FREIGHTLINER - AIRLINER SUSPENSION - SERVICE -2013 Freightliner Cascadia Стр.

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SUSPENSION

Freightliner Airliner Suspension

DESCRIPTION & OPERATION

GENERAL INFORMATION

Freightliners AirLiner Suspension system is a single axle or tandem axle suspension using a
combination of air and leaf springs. The suspension is rated at several weight ratings up to 46,000
pounds (20 865 kg). Top of air spring is bolted to a bracket on frame rail or through the bottom flange
of the frame rail; Air spring bottom is bolted to rear end of tapered leaf spring assembly or, for 23,000
LB (10 433 kg) and 46,000 LB suspensions, to a cross bar. Axle housing is fastened to leaf spring
assembly by U-bolts and a control rod, mounted between axle housing and frame rail, can be used to
help locate the assembly laterally.

Air springs compensate for changes in road conditions and vehicle load, maintaining vehicle height and
also absorb road shock.

A height control valve (Leveling Valve) regulates air flow into or out of all air springs there by
controlling all air in system. As air springs compress or expand, changes in clearance between vehicle
frame and differential housing activate the height control valve through a leveling valve Linkage Rod.
The leveling valve is mounted on the rear frame crossmember. An overtravel lever extends horizontally
from the end of the leveling valve control shaft to a linkage arm that connects to the leveling valve
linkage bracket welded to the differential housing.

When load changes and overtravel lever turns the leveling valve control shaft which activates either the
intake or exhaust valve section of the height control valve adjusting the volume of air in air springs,
until frame returns to normal ride height, and overtravel lever returns to the (horizontal) neutral
position.

The pressure holding valve is located in the air line to the height control valve, and is preset to maintain
a minimum pressure of 65 psi (448 kPa) in vehicle secondary air system if leaks should occur in air
suspension system.

GENERAL GUIDELINES

In order to for the air suspension system to operate reliably, air system must be kept free from oil,
moisture, or foreign material. Visually inspect and maintain air system components regularly.

CAUTION: Failure to take precautions against moisture, oil, or other foreign

material entering the air system will eventually lead to sludge
forming in air system. Sludge adversely affects operation of air
suspension system and other air system components such as
braking components.

Use only SAE grade 8 bolts and grade G prevailing torque locknuts when attach spring hangers and
brackets to frame.

ON-VEHICLE SERVICING
HEIGHT CONTROL VALVE TESTING

Height Control Valve (Leveling Valve) controls air suspension system and responds to changes in
height. Correct adjustment of the valve is critical in maintaining correct suspension ride height. Always
verify correct operation of vale before replacing valve.

1. Disconnect height control valve linkage from overtravel lever.

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NOTE: overtravel lever runs between height control valve adjusting

locknut and height control valve linkage adjusting clamp.

2. Move overtravel lever up approximately 45 degrees from neutral position. Air should be heard
passing through valve to indicate that section of valve is operating correctly.

NOTE: Typically, neutral position of valve is when overtravel level is

parallel to ground.

3. Return the valve to the neutral position and verify that air should stops flowing. If air stops
flowing, valve is operating properly.
4. Move overtravel lever down approximately 45 degrees from neutral position. Air should be heard
exhausting from valve to indicate that section of valve is operating correctly.
5. Return the valve to the neutral position and air should stop in neutral position to indicate valve is
operating correctly.
6. If valve operates properly as outlined in steps 2 through 5, no further testing is necessary. Re-
connect height control valve linkage to overtravel lever and secure linkage with a cotter pin.

If valve adjustment is required, go to Height Control Valve Adjustment.

If valve replacement is required, go to Height Control Valve Replacement.

REAR AXLE ALIGNMENT

NOTE: Before proceeding with rear axle alignment adjustment, verify that axle
alignment is needed.

1. Loosen spring mounting eye bolts to allow end of leaf spring to slide forward and backwards in
spring hanger.
2. Move axle forward or backward until it is aligned within tolerances for rear axle alignment.
3. When axle is in proper alignment, install alignment shim(s) to take up slack between spring
hanger and spring pin.

IMPORTANT: Same number of shims MUST be installed on both ends of spring

pin.

4. Torque leaf spring mounting eye bolt to specifications. See TORQUE SPECIFICATIONS.
5. Verify that axle alignment is within specifications. Repeat above procedures if required until
alignment is within specifications.

REAR AXLE TRACKING

Single Axle

1. At forward edge of right rear tire, measure from inside of tire to right frame rail and record
measurement.
2. At rear edge of left rear tire, measure distance from inside of tire to outer side of left frame rail
and record measurement.

IMPORTANT: Right side measurement should not vary by more than 1/4-inch (6
mm) from left side measurement.

3. If measurements vary by more than 1/4-inch (6 mm), loosen fasteners holding lateral torque rod
to frame rail and add or remove torque rod shims as required.
4. Torque rod fasteners to specifications after tracking adjustment. See TORQUE

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SPECIFICATIONS.

NOTE: Torque rods can be ether pin style or Taper pin style at the
fasteners, which required different torque values.

Tandem Axles

1. Verify tracking of forward-rear axle. See .Single Axle.

2. At forward-rear drive axle, measure distance from inner side of right rear tire to outer side of
right frame rail. Measure at forward edge of tire.
3. On both sides of rear-rear drive axle, measure distance from inside of rear tires to each frame rail.
Take measurements at rear edge of each tire.

IMPORTANT: Measurements at rear-rear axle should not vary by more than 1/4-
inch (6 mm) from measurement on forward-rear axle.

