Dodge Durango (DN). Manual — part 35

Fig. 5 Reverse Powerflow

1 – FRONT CLUTCH ENGAGED
2 – OUTPUT SHAFT
3 – LOW/REVERSE BAND APPLIED
4 – INPUT SHAFT

5 – OUTPUT SHAFT
6 – INPUT SHAFT
7 – FRONT CLUTCH ENGAGED
8 – LOW/REVERSE BAND APPLIED

Fig. 6 First Gear Powerflow

1 – OUTPUT SHAFT
2 – OVER-RUNNING CLUTCH HOLDING
3 – REAR CLUTCH APPLIED
4 – OUTPUT SHAFT

5 – OVER-RUNNING CLUTCH HOLDING
6 – INPUT SHAFT
7 – REAR CLUTCH APPLIED
8 – INPUT SHAFT

21 - 6

42/44RE AUTOMATIC TRANSMISSION

DN

DESCRIPTION AND OPERATION (Continued)

SECOND GEAR POWERFLOW

In drive-second (Fig. 7), the same elements are

applied as in manual-second. Therefore, the power
flow will be the same, and both gears will be dis-
cussed as one in the same. In drive-second, the trans-
mission has proceeded from first gear to its shift
point, and is shifting from first gear to second. The
second gear shift is obtained by keeping the rear
clutch applied and applying the front (kickdown)
band. The front band holds the front clutch retainer
that is locked to the sun gear driving shell. With the
rear clutch still applied, the input is still on the front
annulus gear turning it clockwise at engine speed.
Now that the front band is holding the sun gear sta-
tionary, the annulus rotation causes the front planets
to rotate in a clockwise direction. The front carrier is
then also made to rotate in a clockwise direction but
at a reduced speed. This will transmit the torque to
the output shaft, which is directly connected to the
front planet carrier. The rear planetary annulus gear
will also be turning because it is directly splined to
the output shaft. All power flow has occurred in the
front planetary gear set during the drive-second
stage of operation, and now the over-running clutch,

in the rear of the transmission, is disengaged and
freewheeling on its hub.

DIRECT DRIVE POWERFLOW

The vehicle has accelerated and reached the shift

point for the 2–3 upshift into direct drive (Fig. 8).
When the shift takes place, the front band is
released, and the front clutch is applied. The rear
clutch stays applied as it has been in all the forward
gears. With the front clutch now applied, engine
torque is now on the front clutch retainer, which is
locked to the sun gear driving shell. This means that
the sun gear is now turning in engine rotation (clock-
wise) and at engine speed. The rear clutch is still
applied so engine torque is also still on the front
annulus gear. If two members of the same planetary
set are driven, direct drive results. Therefore, when
two members are rotating at the same speed and in
the same direction, it is the same as being locked up.
The rear planetary set is also locked up, given the
sun gear is still the input, and the rear annulus gear
must turn with the output shaft. Both gears are
turning in the same direction and at the same speed.
The front and rear planet pinions do not turn at all
in direct drive. The only rotation is the input from

Fig. 7 Second Gear Powerflow

1 – KICKDOWN BAND APPLIED
2 – OUTPUT SHAFT
3 – REAR CLUTCH ENGAGED
4 – OUTPUT SHAFT
5 – OVER-RUNNING CLUTCH FREE-WHEELING

6 – INPUT SHAFT
7 – REAR CLUTCH APPLIED
8 – KICKDOWN BAND APPLIED
9 – INPUT SHAFT

DN

42/44RE AUTOMATIC TRANSMISSION

21 - 7

DESCRIPTION AND OPERATION (Continued)

the engine to the connected parts, which are acting
as one common unit, to the output shaft.

FOURTH GEAR POWERFLOW

Fourth gear overdrive range is electronically con-

trolled and hydraulically activated. Various sensor
inputs are supplied to the powertrain control module to
operate the overdrive solenoid on the valve body. The
solenoid contains a check ball that opens and closes a
vent port in the 3-4 shift valve feed passage. The over-
drive solenoid (and check ball) are not energized in first,
second, third, or reverse gear. The vent port remains
open, diverting line pressure from the 2-3 shift valve
away from the 3-4 shift valve. The overdrive control
switch must be in the ON position to transmit overdrive
status to the PCM. A 3-4 upshift occurs only when the
overdrive solenoid is energized by the PCM. The PCM
energizes the overdrive solenoid during the 3-4 upshift.
This causes the solenoid check ball to close the vent
port allowing line pressure from the 2-3 shift valve to
act directly on the 3-4 upshift valve. Line pressure on
the 3-4 shift valve overcomes valve spring pressure
moving the valve to the upshift position. This action
exposes the feed passages to the 3-4 timing valve, 3-4
quick fill valve, 3-4 accumulator, and ultimately to the
overdrive piston. Line pressure through the timing

valve moves the overdrive piston into contact with the
overdrive clutch. The direct clutch is disengaged before
the overdrive clutch is engaged. The boost valve pro-
vides increased fluid apply pressure to the overdrive
clutch during 3-4 upshifts, and when accelerating in
fourth gear. The 3-4 accumulator cushions overdrive
clutch engagement to smooth 3-4 upshifts. The accumu-
lator is charged at the same time as apply pressure acts
against the overdrive piston.

