1983 FIAT UNO differential

25Unscrew the union nut and detach the
hydraulic fluid line from the operating cylinder
(photo).
26Undo the cylinder/mounting bracket
retaining bolts and lift clear the cylinder
together with the bracket (photo). Release the
retaining clip and separate the cylinder from
the bracket.
27To dismantle the cylinder, prise free and
pull back the dust boot, withdrawing it
together with the operating rod.
28Invert the cylinder and shake free the
piston and seal assembly. If it is stuck inside
the cylinder, remove the bleed screw then
apply moderate air pressure (from a foot
pump) into the bleed port and catch the
cylinder in a clean cloth as it is ejected.
29Remove the seals noting their orientation.
Clean all components in methylated spirits or
new hydraulic fluid. If the cylinder is damaged,
scored or badly worn it must be renewed. The
seals must always be renewed once they are
removed.
30Assemble the new seals to the piston and
lubricate the cylinder, seals and piston
assembly with new hydraulic fluid (of the
specified type) before assembling them.
Ensure that the seals are fitted the correct
way round (as noted during removal).
31Renew the dust boot, fit and secure the
operating rod into position then refit the dust
boot over the cylinder. If removed, refit the
bleed screw.
32Reconnect the cylinder to the mounting
bracket and refit the combined assembly to
the vehicle in the reverse order of removal.
Ensure the hydraulic union is clean and take
care not to damage the threads as it is
reconnected.
33Remove the polythene seal from the
hydraulic reservoir filler neck, top up the fluid
level and bleed the system as described
below.
Clutch hydraulic system -
bleeding#
34The clutch hydraulic circuit is bled in
much the same manner to that described for a
brake circuit. Refer to Section 12 in Chapter 8
and proceed as described, but note that the
bleed screw for the clutch circuit is located inthe end of the operating cylinder (see
photo 11.25). The clutch hydraulic circuit
reservoir is mounted in the engine
compartment on the left-hand side near the
bulkhead and is separate from the master
cylinder. As the system is being bled, ensure
that the fluid level in the reservoir is
maintained between the MIN and MAX level
marks. Do not allow the fluid level to drop
below the MIN level mark otherwise air will
enter the system and greatly lengthen the
operation. Wipe clean any fluid spillage from
the paintwork or adjacent components as it
has a corrosive effect if left.
12 Transmission
PART A:
1301 CC TURBO IE ENGINE
Description
1The transmission is of five-speed type,
based on that used in the Fiat Strada 105 TC.
2For all practical purposes, the operations
described in Chapter 6 apply, but observe the
following differences.
Gearchange linkage -
removal and refitting Á
3This is of two-rod type.
4Remove the gaiter and disconnect the rodsat the gear lever end as described in Chap-
ter 6, Section 3.
5Disconnect the rods at the transmission
end by unscrewing the nuts and bolts which
connect the linkage rods to the selector rods
(photo).
6Extract the spring clip which retains the end
of the short link rod (photo).
Gearchange linkage
(Antiskid models) - general
7The gearchange linkage and internal
selector arrangement has been modified, as
shown in Fig. 13.89.
Final drive output shafts -
description and
oil seal renewal
#
8The output shafts on this transmission
incorporate a flange on the left-hand side, to
which a coupling flange on the driveshaft is
bolted. On the right-hand side, an
intermediate shaft (see Section 13) is splined
directly into the differential side gear.
9A leaking oil seal may be renewed on the
left-hand side of the final drive casing after
first disconnecting the driveshaft. Then using
two levers, prise out the flange/stub shaft
against the tension of its retaining circlip.
10Unbolt and remove the bearing cover.
When refitting the cover, make sure that the
O-ring is in good condition.
11To renew the oil seal on the right-hand
side, first remove the intermediate driveshaft,
and then prise the defective seal out of the
final drive housing using a suitable tool.
