1973 FIAT 500 Wheels

CHAPTER 1
THE ENGINE
1 :1
1 :2
1 :3
1 :4
1 :5
1 :6
1 :7
1 :8
1:9
1 :10
1 :11Description
Engine removal (sedan—all versions)
Engine removal (station wagon)
Engine disassembly (sedan—all versions)
Engine disassembly (station wagon)
Cylinder head removal, servicing and
replacement
Timing gear overhaul
Crankcase and cylinders
Piston assembly
Connecting rods
Crankshaft and main bearings
1 :1 Description
The 'New 500' two-cylinder aircooled engine operates
on the four-stroke 'Otto Cycle' and is fitted directly to
the transmission unit which incorporates the rear drive
assembly as shown in FIG 1 :1 and FIG 1 :2.
With the power unit fitted at the rear several advantages
are obtained including better load distribution to the
wheels when the vehicle is loaded, elimination of propeller
shaft reducing the size of centre tunnel and better use of
available space.
The cylinder block comprises t w o cast iron cylinder
barrels w i t h cooling fins. The bottom of the cylinders fit
into machined seats in the aluminium crankcase.
The aluminium crankcase carries eight studs on which
are located the t w o cylinder barrels w i t h the aluminium
cylinder head on the top.
A two bush crankshaft of special cast iron is fitted into
the lower half of the crankcase. The crankshaft is
F5009 provided with a counterweight and is hollow to allow for
lubrication.
The steel connecting rods have thin wall bearing halves
on the big-end, and bronze bushes in the small-end. The
offset piston pin is of steel and retained in the piston by
two circlips.
Light alloy pistons are used and are of the taper-oval-
shaped type with a maximum diameter at the base of the
skirt, along an axis perpendicular to the piston pin. Pistons
are fitted with four rings as follows, one compression at
the top, two standard oil scraper rings and one side slotted
oil scraper ring.
The one-piece aluminium cylinder head is finned to
provide a larger cooling surface and carries the inlet and
exhaust manifolds.
The inlet passages merge into a single centralized
flange onto which is mounted the carburetter. The exhaust
passages run almost parallel to the axis of the engine. 1 :12
1 :13
1 :14
1 :15
1 :16
1 :17
1 :18
1 :19
1 :20
1 :21
1 :22Flywheel and starter ring gear
The oil pump
Lubrication, oil filter, relief valve
Valve timing
Valve stem to rocker clearance
Engine assembly (sedan—all versions)
Engine assembly (station wagon)
Power plant mounting
Adjustment of generator and fan belt drive
Modifications
Fault diagnosis

CHAPTER 6
GEARBOX AND DIFFERENTIAL UNIT
6:1
6:2
6:3
6:4
6:5
6:6Description
Removal of gearbox/differential unit
Dismantling — gearbox
Reassembly — gearbox
Dismantling — differential and final drive
Reassembly— differential and final drive6:7
6:8
6:9
6:10
6:11
6:12Final drive gear set adjustment
Replacement of gearbox/differential unit
Swing axle shafts and slip joints
Gear shift control mechanism
Modifications
Fault diagnosis
6 :1 Description
The gearbox and differential unit are housed in an
aluminium alloy casing made up of t w o parts which split
at the differential centre line. The output drive is trans-
mitted by means of t w o half axle drive shafts coupled
through wheel shafts and slip joints to the rear wheels (see
FIG 6 : 1)
The gearbox provides four forward-speeds and a reverse,
the fourth-speed being considered as an overdrive. All
gears except first and reverse gears, which are straight
toothed sliding gears, are in constant mesh and have heli-
cal teeth. No synchromesh is provided, gear engagement
being completed by sliding shifter sleeves of the dog
clutch type. The first-speed gear slides on the outside of
the third and fourth shifter sleeve, whilst the reverse gear
train moves on a fixed shaft. The clutch shaft is integral
with the third, top and combined and first and second gear
pinions, whilst the second gear pinion is splined at the
front end. An internal splined
coupling sleeve joins the
clutch shaft and the input shaft and transmits the power
from the engine to the gearbox. The mainshaft and
differential drive pinion are combined together and besides
carrying the constant mesh gears and the sliding first gear
pinion, it also has attached the sliding sleeves and hubs.
F50065 The speedometer drive pinion is located at the front end.
The gearbox/differential casing is attached to the engine
by six studs which locate in the crankcase. The front of the
unit rests upon the rubber mounted support which is
secured to the body floor.
The complete unit comprises three detachable parts
made up as follows:
1 The support for the connection of the gearbox to the
engine which also acts as part of the differential front
end and clutch/flywheel housing at rear.
2 A central body which is divided into two compartments.
The front compartment contains first, third, fourth and
reverse gears w i t h the primary shaft, layshaft and reverse
shaft as well as the necessary gear selection striker rods
and forks. The rear of this compartment also forms a half
cover for the differential unit.
3 The gearbox casing cover, which contains the second-
speed gears together with the relative fork, gear
selection rod and speedometer drive gears.
The central part of the casing is provided with a top
inspection cover. The primary shaft is coupled to the clutch
shaft through an internally splined sleeve and t w o pins
which are retained by rings. The primary shaft together
with the first, third and fourth driving gears form a cluster.

