automatic transmission DODGE RAM 2001 Service Repair Manual

The pressure created in the fluid is equal to the force
applied, divided by the piston area. If the force is 100
lbs., and the piston area is 10 sq. in., then the pres-
sure created equals 10 PSI. Another interpretation of
Pascal's Law is that regardless of container shape or
size, the pressure will be maintained throughout, as
long as the fluid is confined. In other words, the
pressure in the fluid is the same everywhere within
the container.
FORCE MULTIPLICATION
Using the 10 PSI example used in the illustration
(Fig. 192), a force of 1000 lbs. can be moved with a
force of only 100 lbs. The secret of force multiplica-
tion in hydraulic systems is the total fluid contact
area employed. The illustration, (Fig. 192), shows an
area that is ten times larger than the original area.
The pressure created with the smaller 100 lb. input
is 10 PSI. The concept ªpressure is the same every-
whereº means that the pressure underneath the
larger piston is also 10 PSI. Pressure is equal to the
force applied divided by the contact area. Therefore,
by means of simple algebra, the output force may be
found. This concept is extremely important, as it is
also used in the design and operation of all shift
valves and limiting valves in the valve body, as well
as the pistons, of the transmission, which activate
the clutches and bands. It is nothing more than
using a difference of area to create a difference in
pressure to move an object.
PISTON TRAVEL
The relationship between hydraulic lever and a
mechanical lever is the same. With a mechanical
lever it's a weight-to-distance output rather than a
pressure-to-area output. Using the same forces and
areas as in the previous example, the smaller piston
(Fig. 193) has to move ten times the distance
required to move the larger piston one inch. There-fore, for every inch the larger piston moves, the
smaller piston moves ten inches. This principle is
true in other instances also. A common garage floor
jack is a good example. To raise a car weighing 2000
lbs., an effort of only 100 lbs. may be required. For
every inch the car moves upward, the input piston at
the jack handle must move 20 inches downward.
Fig. 191 Pressure on a Confined Fluid
Fig. 192 Force Multiplication
Fig. 193 Piston Travel
BR/BEAUTOMATIC TRANSMISSION - 42RE 21 - 239
PISTONS (Continued)

PLANETARY GEARTRAIN/
OUTPUT SHAFT
DESCRIPTION
The planetary gearsets (Fig. 194) are designated as
the front, rear, and overdrive planetary gear assem-
blies and located in such order. A simple planetary
gearset consists of three main members:
²The sun gear which is at the center of the sys-
tem.
²The planet carrier with planet pinion gears
which are free to rotate on their own shafts and are
in mesh with the sun gear.
²The annulus gear, which rotates around and is
in mesh with the planet pinion gears.
NOTE: The number of pinion gears does not affect
the gear ratio, only the duty rating.
OPERATION
With any given planetary gearset, several condi-
tions must be met for power to be able to flow:
²One member must be held.
²Another member must be driven or used as an
input.
²The third member may be used as an output for
power flow.
²For direct drive to occur, two gear members in
the front planetary gearset must be driven.
NOTE: Gear ratios are dependent on the number of
teeth on the annulus and sun gears.
DISASSEMBLY
(1) Remove planetary snap-ring (Fig. 195).
(2) Remove front annulus and planetary assembly
from driving shell (Fig. 195).
(3) Remove snap-ring that retains front planetary
gear in annulus gear (Fig. 196).
Fig. 195 Front Annulus And Planetary Assembly
Removal
1 - DRIVING SHELL
2 - FRONT ANNULUS AND PLANETARY ASSEMBLY
3 - PLANETARY SNAP-RING
Fig. 196 Front Planetary Snap-Ring Removal
1 - FRONT ANNULUS GEAR
2 - PLANETARY SNAP-RING
Fig. 194 Planetary Gearset
1 - ANNULUS GEAR
2 - SUN GEAR
3 - PLANET CARRIER
4 - PLANET PINIONS (4)
21 - 240 AUTOMATIC TRANSMISSION - 42REBR/BE

(4) Remove tabbed thrust washer and tabbed
thrust plate from hub of front annulus (Fig. 197).
(5) Separate front annulus and planetary gears
(Fig. 197).
(6) Remove front planetary gear front thrust
washer from annulus gear hub.