12Apply grease to the new seal lips before
refitting the intermediate shaft or the stub
shaft. Tighten all bolts to the specified torque.
PART B:
1372 CC IE AND 1372 CC
TURBO IE ENGINES
Description
1The transmission is of five-speed type,
based on that used in the FIAT Tipo. The
transmission is mounted in-line with the
engine and is located in the left-hand side of
the engine compartment. Drive from the
clutch is transferred through the input shaft
and the mainshaft to the integrally-located
13•94 Supplement: Revisions and information on later models
12A.6 Gearchange link rod spring clip
(arrowed) on the 1301 cc Turbo ie engine12A.5 Gearchange rod connections at
transmission (1301 cc Turbo ie engine)
11.26 Clutch operating lever (A) and
operating cylinder bracket-to-transmission
housing bolt (B)11.25 Clutch operating cylinder showing
hydraulic line connection and bleed nipple
(arrowed)

final drive unit. The inboard end of each
driveshaft locates in the differential. All helical
gear clusters are in constant mesh, with the
fifth gear assembly located on an intermediate
plate mounted on the rear end of the gearbox.
Gear engagement is made by sliding
synchromesh hubs. Gearchanges are made
via a central floor-mounted gear lever.
MaintenanceÁ
2Maintenance is limited to periodically
checking the oil level, topping up as required,
renewing the oil, and visually inspecting the
transmission for oil leaks. The most likely
source of an oil leak will be from the driveshaft
seals.
Oil level - checkingÁ
3For improved access, jack up the vehicle
and support it on axle stands. Note that the
vehicle must be level in order to carry out this
check.
4If the transmission is hot due to the car
having been driven recently, allow it to cool
before making the check; oil foams when hot
and can produce a false level reading. Wipe
the area around the filler plug then unscrew
and remove the plug from its location in the
front of the casing. The oil should be level with
the base of the filler plug hole.
5If necessary, top up with oil of the specified
grade.
6On completion refit the filler plug, wipe
clean any oil spillage, then lower the car to the
ground.
Oil - renewalÁ
7The transmission oil should ideally be
drained when hot (directly after the vehicle
has been used). For improved access, jack up
the vehicle and support it on axle stands.
Note that the vehicle must be level to ensure a
correct level reading when topping up.
8Wipe clean the area around the filler plug on
the front face of the transmission casing, then
unscrew and remove the plug.
9Position a suitable container underneath
the drain plug (located at the left-hand end of
the transmission). Unscrew the plug and allow
the oil to drain into the container. Oil will start
to drain before the plug is fully withdrawn so
take precautions against scalding. Wait about
ten minutes to allow the oil to drain fully.
10When the oil has finished draining, clean
around the threads of the drain plug and its
location in the transmission casing, then refit
the plug and tighten it.
11Refill the transmission with the specified
quantity and grade of oil through the
filler/lever plug hole. With the vehicle level and
the transmission cold check the oil level as
described above, then refit and tighten the
plug. Lower the vehicle to complete.
Gearlever and linkages - general
12The component parts of the gearchange
and selector assemblies are shown in
Figs. 13.91 and 13.92. They do not normally
Supplement: Revisions and information on later models 13•95
Fig. 13.90 Exploded view of the transmission unit fitted to 1372 cc models (Sec 12)
13
Fig. 13.89 Gearchange control linkage on the 1301 cc Turbo ie model with Antiskid
(Sec 12)

PART C: 999 CC AND
1108 CC WITH C514 TYPE
TRANSMISSIONS
Description
1A new 5-speed transmission was
introduced to selected models during 1992.
Identified by the way reverse gear is engaged.
The gear knob needs to pressed downwards
whilst pushing the lever to the extreme right.
2The new design includes control cables as
well as rods for gear selection, see Fig. 13.94.
MaintenanceÁ3At the time of writing, no maintenance
instructions were available, however should
selecting gears become difficult, check the
following.
