings:
Bearing bushes are of the porous bronzed type and
must not be reamed after fitting. Worn bearings should
be withdrawn by screwing a tap into them and pulling
on the tap. New bushes must be immersed in engine oil
for approximately twenty four hours before fitting. Press
them into place using a suitably sized drift which has a
spigot the length of the bearing and the diameter of the
starter shaft. When this is withdrawn after fitting, the
bore of the bush should be correct to size.
The pinion drive:
This unit is shown in FIG 11:5. The chief sources of
trouble are a dirty unit or a broken starting engagement

parking position the trouble will be found in the sliding
sector which fails to open the switch D (see FIG
11 :16) . Check by removing the four motor cover
mounting screws and uncover the sliding sector. If
possible suitably bend the sector to bring it against
into contact with the rod tip of switch D.
3 If the automatic parking of the blades does not occur
when the switch lever is fully depressed to the parking
position but the motor stops when the switch is
operated the cause of the trouble is that the switch D
is not closing and consequently no current is flowing
between the terminals C and INT. This will probably
be due to dirt lodged between the movable contact
and the fixed contacts of switch D. Thoroughly wash
the components with petrol and if necessary reface
the contacts using a very fine file.
4 Should the motor unit be noisy in operation although
still operating reliably the noise is probably due to the
reduction gear operation, whereby the pinion and
worm are excessively worn or a tooth chipped. The
motor unit must be renewed as motor unit parts are
not available in service.
5 If the switch lever is pushed upwards to the 'on'
position or depressed downwards to the Parking
position and the wiper is still inoperative thoroughly
check all terminal connections for tightness and
cables for damage which if all appear to be correct the
failure of the wiper to operate indicates an internal
fault of the motor unit which
should be repaired or
renewed as necessary.
Removal and refitting the motor:
Remove the wiper arms and the electrical connections
to the motor. Dismantling is a straightforward operation
providing that as all items are removed so they are
inspected and a note made of their locations. However,
reassembly requires more care and the following
procedure should be adopted.
1 Mount the wiper unit onto the body by fully tightening
the nuts fixing the pivots onto which the arms are
fitted. Ensure t h a t the rubber sealing bushes between
the pivots and body are correctly assembled to prevent
water ingress. Slightly lubricate with glycerine.
2 Secure the mounting bracket lower edge to the body
by means of the special square bracket. It is important
not to distort the mounting bracket and ease of
assembly is ensured by elongated holes in the square
bracket. By suitable adjustment the linkages will not
be subjected to distortion or abnormal stresses during
operation.
3 Fit the motor unit to the mounting bracket tightening
the screws and reassemble the main link to the pivot
lever. Ensure t h a t the l o c k i n g of the fastener on the
pivot lever is secure so that it does not become loose
during operation.
4 Remake all the electrical connections and run the
motor for a short time whilst checking all the switch
positions including the automatic parking. It is at this
position that the wiper blades and arms are assembled
to the wiper mechanism.
5 Onto the pivots, install the shims, snap ring, wiper arm,
plain washer and lockwasher. Fully tighten the nuts
with the wiper arms in the parked position.
F500
FIG 11 :17 Headlamp removal
Key to Fig 11:17 1 Screw for vertical beam adjustment
2 Screw for horizontal beam adjustment 3 Headlamp
locating hook 4 Headlamp retaining ring and spring
5 Lamp unit 6 Bulb spring retainers 7 Bulb
8 Junction block
6 Ensure that the wiper arms can be tilted 100 deg.
downwards without striking against the cowl or front
compartment lid. Also ensure that the blade pressure
on the glass is 10.6 to 12.3 oz.
1 1 : 9 The lighting system
Description:
The lighting system comprises t w o headlights with
double filament bulbs of 45 watts for main beam and
40 watts for dip. Headlight control is operated through
the outer light switch below the steering wheel after the
toggle switch at the centre of the instrument panel has
been operated.