4. If measurements taken at rear-rear axle vary more than 1/4-inch (6 mm) from measurement taken
at front-rear axle, loosen fasteners holding axle lateral torque rod at rear-rear drive axle to frame
rail and add or remove torque-rod shims as needed.
5. Torque rod fasteners to specifications after tracking is adjusted. See TORQUE
SPECIFICATIONS.

NOTE: Torque rods can be ether pin style or Taper pin style at the
fasteners, which required different torque values.

ADJUSTING
HEIGHT CONTROL (LEVELING) VALVE

General Information

NOTE: Adjust height control valve with vehicle on level surface.

CAUTION: Failure to adjust height control valve will adversely affect driveline
angles, and if air springs are set too high, driver may have difficulty
backing vehicle under a trailer. If air springs are set too low, rapid
suspension system parts wear of will occur.

NOTE: A new height control valve manufactured by Barksdale Inc. replaced

Meritor WABCO valves on Freightliner trucks manufactures after 25 July
1997. Vehicles with tandem-axle AirLiner rear suspensions, the
Barksdale valve linkage rod is attached to the forward drive axle instead
of rearmost drive axle, and valve is mounted on frame rail.

There are two types of WABCO height-control valve, adjustable and fixed. Suspension height is
changed by tilting the height-control valve up or down on adjustable installations, and on fixed
installations, suspension height is changed by adjusting length of vertical linkage rod.

There are two types of WABCO height control valve installations: adjustable and fixed.

On adjustable installations, the suspension height is changed by tilting the height control valve up or
down. On fixed installations, the height is changed by adjusting the length of the vertical linkage. Use
the applicable procedure below to adjust the suspension height.

Height Control Valve Adjustment - WABCO Adjustable Valves

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IMPORTANT: There must be no load on the chassis when checking AirLiner

suspension height. Trucks MUST be empty and no trailers hooked up to
tractors and vehicle must be parked on level surface.

1. Using a light application of brakes. Put transmission in neutral and build secondary air pressure
to at least 100 psi (690 kPa), then turn engine off.

NOTE: Do not apply the parking brakes.

2. Mark location of front and rear tires on ground or shop floor then chock tires on one axle only.
3. Verify length of overtravel lever between its pivot points. Length should be 8-inches (203 mm)
Adjust overtravel lever as required using procedures outlined below.

NOTE: Overtravel lever runs from height control valve adjusting lock nut
to adjustment clamp on linkage rod.

A. Loosen adjustment locknut on height control valve control shaft.

B. Move overtravel lever forward or backward until length between its pivot points is 8 inches
(203 mm).
C. Torque height control valve adjustment locknut on height control valve to specifications.
See TORQUE SPECIFICATIONS.

NOTE: AirLiner suspension systems have three types of axle seats.

l One-piece, cast axle seat, that IS NOT WELDED to axle

housing
l One-piece, cast axle seat, that IS WELDED to axle housing
l Two-piece, fabricated axle seat that IS WELDED to axle
housing

IMPORTANT: Axle seats that are two-piece welded type, subtract 1/4 inch (6 mm)
from minimum, target, and maximum heights when adjusting
suspension height.

4. Measure distance from left forward most axle stop mounted on frame to top of axle U-bolt on
axle and verify that distances are within specification for suspensions shown in Suspension Ride
Height Measurements.
5. If distance is within specifications, apply parking brake and remove chocks from tires. If
measurement is not within specifications, go to 6.
6. Loosen two fasteners attaching height-control valve to mounting bracket.
7. Rotate height-control valve clockwise (facing valve from driver's side of vehicle) and allow air to
exhaust from valve until distance from bottom of left forward most axle stop to top of U-bolt is 2
inches (51 mm) or less.
8. Rotate height-control valve counterclockwise, and raise suspension height to target height shown
in Suspension Ride Height Measurements for suspension application installed on vehicle. Stop
air flow to air bag by rotating height-control valve clockwise.
9. Center height control valve using following procedures.
A. Rotate valve slightly clockwise and counterclockwise until you can insert a .16 (4-mm) pin
or drill bit into valve centering hole. DO NOT rotate valve too much or suspension height
will change.
B. Firmly tighten height-control valve mounting fasteners.
10. Drive vehicle unloaded approximately 1/4 mile (1/2 km), then park vehicle in same location
(previously marked in step 2.

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NOTE: Park truck with light brake application, re-chock tires on one axle
only, and put transmission in neutral. DO NOT apply the parking
brakes.

11. Verify ride height is within specifications shown in Suspension Ride Height Measurements
based on suspension type. Repeat adjustment procedures if measurement is not within
specifications.
12. Apply parking brakes and remove wheel chocks when adjustments are complete and within
specifications.

Height Control Valve Adjustment - WABCO Fixed Valves

IMPORTANT: There must be no load on the chassis when checking AirLiner

suspension height. Trucks MUST be empty and no trailers hooked up to
tractors and vehicle must be parked on level surface. Adjustment
changes are made by adjusting length of linkage rod.

1. Using a light application of brakes. Put transmission in neutral and build secondary air pressure
to at least 100 psi (690 kPa), then turn engine off.

NOTE: Do not apply the parking brakes.

2. Mark location of front and rear tires on ground or shop floor then chock tires on one axle only.
3. Verify that length of overtravel lever between its pivot points is with specifications listed in
OVERTRAVEL LEVER LENGTH SPECIFICATIONS for axle installed. Adjust overtravel
lever as required using procedures outlined below.
A. Loosen adjustment locknut on height control valve control shaft.
B. Move over-travel lever forward or backward until it is at correct length.
C. Torque adjustment locknut to specifications. See TORQUE SPECIFICATIONS.

NOTE: Overtravel lever runs from height control valve adjusting lock nut
to adjustment clamp on linkage rod.