(7) Separate and remove driving shell, rear plane-
tary and rear annulus from output shaft (Fig. 198).
(8) Remove front planetary rear thrust washer
from driving shell.
(9) Remove tabbed thrust washers from rear plan-
etary gear.
(10) Remove lock ring that retains sun gear in
driving shell. Then remove sun gear, spacer and
thrust plates.
INSPECTION
Check sun gear and driving shell condition.
Replace the gear if damaged or if the bushings are
scored or worn. The bushings are not serviceable.
Replace the driving shell if worn, cracked or dam-
aged.
Replace planetary gear sets if gears, pinion pins, or
carrier are damaged in any way. Replace the annulus
gears and supports if either component is worn or
damaged.
Inspect the geartrain spacers, thrust plates, snap-
rings, and thrust washers. Replace any of these parts
that are worn, distorted or damaged. Do not attempt
to reuse these parts.
The planetary gear thrust washers are different
sizes. The large diameter washers go on the front
planetary and the smaller washers go on the rear
planetary. All the washers have four locating tabs onthem. These tabs fit in the holes or slots provided in
each planetary gear.
Inspect the output shaft carefully. Pay particular
attention to the machined bushing/bearing surfaces
on the shaft and the governor valve shaft bore at the
shaft rear.
Replace the output shaft if the machined surfaces
are scored, pitted, or damaged in any way. Also
replace the shaft if the splines are damaged, or
exhibits cracks at any location (especially at the gov-
ernor valve shaft bore).
The annulus gears can be removed from their sup-
ports if necessary. Just remove the snap-rings and
separate the two parts when replacement is neces-
sary. In addition, the annulus gear bushings can be
replaced if severely worn, or scored. However it is not
necessary to replace the bushings if they only exhibit
normal wear. Check bushing fit on the output shaft
to be sure.
ASSEMBLY
(1) Lubricate output shaft and planetary compo-
nents with transmission fluid. Use petroleum jelly to
lubricate and hold thrust washers and plates in posi-
tion.
(2) Assemble rear annulus gear and support if dis-
assembled. Be sure support snap-ring is seated and
that shoulder-side of support faces rearward (Fig.
199).
(3) Install rear thrust washer on rear planetary
gear. Use enough petroleum jelly to hold washer in
place. Also be sure all four washer tabs are properly
engaged in gear slots.
(4) Install rear annulus over and onto rear plane-
tary gear (Fig. 199).
Fig. 197 Front Planetary And Annulus
Gear Disassembly
1 - FRONT ANNULUS
2 - THRUST WASHER
3 - THRUST PLATE
4 - FRONT THRUST WASHER
5 - FRONT PLANETARY
Fig. 198 Removing Driving Shell, Rear Planetary
And Rear Annulus
1 - REAR ANNULUS
2 - REAR PLANETARY
3 - DRIVING SHELL
4 - OUTPUT SHAFT
BR/BEAUTOMATIC TRANSMISSION - 42RE 21 - 241
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(5) Install assembled rear planetary and annulus
gear on output shaft (Fig. 200). Verify that assembly
is fully seated on shaft.
(6) Install front thrust washer on rear planetary
gear (Fig. 201). Use enough petroleum jelly to hold
washer on gear. Be sure all four washer tabs are
seated in slots.
(7) Install spacer on sun gear (Fig. 202).
(8) Install thrust plate on sun gear (Fig. 203). Note
that driving shell thrust plates are interchangeable.
Use either plate on sun gear and at front/rear of
shell.
Fig. 199 Assembling Rear Annulus And Planetary
Gear
1 - REAR ANNULUS GEAR
2 - TABBED THRUST WASHER
3 - REAR PLANETARY
Fig. 200 Installing Rear Annulus And Planetary On
Output Shaft
1 - REAR ANNULUS AND PLANETARY GEAR ASSEMBLY
2 - OUTPUT SHAFT
Fig. 201 Installing Rear Planetary Front Thrust
Washer
1 - FRONT TABBED THRUST WASHER
2 - REAR PLANETARY GEAR
Fig. 202 Installing Spacer On Sun Gear
1 - SUN GEAR
2 - SUN GEAR SPACER
Fig. 203 Installing Driving Shell Front Thrust Plate
On Sun Gear
1 - SPACER
2 - SUN GEAR
3 - THRUST PLATE
21 - 242 AUTOMATIC TRANSMISSION - 42REBR/BE
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(9) Hold sun gear in place and install thrust plate
over sun gear at rear of driving shell (Fig. 204).
