FRONT AXLE - 248FBI
TABLE OF CONTENTS
page page
FRONT AXLE - 248FBI
DESCRIPTION...........................45
OPERATION.............................45
DIAGNOSIS AND TESTING.................46
AXLE................................46
REMOVAL..............................50
INSTALLATION...........................50
ADJUSTMENTS..........................50
SPECIFICATIONS........................58
SPECIAL TOOLS.........................58
AXLE SHAFTS
REMOVAL..............................60
INSTALLATION...........................60
AXLE SHAFTS - INTERMEDIATE
REMOVAL..............................60
INSTALLATION...........................61
AXLE SHAFT SEALS
REMOVAL..............................61
INSTALLATION...........................61
AXLE VACUUM MOTOR
DESCRIPTION...........................62
OPERATION.............................62
DIAGNOSIS AND TESTING.................63VACUUM MOTOR.......................63
REMOVAL..............................65
DISASSEMBLY...........................65
ASSEMBLY.............................65
INSTALLATION...........................65
SINGLE CARDAN UNIVERSAL JOINTS
REMOVAL..............................65
INSTALLATION...........................66
PINION SEAL
REMOVAL..............................66
INSTALLATION...........................66
DIFFERENTIAL
REMOVAL..............................68
DISASSEMBLY...........................68
ASSEMBLY.............................69
INSTALLATION...........................69
DIFFERENTIAL CASE BEARINGS
REMOVAL..............................71
INSTALLATION...........................71
PINION GEAR/RING GEAR
REMOVAL..............................72
INSTALLATION...........................74
FRONT AXLE - 248FBI
DESCRIPTION
The housing for the 248 Front Beam-design Iron
(FBI) axle consists of an iron center casting with
tubes on each side. The tubes are pressed into and
welded to the differential housing.
The integral type housing, hypoid gear design has
the centerline of the pinion set below the centerline
of the ring gear.
The axle has a vent used to relieve internal pres-
sure caused by lubricant vaporization and internal
expansion.
The axles are equipped with semi-floating axle
shafts, meaning that loads are supported by the hub
bearings. The axle shafts are retained by nuts at the
hub bearings. The hub bearings are bolted to the
steering knuckle at the outboard end of the axle tube
yoke. The hub bearings are serviced as an assembly.
The axles are equipped with ABS brake sensors.
The sensors are attached to the knuckle assemblies
and the tone rings are pressed onto the axle shaft.
Use care when removing axle shafts as NOT to
damage the tone wheel or the sensor.The stamped steel cover provides a means for
inspection and servicing the differential.
The 248 FBI axle have the assembly part number
and gear ratio listed on a tag. The tag is attached to
the housing cover by one of the cover bolts. Build
date identification codes are stamped on the cover
side of a axle tube.
The differential case is a one-piece design. The dif-
ferential pinion mate shaft is retained with a roll
pin. Differential bearing preload and ring gear back-
lash is adjusted by the use of shims. The shims are
located between the differential bearing cones and
case. Pinion bearing preload is set and maintained by
the use of a collapsible spacer.
The axle differential covers can be used for identi-
fication of the axle (Fig. 1). A tag is also attached to
the cover.
OPERATION
The axle receives power from the transfer case
through the front propeller shaft. The front propeller
shaft is connected to the pinion gear which rotates
the differential through the gear mesh with the ring
gear bolted to the differential case. The engine power
is transmitted to the axle shafts through the pinion
BR/BEFRONT AXLE - 248FBI 3 - 45
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the wheels and tires.
(3) Remove the brake calipers and rotors. Refer to
Group 5, Brakes, for proper procedures.
(4) Remove ABS wheel speed sensors, if equipped.
Refer to Group 5, Brakes, for proper procedures.
(5) Disconnect the axle vent hose.
(6) Disconnect vacuum hose and electrical connec-
tor at disconnect housing.
(7) Remove the front propeller shaft.
(8) Disconnect the stabilizer bar links at the axle
brackets.
(9) Disconnect the shock absorbers from axle
brackets.
(10) Disconnect the track bar from the axle
bracket.
(11) Disconnect the tie rod and drag link from the
steering knuckles.
(12) Position the axle with a suitable lifting device
under the axle assembly.
(13) Secure axle to lifting device.
(14) Mark suspension alignment cams for installa-
tion reference.
(15) Disconnect the upper and lower suspension
arms from the axle bracket.
(16) Lower the axle. The coil springs will drop
with the axle.