4. Measure distance from bottom of left forward most axle stop to top of axle U-bolt or U-Bolt pad
and verify that measurement is within specifications listed in Suspension Ride Height
Measurements for installed suspension system. If measurement is within specifications, apply
the parking brakes and remove wheel chocks.
5. Determine how much suspension height needs to be adjusted so suspension height will match
target height shown in Suspension Ride Height Measurements. Using Vertical Linkage
Lengths, determine amount of length linkage rod needs changed and adjust rod length as needed,
adding or subtracting amount shown in Vertical Linkage Lengths as required to reach target
height determined from Suspension Ride Height Measurements. Use below procedures to
adjust linkage rod:
A. Loosen both linkage adjustment clamps.
B. Slide flexible end-sections of linkage over linkage rod until rod is correct length.

NOTE: If linkage rod is too short, it must be replaced with a new rod,
part number 16-13485-000. Linkage rod has to be long enough
so that at least 1/2 inch (13 mm) of it fits into both flexible end-
sections of linkage.

NOTE: Lengthening linkage rod length increases suspension height

and decreasing linkage rod length decreases suspension
height.

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C. Tighten adjustment clamps.

Vertical Linkage Lengths

Vertical Linkage Length Change In Inches
Suspension Height Change In Inches (mm) (mm)
1/16 (2) 1/16 (2)
1/8 (3) 3/16 (5)
3/16 (5) 1/4 (6)
1/4 (6) 5/16 (8)
5/16 (8) 3/8 (10)
3/8 (10) 1/2 (13)
7/16 (11) 9/16 (14)
1/2 (13) 5/8 (16)
9/16 (14) 3/4 (19)
5/8 (16) 13/16 (21)
11/16 (17) 7/8 (22)
3/4 (19) 1 (25)
13/16 (21) 1-1/16 (27)
7/8 (22) 1-3/16 (30)
15/16 (24) 1-1/4 (32)
1 (25) 1-5/16 (33)

6. Drive vehicle unloaded approximately 1/4 mile (1/2 km), then park vehicle in same location
(previously marked in step 2.

NOTE: Park truck with light brake application, re-chock tires on one axle
only, and put transmission in neutral. DO NOT apply the parking
brakes.

7. Verify ride height is within specifications shown in Suspension Ride Height Measurements
based on suspension type. Repeat adjustment procedures if measurement is not within
specifications.
8. Apply parking brakes and remove wheel chocks when adjustments are complete and within
specifications.

Height Control Adjustment - Barksdale Valves

IMPORTANT: There must be no load on the chassis when measuring AirLiner

suspension height. Trucks MUST be empty and no trailers hooked up to
tractors and vehicle must be parked on level surface.

1. Using a light application of brakes. Put transmission in neutral and build secondary air pressure
to at least 100 psi (690 kPa), then turn engine off.

NOTE: Do not apply the parking brakes.

2. Mark location of front and rear tires on ground or shop floor then chock tires on one axle only.

NOTE: Stud bolt that fastens lever arm to linkage rod is oriented correctly
when linkage rod is vertical as viewed from side of vehicle. Stud
bolt connects Linkage Rod to Lever Rod.

3. Measure ride height from left forward most axle stop and suspension. Refer to Suspension Ride
Height Measurements for ride height specifications for various suspensions systems.

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IMPORTANT: Before measuring suspension height, make sure there is no load

on chassis and trailers are not connected to tractors. Trucks must
be empty.

IMPORTANT: Suspension systems with Dual-Leaf Springs, and all Vehicles built
prior to August 24, 2001, measure between top of U-bolt and
bottom of axle stop. Suspension systems with Single-Leaf Springs
and built after August 24,2001 measure between top of U-bolt pad
and bottom of the axle stop flange.

NOTE: If measurement is within specifications, no adjustments are

required.

4. If distance is within specifications, apply parking brake and remove chocks from tires. If
measurement is not within specifications, go to 5.
5. Adjust suspension height to specifications shown in Suspension Ride Height Measurements.
A. Loosen two fasteners attaching height control valve to valve mounting bracket.
B. Adjust position of height control valve body until distance from bottom of left forward
most axle stop to top of axle U-bolt or U-Bolt pad is within specifications. See Suspension
Ride Height Measurements for specifications and measuring points for suspension
system.
C. Center lever arm on height control valve by inserting a 0.16-inch (4 mm) pin into hole in
lever arm and aligning the hole with valve body.
D. Tighten two fasteners attaching valve to mounting bracket.
E. Remove pin from hole in lever arm.
6. Drive vehicle unloaded approximately 1/4 mile (1/2 km), then park vehicle in same location
(previously marked in step 2 of original measurement.

NOTE: Park truck with light brake application, re-chock tires on one axle
only, and put transmission in neutral. DO NOT apply the parking
brakes.

7. Verify ride height is within specifications shown in Suspension Ride Height Measurements
based on suspension type. Repeat adjustment procedures if measurement is not within
specifications.
8. Apply parking brakes and remove wheel chocks when adjustments are complete and within
specifications.

RIDE HEIGHT ADJUSTMENT

NOTE: This procedure is applicable only for height-control valves. DO NOT use
this procedure for height sensors (installed on vehicles with ECAS
(Electronically Controlled Air Suspension)). Go to ECAS Ride Height
Adjustment for more information.

NOTE: Ensure no load is present on chassis prior to inspecting suspension

height. Ensure trucks are empty and unhitch trailer from tractors.

NOTE: This procedure is also followed on vehicles with dual ride height control,
because adjustment of single valves (but with two height gauge blocks)
and both height control valves can be made simultaneously. During
adjustment, disconnect both linkages. After attaining correct ride height
on both sides, reposition both valves.

