1970 FIAT 500 clutch

FIG 5 . 4 Clutch cover assembly inspection diagram
500F, L and later Station wagon
KeytoFig5:4 1 Clutch cover 2 Pressure plate
3 Clutch release flange plate 4 Diaphragm spring rings
5 Diaphragm spring retainer plate 6 Diaphragm spring
7 Clutch release flange
X =1.463 ± .043 inches
F = direction of clutch release flange movement
8 mm = .31 5 inch = release travel
5 mm = .197 inch = maximum allowance for driven plate lining
wear7.9 mm = .311 inch
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5:5 Installation of clutch on flywheel
Before assembling the clutch cover assembly and
driven plate the following parts of the unit should be assembly proceed as follows:
1 Position the clutch cover assembly on Fiat fixture
A.62038 with a spacer .311 inch thick between the
cover and the plate.
2 Operate the clutch mechanism for four complete
throw-out strokes by applying a load of at least 181 Ib
on the release flange as shown by the arrow 'F' in
FIG 5:4.
3 Check that w i t h a withdrawal travel of .315 inch the
pressure plate is displaced .071 inch. Also check that
the distance'X' (see FIG 5 :4) is 1.463 inch ± .043 inch.
Should the results obtained not compare w i t h the
manufacturers recommended figures, then the clutch
cover assembly should be renewed.
FIG 5:6 Fixture A.62038 for clutch disassembly, re-
assembly and adjustment (new 500, 500D sedan and early
station wagon)
FIXTURE A . 62038
T-HANDLES CARRIER RING
LEVERBOLT NUTS
(LEVER ADJUSTMENT) FIG 5 : 5 Installing the clutch on flywheel using pilot
A.62023 (new 500, 500D sedan and early station wagon) to
centre the driven platePILOT A. 62023 FOR
DRIVENPLATE CENTERING

lubricated using Fiat Jota 3 grease.
1 Pressure plate—boss outer faces.
2 Clutch cover—withdrawal lever fulcrum.
3 Withdrawal lever stopnuts—contact face.
4 Withdrawal lever carrier ring — lever contact face.
5 Crankcase end pilot bushing lubricated with Fiat KG.15
grease.
6 Lubricate contact faces of driven plate and clutch shaft.
To install the clutch assembly proceed as follows:
1 Ensure t h a t there is no grease or oil on the faces of the
driven plate or flywheel face and position with the
raised part of the hub towards the transmission unit.
2 Locate Fiat tool A.70085 (diaphragm clutch) or
A . 6 2 0 2 3 (coil spring clutch) or a suitably sized drift,
through the driven plate hub and position in crankshaft
pilot bushing. Gradually tighten the clutch unit
mounting screws working diagonally and finally tighten
to a torque wrench setting of 5.8 to 7.2 Ib ft.
5 : 6 Pilot bushing
Whenever the clutch unit is being renewed or over-
hauled it is essential that the crankshaft pilot bush is
checked for excessive wear or damage. Also check that
FIG 5 : 7 Side sectional view of clutch and throw-out
mechanism - 5 0 0 Sedan (11OF), late Station Wagon. Value
1.5 mm (.059 inch) refers to the clearance to be obtained
through the adjustment of clutch throw-out yoke rod
F50063
The withdrawal mechanism comprises a forked lever
(see FIG 5 : 8), which is located in the clutch housing and 5:7 Withdrawal mechanism
New 500 and 500D models:
the spigot on the bush end is in a good serviceable con-
dition. The maximum clearance between the clutch shaft
spigot and the bush should not be greater than .0059 inch
otherwise the pilot bush must be renewed. To remove the
pilot bush use Fiat puller A.40006/1 /2 or a small universal
internal bush and bearing removal tool.
To fit a new bush use a suitably sized drift and drive the
bush fully home and lubricate well with Fiat KG.15 grease. FIG 5 : 9 Clutch controls and adjusting mechanism LEVER RETURN SPRING
ADJUSTABLETIE R O DCLUTCH RELEASE LEVER NUT A N D JAM NUT
FOR TIE R O D CLUTCH RELEASE BOWDEN FIG 5:8 Clutch throw-out mechanism
CLUTCHSHAFT
LEVER-AND-SHAFT
RELEASE
RELEASETHRUST RING
FORK-TO-THRUSTFASTENERS RING
CARBON
RING
WITHDRAWAL FORKCLUTCH

