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(153)
CLUTCH, TRANSMISSION, UNIVERSAL JOINT
TRANSMISSION
4-25
4-22 SERVICE RECOMMENDATIONS
Gear teeth will be seriously damaged and
possibly broken, by failure of car operator to
fully engage gears on every shift before engag-
ingclutch and applyinfl engine power.
The type of damage resulting from failure to
obtain full engagement is shown in figure 4-32.
The conditions illustrated were produced on
new gears intentionally shifted improperly a
few times to determine what damage would
result.
Considerable damage to gears and bearings
will result from running at abnormal speeds in
reverse, first, and second speed gears. This
practice is also detrimental to the engine.
4-23 TROUBLE DIAGNOSIS
a. Hard Shifting and Block-Out
Hard shifting may be caused either by con-
ditions in shift control mechanism in steering
column or by conditions in transmission assem-
bly. Disconnect lower shift rod at idler lever to
determine which unit is at fault.
Conditions in shift control mechanism which
may cause hard shifting are:
(1)
Control shaft
upper or lower bearing scored or distorted.
(2)
Control lever housing upper thrust washer
broken or improperly installed in signal switch
housing.
(3)
Selector control rod bent or rub-
ber sleeves binding against jacket.
Conditions in transmission assembly which
may cause hard shifting are:
(1)
If
there is
excessive resistance at start of shift, shifter
yoke shaft poppet spring probably too stiff.
(2)
Shifter yoke shaft may be bent.
(2)
Selec-
tor shaft bent, or binding in oil seal may cause
hard 'shift ing or hard selection.
Block-out of second or third gear may be
caused by scored synchronizing drums or the
cones on gears. In Series 40-50, rough cam
surfaces on ends of sliding sleeve or on syn-
chronizing drums will also cause block-out.
b. Low and Reverse Gear Clash
.Transmission gears can be made to clash by
shifting into low or reverse gear too quickly
after clutch pedal is depressed, even though
clutch is in perfect working order. This is be-
cause inertia of clutch driven plate causes the
plate to spin until it is stopped by friction of
transmission and transmission lubricant.
Series 70 driven plates are larger in diameter
and heavier than Series 40-50 plates, therefore,
Series 70 plates have more inertia and will spin
for a greater length of time after clutch is dis-
engaged. With warm transmission lubricant
and low friction transmission bearings, a
reasonable amount of spin is to be expected.
The spin does not occur when shifting quickly
into second or high gear because the synchro-
nizing unit stops the driven plate.
To eliminate gear clash, sufficient time MUST
be allowed before shifting into low after pedal
is depressed or else starts must be made in
second gear. There is no objection to making
starts in second gear on level ground since the
clutch slippage under ordinary driving condi-
tions is not sufficient to produce enough heat to
damage driven plate facings.
If
gear clash continues after allowing proper
time for clutch driven plate to stop, check
clutch pedal lash and adjust to specified limits.
See paragraph 4-7. In exceptional cases of
driven plate spinning, clutch pedal lash should
be maintained at
%".
Make sure that id(e speed
of engine when hot is 450 RPM. A faster idle
aggravates driven plate spinning.
Conditions within the transmission which
may cause gear clash are:
(1)
Faulty synchro-
nizing drums or cone surfaces;
(2)
Excessive
main shaft end play;
(3)
On Series 70, weak
or broken detent springs in gear synchronizing
clutch. Gear clash also may be caused by a
dragging clutch
plate.
c. Noise in Neutral
With car standing, engine running, and
transmission in neutral, the transmission parts
in operation are: main drive gear and bearing,
counter gear and bearings, reverse idler gear,
second speed gear, main shaft pilot bearing.
Disengaging clutch will stop movement of all
these parts. By disengaging and engaging clutch
it can be determined whether noise originates
in these transmission parts and whether the
noise is normal. Noise in neutral in the form of
a constant regular click is usually caused by
a
nicked gear or bearing.
d. Gear Noise
Some gear noise is to be expected in all ex-
cept third speed. Comparison with another car
is the only means of determining whether or
not gear noise is excessive. Before removing
transmission for correction of gear noise deter-
mine by test which gears are noisy under load,
so that these can be thoroughly inspected when
removed.
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