(17) Remove the coil springs from the axle bracket.
INSTALLATION
CAUTION: Suspension components with rubber
bushings should be tightened with the weight of the
vehicle on the suspension, at normal height. If
springs are not at their normal ride position, vehicle
ride comfort could be affected and premature bush-
ing wear may occur. Rubber bushings must never
be lubricated.
(1) Support the axle on a suitable lifting device.
(2) Secure axle to lifting device.
(3) Position the axle under the vehicle.
(4) Install the springs, retainer clip and bolts.
(5) Raise the axle and align it with the spring
pads.
(6) Position the upper and lower suspension arms
in the axle brackets. Install bolts, nuts and align the
suspension alignment cams to the reference marks.
Do not tighten at this time.
(7) Connect the track bar to the axle bracket and
install the bolt. Do not tighten at this time.
(8) Install the shock absorber and tighten bolts to
121 N´m (89 ft. lbs.) torque.(9) Install the stabilizer bar link to the axle
bracket. Tighten the nut to 37 N´m (27 ft. lbs.)
torque.
(10) Install the drag link and tie rod to the steer-
ing knuckles and tighten the nuts to 88 N´m (65 ft.
lbs.) torque.
(11) Install the ABS wheel speed sensors, if
equipped. Refer to group 5, Brakes, for proper proce-
dures.
(12) Install the brake calipers and rotors. Refer to
Group 5, Brakes, for proper procedures.
(13) Connect the vent hose to the tube fitting.
(14) Connect vacuum hose and electrical connector
to disconnect housing.
(15) Install front propeller shaft.
(16) Check and add differential lubricant, if neces-
sary. Refer to Lubricant Specifications in this section
for lubricant requirements.
(17) Install the wheel and tire assemblies.
(18) Remove the supports and lower the vehicle.
(19) Tighten the upper suspension arm nuts at
axle to 121 N´m (89 ft. lbs.) torque. Tighten the
upper suspension arm nuts at frame to 84 N´m (62 ft.
lbs.) torque.
(20) Tighten the lower suspension arm nuts at
axle to 84 N´m (62 ft. lbs.) torque. Tighten the lower
suspension arm nuts at frame to 119 N´m (88 ft. lbs.)
torque.
(21) Tighten the track bar bolt at the axle bracket
to 176 N´m (130 ft. lbs.) torque.
(22) Check the front wheel alignment.ADJUSTMENTS
Ring and pinion gears are supplied as matched
sets only. The identifying numbers for the ring and
pinion gear are etched into the face of each gear (Fig.
4). A plus (+) number, minus (±) number or zero (0) is
etched into the face of the pinion gear. This number
is the amount (in thousandths of an inch) the depth
varies from the standard depth setting of a pinion
etched with a (0). The standard setting from the cen-
ter line of the ring gear to the back face of the pinion
is 127 mm (5.00 in.). The standard depth provides
the best gear tooth contact pattern. Refer to Back-
lash and Contact Pattern in this section for addi-
tional information.
Compensation for pinion depth variance is
achieved with a select shim/oil baffle. The shims are
placed between the rear pinion bearing and the pin-
ion gear head (Fig. 5).
If a new gear set is being installed, note the depth
variance etched into both the original and replace-
ment pinion. Add or subtract this number from the
thickness of the original depth shim/oil slinger to
compensate for the difference in the depth variances.
Refer to the Depth Variance chart.
3 - 50 FRONT AXLE - 248FBIBR/BE
FRONT AXLE - 248FBI (Continued)
BINDING AND STICKING
CONDITION POSSIBLE CAUSE CORRECTION
DIFFICULT TO TURN WHEEL
STICKS OR BINDS1. Low fluid level. 1. Fill to proper level.
2. Tire pressure. 2. Adjust tire pressure.
3. Steering components (ball
joints/tie rod ends).3. Lube, inspect and repair as
necessary.
4. Loose belt. 4. Adjust or replace.
5. Low pump pressure. 5. Pressure test and replace if
necessary.
6. Column shaft coupler binding. 6. Replace coupler.
7. Steering gear worn or out of
adjustment.7. Repair or replace gear.
INSUFFICIENT ASST. OR POOR RETURN TO CENTER
CONDITION POSSIBLE CAUSE CORRECTION
HARD TURNING OR MOMENTARY
INCREASE IN TURNING EFFORT1. Tire pressure. 1. Adjust tire pressure.