FIG 5:10 Clutch throw-out mechanism
Key to Fig 5:10 1 Clutch throw-out yoke
2 Yoke return spring 3 Rod nut and counternut
4 Adjustable rod 5 Clutch throw-out
onto this shaft the outer operating lever is attached by
means of a key.
A return spring connected to the outer operating lever
is anchored onto the gearbox casing. When the clutch is in
its normal position the spring keeps the central thrust
carbon ring away from the withdrawal levers carrier ring.
The carbon ring is pressed against the carrier ring by the
throw-out ring which is connected to the forked lever as
shown in FIG 5 : 8 .
The clutch pedal must have free travel of 1"3/8 to 1"9/16 inch.
Should any adjustment be necessary release the locknut
from the adjustable tie rod and adjust the position of the
tie rod until the correct adjustment is obtained. Tighten the
locknut.
500F. L and later station wagon:
The free travel of the clutch pedal should be 19/32 to
1"3/16 inch which corresponds to a clearance of .059 inch
between the throw-out sleeve and the ring (see FIG 5 : 7).
Should any correction be necessary release the adjust-
able rod locknut (see FIG 5:10), and reposition the
adjustable rod using the rod nut until the recommended
clutch pedal travel is obtained. Retighten the locknut.
5 : 8 Fault diagnosis
(a) Drag or spin
1 Oil or grease on driven plate lining
64
(g) Driven plate fracture
1 Check 2 and 3 in (a)
2 Drag and distortion due to hanging gearbox in plate hub (f) Tick or knock
1 Worn first motion shaft spigot or bearings
2 Badly worn splines in driven plate hub
3 Release plate out of line
4 Faulty Bendix drive on starter motor
5 Loose flywheel
(e) Rattle
1 Check 3 in (c)
2 Worn release mechanism
3 Excessive backlash in transmission
4 Wear in transmission bearings
5 Release bearing loose on fork (d) Judder
1 Check 1, 2 and 3 in (a)
2 Pressure plate not parallel with flywheel face
3 Contact area of driven plate linings not evenly distribu-
ted
4 Bent first-motion shaft
5 Buckled driven plate
6 Faulty power unit mountings
7 Worn suspension mountings
8 Weak rear springs
9 Loose drive shafts (c) Slip
1 Check 1, 2 and 3 in (a)
2 Check 2 in (b)
3 Weak pressure springs or diaphragm spring (b) Fierceness or snatch
1 Check 1, 2 and 3 in (a)
2 Worn clutch linings 2 Misalignment between engine and gearbox first motion
shaft
3 Driven plate hub binding on first motion shaft splines
4 Binding of first motion shaft spigot bearing
5 Distorted clutch plate
6 Warped or damaged pressure plate or clutch cover
7 Broken driven plate linings
8 Dirt or foreign matter in clutch

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.

