1958 FIAT 500 wheel torque

CHAPTER 9
THE STEERING SYSTEM
9 : 5 Relay lever and support
9 : 6 Steering rods
9 : 7 Front wheel toe-in
9 : 8 Fault diagnosis 9:1 Description
9 : 2 Steering wheel removal and refitting
9 : 3 Steering box removal and refitting
9 : 4 Steering box dismantling and reassembly
9:1 Description
The steering gear fitted to the new 500 range of
vehicles is of the worm screw and sector type with a
steering ratio of 1:13. The steering gearbox is located on
the front lefthand side of the dash wall on the scuttle as
shown in FIG 9:1. The steering gear comprises a pitman
arm and relay lever pivoting on a pin supported on the
body. A central track rod connects the pitman arm to the
relay lever. T w o track rods connect the pitman arm and
relay lever to the knuckle arms.
9:2 Steering wheel removal and refitting
To remove the steering wheel proceed as follows:
1 Disconnect the battery positive terminal clamp and
remove the horn control from the steering wheel.
2 Remove the cable from the push button seating and the
cable insulation sleeve.
3 Using a suitably sized box spanner or Fiat wrench
A.8279 unscrew the steering wheel to shaft nut as
shown in FIG 9:2.
4 Using the palm of the hands against the back of the
steering wheel rim gently tap the steering wheel
forwards so releasing it from the inner shaft.
F50097 5 Reassembly is the reverse procedure to dismantling.
Care should be taken to ensure that the front wheels
are located in the straight ahead position when the
steering wheel is being replaced otherwise the steering
wheel spokes will not be correctly positioned.
9 : 3 Steering box removal and refitting
To remove the steering box from the vehicle proceed
as follows:
1 From inside the vehicle remove the steering column
clamp bolt 6 (see FIG 9 : 3) after flattening the lock-
washer 7.
2 From the underside of the vehicle remove the t w o
tie rod locking nuts from the pitman arm and then using
Fiat tool A.46006 or a suitable t w o leg puller withdraw
the pins from the seats.
3 Remove the three nuts holding the steering box to the
body panel. Ease out the worm screw from the
steering shaft and lift away the steering box.
4 To refit the steering box is the reverse procedure to
dismantling. The steering box to body mounting nuts
should be tightened to a torque wrench setting of
14 Ib/ft to 18 Ib/ft.

RIGHT HAND TIE ROD
RELAY LEVER SUPPORTINTERMEDIATE TIE ROD!
STEERING BOX!
LEFT HAND TIE ROD
FIG 9 :1 Steering box, idler member and steering linkage arrangement on vehicle
FIG 9 : 2 Securing steering wheel mounting nut
Key
to Fig 9:2(Tightening torque: 29 to 36 Ib ft)
9 : 4 Steering box dismantling and reassembly
1 Remove the steering gear housing cover complete
with the adjusting screw and locking nut and drain the
oil from the unit.
2 Using Fiat puller A.4005.1.5 or a universal t w o leg
puller remove the pitman arm.
3 Remove the cotter pin from the lower thrust bearing
adjusting nut and unscrew this nut.
4 Remove the sealing ring at the sector shaft lower end
and using Fiat tool A.8065 loosen the eccentric bush
adjuster plate bolt and remove both the bolt and the
adjusting plate. Also remove the upper sealing ring.
98
5 Lift out the sector together with the upper thrust
washer and shims.
6 Remove the steering worm screw by pulling out from
below. The two bearing inner rings will remain on the
worm screw whilst the lower bearing outer ring will
remain in the housing.
7 Remove the oil seal using Fiat tool A.10110 followed
by the worm screw upper bearing outer ring using
Fiat tool A.66040 or a suitably sized drift.
Inspection:
1 Carefully inspect the sector teeth and the worm screw
threads to see that there are no signs of seizure,
indentations or scoring. Check that the contact faces
indicate that meshing between the two parts is taking
place at the centre.
2 Check the clearance between the eccentric bush 5
(see FIG 9 : 5) and the worm sector 11 which must not
exceed .0039 inch. These items have an initial
assembly clearance of .00 to .0016 inch. It should be
noted that if the eccentric bushing to sector shaft
clearance exceeds .0039 inch a new bushing should
be installed and its inner face reamed using Fiat
reamer U.0360.20.
3 Ensure that the worm screw is not distorted. The
permissible out of true is .0019 inch.
Adjustment:
1 If the backlash between the worm screw and the
sector is excessive it should be adjusted by first dis-
connecting the pitman arm and its relevant seal.
Remove the screw 7 (see FIG 9 : 5) fixing the abut-
ment plate 6. Rotate the eccentric bush 5 by the
adjustment plate and move the sector in towards the
worm screw. The adjustment plate should be secured
again using the second fixing hole.
Should the adjustment plate already be fixed in the
second hole remove the plate from the bush and
rotate one or more serrations and re-secure.