A double filament bulb for the front parking and
direction indicator lights is located below the headlights:
alternatively, the parking light may be incorporated in the
headlamp unit. The bulb is of 5 watt rating for the parking
lights and 20 watts for the direction indicator lights.
Two side direction indicator lamps are fitted with 2.5
w a t t b u l b s . The rear number plate is illuminated by a 5
watt bulb operated from the main lighting circuit.
Two three purpose rear light units are fitted and are
provided with a one single filament 20 watt bulb for the
direction indicator and one double filament bulb of 5 watt
rating for the parking circuit and 20 watt for stoplights.
Headlamp removal:
The headlamp on earlier cars may be removed from the
front panel by slightly depressing the lens and rotating the
unit counterclockwise through 15 deg. on later cars a
retaining spring is unhooked inside the front compart-
ment and the lamp can then be lifted out (FIG 11 :17).
121

Lamp brilliance varies w i t h the speed of t h e car:
Check the condition of the battery. Examine the battery
connections. Make sure they are tight and renew faulty
cables.
11:10 Panel and warning lights:
All the gauges are clustered in a single instrument
mounted on the dashboard above the steering column.
Incorporated in this cluster is the parking light pilot light,
generator charge indicator, fuel reserve supply indicator,
low oil pressure indicator, and the speedometer w i t h
mileage recorder.
The parking lamp indicator glows green when the
ignition lock switch key is in either position 1 or 2 once
the toggle switch on the instrument panel has been
operated.
The generator charge indicator shows red only when
the ignition is turned on. It should be extinguished when
the generator output is sufficient for battery charge
(12.6 ± 0.2 volts) with the engine running at a speed
of 1100 rev/min and the headlights switched off.
The fuel reserve supply indicator shows red only when
the ignition is turned on and the amount of fuel in the
petrol tank has dropped to approximately .8 to 1.1
Imp. gallons.
The low oil pressure indicator shows red only when the
ignition is turned on and should be extinguished when
the oil pressure reaches 7.1 to 21.3 Ib/sq in, and opens
the sending unit contacts. Once the engine is at normal
operating temperature but at a speed below 1000 rev/
min the indicator might light up even the pressure is under
control and with normal operation.
All the bulbs fitted to the above described units are of
the tubular 2.5W type and to renew a bulb extract the
bulb holder from the rear of t h e instrument cluster and
release the bulb which is attached by a normal bayonet
coupling.
Fuel reserve supply indicator sender u n i t:
The fuel reserve supply indicator should be checked for
correct indication by allowing the fuel tank to empty and
then inserting .8 to 1.1 Imp. gallons at which stage the
light should extinguish. Any failure to do so should be
checked as follows:
1 Ensure that the indicator bulb operates correctly.
2 Check for complete circuit between the sender unit and
the indicator bulb.
3 If the sender unit float bracket is distorted the bulb
will
indicate a reserve supply of fuel greater or smaller than
specified. The bracket should be adjusted to give
correct indication of fuel level.
4 The sender unit could have been inadvertantly
damaged in which case the unit must be renewed.
11 :11 The horn
The horn circuit comprises the horn, push button at the
centre of the steering wheel and normal earth return
electrical circuit through the car body. One terminal is
connected to the battery whilst the other to the push
button on the steering wheel which when the button is
depressed the circuit will be closed so causing the horn
to operate.
F500
FIG 11 : 21 Number plate lamp
Key to Fig 11 : 21 A Lens and light cap mounting screws
B Lens
FIG 11 : 22 Horn (opened)
Key to Fig 11:22 1 Body 2 Diaphragm 3 Armature
4,5,6 Core 7 Cable: terminal-condenser-stationary contact
8 Cable: terminal-magnetizing coil end 9 Magnetizing coil
FIG 11 :23 Horn sound adjustment. Obtained by adjust-
ing the armature air gap
123

Before removing an apparently faulty horn check the
wiring and connections. Check that the mounting bolts
are tight and that the horn does not foul any adjacent part.
