4

91005-004 91005-104

12.5

80913-106

11

91005-106

11.75

80913-107 10.25

91005-107

11

80913-108

9.5

91005-108

10.5

80913-109

9

91005-109

10.25

80913-110

8.75

91005-110

9.5

80913-111

7.75

91005-111

17730-301

11

Parts List

ULTIMAAX® for Kenworth Vehicles
SECTION 5

Special Tools
SADDLE ASSEMBLY TOOLS
DISASSEMBLY TOOL

ASSEMBLY TOOL

Hendrickson Part No. 66086-113L

Hendrickson Part No. 66086-108L

CENTER BUSHING TOOLS
RECEIVING TOOL

INSTALLATION TOOL

REMOVAL TOOL

Hendrickson Part No. 66086-112

Hendrickson Part No. 66086-107

Hendrickson Part No. 66086-110

BAR PIN STYLE END BUSHING TOOLS – 46K • 52K
RECEIVING TOOL

INSTALLATION TOOL

REMOVAL TOOL

Hendrickson Part No. 66086-111

Hendrickson Part No. 66086-106

Hendrickson Part No. 66086-109

ADAPTER STYLE END BUSHING TOOLS – 60K • 70K
End Bushing
Removal / Replacement Adapter
OTC Part Number 208350

Clamp
OTC Part Number 208349

Hendrickson Part No. 66086-101
OTC Part No. 1763
Visit otctools.com



Center Bushing
Removal / Replacement Adapter
OTC Part Number 28541
Not Needed for this publication

12

17730-301

ULTIMAAX® for Kenworth Vehicles
TORQUE ROD BUSHING TOOLS
These shop made tools are made from cold rolled steel or equivalent. The drawings are for reference only,
Hendrickson does not supply these tools.

RECEIVING TOOL

17730-301

INSTALLATION / REMOVAL TOOL

13 

ULTIMAAX® for Kenworth Vehicles
SECTION 6

Preventive Maintenance
Following appropriate inspection procedures is important to help ensure the proper maintenance
and operation of the suspension system and component parts. Hendrickson recommends the
ULTIMAAX severe-duty rear suspension be inspected at pre-delivery, the first in-service inspection
and regular preventive maintenance intervals. Off-highway and severe service operating conditions may require more frequent inspections than on-highway service operation. Inspection must
include the following items and other components referenced in this section.
NOTE

Torque values shown in this publication apply only if Hendrickson supplied fasteners are used. If
non-Hendrickson fasteners are used, follow the torque specification listed in the vehicle manufacturer’s service manual.

HENDRICKSON RECOMMENDED
INSPECTION INTERVALS

PRE-DELIVERY
INSPECTION

FIRST IN-SERVICE
INSPECTION

Every
3 Months / 600 Hours

Inspect progressive load spring (PLS)
Visually Inspect proper assembly and function. Check
for all of the following and replace components as
necessary:
• S igns of unusual movement, loose or missing
components
• S igns of abrasive or adverse contact with other
components (example: brake lines, wheel wells,
frame hangers, etc.)
• Damaged, or cracked parts
• Proper suspension function, alignment
Inspect torque rods (Longitudinal, Transverse and
V-rods) and equalizing beam end connections

PREVENTIVE
MAINTENANCE

Within the first
500 miles
(500 km)

Inspect fasteners for proper torque as recommended
in the Torque Specification Section of this publication
with special attention to the following suspension
connections:
• Equalizing beam end connection
• Saddle cap connection
• Frame hanger to frame rail connection
• Center bushing

Within the first
1,500 miles
(2,500 km) or
100 Hours

Every
6 Months / 1200 Hours
or
25,000 miles /
40,000 km

Every
12 Months /
2400 Hours

Verify the alignment of axles are within the vehicle
manufacturer’s tolerances.

COMPONENT INSPECTION
Following appropriate inspection procedures is important to help ensure the proper maintenance
and operation of the ULTIMAAX severe-duty rear suspension system and component parts. Look
for and replace worn, damaged, bent or cracked parts.
■■ Cross tube — Clean the cross tube and inspect it for cracks or excessive wear 8" to 10" from

each end where it enters into the equalizing beam center bushings. Use a straight edge to
check the straightness of the cross tube. If there is a doubt as to fracture, wear or straightness,
replacement is necessary.

Preventive Maintenance

14

17730-301

ULTIMAAX® for Kenworth Vehicles
■■ Equalizing beam assembly — Check the overall condition of the equalizing beam for dents,

dings, or other damage. Check the beam end connections for tearing or extreme bulging.
Check for any metal-to-metal contact in the bushed joints. Refer to Equalizing Beam End
Connection Inspection in this section.

■■ Fasteners — Look for any loose, missing or damaged fasteners on the entire suspension.

Make sure all fasteners are tightened to a torque value within the specified torque range.
See recommended torque specifications for Hendrickson supplied fasteners in Torque
Specification Section of this publication. For fasteners not supplied by Hendrickson, see vehicle manufacturer. Use a calibrated torque wrench to check torque in the tightening direction.
As soon as the fastener starts to move, record the torque. Correct the torque as necessary.

NOTE

Hendrickson recommends the use of Grade 8 bolts, hardened washers, and Grade C locknuts.
Hardened washers are not necessary when flange head fasteners are used.

NOTE

Torque values shown in this publication apply only if Hendrickson supplied fasteners are used. If
non-Hendrickson fasteners are used, follow the torque specification listed in the vehicle manufacturer’s service manual.
■■ Saddle cap fasteners — Inspect the locknuts for proper torque to prevent wear of the beam

center bushing into the saddle. See Torque Specification Section of this publication for recommended torque requirements.

■■ Shock absorbers — Look for any signs of dents or leakage. Misting is not considered a leak.

See Shock Absorber Inspection in this section.

■■ Torque rods (Transverse / Longitudinal / V-rods) — The torque rods must be connected and

in good working condition when operating the vehicle.

■■ Wear and damage — Inspect all parts of the suspension for wear and damage. Look for bent

or cracked parts.

See vehicle manufacturer’s applicable publications for other preventive maintenance
­requirements.

CENTER BUSHING
VISUAL INSPECTION
An inspection of the center bushing is necessary when a vehicle is in the shop for major repair
work and at regular preventive maintenance intervals.
NOTE
FIGURE 6-1

ULTIMAAX center bushing is designed with voids at front and rear, see Figure 6-1. These voids are
not an indication of wear.
CENTER BUSHING Two Hole Design
ULTIMAAX 46K • 52K • 60K
Void

Void

CL
Second Locating
Bottom Hole
must be on bottom

17730-301

CENTER BUSHING Circlip Design
ULTIMAAX 70K
Void

Void

Horizontal Centerline
Verify the voids are
perpendicular to the
horizontal centerline

CL
Center Hole
Circlip

Center Hole

15

Preventive Maintenance

ULTIMAAX® for Kenworth Vehicles
1. Visually inspect the center bushing for signs of movement or excessive wear such as frayed,
bulging or distorted rubber in the center bushing.
2. Replacement is necessary if:
■■

Any metal to metal contact is visible.

■■

Any signs that the bushing inner metal is not centered in the bushing.

■■

Any equalizing beam to saddle contact.

EQUALIZING BEAM END CONNECTION
An inspection of the beam end connections are necessary when a vehicle is in the shop for
major repair work and at regular preventive maintenance intervals. Periodic visual inspection by
the driver and service personnel is also recommended.
■■

NOTE

Bar Pin Style ULTIMAAX 46K•52K, see Figure 6-2

The equalizing beam end connection requires that the fasteners are tightened to torque specifications, see Figure 6-2, to maintain the clamp load of the axle bracket legs to the bar pin. All bushing
motion is accommodated by rubber deflection.
FIGURE 6-2
ULTIMAAX
46K • 52K Shown

VISUAL INSPECTION

Axle Bracket
Supplied by
Manufacturer

1. Chock the wheels.
2. Visually inspect suspension components for signs of movement or
excessive wear.
■■

■■

SERVICE HINT

1" Locknut
Tightening Torque
525 ± 75 ft. lbs
(712 ± 102 Nm)

Inspect alignment shims
in equalizing beam end for
looseness. Lightly tap on the
alignment shims to see if they
can be moved. If movement is
detected, tighten fasteners to
the proper torque value, see
Figure 6-2.

Bar Pin

Bar Pin
Shim
1" Bolt,Tightening Torque

575 ± 75 ft. lbs (780 ± 102 Nm)
Inspect the equalizing beam end
connection for signs of excessive wear or looseness.