PRIMARY SHAFT-TO-CLUTCH
SHAFT MOUNTING PINCLUTCH SHAFT SEAL PRIMARY SHAFT WITH
1st, 3 r d A N D 4 t h SPEED
GEAR CLUSTER
2 n d SPEED
DRIVE GEARPRIMARY SHAFT
FRONT BALL BEARINGPRIMARY SHAFT
REAR BALL BEARING
PRIMARY
SHAFT-TO-CLUTCH
i SHAFT JOINING SLEEVEJOINING SLEEVELOCKRING
SPEED SELECTOR LEVER
CLUTCH SHAFT
LAYSHAFT WITH BEVEL PINION
SPEEDOMETER DRIVE GEAR
2 n d SPEED ENGAGEMENT
SLIDING SLEEVE
2 N D SPEED DRIVEN GEAR
LAYSHAFT FRONT BALL
BEARING
3 r d SPEED DRIVEN GEARHUB FOR
SLEEVE
3rd AND 4th/
SPEED ENGAGEMENT
SLIDING SLEEVE4 t h SPEED
DRIVEN GEARLAYSHAFT REAR ROLLER BEARING
LAYSHAFT-TO-PINION
ADJUSTMENT WASHER 1st SPEED AND)
REVERSE SLIDING GEAR
FIG 6:1Gearbox-differential unit longitudinal section
On the primary shaft extension outside the main central
body is mounted the second-speed driving gear. The
primary shaft is supported at both ends by ballbearings
whilst the clutch shaft rotates in a bronze spigot bush which
is press fitted into the end of the crankshaft. An oil seal is
fitted in the clutch shaft passage seat in the c o n n e c t i o n
support. The layshaft, together with the drive pinion of the
differential unit is supported at the front by a ballbearing
race. The layshaft carries the pinion adjustment shim, the
fourth-speed driven gear and its bushing, the hub and
relevant engagement sleeve for the t h i r d - and fourth-
speed w i t h first-speed and reverse-speed, the third-speed
gear and bushing and, outside the casing the second gear
and bushing, the hub with relevant second-speed engage-
ment sleeve and the speedometer drive gear.
The gears are operated by a gear selection lever mounted
on the tunnel situated between the two front seats. This
operates through a rod actuating the selector and shifting
mechanism which is housed in the gearbox casing cover.
Refer to FIG 6 :3 where it will be seen th a t the positioning
of the striker rods is ensured by a spring-loaded ball-
bearing. The risk of engaging two gears at the same time is
eliminated by three rollers which slide in suitable slots
machined in the rod (see FIG 6 : 4).
The differential unit and the final drive gear train are
housed in the t w o semi-covers which
have previously
been described, the final drive pinion being integral with
the layshaft. The differential casing may be split into t w o
halves. The bevel gear is fitted on one of the halves and is
66
secured by the same screws joining the two halves
together. The differential side gears are internally splined
into which are located the splined axle shaft ends which
are able to slide by means of a specially designed slip joint.
Two specially shaped rubber oil boots are inserted on the
swing axle shafts and fit over the side gear extensions to
ensure that there is no loss of lubricant or the ingress
of dirt.
The transmission and differential unit to suit the station
wagon differs from the sedan in that the transmission to
engine mounting plate and the bellhousing are modified to
suit the engine repositioned on its side.
6 : 2 Removal of gearbox/differential unit:
The complete unit may be removed whilst the engine
remains in situ and to remove this unit proceed as follows:
1 Disconnect the battery positive cable and jack up the
rear of t h e vehicle and place on firmly based stands.
2 Disconnect all control cables and wiring from the
starter motor and the clutch lever. Remove the starter
motor, the clutch lever reaction spring and the clutch
cable support on the gearbox.
3 Remove the three bolts securing each of the driving
shaft flanges to the flexible coupling at the wheel ends
and carefully take out the inner spring.
4 Disconnect the shifter rod from the gearshift lever at the
gearbox extension and also the
speedometer drive
cable. Remove also the flywheel undercover. Place a
suitable support under the engine.

FIG 6 :2 Gearbox gears, forks and striker rods
KeytoFig6:2 1 Rear roller bearing 2 Layshaft with bevel pinion 3 Front ballbearing 4 Front bearing plate
5 Bushing 6 Fourth-speed driven gear 7 Third- and fourth-speed sliding sleeve 8 First and reverse sliding gear
9 Sliding sleeve hub 10 Third-speed driven gear 11 Bushing 12 Bushing 13 Second-speed driven gear
14 Second-speed sliding sleeve 15 Second-speed sliding sleeve hub 16 Speedo drive gear 17 Reverse sliding gear
18 Reverse sliding gear shaft 19 Clutch shaft 20 Clutch shaft-to-primary shaft sleeve 21 Primary shaft rear ballbearing
22 Primary shaft with first and reverse, third and fourth gear train 23 Primary shaft front ballbearing 24 Second-speed drive gear
25 First gear fork 26 First and second gear striker rod with second gear fork 27 Reverse gear fork 28 Reverse gear striker rod
29 Third and fourth gear fork 30 Third and fourth striker rod 31 Gear selector and engagement lever
SPRING
GUIDE BUSHES
REVERSESTRIKER R O D
BALL SPRINGS
POSITIONING BALLS STRIKER R O D
BALL SPRING
COVER PLATE
1st A N D 2 n d SPEED
STRIKER R O D3 r d A N D 4 t h SPEED
STRIKER R O D
FIG 6 : 3 Detail of gearbox section through striker rod
positioning ball springs
F50067 5 Using a garage type hydraulic jack fitted with Fiat
support Arr.2076 carefully placed under the gearbox-
differential unit take the weight of the unit from the
front mounting. Carefully remove the nuts securing the
transmission unit to the engine and also the nuts that
secure the transmission front support to the body
brackets.
6 Carefully draw the transmission forwards away from
the engine taking very great care that no weight is
allowed to act on the clutch shaft until the end of the
clutch shaft is clear of the flywheel and clutch cover
assembly. Carefully lower the transmission to the floor.
7 Remove the front support together with its rubbers,
drain the oil from the transmission unit and thoroughly
wash the outside to remove all traces of dirt and grease
and dry using a compressed air jet. The transmission is
now ready for dismantling.
6:3 Dismantling— gearbox
Before dismantling the gearbox ensure that the exterior
is thoroughly clean and then proceed as follows:

