1998 DODGE RAM 1500 Transmission install

OD THRUST PLATE SELECTION
(1) Place overdrive unit in vertical position. Mount
it on blocks, or in workbench with appropriate size
mounting hole cut into it. Be sure unit is facing
upward for access to direct clutch hub. Also be sure
output shaft is not loaded and internal components
are moved rearward for accurate measurement.
(2) Determine correct thickness overdrive piston
thrust plate as follows:
(a) Position Gauge Tool 6311 across face of over-
drive case. Then position Dial Caliper C-4962 over
gauge tool (Fig. 174).
(b) Measure distance to clutch hub thrust bear-
ing seat at four points 90É apart. Then average
measurements by adding them and dividing by 4.
(c) Select and install required thrust plate from
information in thrust plate chart (Fig. 175).
(3) Leave Alignment Tool 6227-2 in place. Tool will
keep planetary and clutch hub splines in alignment
until overdrive unit is ready for installation on trans-
mission.
(4) Transmission speed sensor can be installed at
this time if desired. However, it is recommended that
sensor not be installed until after overdrive unit is
secured to transmission.
OVERDRIVE PISTON
(1) Install new seals on overdrive piston.
(2) Stand transmission case upright on bellhous-
ing.
(3) Position Guide Ring 8114-1 on outer edge of
overdrive piston retainer.
(4) Position Seal Guide 8114-3 on inner edge of
overdrive piston retainer.
(5) Install overdrive piston in overdrive piston
retainer by:
(a) Aligning locating lugs on overdrive piston to
the two mating holes in retainer.
(b) Lubricate overdrive piston seals with Mopart
ATF+4.
(c) Install piston over Seal Guide 8114-3 and
inside Guide Ring 8114-1.
(d) Push overdrive piston into position in
retainer.
(e) Verify that the locating lugs entered the lug
bores in the retainer.
(6) Install intermediate shaft spacer on intermedi-
ate shaft.
(7) Install overdrive piston thrust plate on over-
drive piston.
(8) Install overdrive piston thrust bearing on over-
drive piston.
(9) Install transmission speed sensor and o-ring
seal in overdrive case.
Fig. 174 Overdrive Piston Thrust Plate Measurement
1 - SPECIAL TOOL 6311
2 - DIRECT CLUTCH HUB THRUST BEARING SEAT
3 - SPECIAL TOOL C-4962
Fig. 175 Overdrive Piston Thrust Plate Selection
21 - 234 AUTOMATIC TRANSMISSION - 48REDR
OVERDRIVE UNIT (Continued)

INSTALLATION
(1) Be sure overdrive unit Alignment Tool 6227-2
is fully seated before moving unit. If tool is not
seated and gear splines rotate out of alignment, over-
drive unit will have to be disassembled in order to
realign splines.
(2) If overdrive piston retainer was not removed
during service and original case gasket is no longer
reusable, prepare new gasket by trimming it.
(3) Cut out old case gasket around piston retainer
with razor knife (Fig. 176).
(4) Use old gasket as template and trim new gas-
ket to fit.
(5) Position new gasket over piston retainer and
on transmission case. Use petroleum jelly to hold
gasket in place if necessary. Do not use any type of
sealer to secure gasket. Use petroleum jelly only.
(6) Install selective spacer on intermediate shaft, if
removed. Spacer goes in groove just rearward of
shaft rear splines (Fig. 177).
(7) Install thrust bearing in overdrive unit sliding
hub. Use petroleum jelly to hold bearing in position.
CAUTION: Be sure the shoulder on the inside diam-
eter of the bearing is facing forward.(8) Verify that splines in overdrive planetary gear
and overrunning clutch hub are aligned with Align-
ment Tool 6227-2. Overdrive unit cannot be installed
if splines are not aligned. If splines have rotated out
of alignment, unit will have to be disassembled to
realign splines.
(9) Carefully slide Alignment Tool 6227-2 out of
overdrive planetary gear and overrunning clutch
splines.
(10) Raise overdrive unit and carefully slide it
straight onto intermediate shaft. Insert park rod into
park lock reaction plug at same time. Avoid tilting
overdrive during installation as this could cause
planetary gear and overrunning clutch splines to
rotate out of alignment. If this occurs, it will be nec-
essary to remove and disassemble overdrive unit to
realign splines.
(11) Work overdrive unit forward on intermediate
shaft until seated against transmission case.
(12) Install bolts attaching overdrive unit to trans-
mission unit. Tighten bolts in diagonal pattern to 34
N´m (25 ft-lbs).
(13) Connect the transmission speed sensor and
overdrive wiring connectors.
(14) Install the transfer case, if equipped.
(15) Align and install rear propeller shaft, if nec-
essary. (Refer to 3 - DIFFERENTIAL & DRIVELINE/
PROPELLER SHAFT/PROPELLER SHAFT -
INSTALLATION)
Fig. 176 Trimming Overdrive Case Gasket
1 - GASKET
2 - SHARP KNIFE
Fig. 177 Intermediate Shaft Selective Spacer
Location
1 - SELECTIVE SPACER
2 - SPACER GROOVE
3 - INTERMEDIATE SHAFT
DRAUTOMATIC TRANSMISSION - 48RE 21 - 235
OVERDRIVE UNIT (Continued)