(10) Position wood block on bench and support sun
gear on block (Fig. 205). This makes it easier to align
and install sun gear lock ring. Keep wood block
handy as it will also be used for geartrain end play
check.(11) Align rear thrust plate on driving shell and
install sun gear lock ring. Be sure ring is fully seated
in sun gear ring groove (Fig. 206).
(12) Install assembled driving shell and sun gear
on output shaft (Fig. 207).
Fig. 204 Installing Driving Shell Rear Thrust Plate
1 - DRIVING SHELL
2 - SUN GEAR
3 - REAR THRUST PLATE
Fig. 205 Supporting Sun Gear On Wood Block
1 - SUN GEAR
2 - DRIVING SHELL
3 - WOOD BLOCK
Fig. 206 Installing Sun Gear Lock Ring
1 - LOCK RING GROOVE
2 - SUN GEAR LOCK RING
3 - DRIVING SHELL
4 - REAR THRUST PLATE
Fig. 207 Installing Assembled Sun Gear And Driving
Shell On Output Shaft
1 - SUN GEAR/DRIVING SHELL ASSEMBLY
2 - OUTPUT SHAFT
BR/BEAUTOMATIC TRANSMISSION - 42RE 21 - 243
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(13) Install rear thrust washer on front planetary
gear (Fig. 208). Use enough petroleum jelly to hold
washer in place and be sure all four washer tabs are
seated.
(14) Install front planetary gear on output shaft
and in driving shell (Fig. 209).
(15) Install front thrust washer on front planetary
gear. Use enough petroleum jelly to hold washer in
place and be sure all four washer tabs are seated.
(16) Assemble front annulus gear and support, if
necessary. Be sure support snap-ring is seated.(17) Install front annulus on front planetary (Fig.
209).
(18) Position thrust plate on front annulus gear
support (Fig. 210). Note that plate has two tabs on it.
These tabs fit in notches of annulus hub.
(19) Install thrust washer in front annulus (Fig.
211). Align flat on washer with flat on planetary hub.
Also be sure washer tab is facing up.
Fig. 209 Installing Front Planetary And Annulus
Gears
1 - FRONT PLANETARY GEAR
2 - FRONT THRUST WASHER
3 - FRONT ANNULUS GEAR
Fig. 210 Positioning Thrust Plate On Front Annulus
Support
1 - FRONT ANNULUS
2 - THRUST PLATE
Fig. 211 Installing Front Annulus Thrust Washer
1 - WASHER FLAT ALIGNS WITH FLAT ON PLANETARY HUB
2 - FRONT ANNULUS THRUST WASHER
3 - TAB FACES FRONT
Fig. 208 Installing Rear Thrust Washer On Front
Planetary Gear
1 - FRONT PLANETARY GEAR
2 - REAR TABBED THRUST WASHER
21 - 244 AUTOMATIC TRANSMISSION - 42REBR/BE
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(20) Install front annulus snap-ring (Fig. 212). Use
snap-ring pliers to avoid distorting ring during
installation. Also be sure ring is fully seated.
(21) Install planetary selective snap-ring with
snap-ring pliers (Fig. 213). Be sure ring is fully
seated.
(22) Turn planetary geartrain assembly over so
driving shell is facing workbench. Then support
geartrain on wood block positioned under forward
end of output shaft. This allows geartrain compo-
nents to move forward for accurate end play check.
(23) Check planetary geartrain end play with
feeler gauge (Fig. 214). Gauge goes between shoulder
on output shaft and end of rear annulus support.
(24) Geartrain end play should be 0.12 to 1.22 mm
(0.005 to 0.048 in.). If end play is incorrect, snap-ring
(or thrust washers) may have to be replaced. Snap-
rings are available in three different thicknesses for
adjustment purposes.