1. With vehicle parked on a level surface, apply parking brakes, block wheels, and position

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transmission in neutral. Generate secondary air pressure of 100 Psi (690 kPa) minimum, and turn
engine OFF.
2. Maintain distance of 2 In. (5 cm) between blocks and wheels (both ahead and behind). This will
allow vehicle to roll in both directions.
3. Disengage parking brake, and manually roll vehicle forward and aft so that suspension is relieved
from any load.
4. Identify correct suspension ride height.
5. Measure distance between either forward-most axle stop and suspension.

Fig. 1: Measuring Ride Height (Typical)

A. If distance is within specifications, adjustment is not required. Set parking brakes.

B. If distance is not within specifications, disconnect height-control valve linkage from lever
stud.

NOTE: Disconnect both linkages if dual valves are present.

6. If block between axle stop and top pad do not have enough space, lift valve lever. This will allow
air bags to inflate and create space for block fitting. If dual valves are present, lift both levers.

NOTE: Installation of block is not required at this moment.

7. Lock lever in neutral position by inserting 5/32-In. drill bit or nylon rod.

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Fig. 2: Inserting 5/32-In. Drill Bit Or Nylon Rod To Lock Lever In Neutral Position

8. Install height gauge block. If dual valves are present, install block on both sides.
9. With valve lever unpinned, lower suspension using lever and continue to lower until axle stop is
placed on block. If dual valves are present, unpin and lower with both valves.
10. Position lever to neutral and lock lever. Once lever is locked, vehicle is at target ride height. If
equipped with dual valves, lock both levers.

CAUTION: Valve-side mounting studs must be secured in position (using

Allen wrench) during loosening or tightening of nuts (securing
Barksdale height-control valve and mounting bracket).
Mounting studs are threaded into valve body, and will tighten
if nuts are loosened without securing studs. This will result in
crushing of valve body, thus valve will be damaged. Similarly,
if nuts are tighten without securing studs will back studs out,
separation of valve body into two halves will result and
leakage will occur.

11. Loosen nuts securing valve to mounting bracket with Allen wrench securing height-control valve
mounting stud in position. Loosen both valves if equipped with dual valves.

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Fig. 3: Identifying Height Control Valve Mounting Stud Nuts

12. With lever locked in neutral, adjust valve body and continue to adjust until lever is connected to
linkage. Connect linkage. For vehicle ride height, ensure valve body is in correct position and
linkage rod must be vertical. If dual valves are present, adjust and connect both linkages.

NOTE: If no contact is made between linkage and stud, inspect for bent or
damaged surrounding components. Repair if required.

13. Using Allen wrench, secure height-control valve mounting studs. Tighten nut to 95 In. Lbs.
(1100 N.cm). If equipped with dual valves, tighten both nuts.

CAUTION: Valve will be damaged if nuts are overtightened. (For dual

valves, tighten both.)

14. From valve lever stud, disconnect linkage.

NOTE: Disconnect both linkages if equipped with dual valves.

15. In order to raise suspension for removing block, lift and lock valve in neural position. Remove
block.

NOTE: For dual valves, lift and lock both valves, and also remove both
blocks.

16. With pin or drill bit securing height-control lever in neutral position, connect valve lever to
linkage. Unpin and connect both valve levers if equipped with dual valves.
17. Road test an unloaded vehicle for 1/4 mile (1/2 km). Park vehicle on level surface, block wheels
on one axle only, and place transmission in neutral. DO NOT set parking brakes.
18. Inspect vehicle ride height again

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A. If distance is within specifications, ride height is correct and set parking brakes.
B. If distance is not within specifications, perform adjustment procedure again.

Electronically Controlled Air Suspension (ECAS) Ride Height Adjustment

Adjustment procedure is different for height-control sensor installed on vehicles with MeritorWabco
ECAS.

MeritorWabco Software is used to perform calibration procedure for ECAS system for adjusting
vehicle ride height.

REMOVAL & INSTALLATION

HEIGHT CONTROL (LEVELING) VALVE

NOTE: A new type of height control valve manufactured by Barksdale Inc.

replaced Meritor WABCO valves previously used. Vehicles with tandem-
axle AirLiner rear suspensions, the Barksdale valve linkage rod is
attached to forward drive axle instead of rearmost drive axle, and valve
is mounted on frame rail. The Barksdale valves are installed on Century
Class trucks built after July 25, 1997, and FLB, COE and FLD
Conventional trucks built after Sept. 19, 1997.

Meritor WABCO

Removal

1. Park truck on level surface and turn engine off, apply parking brake, and chock front tires.
2. Drain air from system.
3. Disconnect linkage from overtravel lever and exhaust all air from air springs by rotating
overtravel lever down.

NOTE: Overtravel lever runs from adjusting locknut on valve to height

control valve linkage adjustment clamp.

4. Disconnect air lines at height control valve.

NOTE: When disconnecting air lines, mark air lines so they can re-installed
in proper location during installation. Use tape and cover the open
ends of air lines and fittings on valve to prevent dirt or foreign
material from entering valve or air lines.

5. Remove height control valve mounting bolts and nuts, and remove height control valve from
mounting bracket.
6. Remove overtravel lever from height control valve.