1st A N D 2 n d SPEED
STRIKER R O D LOCK
ROLLER1st A N D 2 n d SPEED
STRIKER R O D 3 r d A N D 4 t h SPEED
STRIKER R O D 3 r d A N D 4 t h SPEED
STRIKER R O D LOCK -
ROLLER REVERSE STRIKER
ROD LOCK ROLLER
REVERSESTRIKER R O D
FIG 6 : 4 Detail of gearbox section through striker rod
lock rollers
2 n d SPEED DRIVENGEAR2 n d SPEED ENGAGEMENT SLIDING SLEEVE 2 n d SPEED FORK 1st A N D 2 n d
SPEED STRIKER R O D REVERSE GEAR3rd AND 4th
SPEED STRIKER R O DREVERSE STRIKER R O D2 n d SPEED DRIVE GEAR SPEED SELECTOR LEVER
FIG 6 : 5 Cross section of gearbox through striker rods
with the indication of the gear selector lever angular
displacement
68
AXLE SHAFT-TO-JOINT SLEEVE
OIL BOOT
RING GEAR
FIG 6:6 Differential unit complete with axle shafts
BEARING CONEADJUSTER LOCK RING BEARING HOUSING DIFFERENTIAL CASE
OIL BOOT RETAINER
AXLE SHAFT
1 Remove the speedometer drive support together with
its gears. Remove the front cover together with its
gasket and the gear selection rod (see FIG 6:2).
2 Remove the lock ring and carefully slide the splined
sleeve from the axle shafts. Remove the t w o roller
bearing housings together with the relevent rubber
boot fastening cover, the rubber boots and the adjuster
ring lock rings.
3 Detach the transmission mounting on engine support
and carefully remove the differential case assembly
complete w i t h the ring gear and axle shafts.
4 Open the fasteners and loosen all the shifter fork lock
bolts.
5 Engage t w o gears at the same time so locking the
input shaft and the mainshaft together. Remove the
cotter pins and the nuts on the front end of the input
shaft and the mainshaft.
6 Remove the retaining cover located on the lefthand
side of the gearbox and carefully take out the shifter
rod positioning balls and springs from their bores.
Remove the upper shifter fork shaft and shifter fork,
the middle shifter fork shaft together with its interlock
pin and also the third and fourth gear shifter fork.
Remove the plain washer and speedometer drive
driving gear from the layshaft.
7 Remove the second gear engagement sliding sleeve
together with the shifter fork, shifter fork shaft, sliding
sleeve hub, second-speed driven gear with relevent
bush and the first gear engagement
fork. Take very
great care not to drop the safety rollers whilst extract-
ing the striker rods.
8 Remove the second-speed driving gear from the input
shaft. Release the reverse shaft retaining screw and
remove the shaft together with the reverse gear cluster.
Remove the layshaft front bearing retaining plate.
9 Push the input shaft forwards until both ballbearing
races are pressed from their seating and the coupling
sleeve located between the input shaft and the clutch
shaft can be reached from above. Carefully remove the
retaining ring and a connection pin at the input shaft
side of the coupling sleeve and carefully withdraw the
clutch shaft and coupling sleeve.
10 Remove the input shaft front bearing race. Tilt the
primary shaft in the casing and remove it from the
gearbox housing. Remove the rear bearing. Carefully

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