4The gear lever should rest vertically in
neutral. If it does not, alter the gear selector
adjustable rod, as appropriate.
5Whilst turning the adjustment nut,
counterhold with a 10 mm open ended
spanner, located in the notch built into the
sleeve. Refer to Fig. 13.95.
13 Driveshafts
Inboard joint boots (non-Turbo
models, September 1987 on) -
modification
1Modified boots have been fitted to the
differential ends of the driveshafts on non-
Turbo models produced after September 1987.
2The new boots incorporate a seal/bearing
assembly, and it is very important when a
boot is being fitted to the driveshaft that it is
located as shown in Fig. 13.96.
13•98 Supplement: Revisions and information on later models
Fig. 13.96 Driveshaft boot positioning diagram - later non-Turbo models (Sec 13)
Left-hand shaft
With 4-speed transmission,
A = 143.0 mm (5.63 in)
With 5-speed transmission,
A = 133.0 mm (5.24 in)Right-hand shaft
With 4-speed transmission,
A = 123.0 mm (4.84 in)
With 5-speed transmission,
A = 108.9 mm (4.25 in)
Fig. 13.94 C514 type 5-speed transmission
1 Sliding part of gear
lever
2 Reverse gear inhibitor
device flexible control
cable
3 Gear selector control
rod
4 Gear engagement
control cable
5 Gear selector
adjustable control rod
6 Gear selector and
engagement control
shaft
7 Reverse gear inhibitor
device
B = 0 to 1 mm (0 to 0.04 in)
Fig. 13.95 Gear selector adjustable rod (C514 type transmissions)
A Adjusting nut B Location of notch in outer sleeve

Glossary of Technical TermsREF•13
REF
A
ABS (Anti-lock brake system)A system,
usually electronically controlled, that senses
incipient wheel lockup during braking and
relieves hydraulic pressure at wheels that are
about to skid.
Air bag An inflatable bag hidden in the
steering wheel (driver’s side) or the dash or
glovebox (passenger side). In a head-on
collision, the bags inflate, preventing the
driver and front passenger from being thrown
forward into the steering wheel or windscreen.
Air cleanerA metal or plastic housing,
containing a filter element, which removes
dust and dirt from the air being drawn into the
engine.
Air filter elementThe actual filter in an air
cleaner system, usually manufactured from
pleated paper and requiring renewal at regular
intervals.
Allen keyA hexagonal wrench which fits into
a recessed hexagonal hole.
Alligator clipA long-nosed spring-loaded
metal clip with meshing teeth. Used to make
temporary electrical connections.
AlternatorA component in the electrical
system which converts mechanical energy
from a drivebelt into electrical energy to
charge the battery and to operate the starting
system, ignition system and electrical
accessories.
Ampere (amp)A unit of measurement for the
flow of electric current. One amp is the
amount of current produced by one volt
acting through a resistance of one ohm.
Anaerobic sealerA substance used to
prevent bolts and screws from loosening.
Anaerobic means that it does not require
oxygen for activation. The Loctite brand is
widely used.
AntifreezeA substance (usually ethylene
glycol) mixed with water, and added to a
vehicle’s cooling system, to prevent freezing
of the coolant in winter. Antifreeze also
contains chemicals to inhibit corrosion and
the formation of rust and other deposits that
would tend to clog the radiator and coolant
passages and reduce cooling efficiency.
Anti-seize compoundA coating that
reduces the risk of seizing on fasteners that
are subjected to high temperatures, such as
exhaust manifold bolts and nuts.
AsbestosA natural fibrous mineral with great
heat resistance, commonly used in the
composition of brake friction materials.Asbestos is a health hazard and the dust
created by brake systems should never be
inhaled or ingested.
AxleA shaft on which a wheel revolves, or
which revolves with a wheel. Also, a solid
beam that connects the two wheels at one
end of the vehicle. An axle which also
transmits power to the wheels is known as a
live axle.
