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7-14
GROUP 7-
AUTOMATIC TRANSMISSION
TABLE 1 CONTROL PRESSURE CHECKS
IDLE PRESSURE (PSI)
200CID
58-66
250CID
58-70
Note -
Check pressures with
transmission fluid at normal opera-
ting temperature.
CONTROL PRESSURE AFTER CUT
BACK TOO HIGH
High control pressure may be
caused by incorrect downshift cable
adjustments, faulty governor, modu-
lator valve or regulator valve opera-
tion.
SHIFT POINT CHECKS
Check the light throttle upshifts in
D. The transmission should start in
first gear, shift to second, and then
shift to third within the shift points
specified in the specifications section
(Part 7-4).
While the transmission is in third
gear, depress the accelerator pedal
through the K.D. detent (to the
floor). The transmission should shift
from third to second or third to first,
depending on the car speed.
Check the closed throttle down-
shift from third to first by coasting
down from about 30 mph in third
gear. The shift should occur within
the limits specified in the specifica-
tions section.
With the transmission in third
gear and road speed over 30 mph, the
transmission should shift to second
gear when the selector lever is moved
from D to 2 or 1. The transmission
will downshift from second or third
to first gear when 1 is selected
below approximately 20 mph. This
check will determine if the gov-
ernor pressure and shift control
valves are functioning properly.
During the shift check operation,
if the transmission does not shift
within specifications or certain gear
ranges cannot be obtained, refer to
the Diagnosis Guide to resolve the
problem.
ROAD TEST PROCEDURES
Test 1. Check that the starter only
operates with the selector in
"P" and "N" and that if a
reversing light is fitted it only
operates in "R".
Test 2. Apply the brakes and, with
the engine idling, select N-D,
N-1, N-2, N-R. Transmission
engagement should be felt in
STALL PRESSURE (PSI)
200CID
200-250
250-CID
200-250
each position selected.
Test 3. Check converter stall speed
with the transmission in "1"
after connecting a tachometer
to the engine and applying the
hand-brake. Allow the engine
and transmission to reach nor-
mal operating temperature and
then momentarily depress to
the kick-down position, noting
the tachometer reading. Do not
stall for more than ten seconds,
otherwise the transmission will
overheat. Check for slip or
clutch squawks. (Refer Table 1 ).
Test 4. With the transmission at
normal operating temperature,
select "D", release the brakes
and accelerate with minimum
throttle opening checking for
first to second and second to
third changes. At minimum
throttle openings the changes
may be difficult to detect.
Confirmation that the trans-
mission is in third gear mar,
be obtained by selecting "2 '
when a third to second change
should be felt.
Test 5. (a) At 30 m.p.h. in third
gear, depress the accelerator to
the "kick-down" position where
the transmission should change
to second.
(b) At 15 m.p.h. in third gear,
depress the accelerator to full
throttle position. The trans-
mission should change to first
gear.
Test 6. (a) Stop the car and re-start
using full throttle acceleration.
Check the change speeds for
first to seconel and second to
third: refer shift speed chart in
the specification section.
(b) At 40 mph in third gear,
release the accelerator and
select "1". Check for third to
second change and engine brak-
ing. Check that the second to
first change occurs below 20
p1ph and for engine braking.
Test 7. Stop the car with "1" still
engaged, release the brakes and,
using full throttle accelerate to
STALL SPEEDS (RPM)
200CID
1800-1900
250CID
1850-1950
20 mph. Check for slip and
clutch squawk, and no upward
changes.
Test 8. Stop and select "R". Release
the.
brakes and reverse using
full throttle if possible. Check
for slip or clutch squawk.
Test 9. Stop the car facing downhill
with the brakes and select "P".
Release the brakes and check
that the parking pawl holds the
car. Re-apply the brakes before
disengaging the parking pawl.
Repeat with the car facing up-
hill.
AIR PRESSURE CHECKS
A NO DRIVE condition can exist,
even with correct transmission fluid
pressure, because of inoperative
clutches, bands. The inoperative
units can be located through a series
of checks by substituting air pressure
for the fluid pressure to determine
the location of the malfunction.
When the selector lever is at D, 2,
or 1, a NO DRIVE condition may
be caused by an inoperative forward
clutch. A NO DRIVE condition at D
may be caused by an inoperative
forward clutch or one-way clutch.
When there is no drive in "1", the
difficulty could be caused by im-
proper functioning of the forward
clutch and the one-way clutch. The
low-reverse band cannot be checked
in "1". If the low-reverse band or
clutch fails, the one-way clutch will
hold the gear train and operation will
be normal except that there will be
no engine braking. Failure to drive
in reverse range could be caused by a
malfunction of the reverse-high clutch
or low-reverse band. If the trans-
mission fails to drive in reverse range
but operates normally in D, 1 or 2, it
indicates failure of the low and
reverse band.
To make the air pressure checks,
drain the transmission fluid, and then
remove the oil pan and the control
valve body
assembly.
The inoperative
units can be located by introducing
air pressure into the transmission
case passages leading to the clutches,
servos, and governor.
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