1972 FIAT 500 starter

TOOL A 62039
TOOLA. 62040 PIN WRENCH A. 52022
FIG 6:15 Adjusting ring gear-to-pinion backlash and
differential bearing play, using special wrench A.52022
reading on the dial gauge should be between .0031 to
.0047 inch. The actual clearance is adjusted by
screwing in one adjusting nut and screwing out the
other by the equivalent amount using Fiat spanner
A.52022 as shown in FIG 6:15.
4 Remove Fiat tool A.62041 and using Fiat support
A.62040 mount the special dynamometer A.95697 and
adaptor on the axle shaft. Rotate the axle shaft several
turns so seating the bearings and then check using
the dynamometer the rotation torque.
5 If necessary tighten or slacken the adjusters until the
specified torque of 1.01 ± .07 lb ft is obtained. This
operation must be very carefully carried out because if
one adjuster is set differently with respect to the other,
a variation in ring gear to pinion backlash may take
place, resulting in a variation of rotation torque. After
any adjustments always recheck on the ring gear to
pinion backlash and if necessary readjust and then
repeat the rotation torque check.
6 Finally check the tooth contact between the pinion
and ring gear as detailed in the following instructions:
Check and adjustment of tooth contact between
pinion and ring gear:
1 Carefully apply to the ring gear teeth a thin layer of
engineers' blue and gently rotate the differential whilst
holding the axle shaft firmly but allowing them to slip
slightly so as to have the unit working under load
conditions.
2 A contact impression will be left on the ring gear teeth
and the contact will be correct when the drive pinion
tooth contact pattern is evenly distributed on the ring
gear teeth as shown in FIG 6:16. Should the tooth
contact be incorrect the following observations should
be noted.
Excessive contact on tooth flank. Too deep
meshing — move pinion out from ring gear by reducing
thickness of shim.
Excessive contact on tooth heel. Too slight
meshing—move pinion in towards ring gear by
increasing thickness of shim.
74
6 : 8 Replacement of gearbox—differential unit
Installation is the reverse procedure to removal of the
unit from the vehicle as described in Section 6:2.
However, the following points should be noted:
1 Ensure that the clutch driven disc hub is correctly
aligned with the clutch shaft pilot bush.
2 The complete transmission unit should be carefully
pushed towards the engine and the clutch shaft
inserted into the driven disc hub splines and finally
home into the pilot bush. Extreme care must be taken
to ensure that no weight is placed on the clutch shaft
otherwise distortion may take place.
3 Carefully connect the gearbox rear housing to the
engine crankcase by using the studs, t w o of which
have special location dowels fitted. Screw home
finger tight the gearbox/differential to body to front
support mounting screws inserting the fibre washers.
Lower the hydraulic garage jack and pull it away from
underneath the vehicle. Screw in the four lower
mounting nuts and tighten to a torque wrench setting
of between 18.1 to 21.7 Ib f t.Finally tighten the front
support screws.
4 Reconnect the gear shift control rod and the speedo-
meter drive cable. Insert the springs between the axle
shafts and wheel drive shaft and tighten the
three
mounting screws of each splined sleeve on the
flexible joint to a torque wrench setting of 20.3 Ib ft.
5 Refit the flywheel housing cover. Replace the starter
motor together with its relevant cover and tighten the
two mounting nuts to a torque wrench setting of
18.1 to 21.7 Ib ft. Reconnect the starter control rod,
the t w o starter cables, the clutch control tie rod and
hook up the return spring and secure the clutch
control cable retainer bracket to the gearbox casings.
Reconnect the cable to the battery positive terminal
post
6 Lower the vehicle to the floor gently and then give a
thorough road testing.
6 :9 Swing axle shafts and slip joints
Description:
The t w o axle shafts are connected to the differential
unit through specially designed slip joints which allow
the shafts to swing and slide in the splined housing in
the differential side gear. At the other end, the axle shafts
are connected to the wheel drive shaft flexible joints
using a sliding sleeve. Excessive contact on tooth face. Too slight
meshing—move pinion in towards ring gear by in-
creasing thickness of shim.
Excessive contact of tooth toe. Too deep meshing
—move pinion out from ring gear by reducing thickness
of shim.
With all the above detailed cases, to adjust the pinion
by replacing the shim, the differential unit and drive
pinion shaft must be dismantled. This means that when
the unit is reassembled after the necessary adjustments
have been made, the backlash and bearing rotation
torque must be repeated.