INSPECTION
Inspect condition of each clutch part after cleaning.
Replace the overrunning clutch roller and spring
assembly if any rollers or springs are worn or dam-
aged, or if the roller cage is distorted, or damaged.
Replace the cam if worn, cracked or damaged.
Replace the low-reverse drum if the clutch race,
roller surface or inside diameter is scored, worn or
damaged.Do not remove the clutch race from
the low-reverse drum under any circumstances.
Replace the drum and race as an assembly if
either component is damaged.
Examine the overdrive piston retainer carefully for
wear, cracks, scoring or other damage. Be sure the
retainer hub is a snug fit in the case and drum.
Replace the retainer if worn or damaged.
ASSEMBLY
(1) Temporarily install overdrive piston retainer in
case. Use 3-4 bolts to secure retainer.
(2) Align and start new clutch cam in the trans-
mission case. Be sure serrations on cam and in case
are aligned (Fig. 181). Then tap cam into case just
enough to hold it in place.
(3) Verify that cam is correctly positioned before
proceeding any further. Narrow ends of cam ramps
should be to left when cam is viewed from front end
of case (Fig. 181).
(4) Insert Adapter Tool SP-5124 from Installer/Re-
mover C-3863-A into piston retainer (Fig. 182).
(5) Assemble Puller Bolt SP-3701 and Press Plate
SP-3583-A (Fig. 183).
Fig. 181 Positioning Replacement Clutch Cam In
Case
1 - ALIGN SERRATIONS ON CAM AND IN CASE
2 - CLUTCH CAM
Fig. 182 Positioning Adapter Tool In Overdrive
Piston Retainer
1 - PISTON RETAINER
2 - SPECIAL TOOL SP-5124
Fig. 183 Assembling Clutch Cam Puller Bolt And
Press Plate
1 - PULLER BOLT SP-3701
2 - PRESS PLATE SP-3583-A
DRAUTOMATIC TRANSMISSION - 48RE 21 - 237
OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER (Continued)

