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variations. Note whether the shifts are harsh or spongy,
and check the speeds at which upshifts and downshifts
occur.
Watch closely for slippage or engine speed flare-up
which usually indicates clutch, band or overrunning
clutch problems. If the condition is advanced, an over
haul may be necessary to restore normal operation.
In most cases, a slipping clutch or band can be deter
mined by noting transmission operation in all gearshift
lever positions and by comparing which internal units
are applied in those positions. The Clutch and Band
Application Chart provides a basis for analyzing road
test results.
Clutch and Band Application Chart
Gearshift Lever Position
Drive
Elements
P
R
N
D
2
1
1
2
3
1
2
Front Clutch
•
•
Front Band
•
•
Rear Clutch
Rear Band
•
•
Overrunning
Clutch
•
•
•
60230
Analyzing the Road Test
Refer to the Clutch and Band Application Chart and
note which elements are in use in the various gear
ranges. The rear clutch is applied in all forward ranges
(D, 2, 1). The overrunning clutch is applied in first gear
D and 2 range only and the front band is applied in 1 and
R range only.
For example, if slippage occurs in D and 2 range first
gear but not in 1 range, the overrunning clutch is slip
ping. Similarly, if slippage occurs in any two forward
gears, the rear clutch is slipping.
Applying the same method of analysis, note that both
clutches are applied in D third gear only. If the trans
mission slips in third gear, either the front clutch or the
rear clutch is slipping. By selecting another gear which
does not use one of these units, the slipping clutch can be
determined. For example, if the transmission also slips
in reverse, the front clutch is slipping. If the transmis
sion does not slip in reverse, the rear clutch is slipping.
This process of elimination can be used to determine
the slipping unit and to check operation. The key is
proper use of the Clutch and Band Application Chart.
Although road test analysis will help determine the
slipping unit, the actual cause of a malfunction usually
cannot be ascertained until hydraulic and air pressure
tests are performed. Practically any condition can be
caused by leaking hydraulic circuits or sticking valves.
Unless the condition is obvious, such as no drive in D
range first gear only, do not disassemble the transmis
sion until hydraulic and air pressure tests have been
performed.
AUTOMATIC TRANSMISSION
2C-13
HYDRAULIC PRESSURE TESTS
The hydraulic pressure tests are performed usingTest
Set J-24027. The set consists of five color-coded pressure
hoses, a 400 psi (2 758 kPa) capacity pressure gauge and
a 100 psi (689 kPa) capacity pressure gauge (fig. 2C-14).
The high pressure gauge is used to record rear servo
pressure on R and 1 positions only and the low pressure
gauge is used for all other readings. The test set permits
simultaneous connection to all the pressure ports and
allows sequential or independent pressure readings as
desired.
REAR SERVO *»
Fig. 2C-14 Pressure Tesl Set
Pressure Test Port Location
The accumulator line pressure port is located on the
right side of the case between the front and rear servo
castings just above the oil pan mating surface (fig. 2C-
15).
The governor pressure port faces to the left side in the
front lower center section of the adaptor housing (fig.
2C-16).
Lubrication pressure is measured by installing a T-
fitting in the fluid cooler return line on the left side at
the rear edge of the case halfway to the top of the case
(fig. 2C-16). If inaccessible, use T-fitting at radiator
cooler return line.
The front servo release pressure port is located on the
right side of the case just behind the filler tube opening
just above the oil pan mating surface (fig. 2C-15).
The rear servo apply pressure port is on the right rear
side of the case, facing rearward and just above the oil
pan mating surface (fig. 2C-16).
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Troubleshooting