Installation

1. Install height control valve to valve mounting bracket and torque valve mounting bolt nuts to
specifications. See TORQUE SPECIFICATIONS.
2. Remove tape from air lines and fittings, and connect air lines to valve as marked during removal
procedures. Tighten nylon tube air fittings until only two threads show on fitting. On wire-braid
hose fittings, tighten nut using wrench until firm resistance felt, then turn an additional one-sixth
turn.
3. Connect height control valve linkage to overtravel lever and secure linkage with a cotter pin.
4. Connect overtravel lever to height control valve and insert overtravel lever into valve at hole with
V-shaped mark by the adjustment locknut. Length between pivot points must be 8 inches (20.3

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cm).
5. Close drain on all air system reservoirs and build up air pressure to normal operating pressure.
6. Verify that there are no air leaks at all air lines and fittings. Repair leaks as required.
7. Remove chocks from tires.
8. Adjust height control valve as directed in Height Control Valve Adjustment.

Barksdale Inc.

Removal

1. Park truck on level surface and turn engine off, apply parking brake, and chock front tires.
2. Drain air from system.
3. Remove linkage from overtravel lever and exhaust all air from air springs by rotating overtravel
lever down.

NOTE: Overtravel lever runs from height control valve to stud bolt
connecting overtravel lever to linkage rod.

4. Disconnect air lines at height control valve.

NOTE: When disconnecting air lines, mark air lines so they can re-installed
in proper location during installation. Use tape and cover the open
ends of air lines and fittings on valve to prevent dirt or foreign
material from entering valve or air lines.

5. Remove height control valve mounting bolts and nuts and remove height control valve from
mounting bracket.

Installation

1. Install height control valve to mounting bracket and torque mounting bolt nuts to specifications.
See TORQUE SPECIFICATIONS.
2. Remove tape from air lines and fittings, and connect air lines to valve as marked during removal
procedures. Tighten nylon tube air fittings until only two threads show on fitting. On wire-braid
hose fittings, tighten nut using wrench until firm resistance felt, then turn an additional one-sixth
turn.
3. Connect height control valve linkage to overtravel lever.
4. Close drain on all air system reservoirs and build up air pressure to normal operating pressure.
5. Verify that there are no air leaks at all air lines and fittings. Repair leaks as required.
6. Remove chocks from tires.
7. Adjust height control valve as directed in Height Control Valve Adjustment.

SHOCK ABSORBER

Removal

1. Chock truck tires.

2. Disconnect shock absorber from frame bracket.
l Vehicles built after Sept. 1994, remove locknut, bolt, and washer from top of shock
absorber.
l Vehicles built before Sept. 1994, remove nut, upper retainer, and upper bushing from top
of shock absorber.
3. Compress shock absorber until top mounting stud or bushing clears upper mounting bracket.
4. Remove locknut, bolt, and spacer from shock absorber lower mounting bracket, then remove
shock absorber from vehicle.

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Installation

1. Instal shock absorber into lower bracket and install shock absorber lower mounting bolt, washers,
and locknut

WARNING: Use only retainers included with replacement shock

absorber. DO NOT use washers because they can stick out
over nut and be ejected violently, possibly causing personal
injury and property damage.

2. Attache top of shock absorber to frame bracket on truck using following procedures:
l Trucks built before September 1994, install a retainer and bushing on shock absorber top
stud, then extend shock absorber until stud enters upper bracket and install upper bushing
and retainer onto shock absorber. Verify that the new bushings and retainers are properly
positioned.
l Trucks built after September 1994, extend shock absorber until bushing eye enters upper
mounting bracket and install bolt, washers, and locknut.
3. Torque shock absorber lower mounting locknut to specifications. See TORQUE
SPECIFICATIONS.
4. Torque shock absorber upper mounting nut using following procedures:
1. Trucks built before September 1994, tighten shock absorber upper mounting nut to
compress bushings to 2-1/2 inches (63 mm) as measured from retainers.
2. Trucks built after September 1994, torque shock absorber upper mounting locknut to
specifications. See TORQUE SPECIFICATIONS.

AIR SPRING

Removal

1. Chock front tires and raise vehicle frame and support it using appropriate safety stands so all
weight can be removed from air springs.

NOTE: Leveling valve will automatically release air from air springs when
all weight is removed from suspension.

2. Disconnect air supply line, including brass tee from air spring.

NOTE: Use tape and cover the open ends of air lines and fittings to
prevent dirt or foreign material from entering valve or air lines.

3. Remove locknuts and washers connecting air spring to upper mounting bracket, or to the frame
rail flange.
4. Remove bolts and lockwashers connecting air spring to rear of leaf spring and remove air spring.

NOTE: Suspensions manufactured to 46,000 LB (20 865 kg) or 23,000 LB

(10 433 kg) weight rating have different leaf spring, and an
additional cross bar attached between air spring and rear of leaf
spring.

Installation

NOTE: Suspensions manufactured to 46,000 LB (20 865 kg) or 23,000 LB (10 433
kg) weight rating have different leaf spring, and an additional cross bar
attached between air spring and rear of leaf spring.

1. Install new air spring on rear of leaf spring (or cross bar if equipped), and install washer and

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locknuts that hold air spring (and cross bar if equipped) in position and toque locknuts to
specifications. See TORQUE SPECIFICATIONS.
2. Install air spring onto upper mounting bracket:
l Bracket-mounted air springs: Install air spring to upper mounting bracket. Use 1/2-13
locknut on outside of frame rail and 3/4-16 locknut on inside and torque to specifications.
See TORQUE SPECIFICATIONS
l Flange-mounted air springs: Install air spring to frame rail flange. Use 3/4-16 locknut on
forward stud of air spring, and 1/2-13 locknut on rear stud of air spring and torque to
specifications. See TORQUE SPECIFICATIONS.
.
3. Remove tape from ends of air supply lines, fittings, and brass tee and connect air line to spring.
Tighten nylon tube air fittings until only two threads show on fitting. and tighten wire-braid hose
fitting nut using a wrench until firm resistance if felt, then turn an additional 1/6 turn.
4. Remove safety stands, and lower vehicle to ground, then remove wheel chocks from tires.
5. Verify that there are no air leaks at spring air line and fittings. Repair leaks as required.

