Gearbox-Differential Unit Longitudinal Section; Removal Of Gearbox/Differential Unit - Fiat 500L Workshop Manual

2nd SPEED
DRIVE GEAR
SPEED SELECTOR LEVER
LAYSHAFT WITH BEVEL PINION
SPEEDOMETER DRIVE GEAR
2nd SPEED ENGAGEMENT
SLIDING SLEEVE
2ND SPEED DRIVEN GEAR
LAYSHAFT FRONT BALL
BEARING
3rd SPEED DRIVEN GEAR
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 connection
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 third- and fourth-
speed with 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 that 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 two semi-covers which have previously
been described, the final drive pinion being integral with
the layshaft. The differential casing may be split into two
halves. The bevel gear is fitted on one of the halves and is
66
PRIMARY SHAFT WITH
PRIMARY SHAFT-TO-CLUTCH
1st, 3rd AND 4th SPEED
GEAR CLUSTER
PRIMARY SHAFT
PRIMARY SHAFT
REAR BALL BEARING
FRONT BALL BEARING
HUB FOR
SLEEVE
3rd AND 4th/
SPEED ENGAGEMENT
SLIDING SLEEVE
1st SPEED AND)
REVERSE SLIDING GEAR

Gearbox-differential unit longitudinal section

FIG 6:1
SHAFT MOUNTING PIN
PRIMARY
SHAFT-TO-CLUTCH
i SHAFT JOINING SLEEVE
4th SPEED
LAYSHAFT REAR ROLLER BEARING
DRIVEN GEAR
LAYSHAFT-TO-PINION
ADJUSTMENT WASHER
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 the 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.
CLUTCH SHAFT SEAL
JOINING SLEEVE
LOCKRING
CLUTCH SHAFT