(6) Install assembled puller plate and bolt (Fig.
184). Insert bolt through cam, case and adapter tool.
Be sure plate is seated squarely on cam.
(7) Hold puller plate and bolt in place and install
puller nut SP-3701 on puller bolt (Fig. 185).
(8) Tighten puller nut to press clutch cam into
case (Fig. 185). Be sure cam is pressed into case
evenly and does not become cocked.
(9) Remove clutch cam installer tools.
(10) Stake case in 14 places around clutch cam to
help secure cam in case. Use blunt punch or chisel to
stake case.
(11) Remove piston retainer from case. Cover
retainer with plastic sheeting, or paper to keep it
dust free.
(12) Clean case and cam thoroughly. Be sure any
chips/shavings generated during cam installation are
removed from case.
(13) Install new gasket at rear of transmission
case. Use petroleum jelly to hold gasket in place. Be
sure to align governor feed holes in gasket with feed
passages in case (Fig. 186). Also install gasket before
overdrive piston retainer. Center hole in gasket is
smaller than retainer and cannot be installed over
retainer.
Fig. 186 Installing/Aligning Case Gasket
1 - CASE GASKET
2 - BE SURE GOVERNOR TUBE FEED HOLES IN CASE AND
GASKET ARE ALIGNED
Fig. 184 Positioning Puller Plate On Clutch Cam
1 - SPECIAL TOOL SP-3701
2 - BE SURE PLATE SP-3583-A IS SEATED SQUARELY ON CAM
Fig. 185 Pressing Overrunning Clutch Cam Into
Case
1 - SPECIAL TOOL SP-3583-A
2 - TIGHTEN NUT TO DRAW CAM INTO CASE (NUT IS PART OF
BOLT SP-3701)
3 - SPECIAL TOOL SP-5124
4 - SPECIAL TOOL SP-3701
21 - 238 AUTOMATIC TRANSMISSION - 48REDR
OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER (Continued)

(14) Position overdrive piston retainer on trans-
mission case and align bolt holes in retainer, gasket
and case (Fig. 187). Then install and tighten retainer
bolts to 17 N´m (13 ft. lbs.) torque.
(15) Install new seals on overdrive piston.
(16) Stand transmission case upright on bellhous-
ing.
(17) Position Guide Ring 8114-1 on outer edge of
overdrive piston retainer.
(18) Position Seal Guide 8114-3 on inner edge of
overdrive piston retainer.
(19) Install overdrive piston in overdrive piston
retainer by: aligning locating lugs on overdrive piston
to the two mating holes in retainer.
(a) Aligning locating lugs on overdrive piston to
the two mating holes in retainer.
(b) Lubricate overdrive piston seals with Mopart
Door Ease, or equivalent.
(c) Install piston over Seal Guide 8114-3 and
inside Guide Ring 8114-1.
(d) Push overdrive piston into position in
retainer.
(e) Verify that the locating lugs entered the lug
bores in the retainer.PISTONS
DESCRIPTION
There are several sizes and types of pistons used in
an automatic transmission. Some pistons are used to
apply clutches, while others are used to apply bands.
They all have in common the fact that they are
round or circular in shape, located within a smooth
walled cylinder, which is closed at one end and con-
verts fluid pressure into mechanical movement. The
fluid pressure exerted on the piston is contained
within the system through the use of piston rings or
seals.
OPERATION
The principal which makes this operation possible
is known as Pascal's Law. Pascal's Law can be stated
as: ªPressure on a confined fluid is transmitted
equally in all directions and acts with equal force on
equal areas.º
PRESSURE
Pressure (Fig. 188) is nothing more than force
(lbs.) divided by area (in or ft.), or force per unit
area. Given a 100 lb. block and an area of 100 sq. in.
on the floor, the pressure exerted by the block is: 100
lbs. 100 in or 1 pound per square inch, or PSI as it is
commonly referred to.
Fig. 187 Aligning Overdrive Piston Retainer
1 - PISTON RETAINER
2 - GASKET
3 - RETAINER BOLTS
Fig. 188 Force and Pressure Relationship
DRAUTOMATIC TRANSMISSION - 48RE 21 - 239
OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER (Continued)