CHAPTER 11
THE ELECTRICAL EQUIPMENT
11:1 Description
11:2 Battery
11:3 The generator
11:4 The starter
11:5 The control box
1 1 : 6 Fuses
1 1 : 7 Flasher unit
11:1 Description
All models covered by this manual have 12 volts
electrical systems in which the negative battery terminal
is earthed. There are three units in the regulator box to
control the charging circuit; a cut-out, a current regulator
and a voltage regulator. These are adjustable but it must
be stressed that accurate moving coil meters are required
when checking or altering the settings. Cheap and
unreliable instruments will make accurate adjustments
impossible.
There are wiring diagrams in Technical Data at the end
of this manual to enable those with electrical experience
to trace and correct wiring faults.
For t h e U.K. Market the headlamps are of the double
filament dipping renewable bulb type with adjustments
for individual beam settings.
The battery is located in the front compartment
forward of the petrol tank and the fuses to the rear o f the
petrol tank.
Detailed instructions for servicing the electrical equip-
ment will be found in this chapter, but it must be pointed
out that it is not sensible to try to repair that which is
seriously defective, electrically or mechanically. Such
equipment should be replaced by new units which can
be obtained on an exchange basis.
F500111
11 :8 Windscreen wipers
1 1 : 9 The lighting system
11:10 Panel and warning lights
11:11 The horn
11:12 Lighting and flasher switch
1 1 : 1 3 Fault diagnosis
11.2 The battery
This of the 12-volt lead/acid type and has to meet
heavy demands for current particularly in the winter. To
maintain the performance of the battery at its maximum
it is essential to carry out the following operations.
Keep the top of the battery and surrounding parts dry
and clean, as dampness can cause leakage between the
securing clamps and the battery terminals. Clean off any
corrosion from the metal parts of the battery mounting
with diluted ammonia and paint them with an anti-
sulphuric paint. If the terminal posts are corroded,
remove the cables and clean w i t h diluted ammonia.
Smear the posts w i t h petroleum jelly before remaking the
connections and fit the terminals securely. High electrical
resistance due to corrosion at the terminal posts is often
responsible for lack of sufficient current to operate the
starter motor.
Ensure t h a t the filler plugs are in good condition and
show no signs of cracks. This may cause leakage of
electrolyte and consequent corrosion. Test the condition
of the cells after topping-up the electrolyte level with
distilled water to just above the tops of the separators as
shown in FIG 11 :2 . Never add neat acid. If it is
necessary to make a new electrolyte due to loss by
spillage add sulphuric acid to the
distilled water.
It is highly dangerous to add water to acid.

1
791011 8 234
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

4
53 2 1
7
6
FIG 11 :6 Regulator assembly GN 1.12.16
Key to Fig 11:6 1 Voltage regulator adjusting spring
2 Current regulator adjusting spring 3 Cutout adjusting
spring 4 Voltage regulator adjustment arm 5 Current
regulator adjustment arm 6 Cutout adjustment blade spring
7 Soldering of cutout shunt and series winding
FIG 11:7 Wiring diagram for checking the cutout
closing voltage
Key to Fig 1 1 : 7 GR Regulator GN 1.12.16 G Generator
FIAT DSV 90.12.1 6.3 S V Voltmeter, 20 V scale (0.5%
accuracy) L 12 V, 3 to 5 W bulb
FIG 11:8 Wiring diagram for checking the reverse
current of cutout
Key to Fig 11:8 GR Regulator GN 1.1 2.1 6 G Generator
FIAT DSV 90.1 2.1 6.3 S B Battery, 50 Ah, fully charged
A Ammeter, asymmetrical scale 10-0-15 A V Voltmeter,
20 V scale (0.5% accuracy)
116spring 13. Should any defect be found then the pinion
assembly must be renewed as one complete unit. After
examining to ensure that there are no defects thoroughly
clean using petrol.
Reassembling and refitting the starter:
In both cases this is a simple reversal of the dismantling
procedure. Grease t h e drive splines and the engagement
lever groove in the sleeve.
11:5 The control box:
Description:
The generator regulator fitted to the new 500 model
consists of three separate
units; voltage regulator,
current regulator, cut-out relay (see FIG 11 :6).
The voltage regulator and current regulator relays
comprise a U-shaped body one of whose arms is bent
to form a flange, whilst the other adjustment arm pro-
vides a stop for the hinge spring. The U-shaped body is
secured to the frame by the core threaded shank and
carries, on the flanged end, an armature supported by a
hinge spring which comprises a steel leaf and bi-metal
leaf overimposed in the current regulator and bi-metal
leaf in the voltage regulator. The armature carries the
movable contact.
Fixed contacts of both voltage and current regulators
are mounted on t w o blade springs which are secured to a
single bracket rivetted to the U-shaped adjustment arm.
The design of the t w o fixed contacts carrier blade springs
is such as to permit the adjustment of the contact
position by suitably bending the blade springs. The cut-
out is similar in design to the other two relays as shown
in FIG 11:6. Again the hinge spring is bi-metallic as in
the voltage regulator.
All the armatures are provided w i t h blade springs, so
that the tension may be adjusted to the required setting
value. This adjustment is obtained by bending the
adjustment arms.
The voltage regulator coil comprises a fine wire wind-
ing w i t h a great number of turns, shunt connected to the
generator.
The cut-out coil comprises a fine wire winding with a
great number of turns shunt connected to the generator,
and of a winding comprising a few turns of heavy gauge
wire, which is connected in series w i t h the generator
charge circuit (cut-out series winding).
The current regulator coil comprises a few turns of
heavy gauge wire which is series connected with the
generator charge circuit.
The generator regulator base has three terminals to
which the various cables are connected.
No. 51 — connection to generator positive terminal.
No. 67 — connection to generator field winding.
No. 30 — connection to electrical accessories.
The regulator cover is secured to the base w i t h a
rubber gasket placed in between which seals the unit
against the ingress of moisture or dust.
A regulation resistor is fitted under the base and is
secured to the voltage regulator and current regulator
relay core threaded shanks.

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