Rear seat FIAT 500 1972 1.G User Guide

FIG 6:7 Differential components
Key toFig 6:7 1 Axle shafts 2 Sleeve retainment lockrings 3 Slip joint casings 4 Axle shaft-to-wheel shaft
coupling sleeve 5 Differential case cover w i t h bearing inner race 6 Side gears 7 Oil boot retainment cover
8 Side gear thrust ring 9 Idle pinion shaft 10 Idle pinions 11 Oil boots 12 Differential case w i t h bearing inner race
13 Adjuster retainment ring 14 Bearing housings with retaining nuts and outer races 15 Idle pinion shaft retainment cup
1 6 Bevel gear
withdraw the layshaft together w i t h the final drive
pinion and the roller bearing inner race from the rear.
11 From the inside of the gearbox casing carefully slide off
the following parts from the mainshaft, the drive
pinion adjustment shim, the third and fourth driven
speed gears together with their bushes, the t hird- and
fourth-speed hub and sliding sleeve, the first and
reverse driven gear, and carefully drive out the front
bearings and the bevel pinion rear bearing outer race.
1 2 Using a suitable press, drive out the drive pinion roller
bearing inner race from the end of the mainshaft.
Inspection of components:
Before inspecting the various parts removed from the
gearbox casing thoroughly wash all components and
blow dry using a compressed air jet and then proceed as
follows:
1 Thoroughly inspect the gearbox casing to ensure that it
is not cracked and that the bearing seats are neither
F50069 worn or damaged so allowing the bearing outer ring
to rotate during the normal operation.
2 Thoroughly check the ballbearings to ensure that they
are in perfect condition and that both radial ply and
axial play is not excessive. The maximum permissible
bearing play is as follows:
Front bearings of primary shaft layshaft:
(a) Sideways .002 inch
(b) Endwise .017 inch
Primary shaft rear bearing:
(a) Sideways .002 inch
(b) Endwise .016 inch
Hold the bearings firmly by the outer race and gently
rock the inner race backwards and forwards. The sliding
action produced should be free and silent. If any rough-
ness is felt then the bearings must be renewed. Check
the roller bearings by inspecting the condition of the
rollers as well as the outer and inner races. Always fit
new bearings if there is any doubt as to their efficiency.

