3⁄8"-16 UNF x 1" Lift Air Spring Bolt
19
58035-001
4
3⁄8" Lift Air Spring Split Lock Washer
20
17497-005
4
21
17700-031
¾" Locknut
2
34013-289
Single Shock Absorber Service Kit, Includes
Key Nos. 22-28
22
80335-001
Shock Absorber
2
23
78250-003
Upper Shock Absorber Bracket
2
24
50764-019
¾"-10 UNC x 4½" Upper Shock Bolt
2
25
66137-000
¾"-10 UNC Upper Shock Flange Locknut
2
5⁄8"-11 UNC x 5½" Lower Shock Bolt
26
32043-019
2
5⁄8" Lower Shock Washer
27
22962-004
4
5⁄8" Lower Shock Locknut
28
47764-000
2

****S-cam Service Kit, Axle Set
60961-864
Includes Key Nos. 29-32
60961-869 Fasteners Only, Includes Key Nos. 30-32
29
S-cam Bracket
80023-001 Left Hand
1
80023-002 Right Hand
1
5⁄16"-18 UNC x 3¼" U-bolt
30
64202-000
2
5⁄16"-18 UNC Flange Nut
8
31
75952-000
5⁄16"-18 UNC x 1" Flange Bolt
32
75953-001
4
80692-XXX
***OPTIMAAX Air Controller Module, Includes
Key Nos. 33-34
33
80427-XXX
***OPTIMAAX ECU (Contact OEM for Part No.)
1
34
80860-000
***Splash Shield Assembly
1
35
80426-000
***OPTIMAAX Air Controller Manifold
1
36
Rubber Assembly Oil
1 per Bushing

1
1
1
4
4

2
2
2
4
2

4
1
2

1
1
2

22962-014
17700-010
34013-287

NOTE: * Item included in assembly / kit only, part not sold separately.
** Item required, component supplied by vehicle manufacturer. Hendrickson is not responsible for components not supplied by
Hendrickson, for assistance with maintenance and rebuild instructions on these components see vehicle manufacturer.
*** Not shown, refer to Hendrickson Literature Number 17730-310 for more information.
**** Required for vehicles equipped with drum brakes only.

17730-309

11

Parts List

OPTIMAAX® for Freightliner Vehicles
SECTION 6

Preventive Maintenance
A visual inspection of the OPTIMAAX liftable forward tandem axle and suspension system is necessary to help ensure all such components function to their highest efficiency, see Hendrickson
Recommended Inspection Intervals chart below. Visual inspection must include the following
items and other components referenced in this section:

HENDRICKSON RECOMMENDED
INSPECTION INTERVALS

PRE-DELIVERY

Air Springs for chaffing or any signs of component
damage
Proper torque as recommended in the Torque
Specification section of this publication
Any signs of wear, damage or change in condition
of suspension / axle components
QUIK-ALIGN connection
TRI-FUNCTIONAL Bushing and Thrust Washers
Shock absorbers, Upper Shock Absorber Bracket
and Bolts
Welds (all)

DAILY

MONTHLY

QUARTERLY

■
■

■
■

■

■
■
■

■

■

COMPONENT INSPECTION
■■ Axle — Inspect the axle for cracks, damage or component contact.
■■ Axle beam assembly — Inspect the axle beam assembly for any signs of loosening or dam-

age. See Axle Beam Assembly End Hub in this section. Replace all worn or damaged parts.

■■ Cross member — Inspect the cross member for any signs of loosening or damage. Replace

all worn or damaged parts.

■■ Fasteners — Look for any loose or damaged fasteners on the entire suspension. Make sure

all fasteners are tightened to the specified torque. Refer to Torque Specifications section in this
publication if fasteners are supplied by Hendrickson. Refer to the vehicle manufacturer torque
specifications for any non‑Hendrickson fasteners. Use a QUIK-ALIGN socket tool and a calibrated
torque wrench to check torque in a tightening direction. As soon as the fastener starts to move,
record the torque. Correct the torque if necessary. Replace any worn or damaged fasteners.
■■ Frame hanger — Inspect the frame hanger for any signs of loosening or damage. Inspect all
fasteners securing the frame hanger to the frame rails. Check all fasteners for proper torque.
Replace all worn or damaged parts.
■■ TRI-FUCTIONAL bushing — Inspect the TRI‑FUCTIONAL bushing for wear and damage. See

TRI‑FUCTIONAL Bushing inspection in this section. Replace as necessary.

