Pontiac FIREBIRD 1972 Service Manual page 989

7F-2 1972 PONTIAC SERVICE MANUAL
2. Check transmission oil level.
Fig. 7F-1 M a i n l i n e Pressure Check Chart
I
v
Low Range-
@I000 rpm.
106-1 17
1 15-1 28
3. Make sure vacuum line connections are tight.
4. Check linkage adjustment.
I I
Drive Range-Overrun
(Coast) @25-20 mph.
(20"
Hg. Approx.)
48-53
48-53
ENGINE
6 Cylinder
8 Cylinder
111
Drive Range-ldle
,
Pressure
I. Wide Open Throttle Upshift Pressure Check
I
Drive Range-Wide
Open Throttle Upshift
87-104
99-1 17
1 6 "
Hg.
52-72
53-73
Road test the car to determine its wide open throttle up-
shift pressure point and compare it to the pressure check
chart (Fig. 7F- 1) for upshift pressure points as indicated.
1 0 " Hg.
79-97
81 -1 00
II. "Drive" Range Overrun (Coast) Pressure Check
In addition to the oil pressure gauge, a vacuum gauge
should be installed for this check. With the vehicle coast-
ing in "Drive" range at 25
-
20 m.p.h., with engine vacuum
at approximately 20" Hg., low servo apply (Mainline)
pressure should be as shown on the pressure check chart
(Fig. 7F-1).
Ill. "Drive" Range Idle Pressure Check
With pressure gauge and vacuum gauge installed, with
vehicle at a stop and parking brake applied, shift selector
lever in "Drive" range and engine idling, low servo apply
(Mainline) pressure should be as shown on the pressure
check chart (Fig. 7F-1).
If pressures are not within these ranges, the following
items should be checked for oil circuit leakage:
1. Pressure regulator valve stuck.
2. Vacuum modulator valve stuck.
3. Boost valve stuck.
4. Leak at low servo piston ring (between ring and
bore).
5. Leak at low servo piston rod (between rod and bore).
6. Leak at valve body-to-case gasket.
7. Leak at valve body gaskets.
8. Oil pump clearances.
9. Check passages in transmission case for porosity.
IV. "Low" Range Pressure Check
In addition to the pressure gauge, connect a tachometer,
apply the parking brake, place shift selector lever in
"Low" range and adjust the engine speed to 1,000 r.p.m.
Low servo apply (Mainline) pressure should be as shown
on the pressure check chart (Fig. 7F-1).
If pressures are not within these ranges, check the follow-
ing possibilities:
1. Partially plugged oil suction screen.
2. Broken or damaged low servo ring.
3. Pressure regulator valve stuck.
4. Leak at valve body-to-case gasket.
5. Leak between valve body gaskets.
6. Leak at servo center.
7. Oil pump clearance.
SHIFT POINTS (Fig. 7F-2)
With a tachometer installed, road test the vehicle for its
shift from low to high gear as follows: