height adjustment FIAT 500 1971 1.G Workshop Manual

FIG 2:5 Starting device (choke) diagrammatic section
KeytoFig2:5 A Device fully inserted B Device partially inserted C Device disinserted 2 Air inlet 16 Bowl
19 Throttle 21 Primary venturi 24 Secondary venturi 26 Mixture duct 27 Mixture leaning air orifice
28 Transition duct 29 Transition mixture orifice 30 Starting mixture orifice 31 Transition orifice
32 Starting mixture orifice 33 Starting valve 34 Mixture duct 35 Starting device air orifices 36 Rocker
37 Lever return spring 38 Starting device control lever 39 Control wire screw 40 Cover with support for starting
device control bowden 41 Starting valve spring 42 Spring casing. 43 Starting jet emulsion air orifice
44 Air emulsion reserve well orifice 45 Starting reserve well 46 Starting jet
F50037
FIG 2 : 4 Diagrammatic section of Weber 26.IMB
carburetter
KeytoFig2:4 1 Air corrector jet 2 Air inlet
3 Idle speed mixture duct 4 Idle speed jet holder
5 Idle speed air orifice 6 Filter cover 7 Filter
8 Fuel inlet connection 9 Needle valve seat 10 Needle
11 Float pivot 12 Float 13 Idle speed jet
14 Main jet holder 15 Main jet 16 Bowl
17 Idle speed mixture adjustment screw 18 Idle speed
mixture orifice 19 Throttle 20 Transition hole
21 Primary venturi (not interchangeable) 22 Emulsion
orifices 23 Emulsion well 24 Secondary venturi
(not interchangeable) 25 Main nozzle
design with a 1.0236 inch diameter throat measured at the
height of the throttle shaft. The amount of charge passing
to the manifold is controlled by a throttle butterfly valve
from an accelerator pedal operating a lever secured to the
throttle valve shaft via a cable. The carburetter is fitted with
a progressive action starting device which enables the
driver to suit the mixture richness to the most arduous of
starting conditions, and will enable the engine to run
evenly until it reaches its normal operating temperature.
A dampened needle valve ensures a smooth running
engine as it is not affected by engine vibrations and there-
fore giving a constant fuel level in the carburetter bowl. A
secondary venturi is incorporated in the single casting of
the carburetter body and this has a diameter of 0.8268 inch.
Carburetter operation:
Filtered air flows through the venturi 24 (see FIG 2 :4)
where it mixes w i t h fuel flowing from the nozzle 25 and
the charge is then conveyed to the cylinders through the
primary venturi 21 and throat, where the throttle butterfly
19 controls the amount of charge.
Petrol flows from the main fuel line to the bowl 16
through a gauze filter 7 and needle valve 10, where the
float 12 pivoting at point 1 1 , controls the opening of the
needle 10 so maintaining a constant fuel level. From the
bowl 16 fuel reaches the emulsion well 23 via the metered
main jet 15 where, after having been mixed with the air
coming from the metered air corrector screw 1, through
the emulsion orifices 22 and spray nozzle 25, it finally
reaches the Venturis where it mixes w i t h the air stream

FIG 5:2 Clutch components (new 500, 500D sedan and early station wagon) DRIVEN PLATE
PRESSURE PLATE
LEVER CARRIER LEVER BOLTSBOLT NUTS PRESSURE SPRINGSWITHDRAWAL LEVERS CLUTCH COVER
LEVER CARRIER RING
SPRING
WASHER
FIG 5:3 Clutch assembly installed on engine (new
500, 500D sedan and early station wagon)
61
F500
To check the correct operation of the clutch cover 500 sedan (110.F) late 500 station wagon :
Inspection—diaphragm clutch: 5 Finally tighten down the cover assembly using the three
T-handles and adjust the clearance between the carrier
ring and its central shoulder by means of the three
adjustment nuts.setting the withdrawal levers stroke to
0039 inch. Check this adjustment using Fiat gauge
C.110 and when correct lock the adjustment nuts by
peining to the lever bolts.
500D sedan and early station wagon:
To assemble the clutch cover assembly proceed as
described above but adjust the withdrawal levers as
follows:
1 Secure the clutch cover assembly to Fiat fixture A.62038
with a ring .5413 to .5433 inch thick placed between
the clutch cover plate and the pressure plate.
2 Adjust the height of the three withdrawal levers so that
the lever tips are 1.9094 inch from the face of the Fiat
supporting plate.