■■ Thrust washers — Inspect thrust washers for wear and damage. Look for bent or cracked

parts. See Thrust Washer inspection in this section. Replace as necessary.
■■ Tire wear — Inspect tires for wear patterns that may indicate suspension damage or misalignment. See Tire Inspection in this section.
■■ Wear and damage — Inspect all parts of suspension for wear and damage. Look for bent or
cracked parts. Replace all worn or damaged parts.
See vehicle manufacturer’s applicable publications for other preventive maintenance
­requirements.

Preventive Maintenance

12

17730-309

OPTIMAAX® for Freightliner Vehicles
FRAME HANGER

FIGURE 6-1

VISUAL INSPECTION
1. With the axle beam assembly lowered, inspect the inner
surfaces of the frame hanger.
■■

Some wear (polished metal) on the inner surface of
the frame hanger is considered normal, due to the
pivoting motion inherent with this connection.

■■

Gouges or grooves worn into the frame hanger are
abnormal. If any gouges, grooves or missing metal is
found, the frame hanger must be replaced, refer to the
Component Replacement section of this publication.

PHYSICAL INSPECTION
1. Chock the wheels and apply the parking brakes.
2. Remove tires.
3. Lower the axle beam assembly.
4. Inspect the inner surfaces of the frame hanger and the edges of the axle beam assembly for
wear.
5. Also inspect the TRI-FUNCTIONAL bushing position within the axle beam assembly end hub,
see TRI-FUNCTIONAL Bushing in this section.

AXLE BEAM ASSEMBLY END HUB
VISUAL INSPECTION
Some wear (polished metal) on the edge of the axle beam assembly end hub is considered normal, due to the pivoting motion inherent with this connection.
Missing metal, where the axle beam assembly end hub’s radius edge has been worn away is
considered excessive. Determine how much wear has occurred, see Figure 6-2.
FIGURE 6-2

FIGURE 6-3

The axle beam assembly end hub width when new has a nominal width of 31⁄8", see Figure 6-3.
The amount of axle beam assembly end hub wear can be determined by measuring the width of
the axle beam assembly end hub and subtracting this measured dimension from the new end
hub width. If dimension is less than 3 3⁄32" replacement is necessary, see Table 6-1.

17730-309

13

Preventive Maintenance

OPTIMAAX® for Freightliner Vehicles
TABLE 6-1
AXLE BEAM ASSEMBLY
END HUB MEASUREMENT

TRI-FUNCTIONAL
BUSHING POSITION

REPAIR RECOMMENDATION

Centered

• Replace both thrust washers if worn, refer to TRI-FUNCTIONAL
Bushing Component Replacement section of this publication. Inspect
TRI‑FUNCTIONAL bushing. Refer to the TRI-FUNCTIONAL Bushing inspection in
this section, see Figure 6-8. When complete and re-align the axle, refer to the
Alignment & Adjustments section of this publication.

Off-center

• Refer to the TRI-FUNCTIONAL Bushing inspection in this section, see Figure
6-7. DO NOT attempt to center an off-center bushing, see Figure 6-8.
Replacement of the off-centered bushing is required.
• Install new TRI-FUNCTIONAL bushings, replace both thrust washers, refer
to TRI-FUNCTIONAL Bushing Component Replacement section of this
publication. When complete and re-align the axle, refer to the Alignment &
Adjustments section of this publication.

Not applicable

• Any beam end hub wear into the weld is not acceptable. Replace the axle
beam assembly and thrust washers, refer to the Component Replacement
section of this publication.

31⁄8" ± 1⁄32"
(No wear on the beam end hub)

Less than 33⁄32"
(Worn into the weld)

TRI-FUNCTIONAL BUSHING

FIGURE 6-4

VISUAL INSPECTION
NOTE

It is not necessary to disassemble suspension to inspect
the TRI-FUNCTIONAL bushing.
On an unloaded vehicle, measure from the bottom
edge of the axle beam assembly edge of the bottom
plate to the bottom of the frame hanger flange as
shown in Figure 6-5.
■■ If Dimension A is less than or equal to 9⁄16", the

TRI‑FUNCTIONAL bushing is acceptable.

■■ If Dimension A is greater than 9⁄16", a physical

Thrust
Washer

End
Hub

TRI-FUNCTIONAL
Bushing

Axle Beam
Thrust Assembly
Washer

inspection is necessary. The TRI-FUNCTIONAL bushing connection must be disassembled and
the axle beam assembly lowered to physically inspect the TRI-FUNCTIONAL bushing. Refer to
the Component Replacement Section of this publication for TRI-FUNCTIONAL bushing disassembly instructions.

SERVICE HINT

With the axle beam assembly lowered, Hendrickson recommends also inspecting the thrust washers, axle beam assembly end hub and the interior surfaces of the frame hanger.
FIGURE 6-5

Preventive Maintenance

14

17730-309

OPTIMAAX® for Freightliner Vehicles
TRI-FUNCTIONAL III bushings will typically “settle” in the vertical direction upon suspension installation. It is normal for the voids to have this “settled” appearance, due to cargo and the weight of
the vehicle loading the bushing.
■■ Replacement Required: Cracks in the rubber extending between the void and the bushing’s

inner metal or an excessive amount of vertical movement, are indications that the bushing
needs to be replaced, see Figure 6-6. DO NOT use a pry bar to determine TRI‑FUNCTIONAL
bushing replacement.

FIGURE 6-6

PHYSICAL INSPECTION

FIGURE 6-7

F o r e v a l u a t i o n p u r p o s e s, t h e
TRI‑FUNCTIONAL bushing is considered either centered or off-center with
respect to the axle beam assembly end
hub and considered off‑center when a
portion of it extends outside of the axle
beam assembly end hub on one side
and not on the other, see Figure 6-8 for
typical examples.
The TRI-FUNCTIONAL bushings will flex
and elongate within the axle beam
assembly end hub to control the forces
generated by braking, accelerating, irregular road surfaces, etc. Because of this, it may be difficult
at times to tell the difference between normal bushing operation and an off-center bushing.
FIGURE 6-8

The key to identifying an off-center TRI-FUNCTIONAL III bushing is the thrust washers. If the
thrust washers are in serviceable condition (not missing, cut, worn-through or otherwise deteriorated), the bushing cannot be off-center. However, if an axle beam assembly end hub thrust washer
spacer is worn-through, the potential exists for an off-center condition (as described above).
If the TRI-FUNCTIONAL bushing is off-center, but the axle beam assembly end hub width is acceptable, replace the bushing. Refer to TRI-FUNCTIONAL Bushing in the Component Replacement
section of this publication.
17730-309

15

Preventive Maintenance

OPTIMAAX® for Freightliner Vehicles
THRUST WASHERS

FIGURE 6-9

Thrust washers are located inside the frame hangers on each side of the TRI-FUNCTIONAL bushing, see
Figure 6-9.
NOTE

Hendrickson recommends if one (1) thrust washer
requires replacement that both thrust washers on
each side of the TRI-FUNCTIONAL bushing be replaced.
Refer the Component Replacement Section in this
publication.

VISUAL INSPECTION
NOTE

The lift air spring may need to be removed to aid in visual inspection.
A THRUST WASHER THAT IS COMPLETELY MISSING, HAS BEEN CUT OR WORN THROUGH IS CONSIDERED
ABNORMAL. IF THESE CONDITIONS EXIST, REPLACEMENT IS REQUIRED TO PROLONG THE LIFE OF THE
SUSPENSION.

1. Visually inspect thrust washers. Due to the pivoting motion inherent with this connection,
some thrust washer wear is expected, see Figure 6-10.
■■

Acceptable: Cupping is an acceptable condition where the thrust washer forms around
the axle beam assembly end hub and resembles a shallow dish, see Figure 6-11.

■■

Unacceptable: A missing, cut, worn-through or deteriorated thrust washer requires
replacement, see Figure 6-12. Refer to the Component Replacement section of this
publication.