2. Low fluid level. 2. Fill to proper level.
3. Loose belt. 3. Adjust or replace.
4. Lack of lubrication. 4. Inspect and lubricate steering and
suspension compnents.
5. Low pump pressure. 5. Pressure test and repair as
necessary.
6. Internal gear leak. 6. Pressure and flow test, and repair
as necessary.
STEERING WHEEL DOES NOT
WANT TO RETURN TO CENTER
POSITION1. Tire pressure. 1. Adjust tire pressure.
2. Wheel alignment. 2. Align front end.
3. Lack of lubrication. 3. Inspect and lubricate steering and
suspension compnents.
4. High friction in steering gear. 4. Test and adjust gear as
necessary.
LOOSE STEERING AND VEHICLE LEAD
CONDITION POSSIBLE CAUSE CORRECTION
EXCESSIVE PLAY IN STEERING
WHEEL1. Worn or loose suspension or
steering components.1. Inspect and repair as necessary.
2. Worn or loose wheel bearings. 2. Inspect and repair or adjust
bearings.
3. Steering gear mounting. 3. Tighten gear mounting bolts to
specification.
4. Gear out of adjustment. 4. Adjust gear to specification.
5. Worn or loose steering coupler. 5. Inspect and replace as
necessary.
BR/BESTEERING 19 - 3
STEERING (Continued)
NOTE: A new grommet should be used when ever
the rod is disconnected from the lever.
(3) Remove the shipping lock pin if necessary.
(4) Install the column through the floor pan.
(5) Position the column bracket breakaway cap-
sules on the mounting studs. Install, butloose
assemblethe two upper bracket nuts.
(6) With the front wheels in the straight-ahead
position. Align steering column shaft to the coupler.
Install anewpinch bolt and tighten to 49 N´m (36
ft. lbs.).
(7) Clip the wiring harness on the steering column.
Connect the multi- function switch wiring and
tighten with 7mm socket.
(8) Install the upper fixed shroud.
(9) Be sure both breakaway capsules are fully
seated in the slots in the column support bracket.
Pull the column rearward then tighten upper bracket
nuts to 12 N´m (105 in. lbs.).
(10) Tighten the toe plate to floor pan attaching
nuts to 22.5 N´m (200 in. lbs.).
(11) Install the wiring connections to the column.
Install the lower fixed shroud.(12) Column shift vehicles, install the PRNDL
driver cable. Place shifter in Park position. If indica-
tor needs adjusting, turn thumb screw on cable
retainer to adjust cable.
(13) Install the lock housing shrouds. Install the
tilt lever (if equipped).
(14) Install the knee blocker and steering column
opening cover, (Refer to 23 - BODY/INSTRUMENT
PANEL/STEERING COLUMN OPENING COVER -
INSTALLATION).
(15) Install steering wheel and tighten nut to 61
N´m (45 ft. lbs.), (Refer to 19 - STEERING/COL-
UMN/STEERING WHEEL - INSTALLATION).
(16) Install the airbag, (Refer to 8 - ELECTRICAL/
RESTRAINTS/DRIVER AIRBAG - INSTALLATION).
(17) Column shift vehicles, connect the shift link
rod to the transmission shift lever. Use multi-purpose
lubricant, or an equivalent product, to aid the instal-
lation.
(18) Install the battery ground (negative) cable.
(19) Verify operation of the automatic transmission
shift linkage and adjust as necessary, (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC -
44RE/GEAR SHIFT CABLE - ADJUSTMENTS).
SPECIFICATIONS
TORQUE CHART
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Steering Wheel
Nut61 45 Ð
Steering Coupler
Bolt49 36 Ð
Steering Column
Upper Bracket12 Ð 105
Steering Column
Toe Plate23 Ð 200
KEY-IN IGNITION SWITCH
DESCRIPTION
The key-in ignition switch is integral to the igni-
tion switch, which is mounted on the right side of the
steering column. It closes a path to ground for the
Central Timer Module (CTM) when the ignition key
is inserted in the ignition lock cylinder and thedriver door ajar switch is closed (driver door is open).
The key-in ignition switch opens the ground path
when the key is removed from the ignition lock cyl-
inder. The ground path is also opened when the
driver door ajar switch is open (driver door is closed).
The key-in ignition switch cannot be repaired and,
if faulty or damaged, the entire ignition switch must
be replaced,(Refer to 19 - STEERING/COLUMN/IG-
NITION SWITCH - REMOVAL).
