mission (Fig. 1) with an electronic governor. The
42/44RE is equipped with a lock-up clutch in the
torque converter. First through third gear ranges are
provided by the clutches, bands, overrunning clutch,
and planetary gear sets in the transmission. Fourth
gear range is provided by the overdrive unit that con-
tains an overdrive clutch, direct clutch, planetary
gear set, and overrunning clutch.

The transmission contains a front, rear, and direct

clutch which function as the input driving compo-
nents. They also contain the kickdown (front) and the
low/reverse (rear) bands which, along with the over-

running clutch and overdrive clutch, serve as the
holding components. The driving and holding compo-
nents combine to select the necessary planetary gear
components, in the front, rear, or overdrive planetary
gear set, transfer the engine power from the input
shaft through to the output shaft.

The valve body is mounted to the lower side of the

transmission and contains the valves to control pres-
sure regulation, fluid flow control, and clutch/band
application. The oil pump is mounted at the front of
the transmission and is driven by the torque con-
verter hub. The pump supplies the oil pressure nec-
essary for clutch/band actuation and transmission
lubrication.

The 42/44RE transmission is cooled by an integral

fluid cooler inside the radiator.

21 - 2

42/44RE AUTOMATIC TRANSMISSION

Fig.

42/44RE

ransmission

42/44RE AUTOMATIC TRANSMISSION

21 - 3

DESCRIPTION AND OPERATION (Continued)

IDENTIFICATION

Transmission identification numbers are stamped

on the left side of the case just above the oil pan gas-
ket surface (Fig. 2). Refer to this information when
ordering replacement parts.

GEAR RATIOS

The 42/44RE gear ratios are:
• 1st 2.74:1

• 2nd 1.54:1

• 3rd 1.00:1

• 4th 0.69:1

• Rev. 2.21

OPERATION

The application of each driving or holding component

is controlled by the valve body based upon the manual
lever position and governor pressure. The governor

pressure is a variable pressure input to the valve body
and is one of the signals that a shift is necessary. First
through fourth gear are obtained by selectively applying
and releasing the different clutches and bands. Engine
power is thereby routed to the various planetary gear
assemblies which combine with the overrunning clutch
assemblies to generate the different gear ratios. The
torque converter clutch is hydraulically applied and is
released when fluid is vented from the hydraulic circuit
by the torque converter control (TCC) solenoid on the
valve body. The torque converter clutch is controlled by
the Powertrain Control Module (PCM). The torque con-
verter clutch engages in fourth gear, and in third gear
when the O/D switch is OFF, when the vehicle is cruis-
ing on a level plane after the vehicle has warmed up.
The torque converter clutch will disengage momentarily
when an increase in engine load is sensed by the PCM,
such as when the vehicle begins to go uphill or the
throttle pressure is increased. The torque converter
clutch feature increases fuel economy and reduces the
transmission fluid temperature.

Since the overdrive clutch is applied in fourth gear

only and the direct clutch is applied in all ranges
except fourth gear, the transmission operation for
park, neutral, and first through third gear will be
described first. Once these powerflows are described,
the third to fourth shift sequence will be described.

PARK POWERFLOW

As the engine is running and the crankshaft is rotat-

ing, the flexplate and torque converter, which are also
bolted to it, are all rotating in a clockwise direction as
viewed from the front of the engine. The notched hub of
the torque converter is connected to the oil pump’s
internal gear, supplying the transmission with oil pres-
sure. As the converter turns, it turns the input shaft in
a clockwise direction. As the input shaft is rotating, the
front clutch hub-rear clutch retainer and all their asso-
ciated parts are also rotating, all being directly con-

1 – CONVERTER CLUTCH
2 – TORQUE CONVERTER
3 – OIL PUMP AND REACTION SHAFT SUPPORT ASSEMBLY
4 – FRONT BAND
5 – FRONT CLUTCH
6 – DRIVING SHELL
7 – REAR BAND
8 – TRANSMISSION OVERRUNNING CLUTCH
9 – OVERDRIVE UNIT
10 – PISTON RETAINER
11 – OVERDRIVE CLUTCH
12 – DIRECT CLUTCH
13 – INTERMEDIATE SHAFT
14 – FRONT BEARING

