1998 DODGE RAM 1500 Over drive

BOOST VALVE
The boost valve (Fig. 271) provides increased fluid
apply pressure to the overdrive clutch during 3-4
upshifts (Fig. 272), and when accelerating in fourth
gear. The boost valve also serves to increase line
pressure during torque converter lock-up.
REMOVAL
The valve body can be removed for service without
having to remove the transmission assembly.
The valve body can be disassembled for cleaning
and inspection of the individual components.
The only replaceable valve body components are:
²Manual lever.
²Manual lever washer, seal, E-clip, and shaft
seal.
²Manual lever detent ball.
²Throttle lever.
²Fluid filter.
²Pressure adjusting screw bracket.
²Governor pressure solenoid.
²Governor pressure sensor (includes transmission
temperature thermistor).
²Converter clutch/overdrive solenoid assembly
and harness.
²Governor housing gasket.
²Solenoid case connector O-rings.
(1) Shift transmission into NEUTRAL.
(2) Raise vehicle.
(3) Remove gearshift and throttle levers from shaft
of valve body manual lever.
(4) Disconnect wires at solenoid case connector
(Fig. 273).
(5) Remove the transmission range sensor (Refer
to 21 - TRANSMISSION/AUTOMATIC/TRANSMIS-
SION RANGE SENSOR - REMOVAL).
(6) Position drain pan under transmission oil pan.
(7) Remove transmission oil pan and gasket.
(8) Remove fluid filter from valve body.
(9) Remove bolts attaching valve body to transmis-
sion case.
(10) Lower valve body enough to remove accumu-
lator piston and springs.
Fig. 273 Transmission Case Connector
1 - SOLENOID CASE CONNECTOR
2 - TRANSMISSION RANGE SENSOR
Fig. 271 Boost Valve Before Lock-up
Fig. 272 Boost Valve After Lock-up
21 - 286 AUTOMATIC TRANSMISSION - 48REDR
VALVE BODY (Continued)

(11) Work manual lever shaft and electrical con-
nector out of transmission case.
(12) Lower valve body, rotate valve body away
from case, pull park rod out of sprag, and remove
valve body (Fig. 274).
DISASSEMBLY
CAUTION: Do not clamp any valve body component
in a vise. This practice can damage the component
resulting in unsatisfactory operation after assembly
and installation. Do not use pliers to remove any of
the valves, plugs or springs and do not force any of
the components out or into place. The valves and
valve body housings will be damaged if force is
used. Tag or mark the valve body springs for refer-
ence as they are removed. Do not allow them to
become intermixed.
(1) Disconnect wires from governor pressure sen-
sor and solenoid.
(2) Remove screws attaching governor body and
retainer plate to transfer plate.
(3) Remove retainer plate, governor body and gas-
ket from transfer plate.(4) Remove governor pressure sensor from gover-
nor body.
(5) Remove governor pressure solenoid by pulling
it straight out of bore in governor body. Remove and
discard solenoid O-rings if worn, cut, or torn.
(6) Remove small shoulder bolt that secures sole-
noid harness case connector to 3-4 accumulator hous-
ing (Fig. 275). Retain shoulder bolt. Either tape it to
harness or thread it back into accumulator housing
after connector removal.
(7) Unhook overdrive/converter solenoid harness
from 3-4 accumulator cover plate (Fig. 276).
Fig. 275 Solenoid Harness Case Connector
Shoulder Bolt
1 - SOLENOID HARNESS CASE CONNECTOR
2 - 3-4 ACCUMULATOR HOUSING
Fig. 276 Solenoid Harness Routing
1 - OVERDRIVE/CONVERTER SOLENOID WIRE HARNESS
2 - 3-4 ACCUMULATOR COVER PLATE
Fig. 274 Valve Body
1 - VALVE BODY
2 - WIRE HARNESS
3 - PARK ROD
4 - GOVERNOR PRESSURE SOLENOID
5 - GOVERNOR PRESSURE SENSOR
DRAUTOMATIC TRANSMISSION - 48RE 21 - 287
VALVE BODY (Continued)