AIR SPRING BAG

Removal

1. Park truck on level surface and turn shut engine down. Set parking brake and chock front tires
then raise vehicle frame and support it with appropriate safety stands so all weight is removed
from air springs.

IMPORTANT: DO NOT disconnect shock absorbers while vehicle frame is raised.

Shock absorber limits downward suspension travel and prevents
the piston from being pulled out of air bag.

2. Disconnecting height control valve linkage and hold overtravel lever down to exhaust all air from
air springs.
3. Use a dull instrument and pry air spring bead off piston lip.

CAUTION: DO NOT damage piston.

4. Disconnect air supply line and brass tee (if equipped) from air spring.

NOTE: Tape up ends of air supply line and fitting to prevent dirt or foreign
material from entering

5. Remove locknuts and washers connecting air spring bag to upper mounting bracket and remove
air spring bag.
6. Check piston for residue and remove any if found.

NOTE: It may be easier to remove the piston from the leaf spring and
assemble the bag and piston on a workbench when space is limited
such as when working on the front axle of trucks with tandem
axles. Secure air spring mounting bracket that is attached to the
bag, in a vise. Fully extend air bag and plug air supply port. Apply
soap-and-water to piston lip and air bag bead, and, using a twisting
motion, push piston onto air bag until piston is fully seated. Inspect
circumference of the bag-to-piston connection to verify there is
less than 1/8 inch (3.2 mm) of clearance between air bag and piston
shoulder. The gap should be uniform around the assembly. After
inspecting, remove the plug in air supply port and push the piston

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into the air bag so that it rolls over the piston. Then, install on the
vehicle.

WARNING: Do not add air pressure to air spring assembly when it is not
mounted on truck. Doing so would cause components to
eject from assembly, causing serious personal injury or
property damage.

Installation

1. Install new air spring bag to upper mounting bracket. Use the 1/2-13 locknut on outside of frame
rail, and 3/4-16 locknut on the inside and torque to specifications. See TORQUE
SPECIFICATIONS.
2. Remove tape from ends of air supply line, fitting, and the brass tee (If equipped). Connect air
supply line to air spring and tighten nylon tube air fittings until only two threads show on fitting,
tighten wire-braid hose fittings nut until there firm resistance is felt then tighten an additional 1/6
turn.
3. Verify that air spring bag is fully extended alongside the piston so there are no folds in the bag
near the bead.
4. Fold air spring bag so bead is fully parallel with piston lip.
5. Apply soapy water solution to bead and piston lip.
6. Pull rear of air spring bag over piston lip. Make sure the bead is lowest part of the bag-none of
the bag should droop over the piston. Work front of bag over the piston lip like a button in a
buttonhole.
7. Feeling the bead through the folds of the air spring bag, partially inflate bag to cause snapping of
the bead over the piston lip fully seat it.

NOTE: A snapping sound confirms that bead seated correctly. Air bag
should seat with 10 to 40 psi (69 to 276 kPa). DO NOT overinflate to
try to force bead to seat. If no snapping sound is heard before
reaching 50 psi (345 kPa), release air pressure and realign air bag
bead and piston and try again to seat bag.

8. Inspect circumference of bag-to-piston connection and verify that there is less than 1/8 inch (3.2
mm) of clearance between air bag and piston shoulder. Gap should also be uniform around the
assembly.
9. Connect height control valve and inflate air spring bag. As spring is inflating, the bag should roll
into position over the piston.
10. Verify that suspension ride height is within specifications. See Height Control Valve
Adjustment for instructions.
11. Remove safety stands, lower truck to ground and remove chocks from tires.

LEAF SPRING

WARNING: Do not replace individual leaves of a damaged leaf spring

assembly; replace the complete spring assembly. Visible damage
(cracks or breaks) to one leaf causes hidden damage to other
leaves. Replacement of only the visibly damaged part(s) is no
assurance that the spring is safe. Failure to replace a damaged
spring assembly could cause an accident resulting in serious
personal injury or property damage.

Removal

1. Chock front tires and raise rear of vehicle and support rear axle(s) with appropriate safety stands.
2. Raise vehicle so that all weight is removed from leaf springs, then securely support the frame

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with appropriate safety stands.

NOTE: All weight must be removed from leaf springs before removing
springs.

3. Remove nuts, bolts, and washers from shock absorber lower mounting bracket.
4. Remove the high nuts, flatwasher, and axle clamp from each U-bolt and support the leaf spring
assembly with a jack.
5. Disconnect the bottom of air spring from leaf spring (If air spring mounts to leaf spring). If air
spring mounts to a cross bar, disconnect cross bar from leaf spring.
6. Note number and position of alignment shims installed on spring mounting bolt between spring
hanger and spring pin by spring mounting bolt nut.
7. Remove nut, washers, alignment shim(s), spring mounting bolt, and wear shoe clip from spring
hanger.

WARNING: Make sure spring is properly supported before removing

mounting bolt, Leaf spring assembly is heavy.

8. Remove leaf spring assembly from truck.

Installation

1. Properly support leaf spring assembly with a jack and position spring assembly on spring hanger
then install bolts, wear shoe clips, washers, alignment shims, and hexnuts. Tighten bolts just
enough to hold spring assembly in position.
2. If air spring mounts onto leaf spring, attach air spring and torque washer and locknut to
specifications. See TORQUE SPECIFICATIONS.

NOTE: If air spring mounts to a cross bar, attach cross bar to leaf spring
assembly. The longer bolts attach in forward most holes and
shorter bolts attach in the rear holes.