reassembling and during assembly liberally lubricated
using Fiat W90/M oil (SAE90 EP).
2 The pitman arm nut should be correctly positioned on
reassembly to the sector shaft and both are marked
with notches or a master tooth on the sector will mate
with a double tooth on the pitman arm which will
prevent incorrect reassembly.
3 The pitman arm nut must be tightened to a torque
wrench setting of 72 Ib/ft.
4 Fill the box up to the level and filler plug with SAE90 EP
gear oil.
Refitting the steering box:
To refit the steering box to the vehicle proceed as
follows:
1 Engage the w o r m screw f r o m the steering shaft by
gently manipulating the steering box.
2 Replace the steering box to body nuts and tighten to a
torque wrench setting of 14 to 18 Ib/ft.
3 Replace the t w o track rod pins in their seatings in the
pitman arm and tighten the self-locking nuts to a
torque wrench setting of 18 to 21 Ib/ft.
4 Replace the steering shaft to worm screw mounting
bolt, lock washer and nut.
9 :5 Relay lever and support
The steering idler arm is secured to the body by means
of a support bracket and a rubber bushed pivot bolt. This
is shown in FIG 9 : 7. When this unit is being serviced
the following points should be noted.
1 If there is excessive play between the pin and the
bushes the bushes must be renewed. Also check the
condition of the pin and if there are signs of excessive
wear it must be renewed.
2 To eliminate torsional stresses in the rubber bushes
during assembly the pin nut must be tightened to
torque wrench setting of 39 to 43 Ib/ft, once the
front wheel toe-in has been correctly adjusted w i t h the
wheels set in the straight ahead position.
3 The relay lever support to body mounting nuts must
be tightened to a torque wrench setting of 14 to 18
Ib/ft.
9 : 6 Steering rods (tie rods)
The steering rod is connected to the idler arm and the
drop arm by means of non-adjustable ball joints. The
track rods are connected to the right and left steering
arms by non-adjustable ball joints and comprise t w o
sleeves which are split and having internally threaded
ends. The ball joints are clamped to either end of the
sleeves. To facilitate adjustment one ball joint end has a
lefthand thread and the other a righthand thread.
Adjustment is made by loosening both the clamping bolts
and turning the central sleeve.
To remove the steering rods from the pitman arm, the
relay lever and knuckle arms Fiat pullers A.46006 and
A.6473 or universal ball joint removers should be used.
If excessive play is evident in the ball joint linkage or
the pin is damaged the complete ball joint assembly must
be renewed.
Upon reassembly the tie rod to ball pin knuckle arm
nuts must be tightened to a torque wrench setting of
18 to 21 Ib/ft.
F500101
FIG 9:7 Relay lever support section
FIG 9:8 Front wheel toe-in checking diagram
Key to Fig 9:8 A—B = 000 inch to .079 inch
It is important that all steering linkages are thoroughly
checked at regular intervals and if any parts are suspect
then they must be renewed.
9 : 7 Front wheel toe-in
To check and adjust the front wheel toe-in proceed as
follows:
1 Ensure that the tyres are inflated to the recommended
pressures. Ensure that the steering wheel is in its