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 10:9 Brake fluid reservoir
Key to Fig 1 0 : 9 1 Reservoir 2 Strainer 3 Cap, vented
PARKING BRAKE CONTROL CABLE AND SHEATH
.CABLE ADJUSTING NUTS
SHOE OPERATING LEVER
LEVER RETURN SPRING
FIG 10:10 Parking brake control and adjusting mech-
anism at lefthand side rear wheel
Inspect the surfaces of the plungers and the cylinder
bore. If there is any roughness, scoring or corrosion the
assembly should be renewed. Check that the reaction
spring and thrust washers are not corroded or distorted,
renewing any defective parts.
Reassembling wheel cylinders:
Clean the metal parts thoroughly and dry off any
solvent used. The rubber parts should be renewed auto-
matically when servicing the cylinder. Wet the internal
parts w i t h clean brake f l u i d and reassemble them in the
order shown in FIG 10 : 8 .
10810:7 Self-adjusting device
The new 500 Sedan is equipped with a specially
designed brake shoe clearance self-adjusting device
which eliminates all need for manual adjustment during
service.
Operation:
On either side face of the brake shoe rim are placed t w o
friction washers in line with an adjustment slot which is
machined into the brake shoe (see FIG 10:6). The
friction washers are held against the shoe by a pin and
bush screw together through the slot with a strong
spring in between. The hollow pin fits onto the stud in the
brake housing flange. A clearance of .0315 inch between
the pin hole and stud permits the necessary movement of
the shoes to ensure proper braking under normal
operating conditions. On later models the self-adjuster
assembly is held together by a circlip.
When the shoe clearance adjustment is no longer
correct, the braking action will overcome the resistance of
the friction washers and drag along the shoes into contact
with the drum. Once the brake pedal has been released,
the action of the return springs will be weaker than the
friction of the adjustment washers on the shoes and so
the shoes will remain in the new position taken up. As
further wear of the linings occurs the shoes will again
automatically be repositioned by the device.
Inspection and assembly:
During normal brake overhaul all the components of
the self-adjusting device should be thoroughly checked
and any parts badly worn or damaged must be renewed.
Before reassembly it is advisable to check the spring
rating using Fiat tester A.11493 by
compressing the
spring to a height of .374 inch which should give a
corresponding load reading of 97 ± 4.9 Ib. To re-
assemble the device after testing proceed as follows:
1 Place the pin of the self-adjusting device on support
A.54002/2 and insert first the friction washer followed
by the shoe, the second friction washer, the load spring
and the bushings.
2 Fit wrench A.54002/1 onto the support and by
exerting a slight pressure to overcome the spring load
fully tighten the bush onto the pin. Lock the pin and
bushing using a centre punch. Alternatively, fit the
circlip.
3 Install the shoes onto the brake housing flange and
hook up the t w o return springs. Move the shoes out-
wards as far as they will go and release them. Check
that during the return of the shoes the friction washers
have stayed in their new position.
10:8 Removing a flexible hose
Never try to release a flexible hose by turning the ends
w i t h a spanner. The correct procedure is as follows:
Unscrew the metal pipeline union nut from its con-
nection with the hose. Hold the adjacent hexagon on the
hose w i t h a spanner and remove the locknut which
secures the hose to the brackets. The hose can now be
turned without twisting the flexible part, by using a
spanner on the hexagon at the other end.
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