AxleshaftA single rotating shaft, on either
side of the differential, which delivers power
from the final drive assembly to the drive
wheels. Also called a driveshaft or a halfshaft.
BBall bearingAn anti-friction bearing
consisting of a hardened inner and outer race
with hardened steel balls between two races.
BearingThe curved surface on a shaft or in a
bore, or the part assembled into either, that
permits relative motion between them with
minimum wear and friction.
Big-end bearingThe bearing in the end of
the connecting rod that’s attached to the
crankshaft.
Bleed nippleA valve on a brake wheel
cylinder, caliper or other hydraulic component
that is opened to purge the hydraulic system
of air. Also called a bleed screw.
Brake bleedingProcedure for removing air
from lines of a hydraulic brake system.
Brake discThe component of a disc brake
that rotates with the wheels.Brake drumThe component of a drum brake
that rotates with the wheels.
Brake liningsThe friction material which
contacts the brake disc or drum to retard the
vehicle’s speed. The linings are bonded or
riveted to the brake pads or shoes.
Brake padsThe replaceable friction pads
that pinch the brake disc when the brakes are
applied. Brake pads consist of a friction
material bonded or riveted to a rigid backing
plate.
Brake shoeThe crescent-shaped carrier to
which the brake linings are mounted and
which forces the lining against the rotating
drum during braking.
Braking systemsFor more information on
braking systems, consult the Haynes
Automotive Brake Manual.
Breaker barA long socket wrench handle
providing greater leverage.
BulkheadThe insulated partition between
the engine and the passenger compartment.
CCaliperThe non-rotating part of a disc-brake
assembly that straddles the disc and carries
the brake pads. The caliper also contains the
hydraulic components that cause the pads to
pinch the disc when the brakes are applied. A
caliper is also a measuring tool that can be set
to measure inside or outside dimensions of an
object.
CamshaftA rotating shaft on which a series
of cam lobes operate the valve mechanisms.
The camshaft may be driven by gears, by
sprockets and chain or by sprockets and a
belt.
CanisterA container in an evaporative
emission control system; contains activated
charcoal granules to trap vapours from the
fuel system.
CarburettorA device which mixes fuel with
air in the proper proportions to provide a
desired power output from a spark ignition
internal combustion engine.
CastellatedResembling the parapets along
the top of a castle wall. For example, a
castellated balljoint stud nut.
CastorIn wheel alignment, the backward or
forward tilt of the steering axis. Castor is
positive when the steering axis is inclined
rearward at the top.
Canister
Brake bleeding
Bearing
Air filter

Glossary of Technical TermsREF•15
REF
GGapThe distance the spark must travel in
jumping from the centre electrode to the side
electrode in a spark plug. Also refers to the
spacing between the points in a contact
breaker assembly in a conventional points-
type ignition, or to the distance between the
reluctor or rotor and the pickup coil in an
electronic ignition.
GasketAny thin, soft material - usually cork,
cardboard, asbestos or soft metal - installed
between two metal surfaces to ensure a good
seal. For instance, the cylinder head gasket
seals the joint between the block and the
cylinder head.
GaugeAn instrument panel display used to
monitor engine conditions. A gauge with a
movable pointer on a dial or a fixed scale is an
analogue gauge. A gauge with a numerical
readout is called a digital gauge.
HHalfshaftA rotating shaft that transmits
power from the final drive unit to a drive
wheel, usually when referring to a live rear
axle.
Harmonic balancerA device designed to
reduce torsion or twisting vibration in the
crankshaft. May be incorporated in the
crankshaft pulley. Also known as a vibration
damper.
HoneAn abrasive tool for correcting small
irregularities or differences in diameter in an
engine cylinder, brake cylinder, etc.
Hydraulic tappetA tappet that utilises
hydraulic pressure from the engine’s
lubrication system to maintain zero clearance
(constant contact with both camshaft and
valve stem). Automatically adjusts to variation
in valve stem length. Hydraulic tappets also
reduce valve noise.
