Chrysler 1998 Voyager, Service Manual, Page: 1476 / 1938

GENERAL INFORMATION
31TH TRANSAXLE
NOTE: Safety goggles should be worn at all times
when working on these transaxles.
This transaxle combines torque converter, three
speed transmission, final drive gearing, and differen-
tial into a front wheel drive system. The identifica-
tion markings and usage of the transaxle are charted
in Diagnosis and Tests.
NOTE: Transaxle operation requirements are differ-
ent for each vehicle and engine combination. Some
internal parts will be different to provide for this.
Therefore, when replacing parts, refer to the seven
digit part number stamped on rear of the transaxle
oil pan flange.
Within this transaxle, there are three primary
areas:
(1) Main center line plus valve body.
(2) Transfer shaft center line (includes governor
and parking sprag).
(3) Differential center line.
(4) Center distances between the main rotating
parts in these three areas are held precise to main-
tain a low noise level.
(5) The torque converter, transaxle area, and dif-
ferential are housed in an integral aluminum die
casting. The differential oil sump is common
with the transaxle sump. Separate filling of the
differential is NOT necessary.
(6) The torque converter is attached to the crank-
shaft through a flexible driving plate. Cooling of the
converter is accomplished by circulating the tran-
saxle fluid through a remote cooler. There are two
types of coolers used. An oil-to-water type cooler
located in the radiator side tank and/or an oil-to air
heat exchanger. The torque converter assembly is a
sealed unit that cannot be disassembled.
(7) The transaxle fluid is filtered by an internal fil-
ter attached to the lower side of the valve body
assembly.
(8) Engine torque is transmitted to the torque con-
verter then, through the input shaft to multiple-disc
clutches in the transaxle. The power flow depends on
the application of the clutches and bands. Refer to
Elements in Use Chart in Diagnosis and Tests sec-
tion.
(9) The transaxle consists of:
•
Two multiple-disc clutches
•
An overrunning clutch
•
Two servos
•
A hydraulic accumulator
•
Two bands
•
Two planetary gear sets
This provides three forward ratios and a reverse
ratio. The common sun gear of the planetary gear
sets is connected to the front clutch by a driving
shell. The drive shell is splined to the sun gear and
front clutch retainer. The hydraulic system consists
of an oil pump, and a single valve body which con-
tains all of the valves except the governor valves.
The transaxle sump and differential sump are both
vented through the dipstick. Output torque from the
main center line is delivered through helical gears to
the transfer shaft. This gear set is a factor of the
final drive (axle) ratio. The shaft also carries the gov-
ernor and parking sprag. An integral helical gear on
the transfer shaft drives the differential ring gear.
The final drive gearing is completed with one of two
gear ratios of 2.98 or 3.19 depending on model and
application.
FLUID LEVEL AND CONDITION
NOTE: The transmission and differential sump have
a common oil sump with a communicating opening
between the two.
The torque converter fills in both the P Park and N
Neutral positions. Place the selector lever in P Park
to be sure that the fluid level check is accurate. The
engine should be running at idle speed for at
least one minute, with the vehicle on level
ground. This will assure complete oil level sta-
bilization between differential and transmis-
sion. The fluid should be at normal operating
temperature (approximately 82 C. or 180 F.). The
fluid level is correct if it is in the HOT region (cross-
hatched area) on the dipstick.
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transaxle has too much fluid, the
gears churn up foam and cause the same conditions
which occur with a low fluid level.
In either case, the air bubbles can cause overheat-
ing, fluid oxidation, and varnishing. This can inter-
fere with normal valve, clutch, and servo operation.
Foaming can also result in fluid escaping from the
transaxle dipstick where it may be mistaken for a
leak.
Along with fluid level, it is important to check the
condition of the fluid. When the fluid smells burned,
and is contaminated with metal or friction material
particles, a complete transaxle overhaul is needed.
Be sure to examine the fluid on the dipstick closely.
21 - 2 TRANSAXLE AND POWER TRANSFER UNIT
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