Pontiac FIREBIRD 1972 Service Manual page 1040

7G-2 1972 PONTIAC SERVICE MANUAL
5. Road test car.
Install oil pressure gauge.
Road test using all selective ranges, noting when
discrepancies in operation or oil pressure occur.
Attempt to isolate the unit or circuit involved in
the malfunction.
If engine performances indicates an engine tune-
up is required, this should be performed before
road testing is completed or transmission correc-
tion attempted. Poor engine performance can re-
sult in rough shifting or other malfunctions.
CHECKING PROCEDURES
Before diagnosis of any transmission complaint is at-
tempted, there must be understanding of oil checking
procedure and what appearance the oil should have. Many
times a transmission malfunction can be traced to low oil
level, improper reading of dipstick, or oil appearance;
therefore, a careful analysis of the condition of oil and the
level may eliminate needless repairs.
When checking oil level, the procedure outlined under
FLUID LEVEL, CHECKING PROCEDURE, should
be followed to obtain the most accurate reading.
Also when the dipstick is removed, it should be noted
whether the oil is devoid of air bubbles or not. Oil with air
bubbles gives an indication of an air leak in the suction
lines, which can cause erratic operation and slippage. Wa-
ter in the oil imparts a milky, pink cast to the oil and can
cause spewing.
ROAD TEST
When road testing vehicle, a reliable pressure gauge
should be attached to the line pressure port on the right
side of the transmission case, behind and adjacent to the
intermediate clutch accumulator cover. Observe and re-
cord results of pressure checks, comparing results with
transmission pressures shown under OIL PRESSURE
CHECKS.
Check all the shifts in the following manner:
DRIVE RANGE:
Position selector lever in DRIVE range, accelerating vehi-
cle from 0 mph. A 1-2 and 2-3 shift should occur at all
throttle openings, shift points varying with the throttle
opening. As vehicle speed decreases to 0 mph, a 3-2 and
2-1 shift should occur (Fig. 7G-1).
SUPER RANGE:
Position selector lever in SUPER range, accelerating vehi-
cle from 0 mph. A 1-2 shift should occur at all throttle
openings, the shift point varying with the throttle opening.
No 2-3 shift should be obtained in this range. As vehicle
speed decrease to 0 mph, a 2-1 shift should occur (Fig.
7G-1).
LOW RANGE
Position selector lever in LOW range. No upshift should
occur in this range, regardless of throttle opening (Fig.
7G- 1).
2nd GEAR-OVERRUN BRAKING
Position selector lever in DRIVE range and, with vehicle
speed at approximately 30 mph and foot off accelerator,
move selector lever to SUPER range. Transmission
should immediately downshift to second gear. An increase
in engine rpm and an engine braking effect should be
noted. Line pressure should change from 55 psi to approx-
imately 85 psi in second gear.
Shift points indicated are approximate and should be obtained as follows,
.providing engine tune-up i s satisfactory:
Selector Lever In
-
DRIVE
Full Throttle
Part Throttle
Minimum Throttle
Coasting
SUPER
Fig. 7G-1 Shift Point Information
LOW
Engine Braking
@
46
MPH or Below
Upshifts (MPH)
Engine Braking
@
Any Speed
1-2
50
12-49
10
-
Downshifts (MPH)
2-3
85
22-84
22
-
3-2
75
5 0
-
22
3or
2-1
40
-
-
9