IIgnition timingThe moment at which the
spark plug fires, usually expressed in the
number of crankshaft degrees before the
piston reaches the top of its stroke.
Inlet manifoldA tube or housing with
passages through which flows the air-fuel
mixture (carburettor vehicles and vehicles with
throttle body injection) or air only (port fuel-
injected vehicles) to the port openings in the
cylinder head.
JJump startStarting the engine of a vehicle
with a discharged or weak battery by
attaching jump leads from the weak battery to
a charged or helper battery.
LLoad Sensing Proportioning Valve (LSPV)A
brake hydraulic system control valve that
works like a proportioning valve, but also
takes into consideration the amount of weight
carried by the rear axle.
LocknutA nut used to lock an adjustment
nut, or other threaded component, in place.
For example, a locknut is employed to keep
the adjusting nut on the rocker arm in
position.
LockwasherA form of washer designed to
prevent an attaching nut from working loose.
MMacPherson strutA type of front
suspension system devised by Earle
MacPherson at Ford of England. In its original
form, a simple lateral link with the anti-roll bar
creates the lower control arm. A long strut - an
integral coil spring and shock absorber - is
mounted between the body and the steering
knuckle. Many modern so-called MacPherson
strut systems use a conventional lower A-arm
and don’t rely on the anti-roll bar for location.
MultimeterAn electrical test instrument with
the capability to measure voltage, current and
resistance.
NNOxOxides of Nitrogen. A common toxic
pollutant emitted by petrol and diesel engines
at higher temperatures.
OOhmThe unit of electrical resistance. One
volt applied to a resistance of one ohm will
produce a current of one amp.
OhmmeterAn instrument for measuring
electrical resistance.
O-ringA type of sealing ring made of a
special rubber-like material; in use, the O-ring
is compressed into a groove to provide the
sealing action.
Overhead cam (ohc) engineAn engine with
the camshaft(s) located on top of the cylinder
head(s).Overhead valve (ohv) engineAn engine with
the valves located in the cylinder head, but
with the camshaft located in the engine block.
Oxygen sensorA device installed in the
engine exhaust manifold, which senses the
oxygen content in the exhaust and converts
this information into an electric current. Also
called a Lambda sensor.
PPhillips screwA type of screw head having a
cross instead of a slot for a corresponding
type of screwdriver.
PlastigageA thin strip of plastic thread,
available in different sizes, used for measuring
clearances. For example, a strip of Plastigage
is laid across a bearing journal. The parts are
assembled and dismantled; the width of the
crushed strip indicates the clearance between
journal and bearing.
Propeller shaftThe long hollow tube with
universal joints at both ends that carries
power from the transmission to the differential
on front-engined rear wheel drive vehicles.
Proportioning valveA hydraulic control
valve which limits the amount of pressure to
the rear brakes during panic stops to prevent
wheel lock-up.
RRack-and-pinion steeringA steering system
with a pinion gear on the end of the steering
shaft that mates with a rack (think of a geared
wheel opened up and laid flat). When the
steering wheel is turned, the pinion turns,
moving the rack to the left or right. This
movement is transmitted through the track
rods to the steering arms at the wheels.
RadiatorA liquid-to-air heat transfer device
designed to reduce the temperature of the
coolant in an internal combustion engine
cooling system.
RefrigerantAny substance used as a heat
transfer agent in an air-conditioning system.
R-12 has been the principle refrigerant for
many years; recently, however, manufacturers
have begun using R-134a, a non-CFC
substance that is considered less harmful to
the ozone in the upper atmosphere.
Rocker armA lever arm that rocks on a shaft
or pivots on a stud. In an overhead valve
engine, the rocker arm converts the upward
movement of the pushrod into a downward
movement to open a valve.
Adjusting spark plug gap
Plastigage
Gasket