FLUID

NOTE: Refer

to

the

maintenance

schedules

in

Group 0, Lubrication and Maintenance for the rec-
ommended maintenance (fluid/filter change) inter-
vals for this transmission.

NOTE: Refer to Service Procedures in this group
for fluid level checking procedures.

DESCRIPTION

Mopar

t ATF Plus 3, Type 7176, automatic trans-

mission fluid is the recommended fluid for Daimler-
Chrysler automatic transmissions.

Fig. 8 Direct Drive Powerflow

1 – FRONT CLUTCH APPLIED
2 – OVER-RUNNING CLUTCH FREE-WHEELING
3 – OUTPUT SHAFT
4 – REAR CLUTCH APPLIED
5 – OUTPUT SHAFT

6 – INPUT SHAFT
7 – OVER-RUNNING CLUTCH FREE-WHEELING
8 – REAR CLUTCH APPLIED
9 – FRONT CLUTCH APPLIED
10 – INPUT SHAFT

21 - 8

42/44RE AUTOMATIC TRANSMISSION

DN

DESCRIPTION AND OPERATION (Continued)

Dexron II fluid IS NOT recommended. Clutch

chatter can result from the use of improper fluid.

Mopar

t ATF Plus 3, Type 7176, automatic transmis-

sion fluid when new is red in color. The ATF is dyed red
so it can be identified from other fluids used in the vehi-
cle such as engine oil or antifreeze. The red color is not
permanent and is not an indicator of fluid condition. As
the vehicle is driven, the ATF will begin to look darker
in color and may eventually become brown. This is
normal. A dark brown/black fluid accompanied with
a burnt odor and/or deterioration in shift quality may
indicate fluid deterioration or transmission compo-
nent failure.

FLUID ADDITIVES

DaimlerChrysler strongly recommends against the

addition of any fluids to the transmission, other than
those automatic transmission fluids listed above.
Exceptions to this policy are the use of special dyes
to aid in detecting fluid leaks.

Various “special” additives and supplements exist that

claim to improve shift feel and/or quality. These addi-
tives and others also claim to improve converter clutch
operation and inhibit overheating, oxidation, varnish,
and sludge. These claims have not been supported to
the satisfaction of DaimlerChrysler and these additives
must not be used. The use of transmission “sealers”
should also be avoided, since they may adversely
affect the integrity of transmission seals.

OPERATION

The automatic transmission fluid is selected based

upon several qualities. The fluid must provide a high
level of protection for the internal components by
providing a lubricating film between adjacent metal
components. The fluid must also be thermally stable
so that it can maintain a consistent viscosity through
a large temperature range. If the viscosity stays con-
stant through the temperature range of operation,
transmission operation and shift feel will remain con-
sistent. Transmission fluid must also be a good con-
ductor of heat. The fluid must absorb heat from the
internal transmission components and transfer that
heat to the transmission case.

TORQUE CONVERTER

DESCRIPTION

The torque converter (Fig. 9) is a hydraulic device

that couples the engine crankshaft to the transmis-

sion. The torque converter consists of an outer shell
with an internal turbine, a stator, an overrunning
clutch, an impeller and an electronically applied con-
verter clutch. The converter clutch provides reduced
engine

speed

and

greater

fuel

economy

when

engaged. Clutch engagement also provides reduced
transmission

fluid

temperatures.

The

converter

clutch engages in third gear. The torque converter
hub drives the transmission oil (fluid) pump.

The torque converter is a sealed, welded unit that

is not repairable and is serviced as an assem nbly.

CAUTION: The torque converter must be replaced if
a transmission failure resulted in large amounts of
metal or fiber contamination in the fluid. If the fluid
is contaminated, flush the fluid cooler and lines.

Fig. 9 Torque Converter Assembly

1 – TURBINE
2 – IMPELLER
3 – HUB
4 – STATOR
5 – FRONT COVER
6 – CONVERTER CLUTCH DISC
7 – DRIVE PLATE

DN

42/44RE AUTOMATIC TRANSMISSION

21 - 9

DESCRIPTION AND OPERATION (Continued)