(8) Turn valve body over and remove screws that
attach overdrive/converter solenoid assembly to valve
body (Fig. 277).
(9) Remove solenoid and harness assembly from
valve body (Fig. 278).
(10) Remove boost valve cover (Fig. 279).
(11) Remove boost valve retainer, valve spring and
boost valve (Fig. 280).
Fig. 277 Solenoid Assembly Screws
1 - OVERDRIVE/CONVERTER CLUTCH SOLENOID ASSEMBLY
2 - HARNESS
Fig. 278 Solenoid Assembly
1 - GOVERNOR SOLENOID WIRES
2 - CONVERTER CLUTCH SOLENOID
3 - SOLENOID SCREWS
4 - GOVERNOR SENSOR WIRES
5 - OVERDRIVE SOLENOID
6 - HARNESS
7 - CASE CONNECTOR
Fig. 279 Boost Valve Cover Location
1 - BOOST VALVE HOUSING AND COVER
2 - BOOST VALVE TUBE
Fig. 280 Boost Valve Components
1 - SPRING AND VALVE RETAINER
2 - COVER SCREWS
3 - BOOST VALVE COVER
4 - BOOST VALVE PLUG
5 - BOOST VALVE
6 - BOOST VALVE SPRING
21 - 288 AUTOMATIC TRANSMISSION - 48REDR
VALVE BODY (Continued)

(23) Remove left-side screw and remove 3-4 accu-
mulator housing from valve body (Fig. 291).
(24) Bend back tabs on boost valve tube brace (Fig.
292).(25) Remove boost valve connecting tube (Fig.
293). Disengage tube from upper housing port first.
Then rock opposite end of tube back and forth to
work it out of lower housing.
CAUTION: Do not use tools to loosen or pry the
connecting tube out of the valve body housings.
Loosen and remove the tube by hand only.
(26) Turn valve body over so lower housing is fac-
ing upward (Fig. 294). In this position, the two check
balls in upper housing will remain in place and not
fall out when lower housing and separator plate are
removed.
(27) Remove screws attaching valve body lower
housing to upper housing and transfer plate (Fig.
294). Note position of boost valve tube brace for
assembly reference.
(28) Remove lower housing and overdrive separa-
tor plate from transfer plate (Fig. 294).
Fig. 293 Boost Valve Tube
1 - BOOST VALVE TUBE
2 - LOWER HOUSING
3 - DISENGAGE THIS END OF TUBE FIRST
4 - UPPER HOUSING
Fig. 294 Lower Housing
1 - LOWER HOUSING
2 - OVERDRIVE SEPARATOR PLATE
3 - TRANSFER PLATE AND UPPER HOUSING
Fig. 291 Accumulator Housing, Valve Springs, and
Plug
1 - 3-4 SHIFT VALVE SPRING
2 - CONVERTER CLUTCH VALVE SPRING AND PLUG
3 - 3-4 ACCUMULATOR HOUSING
Fig. 292 Boost Valve Tube Brace
1 - BOOST VALVE TUBE
2 - TUBE BRACE (DOUBLE TAB)
21 - 292 AUTOMATIC TRANSMISSION - 48REDR
VALVE BODY (Continued)

VALVE BODY LOWER HOUSING
(1) Remove timing valve cover.
(2) Remove 3-4 timing valve and spring.
(3) Remove 3-4 quick fill valve, spring and plug.
(4) Remove 3-4 shift valve and spring.
(5) Remove converter clutch valve, spring and plug
(Fig. 303).
(6) Remove converter clutch timing valve, retainer
and valve spring.
Fig. 303 Lower Housing Shift Valves and Springs
1 - 3-4 ACCUMULATOR HOUSING 11 - TIMING VALVE COVER
2 - 3-4 SHIFT VALVE AND SPRING 12 - PLUG
3 - PLUG 13 - 3-4 TIMING VALVE AND SPRING
4 - SPRING RETAINER 14 - LOWER HOUSING
5 - CONVERTER CLUTCH VALVE AND SPRING 15 - ACCUMULATOR END PLATE
6 - CONVERTER CLUTCH TIMING VALVE AND SPRING 16 - 3-4 ACCUMULATOR PISTON AND SPRING
7 - OVERDRIVE SEPARATOR PLATE 17 - E-CLIP
8 - CASE CONNECTOR 18 - 3-4 QUICK FILL SPRING AND VALVE
9 - CONVERTER CLUTCH SOLENOID 19 - SOLENOID GASKET
10 - OVERDRIVE SOLENOID 20 - HARNESS
DRAUTOMATIC TRANSMISSION - 48RE 21 - 297
VALVE BODY (Continued)

