sion (Fig. 1) with an electronic governor. The 42RE is
equipped with a lock-up clutch in the torque con-
verter. First through third gear ranges are provided
by the clutches, bands, overrunning clutch, and plan-
etary gear sets in the transmission. Fourth gear
range is provided by the overdrive unit that contains
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 42RE transmission is cooled by an integral

fluid cooler inside the radiator.

21 - 2

42RE AUTOMATIC TRANSMISSION

Fig.

42RE

ransmission

42RE 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 42RE 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 compo-

nent 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 com-
bine with the overrunning clutch assemblies to gen-
erate 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 cruising on a level plane after the vehicle has
warmed up. The torque converter clutch will disen-
gage 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 econ-
omy 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.

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

21 - 4

42RE AUTOMATIC TRANSMISSION

DESCRIPTION AND OPERATION (Continued)

PARK POWERFLOW

As the engine is running and the crankshaft is

rotating, 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 transmis-
sion with oil pressure. 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 associated parts are also
rotating, all being directly connected to the input
shaft. The power flow from the engine through the
front-clutch-hub and rear-clutch-retainer 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 park-
ing sprag (Fig. 3), which locks the parking 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.

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

42RE AUTOMATIC TRANSMISSION

21 - 5

DESCRIPTION AND OPERATION (Continued)

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