Fig. 212 Installing Front Annulus Snap-Ring
1 - SNAP-RING PLIERS
2 - FRONT ANNULUS SNAP-RING
Fig. 213 Installing Planetary Selective Snap-Ring
1 - SELECTIVE SNAP-RING
2 - SNAP-RING PLIERS
Fig. 214 Checking Planetary Geartrain End Play
1 - OUTPUT SHAFT
2 - REAR ANNULUS GEAR
3 - FEELER GAUGE
BR/BEAUTOMATIC TRANSMISSION - 42RE 21 - 245
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

REAR CLUTCH
DESCRIPTION
The rear clutch assembly (Fig. 215) is composed of
the rear clutch retainer, pressure plate, clutch plates,
driving discs, piston, Belleville spring, and snap-
rings. The Belleville spring acts as a lever to multi-
ply the force applied on to it by the apply piston. The
increased apply force on the rear clutch pack, in com-
parison to the front clutch pack, is needed to hold
against the greater torque load imposed onto the rear
pack. The rear clutch is directly behind the front
clutch and is considered a driving component.
NOTE: The number of discs and plates may vary
with each engine and vehicle combination.
OPERATION
To apply the clutch, pressure is applied between
the clutch retainer and piston. The fluid pressure is
provided by the oil pump, transferred through the
control valves and passageways, and enters the
clutch through the hub of the reaction shaft support.
With pressure applied between the clutch retainer
and piston, the piston moves away from the clutch
retainer and compresses the clutch pack. This action
applies the clutch pack, allowing torque to flow
through the input shaft into the driving discs, and
into the clutch plates and pressure plate that are
lugged to the clutch retainer. The waved spring is
used to cushion the application of the clutch pack.
The snap-ring is selective and used to adjust clutch
pack clearance.
When pressure is released from the piston, the
spring returns the piston to its fully released position
Fig. 215 Rear Clutch
1 - PISTON SPRING 10 - TOP PRESSURE PLATE
2 - REAR CLUTCH PISTON 11 - CLUTCH DISCS (4)
3 - CLUTCH PISTON SEALS 12 - BOTTOM PRESSURE PLATE
4 - OUTPUT SHAFT THRUST WASHER (METAL) 13 - WAVE SPRING
5 - INPUT SHAFT SNAP-RING 14 - CLUTCH PLATES (3)
6 - REAR CLUTCH RETAINER 15 - RETAINER SEAL RING
7 - INPUT SHAFT 16 - SHAFT REAR SEAL RING (PLASTIC)
8 - REAR CLUTCH THRUST WASHER (FIBER) 17 - SHAFT FRONT SEAL RING (TEFLON)
9 - CLUTCH PACK SNAP-RING (SELECTIVE)
21 - 246 AUTOMATIC TRANSMISSION - 42REBR/BE

and disengages the clutch. The release spring also
helps to cushion the application of the clutch assem-
bly. When the clutch is in the process of being
released by the release spring, fluid flows through a
vent and one-way ball-check-valve located in the pis-
ton. The check-valve is needed to eliminate the pos-
sibility of plate drag caused by centrifugal force
acting on the residual fluid trapped in the clutch pis-
ton retainer.
DISASSEMBLY
(1) Remove fiber thrust washer from forward side
of clutch retainer.
(2) Remove input shaft front/rear seal rings.
(3) Remove selective clutch pack snap-ring (Fig.
216).(4) Remove top pressure plate, clutch discs, steel
plates, bottom pressure plate and wave snap-ring
and wave spring (Fig. 216).
(5) Remove clutch piston with rotating motion.
(6) Remove and discard piston seals.
(7) Remove input shaft snap-ring (Fig. 217). It
may be necessary to press the input shaft in slightly
to relieve tension on the snap-ring
(8) Press input shaft out of retainer with shop
press and suitable size press tool. Use a suitably
sized press tool to support the retainer as close to the
input shaft as possible.
CLEANING
Clean the clutch components with solvent and dry
them with compressed air. Do not use rags or shop
towels to dry any of the clutch parts. Lint from such
Fig. 216 Rear Clutch Components
1 - PISTON SPRING 10 - TOP PRESSURE PLATE
2 - REAR CLUTCH PISTON 11 - CLUTCH DISCS (4)
3 - CLUTCH PISTON SEALS 12 - BOTTOM PRESSURE PLATE
4 - OUTPUT SHAFT THRUST WASHER (METAL) 13 - WAVE SPRING
5 - INPUT SHAFT SNAP-RING 14 - CLUTCH PLATES (3)
6 - REAR CLUTCH RETAINER 15 - RETAINER SEAL RING
7 - INPUT SHAFT 16 - SHAFT REAR SEAL RING (PLASTIC)
8 - REAR CLUTCH THRUST WASHER (FIBER) 17 - SHAFT FRONT SEAL RING (TEFLON)
9 - CLUTCH PACK SNAP-RING (SELECTIVE)
BR/BEAUTOMATIC TRANSMISSION - 42RE 21 - 247
REAR CLUTCH (Continued)

materials will adhere to component surfaces and
could restrict or block fluid passages after assembly.
