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7-40
GROUP 7-AUTOMATIC TRANSMISSION
FIG. 5 - Control Pressure
Connecting Points.
4. Adjust
the
engine
idle speed
to
the specified
rpm. If the engine idle
speed·
cannot
be brought within
limits by
adjustment at
the car-
burettor
idle
adjustment
screw,
check the throttle and downshift
linkage for
a
binding condition. If
the linkage
is satisfactory,
check for
vacuum leaks in the transmission
diaphragm unit
(Fig.
7), and its
connecting tubes and hoses. Check
all other vacuum operated units for
vacuum leaks.
=
MANIFOLD
VACUUM
LINE HOSE
TO VACUUM GAUGE
FIG. 6- Typical Vacuum Test
Line Connections
VACUUM UNIT CHECK
To check the vacuum unit for dia--
phragm leakage, remove the unit
from the transmission. Use a dis-
tributor tester equipped with a
vacuum pump (Fig. 7). Set the
regulator knob so that the vacuum
gauge reads 18 inches with the end
of the vacuum hose blocked off.
FIG. 7 - Testing Transmission
Vacuum Unit for Leakage
Then connect the vacuum hose to
the transmission vacuum unit. If
the gauge
still
reads \8 inches, the
vacuum
unit diaphragm is not
leaking. As the hose is removed
from the transmission vacuum unit,
hold a finger over the end of the
control rod. When the hose
is
re-
moved, the internal spring of the
vacuum
unit
should
push
the
control rod outward.
CONTROL PRESSURE TESTS
The test results of the following
checks should agree with the speci-
fications given in Table I. When
performing control pressure tests,
make certain that the service brake
pedal is held in the applied position.
TEST NUMBER I-
CONTROL PRESSURE CHECK
AT ENGINE IDLE
1.
With the transmission in neu-
tral, and at the correct engine idle,
the vacuum gauge should s}low a
minimum of 18 inches at sea level.
TABLE 1-C4 Transmission
If the vacuum reading is lower than
18 inches,
an
engine problem is
indicated
or there
is leakage in the
vacuum
line.
Make necessary re-
pairs to
obtain a
minimum
vacuum
reading
of
18 inches.
At engine idle, check the trans-
mission control pressure gauge at
all
selector
lever positions. Trans-
mission control pressures
should
agree with the
specifications
in
Table I.
At
altitudes
above sea level, it
may not be possible to obtain 18
inches
vacuum at
engine
idle.
At
these altitudes with
idle vacuum
of
less than 18 inches,
refer
to the fol-
lowing specifications to determine
idle
speed
control pressure in for-
ward driving ranges:
Engine
Vacuum
(At
Idle)
17 Inches
16 Inches
15 Inches
14 Inches
13 Inches
12 Inches
II Inches
Control
Pressure
(psi)
0
0
0
.
0
. . . .
0 .
0
0
0
0
5:2-74
0
0
0
0
0
0
0 .
0
0
0
0
0
0
0
52-78
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
52-85
0
0
0
0
0
0
0
0
0
0
0
0 .
0
0
52-90
0
0
0
0
0
0
0
0 .
0 - 0
0
0 .
52-96
0
• • • •
0 .
0 .
0
• • •
0
0
52-101
0
0 .
0
0
0
0
0
0
0
0
0 .
0
0
52-101
2. At engine
idle,
depress and re-
lease the accelerator pedal quickly
and observe the vacuum
gauge.
The
amount of vacuum
should
decrease
and increase with the changes in
throttle openings. If the vacuum
response to changes in throttle
opening is too
slow
the vacuum line
to the diaphragm unit could be re-
stricted. Make the necessary repairs
before completing the test.
TEST NUMBER 2-CONTROL
PRESSURE INCREASE CHECK
The
control
pressure increase
CONTROL PRESSURE AT ZERO OUTPUT SHAn SPEED
Test
En1ine Speed or
Throttle
ShiH Selector
•Control (Line)
No.
Manifold Vacuum
Position
Lewer Position
Pressure (psi)
P.N.D.
52-85
1
Idle-Above 18 Inches
Closed
1.2
52-115
of Vacuum
R
52-180
2
17.0 Approximate
As
D
2 1
Line Pressure
Inches of Vacuum
Required
Increase
3
10 Inches ol Vacuum
As Required
D 2 1
96-110
4
Below
1
inch
Thru detent
D 2
1
143-160
of Vacuum
at stall
R
230-260
1
Transmission oil at normal operating temperature.
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