CHAPTER 7
REAR SUSPENSION AND WHEELS
7:1
7:2
7:3
7:4Description
Removal of rear suspension assembly
Servicing swinging arms
Coil springs
7:1 Description
The rear wheels are independently sprung by means of
coil springs and V-shaped swinging arms acting on coil
springs and telescopic double acting hydraulic shock
absorbers. The swinging arms are m o u n t e d at their inner
ends on 'estendblocks', the coil spring is fitted at the outer
end of the swinging arm. At the wheel end of the suspen-
sion arm is attached a steel pressing to which the brake
backplate and wheel bearing housing are bolted so
forming a swinging unit to which is attached the road
wheel.
The inner pivots are so located vertical wheel move-
ments do not influence the drive shaft length which
means that there is no need to fit a splined joint at the
wheel end. Two taper roller bearings which are separated
by a specially designed collapsible spacer are located in
the rear wheel bearing housing and this carries the axle
shaft. The outer end of the axle shaft is flanged and it
is to this flange that the brake drum is bolted. The splined
inner end carries a rubber cushioned coupling to which
the drive shaft flange is attached.
7 : 2 Removal of rear suspension assembly
1 Jack-up the vehicle and place on firmly based stands.
Remove the road wheel on the side from which the
suspension unit is to be removed.
F50079 7:5
7:6
7:7
7:8Installation of rear suspension assembly
Checking and adjusting rear wheel toe-in
Modifications
Fault diagnosis
2 Using a garage hydraulic jack support the swinging
arm to facilitate the removal of the upper shock
absorber mounting nut which is located inside the
vehicle on the floor. To gain access to the nut remove
the rear wheel housing linings.
3 Unhook the parking brake shoe control lever return
spring.
4 Remove the three screws securing the drive shaft
flange to the flexible coupling. Pull back the sleeve and
remove the inner spring.
5 Remove the brake fluid reservoir cap, remove the filter
and plug the delivery hole in the brake f l u i d reservoir
and disconnect the flexible brake pipe from the
bracket on the body floor.
6 Disconnect the parking brake control tie rod by first
removing the cotter pin and removing the cable eye
from the pin on the shoe control lever. Release the
cable adjustment nuts and free the cable from the
fairlead on the swinging arm.
7 Using the hydraulic jack carefully lower the swinging
arm, fully retract the shock absorber by pushing in the
outer cylinder and carefully pull out the coil spring
together with its mounting rubber rings.
8 Remove the self-locking nut securing the swinging
arm to the internal support welded on the floor.
Extract the mounting pin and note the number and
arrangement of shims between the bushings and the
bracket. This will facilitate reassembly.