3 Check the layshaft and the primary shaft between
centres and using a dial gauge ensure that there is no
distortion. The out of true reading for bearing seats
should be less than .0008 inch. Inspect the splines and
ensure that the side and outerfaces are not indented.
Replace if there are signs of wear. Also inspect the
reverse shaft to ensure that it is perfectly smooth and
not showing signs of pitting or partial seizure.
4 Carefully inspect all gear teeth for signs of excessive
wear or damage. The contact faces must be smooth and
show no signs of indentation marks. Also check that
the backlash between the gears, when correctly
mounted on the surface plate is not greater than .0039
inch. The maximum wear limit is .0079 inch. Check that
the quick engagement front teeth of the second-, third-
and fourth-speed gears are not damaged or excessively
worn. Renew if there are signs of gearchange lever
misuse.
5 Inspect the sliding sleeves and the relevent hubs, ensure
that all the working surfaces are perfectly smooth. The
clearance between the mating parts should not be
greater than .0059 inch. Also inspect the meshing teeth
and ensure that they are in good condition.
6 Check that the gear shifting selector forks are not dis-
torted and that the striker rods freely slide in their seats
in the gearbox casing.
7 Carefully inspect that all the oil seals are in perfect con-
dition and if there is any doubt they should be renewed.
8 Inspect the striker rod locking balls and the safety rollers
and ensure that they slide freely in their seatings. Also
check the ball load spring efficiency and if this shows
signs of weakness then it should be renewed. Any
faults with these items will cause difficulty in engaging
gears or autodisengagement during engine acceleration.
6 : 4 Reassembly—gearbox
To reassemble the components to the gearbox ensure
that all components are thoroughly clean and then pro-
ceed as follows:
1 Press t h e pinion rear roller bearing onto the layshaft.
Install the layshaft in the casing, and at the same time
fit the adjustment shim, the fourth-speed driven gear
together w i t h its bush, the sleeve and hub for third and
fourth gear engagement, the first-speed and reverse
driven gear and the third-speed driven gear with its
hub.
2 Install the front layshaft ballbearing securing the
bearing retainment plate w i t h the screws and finally
lock the screws in position.
3 Insert the primary shaft together with the first, third
and fourth driving gear train in the gearbox housing
and slide t h e rear bearing onto the shaft. Push the
input shaft forward to enable the clutch shaft coupling
to be inserted in t h e rear and to be pulled up the
primary shaft by means of the pin. Do not forget the
retaining ring.
4 Slide the primary shaft backwards so pushing the rear
bearing into its bore. Refit the front bearing onto the
primary shaft.
5 On the layshaft insert the second-speed driven shaft
and bush, the second gear sliding dog sleeve and the
hub. Also insert the second-speed striker rod and the
first-speed fork. Do not forget to fit the safety roller
into its seating.
70
6 Slide the second-speed driving gear onto the primary
shaft. Place the engagement fork on the third- and
fourth-speed engagement sliding sleeve, and insert
the striker rod, lock the relevent fork and fit the safety
roller.
7 Insert the third safety roller and install the reverse shaft
and insert the reverse gear cluster onto it and secure
the shaft by tightening its block bolt. Install the reverse
striker rod w i t h its relevent fork.
8 Now refit the speedometer drive worm gear onto the
layshraft. Tighten the nuts on the primary shaft and the
layshaft, not forgetting to interpose the plain washer
between the speedometer driving worm and the nut,
to a torque wrench setting of 1 8.1 Ib ft to 25.3 Ib ft
(primary shaft) and 28.9 to 36.2 Ib ft (layshaft). It is
recommended that the input shaft and layshaft are
locked together by engaging t w o gears at the same
time. Finally, fit the splitpins.
9 Lock the shifter forks onto their shafts by tightening
their respective bolts and bend up the special locking
plates. Install the three positioning balls and relevant
springs into their bores and refit the cover plate.
10 Install the casing cover together with its relevant
gasket. This will enable correct positioning of the shift
shaft lever so that it engages in the outer ends of the
shifter shafts protruding from the gearbox casing.
11 Install the speedometer drive support on the gearbox
casing and refit the upper gearbox cover.
For subsequent differential operations and adjustments
see Sections 6:6.
6:5 Dismantling—differential and final drive
For the removal of the differential and final drive unit
from the gearbox refer to Section 6:3. To dismantle the
differential assembly
proceed as follows:
1 Remove the retaining ring 2 (see FIG 6 : 7) retaining
the splined sleeve 4 and slide the sleeve off the drive
shaft.
2 Remove t h e retaining covers 7 and the oil boots all
together with the bushes and seals, adjuster ring lock
rings 13, adjuster rings housing 14, and bearing
adjuster and roller bearing outer races.
3 Separate the differential housing halves by unscrewing
and removing the six bolts that keep both the halves and
the crownwheel together. It is advisable to mark the
respective components to ensure correct matching
upon reassembly.
4 Remove the differential pinion shaft retainer ring, also
the differential pinions 10 by removing the shaft and
withdrawing the two axle shafts 1.
5 Remove the differential side gears 6 and relevent thrust
rings 8.
6 Using a press remove the differential bearing inner
races from their seats on the carrier halves.
7 Thoroughly clean all parts and dry using a compressed
air jet.
Inspection:
The components of the differential unit must be
thoroughly inspected for correct operation and to deter-
mine the presence of any wear, damage or other irregulari-
ties. To check the items concerned proceed as follows:
1 Check thoroughly the idle pinion carrier shaft for signs