BR/BECOLUMN 19 - 9
COLUMN (Continued)
DIAGNOSIS AND TESTING - IGNITION SWITCH
AND KEY LOCK CYLINDER
ELECTRICAL DIAGNOSIS
For ignition switch electrical schematics, refer to
Ignition Switch in the appropriate section of Electri-
cal Wiring Diagrams.
MECHANICAL DIAGNOSIS (KEY DIFFICULT TO
ROTATE)
Vehicles equipped with an automatic trans-
mission and a floor mounted shifter:a cable is
used to connect the interlock device in the steering
column assembly, to the transmission floor shift
lever. This interlock device is used to lock the trans-
mission shifter in the PARK position when the key
lock cylinder is rotated to the LOCKED or ACCES-
SORY position. The interlock device within the steer-
ing column is not serviceable. If repair is necessary,
the steering column assembly must be replaced.
(Refer to 19 - STEERING/COLUMN - REMOVAL).
If the ignition key is difficult to rotate to or from
the LOCK or ACCESSORY position, it may not be
the fault of the key cylinder or the steering column
components. The brake transmission shift interlock
cable may be out of adjustment. Refer to Brake
Transmission Shift Interlock Cable Adjustment in
Transmissions for adjustment procedures.
Vehicles equipped with an automatic trans-
mission and a steering column mounted shifter:
an interlock device is located within the steering col-
umn. This interlock device is used to lock the trans-
mission shifter in the PARK position when the key
lock cylinder is in the LOCKED or ACCESSORY
position. If it is difficult to rotate the key to or from
the LOCK or ACCESSORY position, the interlock
device within the steering column may be defective.
This device is not serviceable. If repair is necessary,
the steering column assembly must be replaced.
(Refer to 19 - STEERING/COLUMN - REMOVAL).
Vehicles equipped with a manual transmis-
sion and a floor mounted shifter:on certain mod-
els, a lever is located on the steering column behind
the ignition key lock cylinder. The lever must be
manually operated to allow rotation of the ignition
key lock cylinder to the LOCK or ACCESSORY posi-
tion. If it is difficult to rotate the key to the LOCK or
ACCESSORY position, the lever mechanism may be
defective. This mechanism is not serviceable. If
repair is necessary, the steering column assembly
must be replaced. (Refer to 19 - STEERING/COL-
UMN - REMOVAL).
On other models, the ignition key cylinder must be
depressed to allow it to be rotated into the LOCK or
ACCESSORY position. If it is difficult to rotate the
key to the LOCK or ACCESSORY position, the lockmechanism within the steering column may be defec-
tive. This mechanism is not serviceable. If repair is
necessary, the steering column assembly must be
replaced. (Refer to 19 - STEERING/COLUMN -
REMOVAL).
LOCK CYLINDER HOUSING
REMOVAL
The ignition key must be in the key cylinder for
cylinder removal.
(1) Disconnect negative cable from battery.
(2) If equipped with tilt column, remove tilt lever
by turning it counterclockwise.
(3) Remove upper and lower covers (shrouds) from
steering column (Fig. 8).
(4) If equipped with automatic transmission, place
shifter in PARK position.
(5) A retaining pin (Fig. 9) is located at side of key
cylinder assembly.
(a) Rotate key to RUN position.
Fig. 8 Shroud Removal/InstallationÐTypical
1 - NUT
2 - STEERING WHEEL
3 - TILT LEVER
4 - UPPER SHROUD
5 - PANEL BRACKET
6 - SPACER
7 - NUT
8 - LOWER SHROUD
9 - CLOCK SPRING
19 - 10 COLUMNBR/BE
KEY-IN IGNITION SWITCH (Continued)
REMOVAL
(1) Place the front wheels in a straight-ahead posi-
tion.
(2) Disconnect and cap the fluid hoses from steer-
ing gear.
(3) Remove coupler pinch bolt at the steering gear
and slide shaft off gear (Fig. 3).
(4) Mark the pitman shaft and pitman arm for
installation reference. Remove the pitman arm from
the shaft with Puller C-4150A (Fig. 4).(5) Remove steering gear retaining bolts and nuts.
Remove the steering gear from the vehicle.INSTALLATION
(1) Position the steering gear on the frame rail and
install the bolts. Tighten mounting bolts to specifica-
tions.
(2) Align steering coupler on gear shaft. Install
pinch bolt and tighten to 49 N´m (36 ft. lbs.) torque.
(3) Align and install the pitman arm.