15 – HOUSING
16 – REAR BEARING
17 – OUTPUT SHAFT
18 – SEAL
19 – OVERDRIVE OVERRUNNING CLUTCH
20 – OVERDRIVE PLANETARY GEAR
21 – DIRECT CLUTCH SPRING
22 – OVERDRIVE CLUTCH PISTON
23 – VALVE BODY ASSEMBLY
24 – FILTER
25 – FRONT PLANETARY GEAR
26 – REAR CLUTCH
27 – TRANSMISSION
28 – REAR PLANETARY GEAR

Fig. 2 Transmission Part And Serial Number

Location

1 – PART NUMBER
2 – BUILD DATE
3 – SERIAL NUMBER

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42/44RE AUTOMATIC TRANSMISSION

DESCRIPTION AND OPERATION (Continued)

nected to the input shaft. The power flow from the
engine through the front-clutch-hub and rear-clutch-re-
tainer stops at the rear-clutch-retainer. Therefore, no
power flow to the output shaft occurs because no
clutches are applied. The only mechanism in use at this
time is the parking sprag (Fig. 3), which locks the park-
ing gear on the output shaft to the transmission case.

NEUTRAL POWERFLOW

With the gear selector in the neutral position (Fig.

4), the power flow of the transmission is essentially
the same as in the park position. The only opera-
tional difference is that the parking sprag has been
disengaged, unlocking the output shaft from the
transmission case and allowing it to move freely.

REVERSE POWERFLOW

When the gear selector is moved into the reverse

position (Fig. 5), the front clutch and the rear band
are applied. With the application of the front clutch,
engine torque is applied to the sun gear, turning it in
a clockwise direction. The clockwise rotation of the
sun gear causes the rear planet pinions to rotate
against engine rotation in a counterclockwise direc-
tion. The rear band is holding the low reverse drum,
which is splined to the rear carrier. Since the rear
carrier is being held, the torque from the planet pin-
ions is transferred to the rear annulus gear, which is
splined to the output shaft. The output shaft in turn
rotates with the annulus gear in a counterclockwise
direction giving a reverse gear output. The entire
transmission of torque is applied to the rear plane-
tary gearset only. Although there is torque input to

the front gearset through the sun gear, no other
member of the gearset is being held. During the
entire reverse stage of operation, the front planetary
gears are in an idling condition.

FIRST GEAR POWERFLOW

When the gearshift lever is moved into the drive

position the transmission goes into first gear (Fig. 6).
As soon as the transmission is shifted from park or
neutral to drive, the rear clutch applies, applying the
rear clutch pack to the front annulus gear. Engine
torque is now applied to the front annulus gear turn-
ing it in a clockwise direction. With the front annulus
gear turning in a clockwise direction, it causes the
front planets to turn in a clockwise direction. The
rotation of the front planets cause the sun to revolve
in a counterclockwise direction. The sun gear now
transfers its counterclockwise rotation to the rear
planets which rotate back in a clockwise direction.
With the rear annulus gear stationary, the rear
planet rotation on the annulus gear causes the rear
planet carrier to revolve in a counterclockwise direc-
tion. The rear planet carrier is splined into the low-
reverse drum, and the low reverse drum is splined to
the inner race of the over-running clutch. With the
over-running clutch locked, the planet carrier is held,
and the resulting torque provided by the planet pin-
ions is transferred to the rear annulus gear. The rear
annulus gear is splined to the output shaft and
rotated along with it (clockwise) in an underdrive
gear reduction mode.

Fig. 3 Park Powerflow

1 – LEVER ENGAGED FOR PARK
2 – PARK SPRAG
3 – OUTPUT SHAFT

Fig. 4 Neutral Powerflow

1 – LEVER DISENGAGED FOR NEUTRAL
2 – PARK SPRAG
3 – OUTPUT SHAFT
4 – CAM
5 – LEVER

42/44RE AUTOMATIC TRANSMISSION

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DESCRIPTION AND OPERATION (Continued)

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