of wear, distorting or unevenness of the surfaces as this
part is very heavily pressed when the vehicle is negotia-
ting a corner. If the clearance to the idle pinions exceeds
.0059 inch the shaft must be renewed.
2 Inspect the ring gear and pinion seat, the side gears.and
the idle pinions for correct meshing. This will be shown
up by white marks on the sides of the gear teeth. Check
that none of the teeth are broken, chipped or exces-
sively worn and if any part is suspect then it must be
renewed not forgetting that the ring gear and pinion
come as a matched pair.
3 Inspect the condition of the ball and roller bearings, the
rollers and balls and working faces must not show signs
of pitting wear or cracking and if any part is suspect then
the race must be renewed.
4 Check that there is not any undue wear on the faces of
the thrust rings. Any slight indentations may be evened
out using a fine oil stone but if the damage is excessive
then new rings or oversize rings must befitted as neces-
sary. Thrust rings are supplied as service spares in the
following thicknesses.
Standard .0394 inch
Oversize .0512-.0591 inch
6:6 Reassembly—differential unit
To reassemble the differential case proceed as follows:
1 Press onto the differential half housing which carries
the ring gear one differential bearing inner race ensuring
that it is pushed fully home onto its seating. Install the
thrust ring and side gear (see FIG 6 : 7).
2 From t h e inside of the case insert the axle shaft com-
plete with pivot and runners that form the slip joint.
Also install the idle pinions and carrier shaft. Position
the ring gear onto the housing half and install the
differential pinion shaft retainer ring.
3 Press the other differential bearing inner race onto its
seating on the left differential housing half and replace
the left axle shaft complete with slip joint.
4 J o i n the t w o case halves together and tighten the
retaining screws and also the retaining screws of the
ring gear to a torque wrench setting of 23.1 Ib ft. Secure
all screws by bending up the lockplates.
5 Press t h e differential bearing outer races into their
seatings in the bearing housings and also f i t the o i l seals.
Also install the bearing housings over the driving shafts
together with the adjuster rings.
6 Install the differential unit assembly into the final drive
housing front half and bolt the rear
half onto it. Tighten
the six mounting nuts to a torque wrench setting of
27.5 Ib ft. Finally place the bearing housings in their
seats and tighten the mounting nuts to a torque wrench
setting of 13 lb ft.
It should be noted that after the gearbox has been over-
hauled the complete differential unit should only be in-
stalled after the drive pinion depth adjustments has been
carried out.
6 : 7 Final drive gear set adjustment
The installation and adjustment of the final drive gear
set requires special care otherwise the unit may have to be
dismantled again for further adjustment. So as to establish
the correct mesh of the t w o gears, their relative position is
accurately set during initial assembly at the factory.
F50071 Refer to FIG 6 :8 where it will be seen that t w o numbers
are stamped on the pinion shaft near to the threaded end,
the upper number is the matching number which should
also appear on the crownwheel. The lower number indi-
cates the positive or negative deviation from the theoretical
distance between the centre line of the ring gear and the
pinion face. It is this number which must be taken into
account when calculating the adjusting shim thickness
which has to be fitted between the rear roller bearing and
the fourth-speed gear on the layshaft.
The formula from which the adjusting shim thickness
can be calculated is as follows:
S=A—(B + C)
Where S=shim thickness.
A= distance between the front bearing inner
race and the centre line of the ring gear.
B = distance of the drive pinion face to the ring
gear centre line.
C = t h e total of the widths of the third-speed
gear bush, third- and fourth-speed hub,
fourth-speed gear bush and rear roller
bearing inner race fitted onto the mainshaft
It should be noted that 'A' is the total of half the diameter
of the differential bearing housing seat which is in actual
fact 41.00 mm, and the distance measured between the
front bearing inner race and the differential bearing housing
seat. The last
dimension will have a minimum manufactu-
ring limit of 150.54 mm. Any deviation from this value
must be determined and considered when determining
the total shim thickness 'S'.
A= 150.54 + 41.00 + a (deviation)
To determine deviation 'a' Fiat tool A.62036 should be
assembled to the gearbox casing as shown in FIG 6 : 9
and to take the reading proceed as follows:
1 Assemble the front ballbearing and its retainer into the
gearbox housing and tighten the retainer bolts.
2 Hold the gearbox housing in the vertical position with
the differential side upwards and insert Fiat tool
A.62036 carefully from above into the bearing bore and
lock it firmly by tightening the knurled nut.
3 Using Fiat dial gauge C.689 which has been previously
zeroed on a surface plate should next be mounted
onto the t o p of Fiat tool A.62036 with its pointer resting
on the lowest position of the differential bearing hous-
ing bore as shown in FIG 6:10. To obtain the lowest
point move the pointer to both sides of the bottom dead
centre position so as to obtain the maximum reading.
The distance ' B ' in the formula for calculating the shim
thickness is designed to have a lower manufacturing limit
of 75 mm. Any deviation ' b ' is stamped on the drive pinion.
Therefore to calculate the value of ' B '
B = 7 5 + b (deviation)
The distance 'C' in the formula for calculating the shim
thickness is designed to have a lower manufacturing limit
FIG 6 : 8 Layshaft w i t h final drive pinion. The arrow
points to the number (14) for correct mating with ring
gear and to the centesimal figure (—10) for accurate
mating position of pinion and gear

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.