thrust plate if worn, or severely scored. Replace the
driving shell if distorted, cracked, or damaged in any
way.
Replace all snap-rings during geartrain assembly.
Reusing snap-rings is not recommended.
ASSEMBLY
(1) Lubricate sun gear and planetary gears with
transmission fluid during assembly. Use petroleum
jelly to lubricate intermediate shaft bushing surfaces,
thrust washers and thrust plates and to hold these
parts in place during assembly.
(2) Install front snap-ring on sun gear and install
gear in driving shell. Then install thrust plate over
sun gear and against rear side of driving shell (Fig.
201). Install rear snap-ring to secure sun gear and
thrust plate in driving shell. Note that the large ID
chamfer on the sun gear goes forward.
(3) Install rear annulus gear on intermediate shaft
(Fig. 202).
(4) Install thrust washer to rear planetary gear
(Fig. 203) using petroleum jelly. Be sure washer is
seated against corner witht teh tabs completely in
the locating holes.
(5) Install rear planetary gear in rear annulus
gear (Fig. 204). Be sure planetary carrier is seated
against annulus gear.
Fig. 202 Installing Rear Annulus Gear On
Intermediate Shaft
1 - REAR ANNULUS GEAR
2 - OUTPUT SHAFT
Fig. 203 Installing Rear Annulus Thrust Washer
1 - REAR ANNULUS GEAR
2 - THRUST WASHER
Fig. 204 Installing Rear Planetary Gear
1 - REAR ANNULUS GEAR
2 - REAR PLANETARY GEAR
Fig. 201 Sun Gear Installation
1 - DRIVING SHELL
2 - SUN GEAR
3 - THRUST PLATE
4 - SUN GEAR REAR RETAINING RING
21 - 244 AUTOMATIC TRANSMISSION - 48REDR
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(6) Install tabbed thrust washer on front face of
rear planetary gear (Fig. 205). Seat washer tabs in
matching slots in face of gear carrier. Use extra
petroleum jelly to hold washer in place if desired.
(7) Lubricate sun gear bushings with petroleum
jelly or transmission fluid.
(8) Install sun gear and driving shell on interme-
diate shaft (Fig. 206). Seat shell against rear plane-
tary gear. Verify that thrust washer on planetary
gear was not displaced during installation.
(9) Install tabbed thrust washer in driving shell
(Fig. 207), be sure washer tabs are seated in tab slots
of driving shell. Use extra petroleum jelly to hold
washer in place if desired.
(10) Install tabbed thrust washer on front plane-
tary gear (Fig. 208). Seat washer tabs in matchingslots in face of gear carrier. Use extra petroleum jelly
to hold washer in place if desired.
(11) Install the torlon bushing onto the front plan-
etary carrier hub.
Fig. 205 Installing Rear Planetary Thrust Washer
1 - REAR PLANETARY GEAR
2 - TABBED THRUST WASHER
Fig. 206 Installing Sun Gear And Driving Shell
1 - OUTPUT SHAFT
2 - DRIVING SHELL
3 - REAR PLANETARY GEAR
4 - OUTPUT SHAFT
5 - SUN GEAR
Fig. 207 Installing Driving Shell Thrust Washer
1 - TAB SLOTS (3)
2 - DRIVING SHELL
3 - TABBED THRUST WASHER
Fig. 208 Installing Thrust Washer On Front
Planetary Gear
1 - TABBED THRUST WASHER
2 - FRONT PLANETARY GEAR
DRAUTOMATIC TRANSMISSION - 48RE 21 - 245
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)

(12) Install front annulus gear over and onto front
planetary gear (Fig. 209). Be sure gears are fully
meshed and seated.
(13) Install front planetary and annulus gear
assembly (Fig. 210). Hold gears together and slide
them onto shaft. Be sure planetary pinions are
seated on sun gear and that planetary carrier is
seated on intermediate shaft.
(14) Place geartrain in upright position. Rotate
gears to be sure all components are seated and prop-
erly assembled. Snap-ring groove at forward end of
intermediate shaft will be completely exposed when
components are assembled correctly.
(15) Install new planetary snap-ring in groove at
end of intermediate shaft (Fig. 211).
(16) Turn planetary geartrain over. Position wood
block under front end of intermediate shaft and sup-
port geartrain on shaft. Be sure all geartrain parts
have moved forward against planetary snap-ring.
This is important for accurate end play check.
Fig. 209 Assembling Front Planetary And
Annulus Gears
1 - FRONT ANNULUS GEAR
2 - FRONT PLANETARY GEAR
Fig. 210 Installing Front Planetary And Annulus
Gear Assembly
1 - DRIVING SHELL
2 - ASSEMBLED FRONT PLANETARY AND ANNULUS GEARS
Fig. 211 Installing Planetary Snap
1 - SNAP-RING PLIERS
2 - PLANETARY SNAP-RING
21 - 246 AUTOMATIC TRANSMISSION - 48REDR
PLANETARY GEARTRAIN/OUTPUT SHAFT (Continued)