INSPECTION
Replace the clutch discs if warped, worn, scored,
burned/charred, the lugs are damaged, or if the fac-
ing is flaking off. Replace the top and bottom pres-
sure plates if scored, warped, or cracked. Be sure the
driving lugs on the pressure and clutch plates are
also in good condition. The lugs must not be bent,
cracked or damaged in any way.
Replace the piston spring and wave spring if either
part is distorted, warped or broken.
Check the lug grooves in the clutch retainer. The
clutch and pressure plates should slide freely in the
slots. Replace the retainer if the grooves are worn or
damaged. Also check action of the check balls in the
retainer and piston. Each check ball must move
freely and not stick.
Replace the retainer bushing if worn, scored, or
doubt exists about bushing condition.
Inspect the piston and retainer seal surfaces for
nicks or scratches. Minor scratches can be removed
with crocus cloth. However, replace the piston and/or
retainer if the seal surfaces are seriously scored.
Check condition of the fiber thrust washer and
metal output shaft thrust washer. Replace either
washer if worn or damaged.
Check condition of the seal rings on the input shaft
and clutch retainer hub. Replace the seal rings only
if worn, distorted, or damaged. The input shaft front
seal ring is teflon with chamfered ends. The rear ring
is metal with interlocking ends.
Check the input shaft for wear, or damage. Replace
the shaft if worn, scored or damaged in any way.
ASSEMBLY
(1) Soak clutch discs in transmission fluid while
assembling other clutch parts.
(2) Install new seal rings on clutch retainer hub
and input shaft, if necessary, (Fig. 218) and (Fig.
219).
(a) Be sure clutch hub seal ring is fully seated in
groove and is not twisted.
(3) Lubricate splined end of input shaft and clutch
retainer with transmission fluid. Then press input
shaft into retainer (Fig. 220). Use a suitably sized
press tool to support retainer as close to input shaft
as possible.
(4) Install input shaft snap-ring (Fig. 217).
(5) Invert retainer and press input shaft in oppo-
site direction until snap-ring is seated.
(6) Install new seals on clutch piston. Be sure lip
of each seal faces interior of clutch retainer.
(7) Lubricate lip of piston seals with generous
quantity of MopartDoor Ease. Then lubricate
retainer hub and bore with light coat of transmission
fluid.
(8) Install clutch piston in retainer. Use twisting
motion to seat piston in bottom of retainer. A thin
strip of plastic (about 0.0209thick), can be used to
guide seals into place if necessary.
CAUTION: Never push the clutch piston straight in.
This will fold the seals over causing leakage and
clutch slip. In addition, never use any type of metal
tool to help ease the piston seals into place. Metal
tools will cut, shave, or score the seals.
(9) Install piston spring in retainer and on top of
piston (Fig. 221). Concave side of spring faces down-
ward (toward piston).
(10) Install wave spring in retainer (Fig. 221). Be
sure spring is completely seated in retainer groove.
(11) Install bottom pressure plate (Fig. 216).
Ridged side of plate faces downward (toward piston)
and flat side toward clutch pack.
(12) Install first clutch disc in retainer on top of
bottom pressure plate. Then install a clutch plate fol-
lowed by a clutch disc until entire clutch pack is
installed (4 discs and 3 plates are required) (Fig.
216).
(13) Install top pressure plate.
(14) Install selective snap-ring. Be sure snap-ring
is fully seated in retainer groove.
Fig. 217 Removing Input Shaft Snap-Ring
1 - REAR CLUTCH RETAINER
2 - INPUT SHAFT SNAP-RING
3 - SNAP-RING PLIERS
21 - 248 AUTOMATIC TRANSMISSION - 42REBR/BE
REAR CLUTCH (Continued)