FIG 7 : 1 Rear suspension assembly
Key to Fig 7 : 1 1 Brake shoe control cable and sheath 2 Coil spring 3 Oil boot 4 Axle shaft 5 Bumper
6 Flexible joint 7 Swinging arm 8 Cable adjusting nut 9 Swinging arm-to-front bracket mounting pin
10 Swinging arm front bracket-to-underbody mounting screw 11 Engine front support crossmember 12 Swinging arm
rear self-locking nut 13 Shock absorber-to-swinging arm lower nut 14 Sleeve screws 15 Axle shaft-to-flexible joint sleeve
9 Remove the three swinging external support fixing
bolts securing the outer suspension arm bracket to the
vehicle floor and remove the rear suspension assembly.
Remove the special rubber pad located between the
support bracket and the vehicle floor.
7 : 3 Servicing swing arms
Dismantling:
1 Remove the cotter pin and release the nut fixing the
flexible joint to the wheel shaft. Remove the plain
washer and the joint.
2 Using Fiat tool A.40005.1.9 or a universal two-leg
puller, remove the wheel shaft and brake drum.
Extract the t w o oil seals and both the outer and inner
bearing inner rings, thrust ring of the joint and the
resilient spacer.
3 Using Fiat tool A.6511, remove the t w o bearing outer
rings.
4 Disconnect the brake hydraulic line at the wheel
cylinder and remove the swinging external support.
The bearing housing and brake housing flange may
then be removed.
Inspection :
Thoroughly clean all the parts and install the swinging
arm on Fiat fixture A.66064 as shown in FIG 7 : 4. If the
80
swinging arm has not been distorted its installation on the
fixture should be straightforward. Tighten the clamp
screws 1 (see FIG 7 : 3) on the road wheel brake drum,
connect the swinging arm inner member to the seating
2 on the fixture and finally fit the swinging arm external
support holes on the fixture pins 3. Should difficulty be
experienced in either one of these three operations then
this is an indication that the swinging arm is distorted and
should be straightened or a new assembly fitted. If this
check is satisfactory proceed as follows:
1 Check that the 'estendblocks' are a snug fit in their
respective seatings in the swinging arm and that the
mounting pin slides in freely w it h ou t excessive play.
To renew the 'estendblocks' use Fiat tool A.66056
which is suitable for both their removal and installation.
2 Check that the inner and outer bearing outer rings have
no play in their seatings and that the rollers and cages
are not broken, cracked, show signs of overheating
or are worn.
3 Ensure t h a t the o i l seals f i t snugly on the wheel shaft,
also on the joint spacer or shoulder ring and on the
hub seats. If the oil seals should show any signs of wear
then these should be renewed.
4 Inspect the resilient spacer for signs of hair line cracks,
which if not evident the spacer may be used again as
it is not permanently distorted during assembly.
Should, however, new bearings or bearing housings
be fitted it is considered good practice to fit a new
spacer.

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).

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

FIG 10:7 Master cylinder section
Key to Fig 10:7 1 Plug and spring seat 2 Body 3 Front wheel brake line duct 4 Plunger return spring
5 Compensating hole 6 Plug 7 Supply duct 8 Fluid inlet hole 9 Plunger 10 Plunger snap ring 11 Boot
12 Pushrod 13 Terminal, stoplight switch 14 Rear wheel brake line duct 15 Holes in floating ring carrier for fluid passage
16 Valve 17 Valve carrier 18 Seal
FIG 10:8 Wheel cylinder section
Key to Fig 10:8 1 Shoe actuating stems 2 Boot
3 Plungers 4 Fluid inlet hole 5 Seal rings
6 and 7 Spring thrust cups and plunger reaction spring
Apply the brakes hard for several minutes and inspect the
master cylinder and hydraulic connections for leaks.
10:6 Wheel cylinder operation
Hydraulic pressure from the master cylinder reaches
the fluid in the wheel cylinders by hydraulic pipes and it
forces the plungers 3 (see FIG 1 0 : 8) apart and through
the plungers the brake shoes operate. In the wheel
cylinders the sealing rings 5 are axially compressed by
the cup 6 under the action of the spring 7. The rings are
under the radial and axial action of hydraulic pressure
so that their sealing efficiency is increased as the
hydraulic pressure increases.
Checking wheel cylinders:
Once the wheel cylinders have been removed from
the brake backplate as previously described remove the
rubber boots 2 (see FIG 10:8) on the ends of the cylinder.
The plungers, brake shoe stems and sealing rings will be
pushed out due to normal spring expansion. Remove the
spring thrust cups and plunger reaction spring.
107F500
Master cylinder reassembly:
Ensure that the metal parts are clean. Dry off any
solvent used for cleaning. Renew all the rubber seals as
a matter of course. Wet the internal parts w i t h clean brake
fluid and reassemble them in the order shown in FIG
10:7.
Refitting the master cylinder:
Carefully locate the master cylinder flange to the body
panel ensuring that the pushrod 12 (see FIG 10:7)
correctly locates in the plunger 9. Secure the master
cylinder flange using the t w o nuts and spring washers.
Refit the hydraulic pipes.
Remove the tapered wooden plug from the reservoir
and bleed the system as described in Section 10:10. Dismantling master cylinder:
1 Refer to FIG 10 :7 and remove the plunger and rubber
boot from the cylinder body.
2 Using a pair of circlip pliers remove the plunger
circlip.
3 Carefully slide off from the inside of the cylinder body
the plunger, plunger seal, valve ring carrier, valve ring
and the reaction spring.
4 Remove the stoplight pressure operated switch.
5 Remove the cylinder body stop plug and upper plug.
6 Carefully inspect the master cylinder inner surface and
plunger outer surface to ensure that they have a mirror-
like finish and that the play between the two parts is
not excessive. Any roughness present on the cylinder
inner surface will necessitate renewing the complete
assembly. Scoring or corrosion of the surface will
quickly damage the rubber seals and can lead to
leakage of fluid and consequent partial or complete
brake failure. Check that the plunger return spring is not
corroded or distorted.

