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PART 7-1 AUTOMATIC TRANSMISSION (Borg-Warner}
7-13
3. Firmly apply the parking brake
and start the
engine.
4. With the engine at normal
operating temperature, adjust the
engine idle speed to the specified
rpm. If the engine idle speed cannot
be brought within limits by adjust-
ment at the carburettor idle adjust-
ment screw, check the throttle and
downshift linkage for a binding con-
dition. If the linkage is satisfactory,
check for vacuum leaks into the
engine.
CONTROL PRESSURE TESTS
The test results of the following
checks should agree with the specifi-
cations given in Table 1. When per-
forming control pressure tests, make
certain that the service brake pedal is
held in the applied position.
It is important that both the
engine and transmission are at their
normal operating temperature.
TEST No. 1
CONTROL PRESSURE CHECK
AT ENGINE IDLE
Start the engine and allow it and
the transmission to reach their nor-
mal operating temperatures. At the
correct engine idle speed, check the
transmission control pressure gauge
at all selector lever positions. The
pressure: <>hould agree with the speci-
fications shown in Table 1.
IDLE PRESSURE TOO LOW
Check the downshift cable adjust-
ment and revise as necessary.
Low pressure may also be due to
excessive leakage in the oil pump,
case and control valve body, or a
sticking control pressure regulator
valve.
IDLE PRESSURE TOO HIGH
Check the downshift cable adjust-
ment for excessive pullout, sticking
or non-return of the downshift cam
through incorrect assembly of the
cam spring.
High pressure may also be caused
by sticking regulator valves.
TEST No. 2 -
STALL TEST
Start the engine to allow it to reach
its normal temperature. Apply both
the parking and service brakes while
making tests.
The stall test is made in D, 2,
1 or R at full throttle to check
engine performance, converter clutch
operation or installation and the
holding ability of the forward clutch,
reverse-high clutch and low-reverse
band and the gear train one-way
clutch. While making this test,
do no£ hold the throttle open for
more than five seconds at a time.
Then move the selector lever to
Neutral and run engine at 1000 rpm
for about 15 seconds to cool the con-
verter before making the next test.
If the engine speed recorded by the
tachometer exceeds the maximum
limits specified in Table 1, release the
accelerator
immediately
because
clutch or band slippage is indicated.
STALL SPEED TOO HIGH
A higher stall speed than that
specified indicates that the convertor
is not receiving its required fluid
supply or that slip is occurring, de-
pending on transmission selector
lever position. Excessive engine rpm
only in D, 2 or 1, indicates forward
clutch slippage. Excessive engine
rpm only in R indicates either
reverse-high clutch or low-reverse
band slippage. Excessive engine rpm
only in D indicates gear train one-
way clutch slippage.
STALL SPEED TOO LOW
When the stall test speeds are low
and the engine is properly tuned,
converter stator clutch problems are
indicated. A road test must be per-
formed to determine the exact cause
of the trouble.
If the stall test speeds are 300 to
400 rpm below the specifications
shown in Table 1, and the car cruises
properly but has very poor accelera-
tion, the converter stator clutch is
slipping.
If the stall test speeds are 300 to
400 rpm below the specified values,
and the car drags at cruising speeds
and acceleration is poor, the stator
clutch could be installed backwards.
Remove the converter and check
the stator clutch by replacing with
a converter known to be operating
correctly and retesting.
Below standard acceleration in top
gear above 30 mph combined with a
substantially
reduced
maximum
speed, indicates that the stator one-
way clutch has locke;d in the engaged
condition. This condition will also be
indicated by the transmission over-
heating, although the stall speed will
remain as specified. Renew the con-
verter.
Note - The torque converter is a
sealed unit without a drain plug. The
unit must not be dismantled. If a
converter is unsatisfactory in any
way then it must be replaced.
TEST No. 3
CONTROL PRESSURE AFTER CUT
BACK TEST
The transmission and engine
should be at their normal operating
temperature.
Accelerate the vehicle
with full throttle. During accelera-
tion the control pressure should be
suddenly reduced by modulator valve
operation to the specification shown
in Part 7-4.
CONTROL PRESSURE AFTER CUT
BACK TOO LOW
Low pressure may be caused by
incorrect downshift cable adjustment
or faulty regulator valve operation.
FIG. 12- Gauge set up for Pressure Test
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