Fig. 305 Lower Housing Shift Valves and Springs
1 - 3-4 ACCUMULATOR HOUSING 11 - TIMING VALVE COVER
2 - 3-4 SHIFT VALVE AND SPRING 12 - PLUG
3 - PLUG 13 - 3-4 TIMING VALVE AND SPRING
4 - SPRING RETAINER 14 - LOWER HOUSING
5 - CONVERTER CLUTCH VALVE AND SPRING 15 - ACCUMULATOR END PLATE
6 - CONVERTER CLUTCH TIMING VALVE AND SPRING 16 - 3-4 ACCUMULATOR PISTON AND SPRING
7 - OVERDRIVE SEPARATOR PLATE 17 - E-CLIP
8 - CASE CONNECTOR 18 - 3-4 QUICK FILL SPRING AND VALVE
9 - CONVERTER CLUTCH SOLENOID 19 - SOLENOID GASKET
10 - OVERDRIVE SOLENOID 20 - HARNESS
21 - 300 AUTOMATIC TRANSMISSION - 48REDR
VALVE BODY (Continued)

UPPER AND LOWER HOUSING
(1) Position upper housing so internal passages
and check ball seats are facing upward. Then install
check balls in housing (Fig. 310). Seven check balls
are used. The single large check ball is approxi-
mately 8.7 mm (11/32 in.) diameter. The single small
check ball is approximately 4.8 mm (3/16 in.) in
diameter. The remaining 5 check balls are approxi-
mately 6.3 mm (1/4 in.) in diameter.
(2) Position assembled transfer plate and upper
housing separator plate on upper housing (Fig. 311).
Be sure filter screen is seated in proper housing
recess.(3) Install the Number 10 check ball into the
transfer plate (Fig. 312). The check ball is approxi-
mately 4.8 mm (3/16 in.) in diameter.
(4) Position lower housing separator plate on
transfer plate (Fig. 313).
Fig. 310 Check Ball Locations In Upper Housing
1 - SMALL DIAMETER CHECK BALLS (5)
2 - LARGE DIAMETER CHECK BALL (1)
Fig. 311 Installing Transfer Plate On Upper Housing
1 - FILTER SCREEN
2 - TRANSFER PLATE/SEPARATOR PLATE ASSEMBLY
3 - UPPER HOUSING
Fig. 312 Number 10 Check Ball
1 - NUMBER 10 CHECK BALL (3/169)
Fig. 313 Lower Housing Separator Plate
1 - BE SURE TO ALIGN BORES
2 - TRANSFER PLATE
3 - LOWER HOUSING (OVERDRIVE) SEPARATOR PLATE
21 - 302 AUTOMATIC TRANSMISSION - 48REDR
VALVE BODY (Continued)

(7) Verify that throttle lever is aligned with end of
kickdown valve stem and that manual lever arm is
engaged in manual valve (Fig. 324).
(8) Position line pressure adjusting screw in
adjusting screw bracket.
(9) Install spring on end of line pressure regulator
valve.
(10) Install switch valve spring on tang at end of
adjusting screw bracket.
(11) Install manual valve.
(12) Install throttle valve and spring.
(13) Install kickdown valve and detent.
(14) Install pressure regulator valve.
(15) Install switch valve.
(16) Position adjusting screw bracket on valve
body. Align valve springs and press bracket into
place. Install short, upper bracket screws first and
long bottom screw last. Verify that valve springs and
bracket are properly aligned. Then tighten all three
bracket screws to 4 N´m (35 in. lbs.) torque.
(17) Perform Line Pressure and Throttle Pressure
adjustments. (Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC/VALVE BODY - ADJUST-
MENTS)
(18) Lubricate solenoid case connector O-rings and
shaft of manual lever with light coat of petroleum
jelly.
(19) Attach solenoid case connector to 3-4 accumu-
lator with shoulder-type screw. Connector has small
locating tang that fits in dimple at top of accumula-
tor housing (Fig. 325). Seat tang in dimple before
tightening connector screw.
(20) Install solenoid assembly and gasket. Tighten
solenoid attaching screws to 8 N´m (72 in. lbs.)
torque.(21) Verify that solenoid wire harness is properly
routed (Fig. 326). Solenoid harness must be clear of
manual lever and park rod and not be pinched
between accumulator housing and cover.
Fig. 324 Manual And Throttle Lever Alignment
1 - THROTTLE LEVER
2 - MANUAL LEVER VALVE ARM
3 - MANUAL VALVE
4 - KICKDOWN VALVE
Fig. 325 Solenoid Harness Case Connector
Shoulder Bolt
1 - SOLENOID HARNESS CASE CONNECTOR
2 - 3-4 ACCUMULATOR HOUSING
Fig. 326 Solenoid Harness Routing
1 - OVERDRIVE/CONVERTER SOLENOID WIRE HARNESS
2 - 3-4 ACCUMULATOR COVER PLATE
21 - 308 AUTOMATIC TRANSMISSION - 48REDR
VALVE BODY (Continued)