(4) Install the washer and retaining nut on the pit-
man shaft. Tighten the nut to 251 N´m (185 ft. lbs.).
(5) Connect fluid hoses to steering gear, tighten to
31 N´m (23 ft. lbs.). Add fluid, (Refer to 19 - STEER-
ING/PUMP - STANDARD PROCEDURE).
ADJUSTMENTS
CAUTION: Steering gear must be adjusted in the
proper order. If adjustments are not performed in
order, gear damage and improper steering response
may result.
NOTE: Adjusting the steering gear in the vehicle is
not recommended. Remove gear from the vehicle
and drain the fluid. Then mount gear in a vise to
perform adjustments.
Fig. 2 STEERING GEAR
Fig. 3 Column Shaft
1 - STEERING GEAR
2 - STEERING COUPLER
Fig. 4 Pitman Arm
1 - PITMAN ARM
2 - SPECIAL TOOL C-4150-A
3 - WRENCH
19 - 16 GEARBR/BE
GEAR (Continued)
INSTALLATION
(1) Position idler arm on the frame bracket and
tighten the bolt to specification.
(2) Center steering gear to alignment marks and
install pitman arm.
(3)
Install the lock washer and retaining nut on the
pitman shaft. Tighten the nut to 251 N´m (185 ft. lbs.).
(4) Install center link to ball studs and tighten
retaining nuts to specification.
(5) Install tie-rod ends into center link and tighten
the nuts to 88 N´m (65 ft. lbs.). Install new nuts.(6) Install tie-rod ends into steering knuckles and
tighten nuts to 108 N´m (80 ft. lbs.).
(7) Remove the supports and lower the vehicle to
the surface. Center steering wheel and adjust toe,
(Refer to 2 - SUSPENSION/WHEEL ALIGNMENT -
STANDARD PROCEDURE).
NOTE: Position the clamp on the sleeve so retain-
ing bolt is located on the bottom side of the sleeve.
(8) After adjustment, tighten the tie-rod adjust-
ment sleeve clamp bolt to 61 N´m (45 ft. lbs.).
SPECIFICATIONS
TORQUE CHART
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Pitman Arm
Gear Nut250 185 Ð
Pitman Arm
Center Link Nut11 5 8 5 Ð
Idler Arm
Mounting Bolts271 200 Ð
Idler Arm
Center Link Nut88 65 Ð
Tie Rod
Knuckle Nut108 80 Ð
Tie Rod
Center Link Nut88 65 Ð
Tie Rod
Adjuster Clamp61 45 Ð
SPECIAL TOOLS
STEERING LINKAGE
Remover Ball Stud MB-991113
Puller Tie Rod C-3894-A
Remover Pitman C-4150A
BR/BELINKAGE - 2WD 19 - 39
LINKAGE - 2WD (Continued)
INSTALLATION
(1) Align reference marks and install pitman arm.
(2) Install the lock washer and retaining nut on
the pitman shaft and tighten nut to 251 N´m (185 ft.
lbs.).
(3) Install drag link to the pitman arm. Install the
nut and tighten to 108 N´m (80 ft. lbs.).
(4) Install drag link to the right steering knuckle.
Install the nut and tighten to 88 N´m (65 ft. lbs.).
(5) Install tie rod to the left steering knuckle and
drag link. Install the nuts and tighten to 108 N´m
(80 ft. lbs.).(6) Install steering damper on the axle. Tighten
nut to 95 N´m (75 ft. lbs.).
(7) Install steering damper on the tie rod. Tighten
nut to 81 N´m (60 ft. lbs.).
(8) Remove the supports and lower the vehicle to
the surface. Center steering wheel and adjust toe,
refer to Group 2 Suspension.
(9) After adjustment tighten tie rod adjustment
sleeve clamp bolts to 61 N´m (45 ft. lbs.).
NOTE: Position the clamp on the sleeve so retaining
bolt is located on the bottom side of the sleeve.
SPECIFICATIONS
TORQUE CHART
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Pitman Arm
Gear Shaft251 185 Ð
Drag Link
Pitman Arm108 80 Ð
Drag Link
Tie Rod88 65 Ð
Drag Link
Adjuster Clamp61 45 Ð
Tie Rod End
Knuckle108 80 Ð
Tie Rod End
Adjuster Clamp61 45 Ð
Steering Damper
Axle95 70 Ð
Steering Damper
Tie Rod81 60 Ð
BR/BELINKAGE - 4WD 19 - 41
LINKAGE - 4WD (Continued)