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

indicates a break in the cable from the generator to
regulator. Repeat the test on terminal 67. Finally,
remove the temporary link from the generator. If the
readings are correct, test the regulator as described in
Section 11:5.
Removing generator:
1 Disconnect the leads from the generator.
2 Remove the drive belt as previously described.
3 Release t h e rear mounting bracket at the side of the
power unit.
4 Remove the air cooling ducting from around the fan
and generator area and lift away the unit.
5 Release the blower from the end of the armature shaft
and finally, the mounting bolts from the air ducting.
Dismantling generator:
1 Release the pulley self-locking nut and slide the pulley
off the armature shaft.
2 Remove the t w o Woodruff keys on armature shaft.
3 Unscrew the t w o through bolt nuts and pull out the
bolts.
4 Partially remove the commutator end head to the point
where the brushes are. s t i l l seating on the commutator.
Using a piece of hooked wire relieve the load of the
springs on the brushes by arranging the spring ends
on the brush sides. The brushes will be locked in their
holders and cannot be chipped by striking against the
armature shaft during the commutator end head
removal.
5 Gently ease the commutator and fan end heads apart
and, slide out the armature.
Servicing brushes:
Lift the brushes up in the boxes and hold them in that
position by letting each brush spring bear on the side of
its brush. Fit the commutator end bracket over the
commutator end of the armature shaft and release the
brushes by hooking up the springs using a thin screw
driver. Hold back each spring in turn and move the brush
by pulling gently on the flexible connector. If the brush
moves sluggishly remove it and polish the sides using a
smooth file. Before this operation is actually carried out it
is suggested that the brush is marked before removal so
that it is replaced in its original working position.
inch,The minimum permissible length of a brush is
so renew any t h a t are less than this figure. Test the brush
springs using a spring tension scale. New springs should
have a tension of 1.3 to 1.6 Ib. In service this value could
fall slightly before performance is affected. Always bed in
new brushes by wrapping fine sandpaper round the
commutator, pressing down on the brush and rotating
the commutator under it, or draw the paper t o o and f r o .
If new brushes are fitted always fit genuine Fiat replace-
ments.
Servicing the commutator:
A commutator in good condition should be smooth and
free from pitting or signs of the segments burning. Clean
with a rag moistened in petrol. If necessary, polish using
a fine glasspaper whilst rotating the armature. Never use
emerycloth.
If the commutator is badly worn it may be skimmed
using a centre lathe. Use a high rotational speed and take
F500113
FIG 11 :3 Components of generator
Key to Fig 11 : 3 1 Terminal 51 2 Bearing outer ring
retainment terminal nut 3 Commutator end head 4 Brushes
5 Terminal 67 6 Frame 7 Blower end head
8 Bearing retainer nuts and screws 9 Pulley retainment nut
10 Pulley 11 Head mounting tie rods and nuts
12 Armature 13 Blower retainment nut
FIG 11 :4 Commutator end head of generator DSV
90.12.16.3 S
a light cut using a sharp tool. Remove only enough metal
to clean up the commutator face and then polish with
fine glasspaper. To undercut the insulation between the
segments, it is suggested that a hacksaw blade is ground
on its sides until it is the thickness of the insulation and
carefully work between each pair of segments until the
insulation has been cut to a depth of .0394 inch below the
surface.
A thorough visual inspection may determine the cause
of armature failure. Breaks in armature windings cause
burnt commutator segments. Short-circuited windings
are discoloured by overheating, with badly burnt
commutator segments.