FIGURE 6-10

FIGURE 6-11
ACCEPTABLE CONDITION

NORMAL

Preventive Maintenance

WORN

CUPPED

Cupped
Thrust
Washer

Normal Thrust
Washer

Normal Thrust Washer

FIGURE 6-12
UNACCEPTABLE

Cupped Thrust Washer
Friction generated heat can cause
the thrust washer to cup around
the axle beam assembly end hub.
This is acceptable as long as the
thrust washer remains intact and
is not cut or worn-through.

16

Worn-through
Thrust Washer

Worn Thrust Washer
The thrust washer shows
extreme wear. The thrust washer
circumference is completely
trimmed by the axle beam
assembly end hub. Replacement
required.

17730-309

OPTIMAAX® for Freightliner Vehicles
REPAIR RECOMMENDATIONS
DO NOT USE MORE THAN THE RECOMMENDED NUMBER OF THRUST WASHERS, THIS CAN CAUSE THE
TRI‑FUNCTIONAL BUSHING TO NOT HAVE ENOUGH ROOM WITHIN THE FRAME HANGER TO FUNCTION
PROPERLY AND CAN RESULT IN SEVERE DAMAGE TO THE SUSPENSION.

1. After each TRI-FUNCTIONAL bushing component has been evaluated, use the Table 6-1 to
determine the correct repair action. DO NOT add more thrust washers than what is recommended. A slight degree of freedom is required by the TRI-FUNCTIONAL bushing within the
frame hanger to flex, elongate and otherwise absorb forces generated by braking, accelerating and irregular road surfaces.

TIRE INSPECTION
The leading causes of tire wear are the following, in order of importance:
1. Tire Pressure
2. Toe Setting
3. Thrust Angle
4. Camber
The following tire Inspection guidelines are based upon Technology & Maintenance Council
(TMC) recommended practices. Any issues regarding irregular tire wear where Hendrickson is
asked for assistance will require tire and alignment maintenance records, reference TMC’s literature numbers RP 219A, RP 230, or RP 642.
Tire wear is normally the best indicator of vehicle alignment condition. If tires are wearing too rapidly or irregularly, alignment corrections may be needed. The tire wear patterns described below
can help isolate specific alignment problems.
The most common conditions of concern are:

FIGURE 6-13

FIGURE 6-14

■■

Overall Fast Wear (Miles per 32nd)

■■

Feather Wear

■■

Cupping

■■

Diagonal Wear

■■

Rapid Shoulder Wear (One Shoulder Only)

■■

One-Sided Wear

Overall Fast Wear — Fast wear can be described as exhibiting a good, but accelerated wear
pattern. It is typically caused by operating conditions, such as mountainous terrain, frequency
and severity of turning, abrasive road surfaces in combination with vehicle configurations and
their attributes-such as power steering, heavy axle loads, high wheel cuts, setback axles, short
wheel base tractors, long wheel base straight trucks. To correct this problem, consult with vehicle
and tire manufacturers when specifying equipment or replacing tires. For more information, see
TMC RP 219A publication, page 11. For information on how to accurately measure and record
tire rates, see TMC RP 230 publication.
Feather wear — Tread ribs or blocks worn so that one side is higher than the other resulting in
step-offs across the tread face. Generally, ribs or blocks exhibit this wear. To spot this problem, do
the following:
With one hand flat on the tread of the tire and a firm down pressure, slide your hand across the
tread of the tire. In one direction, the tire will feel smooth and in the opposite direction there will
be a sharp edge to the tread. Typical causes of feather wear include: excessive side force scrubbing, resulting from conditions of m
­ isalignment such as excessive toe, drive axle misalignment,
worn, missing or damaged suspension components, bent tie rods or other chassis misalignment.

17730-309

17

Preventive Maintenance

OPTIMAAX® for Freightliner Vehicles
To correct this problem, tires can be rotated to another axle for maximum utilization of remaining
tread. Additionally, diagnose the vehicle itself and correct misalignment condition as required. If
steer tire feathers are in opposite directions, an improper toe condition is most likely the cause.
For more information, see TMC RP 219A publication, page 5.

FIGURE 6-15

If feather wear on both steer tires is in the same direction, drive axle or other chassis ­misalignment