normal straight-ahead position with the spokes
horizontal. Check that the wheels are in the straight-
ahead position.
2 Load the vehicle to static load conditions or with four
average size passengers.
3 Move the vehicle forwards for a distance of approxi-
mately six yards so that the suspension may settle
correctly.
4 The toe-in measurements should be taken at the same
point of the wheel rim. Measure at A (see FIG 9 : 8)
then back up the car to bring points A to the position B
and remeasure. The value obtained at A should be
equal to or greater than B within .0079 inch.
5 As previously described the steering rods are adjust-
able in length. Loosen the clamps and screw in or out
the adjusting sleeves and before tightening the clamp
ensure that the sleeve slot registers w i t h the clamp
joint. With the clamp fully tightened there should
always be a gap between the joint faces.
6 If the steering gear has been re-installed the correct
front wheel toe-in must be set. Then the relay lever pin
nut must be tightened to a torque wrench setting of 78
to 85 Ib/ft.
9 : 8 Fault diagnosis
(a) Front wheel shimmy
1 Incorrect tyre pressure
2 Incorrect front wheel alignment
3 Loose front wheel bearings
4 Wheels out of balance
5 Loose steering linkage connections
6 Loose steering gear or relay lever support at body
mountings
7 Incorrect fitting of steering worm to worm sector
(b) Hard steering
1 Incorrect tyre pressure
2 Incorrect front wheel alignment
3 Incorrect adjustment of steering worm to worm sector
(c) Hard turning when stationary
1 Incorrect tyre pressure
2 Incorrect adjustment of steering worm to worm sector
102
(d) Pull to one side
1 Incorrect tyre pressure
2 Incorrect front wheel alignment
3 Incorrect front wheel bearing adjustment
4 Distorted kingpin housing or swinging arms
5 Unequal brake adjustment
6 Semi-elliptic spring weak or broken
(e) Rattles
1 Loose steering linkage connections
2 Loose steering gear or relay lever support at body
mountings
3 Semi-elliptic spring weak or broken
4 Lack of lubrication
( f ) Loose steering
1 Incorrect front wheel bearing adjustment
2 Loose steering linkage connections
3 Loose steering gear mountings
4 Incorrect adjustment of steering worm to worm sector
(g) Jerky steering
1 Incorrect front wheel alignment
2 Incorrect front wheel bearing adjustment
3 Wheels out of balance
4 Loose steering linkage connections
5 Loose or incorrect fitting of worm to sector
(h) Side-to-side wander
1 Incorrect tyre pressure
2 Incorrect front wheel alignment
3 Loose steering linkage connections
4 Loose steering gear or relay lever support at body
mountings
5 Incorrect fitting of steering worm to worm sector
6 Distorted kingpin housing or swinging arm
7 Semi-elliptic spring weak or broken
(i) Tyre squeal on turns
1 Incorrect tyre pressure
2 Incorrect wheel alignment
3 Distorted kingpin housing or swinging arms

1
791011 8 234
11
10
16,15
14 13
1265
FIG 11:5 Components of starter
Key to Fig 11:5 1 Drive end head 2 Head shield 3 Frame 4 Switch 5 Commutator cover band
6 and 7 Pin and spring for lever 8 8 Starting engagement lever 9 Head shield 10 and 11 Head fixing tie rods and tubes
12 Pinion, complete 13 Starting engagement spring 14 Drive unit sleeve and free wheel hub 15 Armature
16 Commutator end head
Testing field coils:
When tested w i t h an ohmmeter the reading should be
8+.1—.3 ohms. Failing an ohmmeter use a 12-volt
supply and connect it in series w i t h an ammeter across
the field terminal and the yoke or body. The meter should
read approximately 2 amps. If there is no reading the
field coil winding has a break in it. If the reading is much
more than 2 amps or the ohmmeter records at much less
than 8 ohms it shows that field coil insulation has broken
down. Renewal of the field coils is a specialist operation
best left to a service station.
The armature:
Apart from reconditioning the commutator, there is
little which can be done to the armature itself. Never try
to straighten a bent shaft and do not machine the arma-
ture core. Armature windings are tested w i t h equipment
normally not available to the car owner. The only check
for a suspected faulty armature which the owner can do
is to substitute an armature which is known to be
satisfactory.
Generator bearings:
1 Commutator end head bearings. Remove the ball-
bearing outer race stop bracket mounting screw and
nut, ease o u t t h e stop brackets and the ballbearings.
2 Fan end head bearing. Remove the ballbearing retainer
mounting screw nuts and ease o u t t h e retainers and
the seals. Using a suitably sized drift remove the ball-
bearing.
114Reassembly is the reverse procedure to dismantling
in both cases.
Reassembly and refitting the generator:
This is the reverse procedure to dismantling. The
following points should however be noted.
1 The commutator end head ballbearing outer race stop
bracket mounting screw nut must be tightened to a
torque wrench setting of .80 Ib ft.
2 The pulley and fan-to-generator armature shaft self-
locking nuts must be tightened to a torque wrench
setting of 14.5 Ib ft.
3 To assemble the commutator end bracket to the yoke,
partially withdraw the brushes and trap them in this
position by letting the springs bear on the sides of the
brushes. Fit the bracket to the armature shaft and when
it is about 1/2 inch from the yoke face, lift the springs
using a thin screwdriver or a piece of hooked wire and
this will let the brushes drop onto the commutator.
Check that the springs now bear correctly on the tops
of the brushes and push the bracket fully home.
4 Pack all ballbearings with Fiat Jota 3 grease or an
equivalent grade grease.
11:4 The starter motor
Operation:
When operating the starter hand lever through a
flexible coupling a lever is operated (see FIG 11:5)
which controls the pinion engagement with the flywheel.
As the lever completes its movement it closes the starter