3. Verify that U-bolt pads are correctly positioned on top of axle and fasten spring assembly to axle
using U-bolts, axle clamp, washers, and high nuts. Verify that U-bolt pads and axle clamps are
properly positioned as outlined below:
l Single drive axles that are angled 5 degrees, an arrow on the U-bolt pads MUST point to
front of axle housing. On single-drive axles angled 3 degrees, there is no arrow so make
sure that the axle bump stop on U-bolt pad is positioned toward vehicle centerline.
l Both 5 and 3 degree single-drive axle angles, an arrow on bottom of axle clamp MUST
point toward rear of vehicle.
l On tandem axle suspensions, refer to for U-bolt pad orientation. Arrow on bottom of axle
clamp must point toward rear of vehicle on forward rear axle and toward front of the
vehicle on the rearmost axle.

U-Bolt Pad Orientation for Axles

Axle Designation U-Bolt Pad Orientation
Rockwell SQ 100, SSHD Forward Rear Axle No arrow; axle bump stop
toward vehicle centerline.
Rearmost Axle No arrow; axle bump stop
toward vehicle centerline.
Rockwell RT40-145, RT44- Forward Rear Axle No arrow; axle bump stop
145, RT46-160 toward vehicle centerline.
Rearmost Axle Arrow toward front of vehicle.
Eaton 402, 461 Forward Rear Axle No arrow; axle bump stop
toward vehicle centerline.

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Rearmost Axle No arrow; axle bump stop

toward vehicle centerline.

4. Hand tighten high nuts. In a diagonal or "X" pattern, torque axle U-bolt high nuts to
specifications in four stages. See TORQUE SPECIFICATIONS.
5. Connect shock absorber to its lower mounting bracket and torque to specifications. See
TORQUE SPECIFICATIONS.
6. Torque lower air spring nut to specifications. See TORQUE SPECIFICATIONS.

NOTE: On 23,000 LB and 46,000 LB suspensions, torque locknuts on

bottom of suspension cross bar to specifications. See TORQUE
SPECIFICATIONS.

7. Torque front leaf spring nuts to specifications. See TORQUE SPECIFICATIONS170 ft lbs
(230 N.m).
8. Install wheel and tire assembly and remove safety stands, and lower truck.
9. Verify that the rear axle is in proper alignment. See Rear Axle Alignment.

CONTROL ROD REPLACEMENT

Removal

1. Park truck and shut engine down and apply parking brakes.
2. Chock tires, raise vehicle and support frame rails with appropriate jack stands.
3. Remove bolts holding control rod to frame rail bracket and carefully remove shims, and set aside.
4. Remove control rod.

Installation

1. Position control rod so that end with fasteners angled up at 35 degrees is installed into axle
housing bracket.
2. Install fasteners with bolt heads facing up and tighten fasteners enough to hold control rod in
position.
3. Install shims that were previously removed into original locations.
4. Install other end of control rod in frame rail bracket and install fasteners. Tighten fasteners
enough to hold control rod in position.
5. Torque all control rod fasteners to specifications. See TORQUE SPECIFICATIONS.

NOTE: Control rods on suspensions manufactured to 23,000 LB (10 433

kg) or 46,000 LB (20 865 kg) weight rating are larger and are
attached to axle bracket with a single bolt and have different torque
specifications. See footnote () in TORQUE SPECIFICATIONS.

6. Remove jack stands and lower truck to ground then remove chocks.

SPRING EYE BUSHING REPLACEMENT

WARNING: Do not replace individual leaves of damaged leaf spring assembly;

replace complete assembly. Damage (cracks or breaks) to one leaf
causes hidden damage to other leaves. Replacement of only
damaged part(s) does not guarantee that the spring is safe for use.
Failure to replace a damaged spring assembly could result in an
accident causing in serious personal injury and/or property
damage.

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Removal

1. Park truck on level surface and shut engine down, set parking brake and chock front tires.
2. Raise rear of truck and support rear axle(s) with appropriate safety stands. Raise vehicle so all
weight is removed from leaf springs and securely support frame with appropriate safety stands.
3. Remove wheel and tire assembly for access to suspension system.
4. Remove leaf spring assembly. See Leaf Spring Replacement.

WARNING: Leaf spring assembly is heavy, use care when handling

heavy object to prevent injury.

5. Remove bushing from leaf spring eye.

WARNING: Do not use a cutting torch to remove the outer metal of the
bushing from the spring eye. Welding, torching or cutting the
leaf spring assembly can damage the leaf spring material,
which may result in the failure of the components and cause
serious personal injury, death, or property damage.

A. Use a shop press with 10 ton (9 072 kg) capacity and place spring assembly in shop press
with spring assembly squarely supported on press bed.

NOTE: Spring assembly must be properly support for safety reasons

and to avoid bending spring assembly.

B. Center bushing tool on outer metal of bushing and press bushing from spring eye.
C. Remove burrs or material left behind by old bushing.

Installation

1. Install bushing in leaf spring eye.

A. Position new bushing on shop press.
B. Apply a bonding agent liberally around the outside surface of bushing.

NOTE: Use either Perma-bond HM-160 or Loctite RC-609 or 680, or

equivalent.

C. Press bushing into spring eye.

D. Allow bonding agent to cure for at least 24 hours.

NOTE: After curing time, the bushing MUST resist a minimum 7,700
lb (3 490 kg) pushout force.

2. Install leaf spring assembly. See Leaf Spring Replacement.

3. Install wheel and tire assembly and lower truck to ground.
4. Verify that rear axles are in proper alignment. Align axles if required.
5. Remove chocks from tires.