Removal and installation:
This is a straightforward operation and the only
precaution to be taken is to ensure that the rubber gasket
bonded to the horn body does not become detached. If
the horn is renewed, before installing the new horn bond
the rubber gasket to the new unit with adhesive in
the same position as was on the original horn unit fitted.
Should the horn fail to operate the following points
should be noted.
1 Damaged horn.
2 Broken connection between battery and horn.
3 Broken connection between horn and push button on
steering wheel
4 Damaged push button mechanism.
5 Directional signal and outer lighting changeover
switch blade contact failing to make contact with the
steering wheel hub ring contact.
6 Current lead displaced from the horn blade contact on
the directional signal and outer lighting switch.
7 Distorted or broken diaphragm in horn.
8 Connections or inner windings
broken or burnt.
9 Electro-magnet contact points dirty or excessively
worn.The contacts may be adjusted by the adjusting screw
after the points have been cleaned and refaced.
To adjust the tone of the horn use a ring spanner and
screwdriver as shown in FIG 11 :23.
It is recommended that if the horn unit operation is
unreliable a new unit should be fitted rather than the
original one repaired.
11:12 Lighting and flasher switch
Description:
The two switches provide a directional signal switch
which automatically returns to the rest position once a
turn has been negotiated and the steering wheel is
brought back to the straight-ahead position. The change
over switch controls the outer lights and the headlights
flasher. The complete unit is located under the steering
wheel on the steering column.
Switch unit removal:
1 Carefully pry off the horn push button at the steering
wheel centre using a fine blade screwdriver.
2 Disconnect the positive terminal of the battery.
3 Disconnect the plug in contact in the steering wheel
hub.
4 Unscrew the steering wheel retaining nut from the
inner column and remove the steering wheel from the
shaft.
5 Slacken the bolts securing the steering column support
to the body
6 Remove the plug in contacts from the switch unit
ensuring that their correct location is noted for re-
assembly.7 Remove the switch unit from the steering column.
124
Switch unit installation:
This is the reverse procedure to dismantling. It is
advisable after installation to check that the steering
wheel when in the straight-ahead position and the
directional signal switch lever in neutral, the reference
index on the outer face of the directional signal switch
drum is in line with the index on the steering wheel hub.
This will ensure correct sequence of operation.
11:13 Fault diagnosis
(a) Battery discharged
1 Lighting circuit shorted
2 Terminals loose or dirty
3 Generator not charging
4 Regulator or cut-out units not working properly
5 Battery internally defective
(b) Insufficient charging current
1 Loose or corroded battery terminals
2 Generator driving belt slipping
(c) Battery will not hold a charge
1 Low electrolyte level
2 Battery plates sulphated
3 Electrolyte leakage from cracked casing or top sealing
compound
4 Plate separators ineffective
(d) Battery overcharged
1 Voltage regulator needs adjusting
(e) Generator output low or nil
1 Belt broken or slipping
2 Regulator unit out of adjustment
3 Worn bearings, loose pole pieces
4 Commutator worn, burned or shorted
5 Armature shaft bent or worn
6 Insulation proud between commutator segments
7 Brushes sticking, springs weak or broken
8 Field coil wires shorted, broken or burned
( f ) Starter motor lacks power or will not operate
1 Battery discharged, loose cable connections
2 Starter pinion jammed in mesh with flywheel gear
3 Starter switch faulty
4 Brushes worn or sticking, heads detached or shorting
5 Commutator dirty or worn
6 Starter shaft bent
7 Engine abnormally stiff
(g) Starter motor inoperative
1 Check 1 in (f)
2 Armature or field coils faulty

(h) Starter motor rough or noisy
1 Mounting bolts loose
2 Damaged pinion or flywheel gear teeth
( i ) Lamps inoperative or erratic
1 Battery low, bulbs burned out
2 Faulty earthing of lamps or battery
3 Lighting switch faulty, loose or broken wiring
connections
F500
125
(j) Wiper motor sluggish, taking high current
1 Faulty armature
2 Bearings out of alignment
3 Commutator dirty or short-circuited
(k) Wiper motor operates but does not drive
arms
1 Gearbox components worn