Subaru XT 1988 Service Manual page 689

3-2 AUTOMATIC TRANSMISSION AND DIFFERENTIAL
2. TIME LAG TEST
If the shift lever is shifted while the engine is idling, there will
be a certain time elapse or lag before the shock can be felt.
This is used for checking the condition of the forward clutch,
reverse clutch, low & reverse brake, forward one-way clutch
and low one-way clutch
CAUTION:
(a) Perform the test at normal operation fluid temperature
(50 to BO°C or 122 to 176°F).
(b) Be sure to allow a one minute interval between tests.
(c) Make three measurements and take the average value.
Measure time lag
1) Fully apply the parking brake.
2) Start the engine.
Check idling speed (A/C OFF)
"N" range: 1800: 800 ± 100 rpm
2700: 750 ± 100 rpm
3) Shift the shift lever from "N" to "D" range.
Using a stop watch, measure the time it takes from shifting
the lever until the shock is felt.
Time lag: Less than 1.2 seconds
4) In same manner, measure the time lag for "N"
-+
"R".
Time lag: Less than 1.5 seconds
Evaluation
1) If "N"
-+
"D" time lag is longer than specified:
• Line pressure too low
• Forward clutch worn
• Low one-way clutch not operating properly
2) If "N"
-+
"R" time lag is longer than specified:
• Line pressure too low
• Reverse clutch worn
• Low & Rev. clutch worn
3. LINE PRESSURE TEST
If the clutch or the brake band shows a sign of slippage or
shifting sensation is not correct, the line pressure should be
checked.
• Excessive shocks during upshifting or shifting takes place at
a higher point than under normal circumstances, may be
due to the line pressure being too high.
• Slippage or inability to operate the car may, in most cases,
be due to loss of oil pressure for the operation of the
clutch, brake band or control valve.
1) Line pressure measurement (under no load)
a. Before measuring line pressure, jack-up front wheels
(front-wheel-drive model) or all wheels (4-wheel drive model).
b. Maintain temperature of ATF at approximately 60 to
BO°C (140 to 176°F) during measurement.
(ATF will reach the above temperature after idling the engine
2) Line pressure measurement (under heavy load)
a. Before measuring line pressure, apply both foot and parking
brakes with all wheels chocked (Same as for "stall" test condi-
tions).
b. Measure line pressure for 5 to 10 seconds. Before measuring
it again, idle the engine for 2 to 5 minutes.
c. Before measuring line pressure, always shift the lever
from "0" to "2".
d. Maintain the temperature of ATF at approximately 60 to
BO°C (140 to 176°F) during measurement. (ATF will reach
the above temperature after idling the engine for approxi-
mately 30 minutes with the shift lever in "N" or "P".)
Measuring the line pressure
1) Temporarily attach the
01
L PRESSURE GAUGE
(398573600) to a suitable place in the driver's compartment,
remove the blind plug located in front of the toeboard and
pass the hose of the GAUGE (398573600) to the engine
compartment.
\\
1 Pressure gauge hose
2 Hole in toe board (blank cap hole)
3 Brake pedal
Fig. 322
A13-223
2) Remove the test plug and install OIL PRESSURE GAUGE
ADAPTER (498897100) instead.
Test plug location
L3-1006
for approximately 30 minutes with shift lever in "N" or "P".)
Fig. 323
162