SPECIFICATIONS
SUSPENSION RIDE-HEIGHT MEASUREMENT, DUAL-LEAF SPRING, 20K/21K/22K/40K
HIGH-RIDE
Height Measurement: In. (mm)
Min. Target Max.

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2-3/8 (60) 2-5/8 (67) 2-7/8 (73)

SUSPENSION RIDE-HEIGHT MEASUREMENT, DUAL-LEAF SPRING, 23K/46K/69K

HIGH-RIDE
Height Measurement: In. (mm)
Min. Target Max
2-3/4 (70) 3 (76) 3-1/4 (83)

SUSPENSION RIDE-HEIGHT MEASUREMENT, SINGLE-LEAF SPRING, 20K/40K, HIGH-

RIDE HEIGHT
Height Measurement: In. (mm)
Min. Target Max.
2-3/8 (60) 2-5/8 (67) 2-7/8 (73)

SUSPENSION RIDE-HEIGHT MEASUREMENT, SINGLE-LEAF SPRING, 10K/12K/15K/18K

MID-RIDE HEIGHT & 40K LOW & MID-RIDE HEIGHT
Height Measurement: In. (mm)
Min. Target Max.
2-3/8 (60) 2-1/2 (64) 2-7/8 (73)

SUSPENSION RIDE-HEIGHT MEASUREMENT, SINGLE-LEAF SPRING, 10K/12K/15K

LOW OR EXTRA-LOW RIDE-HEIGHT
Height Measurement: In. (mm)
Min. Target Max.
2-1/8 (54) 2-9/32 (58) 2-5/8 (67)

OVERTRAVEL LEVER LENGTH SPECIFICATIONS

Axle Travel Lever Length In (mm)
Meritor RS23-161 8 (203)
Meritor 23-180 7-3/8 (187)
I Meritor SQ100 9-1/4 (235)
Meritor SSHD 9 (229)
Meritor RT40-145 9-3/4 (248)
Meritor RT44-145 9-3/4 (248)
Meritor RT46-160 8-1/8 (206)
Eaton 23105 SC 7-1/4 (184)
Eaton 402 8-3/8 (213)
Eaton 404 8-3/8 (213)
Eaton 461 8-3/8 (213)

SUSPENSION RIDE HEIGHT MEASUREMENTS

Distance in Inches (mm)
Suspension Type Minimum Target Maximum
Dual Leaf Spring 20/40K High Ride 2-3/8 (60) 2-5/8 (67) 2-7/8 (73)
Dual Leaf Spring 23/46/69K High Ride 2-3/4 (70) 3 (76) 3-1/4 (83)
Single Leaf Spring 20/40K High Ride(1) 2-1/4 (57) 2-1/2 (64) 2-3/4 (70)
Single Leaf Spring 10k/12k/15k/18K Mid Ride 2-3/8 (60) 2-1/2 (64) 2-7/8 (73)
and 40k Low and Mid Ride Height (1)

Single-Leaf Spring, 10k/12k/15k Low or Extra 2-1/8 (54) 2-9/32 (58) 2-5/8 (67)
Low Ride Height
(1) Suspension systems with Dual-Leaf Springs, and all Vehicles built prior to August 24, 2001,
measure between top of U-bolt and bottom of axle stop. Suspension systems with Single-Leaf

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Springs and built after August 24,2001 measure between top of U-bolt pad and bottom of
axle stop.

TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS
Application Bolt/Nut Size Ft. Lbs. (N.m)
Air Spring Lower Mounting Locknuts 1/2-13 55 (75)
Air Spring Upper Mounting Bracket 5/8-11 136 (184)
3/4-16 45 (61)
Air Spring Upper Mounting Locknuts
1/2-13 23 (31)
Axle U-Bolt High Nuts(1)
Stage 1 Hand Tightened
Stage 2 60 (81)
3/4-16
Stage 3 200 (271)
Stage 4 270 to 330 (367 to 449)
Stage Hand Tightened
1
Stage 60 (81)
2
7/8-14
Stage 200 (271)
3
Stage Hand Tightened
4
Stage
1
Stage 60 (81)
2
1 - 14
Stage 200 (271)
3
Stage 520 to 600 (707 to 816)
4
Bottom Locknuts on Suspension Cross Bar 241 (327)
Control Rod Mounting Bolt Locknuts(3) 5/8-11 136 (184)
Height Control Valve Mounting Bolt Nuts 5/16-18 14 (19)
Leaf Spring Mounting Eye Bolt Locknuts 3/4-10 241 (327)
Leaf Spring Mounting Eye Bolts 170 (230)
Leaf Spring Front Nuts 170 (230)
Shock Absorber Lower Mounting Locknuts 3/4-10 170 (230)
Shock Absorber Upper Mounting Locknuts(2) 170 (230)
Spring Hanger Mounting Locknuts 3/4-10 240 (325)
Torque Rod Fastener (Bar Pin Style) 136 (184)
Torque Rod Fastener (Taper Pin Style) 165 (224)
INCH Lbs. (N.cm)
Height Control Valve Adjustment Locknut 1/4 20 62 (700)
(1) Torque U-Bolts in a X pattern during each torquing stage with bolts 1 and 3 in torque
sequence facing toward front of vehicle.

(2) Trucks built from Sept 1994

(3) Control rods on suspensions rated at 23,000 LB (10 433 kg) or 46,000 LB (20 865 kg) are
larger and are attached to axle bracket with a single bolt. Torque fasteners attaching the

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control rod frame bracket to frame rail to 160 to 170 Ibf.ft (217 to 230 N.m), and bolt
connecting control rod to axle housing to 175 to 225 Ibf.ft (237 to 305 N.m).

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS
Application INCH Lbs. (N.cm)
Height-Control Valve Nuts 95 (1100)

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