high bearing preload. To reset remove the wheel shaft
and fit a new resilient spacer. Repeat the rotation
torque test.
Swinging arm adjustment:
To adjust the swinging arm use Fiat fixture A.66064 as
shown in FIG 7 : 3 and proceed as follows:
1 At points A and B as indicated in FIG 7 : 4 between the
'estendblock' and the swinging arm to body front
mounting bracket fit three shims on each side. To
ensure that the shims are correctly centred use Fiat
alignment bar A.66057.
2 Whilst removing the alignment bar, carefully slip in the
mounting pin and screw on the nut. Once the rear
wheel geometry adjustment has been completed this
nut should be tightened to a torque wrench setting
of 43.4 to 50.6 Ib ft.
3 At points C and D (see FIG 7 : 4) , insert the number of
shims required to fill in the gap between the 'estend-
block' and the two fixture shoulders. Having deter-
mined the number of shims required both at locations
C and D, these must later be fitted between the
'estendblock' and the shoulders on the swinging arm
to body mounting bracket.
7 : 4 Coil springs
The coil springs should be thoroughly cleaned and all
traces of rust removed. Inspect the spring coils for hair
line cracks, which if evident, a new pair of springs must
be fitted to ensure correct vehicle height and stability.
Check the free
height and the height under loading of
the coil springs and these must correspond to the figures
quoted in Technical Data.
7:5 Installation of rear suspension assembly
To replace the rear suspension assembly proceed as
follows:
1 Insert the swinging arm inner end in the mounting
bracket which is welded onto the body floor. Place
between the 'estendblock' and bracket the number of
adjustment shims as previously determined using Fiat
fixture A.66064 as shown in FIG 7 : 4. Insert the Fiat
alignment bar A.66057 through 'estendblock' and
shims, aligning them with the holes in the mounting
bracket. Firmly hold the entire assembly using a garage
hydraulic jack if necessary, and carefully remove the
alignment bar and at the same time ease in t h e
mounting pin. Secure the nut which once the rear
wheels geometry has been checked must be tightened
to a torque wrench setting of 43.4 to 50.6 Ib/ft.
2 Screw in finger tight the three swinging arm external
bracket to body floor mounting screws together w i t h
the plain and spring washers. The screws will have to
be tightened to a torque wrench setting of 28.9 to
36.2 Ib/ft once the rear wheel geometry has been
adjusted.
3 Carefully insert the coil spring, lower insulator ring
onto the swinging arm, insert the spring on the shock
absorber which should be previously secured to the
arm and position the spring onto its seat on the arm.
Place the upper insulator ring onto the spring, raise the
suspension assembly using a garage hydraulic jack and
insert the spring onto its seating under the body floor.
F50083 4 Ensure that the shock absorber to floor rubber ring has
been correctly fitted and extend the shock absorber
until its upper mounting pin protrudes into the vehicle
through the hump in the floor panel. Secure the shock
absorber by its mounting nut and lockwasher having
first inserted the rubber ring and plain washer.
5 Refit the rear wheel housing in place, reconnect the
brake line to the connection on body floor and remove
the plug from the output hole in the brake fluid
reservoir. Bleed the hydraulic brake system as
described in Chapter 10.
Key to Fig 7:8 k Distance of centre rear bracket, for
jacking up the vehicle, from floor level (8.90 inch)
Half-track = 22.264 inch ±.059 inch
FIG 7 : 8 Position of rear suspension f o r rear wheel
toe-in inspection and adjustment ('500 Station Wagon') FIG 7 : 7 Adjusting rear wheel toe-in angle
Key to Fig 7 : 7 Rear wheel plane must be perpendicular to
ground and parallel to car longitudinal centerline with a
tolerance of 0° 10'
To adjust rear wheel geometry, move suitably the swinging arm
outer support. Slight movements are permitted by the play
existing between the support holes A and the mounting screws.
Screws B must be tightened to 28.9 to 36.2 Ibft (4000 to 5000
kg mm). Nuts C must be tightened to 43.4 to 50.6 Ib ft (6000
to 7000 kgmm), after adjustment has been carried out. (These
directions and specifications are also applicable to 500 Station
Wagon).