An equalizing beam end connection that is visibly cleaner than the other connections may indicate a loose connection.
FIGURE 6-3

GOOD BUSHING

WORN BUSHING

Axle Bracket

Axle Bracket

C
L

C
L

A GOOD bushing will result in the equalizing beam
end hub appearing to be centered with the
centerline of the end bushing in the axle bracket

Preventive Maintenance

16

A WORN bushing will result in the equalizing beam
end hub appearing to be 5/8" (15 mm) offset/below
the centerline of the end bushing in the axle bracket

17730-301

ULTIMAAX® for Kenworth Vehicles
■■

Look for worn, frayed or distorted rubber in the bar pin beam end bushing, see Figure 6-3.

■■

Look for the equalizing beam to be lower in the beam hanger, see Figure 6-3.

■■

If the bar pin beam end bushing is visually offset a floor jack test should be performed,
refer to Jack Test in this section.
FIGURE 6-4
Axle Bracket

JACK TEST
1. Place a jack under each beam end as shown. Raise the
jack to check for movement in the connection or rubber
components, see Figure 6-4.
NOTE

The gap at each side of the visible rubber on the lower
part of the end bushing is normal, see Figure 6-4, and is
not an indication to replace the bushing. Because all rubber
end bushings are in compression, with the load bearing on
the top side, the lower side of the rubber is slightly relieved,
allowing the rubber to move inward, and a gap appears.

Floor
Jack

Gap in rubber
of bar pin end
bushing is
normal

PHYSICAL INSPECTION
IF BAR PIN MOVEMENT OR LOOSENESS IS NOTED IN ANY OF THE EQUALIZING BEAM END HUBS,
DO NOT OPERATE THE VEHICLE. REPLACE THE RUBBER END BUSHINGS AND ALL CONNECTING
PARTS IF NECESSARY. THE ABOVE CONDITION CAN RESULT IN COSTLY REPAIR, DOWNTIME,
POSSIBLE SEPARATION OF COMPONENTS, ADVERSE VEHICLE HANDLING, PROPERTY DAMAGE,
OR PERSONAL INJURY.

SERVICE HINT

An equalizing beam end connection that is visibly cleaner than the other connections may indicate a loose connection.
2. If bar pin end bushing movement or looseness is detected in the equalizing beam end hub,
replace the end bushings and all connecting parts. Refer to the Component Replacement
Section of this publication.
3. Check and record torque values, as received, for each 1" bar pin fastener, see Figure 6-2.
Ensure all fasteners are tightened to:
■■ At the locknut to
525 ± 75 foot pounds torque, or
■■

At the bolt head to

575 ± 75 foot pounds

4. Recheck equalizing beam end connections for signs of looseness.
■■

Inspect alignment shims in equalizing beam end for looseness. Lightly tap on the alignment shims to see if they can be moved. If movement is detected, tighten fasteners to the
proper torque value, see Figure 6-2.

■■

Inspect equalizing beam end connection for signs of excessive wear or looseness.

5. If bar pin looseness is still detected in any of the equalizing beam end hub, DO NOT operate
the vehicle. One or more components will require replacement, see Component Replacement
Section of this publication.

17730-301

17

Preventive Maintenance

ULTIMAAX® for Kenworth Vehicles
■■

Adapter Style ULTIMAAX 60K•70K, see Figure 6-5
FIGURE 6-5
ULTIMAAX 60K • 70K Shown

VISUAL INSPECTION

Equalizing
Beam

1. Chock the wheels.

Cotter Pin

2. Visually inspect suspension
components for signs of movement or excessive wear.
■■

Inspect equalizing beam
end connection for signs
of excessive wear or
looseness.

17/8" Slotted Nut
Beam End Adapter
Adapter Style
End Bushing

Beam End Shaft
Beam End Adapter
17/8" Slotted Nut

■■

Look for worn, frayed or distorted rubber in the beam, see Figure 6-6.

■■

Look for the equalizing beam to be lower in the axle bracket, see Figure 6-6.

■■

If the adapter style end bushing is visually offset, a floor jack test should be performed,
refer to Jack Test in this section.

FIGURE 6-6

WORN BUSHING

GOOD BUSHING
Axle Bracket

Axle Bracket

C
L

C
L

A GOOD bushing will result in the equalizing
beam end hub appearing to be centered
with the centerline of the end bushing
in the axle bracket

A WORN bushing will result in the equalizing
beam end hub appearing to be 5/8" (15 mm)
offset/below the centerline of the end bushing