FIG 7:9 Adjusting rear wheel toe-in on '500 StationWagon'
FIG 7:10 Checking left rear wheel toe-in
84
6 Insert the inner spring between the axle shaft and the
wheel shaft and couple the spline sleeve to the joint
and tighten the screws to a torque wrench setting of
20.3 Ib/ft.
7 Reconnect the parking brake tie rod and adjust the
position of the cable using the two stretchers.
8 Refit the wheels and draw up the mounting screws to
a torque wrench setting of 32.5 to 39.8 Ib/ft. Carefully
lower the vehicle to the floor.
7 :6 Checking and adjusting rear wheel toe-in
This check should be carried out by a Fiat agent as
special setting equipment is necessary. However, details
of this check are given for reference purposes:
To check and adjust the rear wheel geometry proceed
as follows:
1 Place the vehicle on firmly based stands and remove
the front and rear wheels.
2 Install Fiat fixtures A.66062 as shown in FIG 7:12 to
enable correct spring compression and wheel location
in the vertical position.
3 Lift the rear suspensions by compressing the coil
springs and shock absorbers using garage hydraulic
jacks. Screw on the fixture lower shank until the
index registers with the mark 'Nuova 500' stamped on
the bracket. In this position the wheel plane is vertical
and the centre O (see FIG 7 : 6) of wheel shaft results
at 5.00 inch from the buffer stop bracket.
4 Secure Fiat support C.696/3 to the wheel drum and
connect gauge C.696 to the support. Tighten the two
clamping screws as shown in FIG 7:12.
5 Apply at the front of Fiat gauge C.696 bracket
numbered C.696/3 as shown in FIG 7:11.
6 Check that the pin mounted on the front end of the
bracket C.696/3 is in touch with the front suspension
swinging arm pin (see FIG 7:11). If these conditions
are not complied with, proceed with item 7.
Wheel toe-in angle
will vary by 0° 10' under
a movement of some 7/32 inch measured at 72.476 inch
from wheel centre for Model 500D, and at 76.413 inch
from wheel centre for 500 Station Wagon NOTE - - that the toe-in angle
Key to Fig 7 : 9 A Front support B Screw holes for
fixing support to underbody C Swinging arm pin nuts

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

CHAPTER 8
FRONT SUSPENSION AND HUBS
8:1
8:2
8:3
8:4
8:5
8:6Description
Front suspension removal and dismantling
Leaf spring
Swinging arms
Kingpin housing
Steering knuckle and wheel hub
8:1 Description
The independent front suspension assembly fitted to
the 'new 500' range comprises a transverse leaf spring
which is anchored to the body through two rubber
mountings and kingpins through 'estendblocks' as
shown in FIG 8:1. The leaf spring also acts as an anti-
roll bar which gives normal spring reaction even when the
front road wheels encounter a rough road surface.
Special polyethylene insulating strips are fitted
between the five springs leaves which are all clamped
together by t w o rubber cushioned clamps.
Upper movement of the kingpins in the swinging arm
is obtained by 'estendblocks'. The half arms are anchored
to the body as shown in FIG 8 : 3 and pivot on their pins
through rubber bushes. Double acting hydraulic shock
absorbers are fitted to the kingpin housings at the lower
end and anchored at the top to the vehicle body. Two
rubber buffers are secured to brackets mounted onto the
body to limit the spring oscillations. The spring centre
bolt is also fitted with a rubber pad.
8 : 2 Front suspension removal and
dismantling
To remove the front suspension assembly proceed as
follows:
F50087
1 Remove the hub caps 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 Disconnect the steering linkages from the pitman arm,
the drag link and the steering knuckle arms.
3 Remove the shock absorber upper mounting nut from
the body, lift away the half rubber bush and push d o w n
the outer cylinder.
4 Blank off the brake fluid reservoir outlet by inserting
a suitable wooden peg through the reservoir filler
opening and disconnect the brake hydraulic lines at
the wheel cylinders.
5 Fit Fiat crossbeam Arr.2072 under the leaf spring
and support this, using a garage hydraulic jack.
6 Remove the self-locking nut securing the leaf spring
to the kingpin housing and ease o u t the spring
mounting bolt taking care not to damage the thread.
Also remove the nuts securing the swinging arm pin
to studs on the body and remove the swinging arm
assembly. Carefully lift out the adjusting shims and
spacers from the studs making a careful note of the
number of the shims and their locations.
7 Remove the nuts securing the leaf spring elastic
mounting to the body (see FIG 8 : 4) , and lower the 8:7
8:8
8:9
8:10
8:11Hydraulic damper
Front suspension assembly and
installation
Steering geometry
Modifications
Fault diagnosis

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