■■

Steel leaf spring — Look for cracks. Replace if cracked or broken. Check the front bushings for any wear or deterioration. Replace leaf spring assembly if any of the previous
conditions are observed. See the Component Replacement Section of this publication for
replacement procedure.
Operation — All steering components must move freely through the full range of motion
from axle stop to axle stop.
Steering pivot points — Check for looseness at all pivot points. Inspect and lubricate all pivot
points. Refer to the STEERTEK NXT High Capacity Greasing and Lubrication Specifications Table
7-1, in this section.
STEERTEK NXT High Capacity axle and Tie Rods — Inspect for any cracks or dents on the
axle, and also refer to the Tie Rod Ends Inspection and Lubrication Section in this publication.
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.
■■

Towing Procedures

12

17730-311

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
LUBRICATION INTERVALS
For vehicles equipped with the STEERTEK NXT High Capacity steer axle system, regular lubrication
intervals should be f­ollowed to help prevent premature wear to the kingpin bushings and tie rod
ends, see Lubrication Specification Table 7-1 below.
NOTE

The recommended service lubrication interval is a guideline, the vehicle may require increased
lubrication interval depending on severity of operation.

TABLE 7-1

STEERTEK NXT High Capacity — Greasing and Lubrication Specifications
Component
Kingpin Bushings

Greasing Interval

Tie Rod Ends

Maximum of 10,000 miles
(16,100 kilometers) or 90
days, whichever comes first.

Drag Link

See Vehicle Manufacturer

Threaded Pin

Every 3 months

Grease

NLGI Grade

Multipurpose
Grease

2

Lithium Base
Grease

2

Outside Temperature
Refer to the lubricant ­manufacturer’s
specifications for the temperature
service limits applicable to your area.

NOTE: Lubrication greases acceptable for use on the STEERTEK NXT will carry a designation of NLGI #2 EP and rated
GC‑LB or equivalent.

KINGPIN LUBRICATION
1. Place vehicle on the ground.
2. Prior to greasing the kingpins on the vehicle, the suspension must be in a loaded condition.
3. Clean off all the grease zerks and grease gun tip with a clean shop towel prior to lubrication.
4. Lubricate the kingpins through the grease zerks on the top and bottom of the steering knuckle,
see Lubrication Specification Table 7-1 above.
5. Force the required lubricant into the upper and lower kingpin grease zerks, (Figure 7-1) until
new lubricant flows out from the upper kingpin connection and steering knuckle and the
thrust bearing purge location, see Figures 7-1 and 7-2.
NOTE

Greasing at the lower zerk should purge grease from the thrust bearing shell. The left and right
side of the STEERTEK NXT High Capacity steer axle system have steel roller thrust bearings.
FIGURE 7-1
Upper
Grease Zerk

17730-311

FIGURE 7-2
Grease Purge

13

Grease Purge

Preventive Maintenance

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
TIE ROD END LUBRICATION
LUBRICATION PROCEDURE
1. Turn the vehicle wheels straight ahead.
2. Wipe the grease zerk and grease gun tip with clean shop towels.
3. Wipe the seal / boot clean with shop towels.
4. Attach a grease gun to the grease zerk. Either a hand or pneumatic grease gun is acceptable.
If air operated grease gun is used, system air pressure should not exceed 150 psi (1035 kPa).
EXCEEDING THE MAXIMUM AIR PRESSURE TO THE GREASE ZERK CAN CAUSE DAMAGE TO THE DUST
BOOT AND COMPONENT FAILURE.
FIGURE 7-3

5. Dirt, water, and discolored old grease
should flow from the relief vents or purge
holes near the boot crimp or bellows
area, see Figure 7-3. Continue to purge
grease until fresh grease flows from the
purge area.
6. If the tie rod end is designed for lube service and it will not accept grease proceed
as ­follows:

Dust Boot
Boot Crimp

a. Remove the grease zerk
b. Inspect the threaded grease zerk hole
in the tie rod end and remove any
Zerk Fitting
obstructions
c. Install a new grease zerk
d. Continue the lubrication procedure
e. If the tie rod end will not accept grease following this procedure it will be necessary to
replace the tie rod end, (see Tie Rod End replacement in the Component Replacement
Section of this publication)
7. Apply grease until all the old grease is purged from the boot and fresh grease is coming out.

TIE ROD ENDS
INSPECTION
Before beginning this inspection procedure, the entire system must be unloaded (i.e., the front
end of the vehicle must be raised and supported with safety stands).
DO NOT GREASE THE TIE ROD ASSEMBLY BEFORE PERFORMING THE INSPECTION. DOING SO CAN
INHIBIT EFFORTS TO DETERMINE ACTUAL WEAR.
REPLACE THE ENTIRE TIE ROD END IF THE BOOT IS TORN OR MISSING, FAILURE TO DO SO CAN CAUSE
PREMATURE WEAR OF THE TIE ROD END.

1. Block rear wheels of vehicle. Using the bottom of the axle beam or the frame rails, raise the
front end off the ground and support with stands.
2. With the engine off, turn the wheels from full left to full right and then return to the straightahead position.
3. Check that the boots are in place and completely installed over the tie rod ends.
4. Check for cracking or tears in the boots. Also check the boot seals for damage. Replace the
entire tie rod end if the boot is damaged.

Preventive Maintenance

14

17730-311

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
THE COTTER PIN MUST BE INSTALLED CORRECTLY THROUGH THE TIE ROD END WITH THE CASTLE NUT
TIGHTENED TO THE PROPER TORQUE SPECIFICATION IN ORDER TO SECURELY ATTACH THE TIE ROD.
LOSS OF THE COTTER PIN CAN CAUSE THE TIE ROD END NUT TO BECOME LOOSE AND ADVERSELY
AFFECT VEHICLE STEERING AND POSSIBLY RESULT IN TOTAL LOSS OF STEERING CONTROL.

5. Check that the tie rod end nut is installed and secured with a cotter pin. If the cotter pin is
missing, check the nut torque specification and then install a new cotter pin. Always tighten
the castle nut to specified torque when setting the cotter pin. DO NOT back off the nut to insert
cotter pin.
IT IS CRITICAL TO CHECK THE 5⁄ 8" TIE ROD CLAMP BOLT HEAD LOCATION TO VERIFY THE CLAMP
FASTENERS HAVE SUFFICIENT CLEARANCE AWAY FROM THE LOWER SHOCK ABSORBER MOUNT
AT FULL WHEEL CUT. THE FASTENERS MUST NOT CONTACT THE LOWER SHOCK ABSORBER MOUNT.
FAILURE TO DO SO CAN CAUSE ONE OR MORE COMPONENTS TO FAIL CAUSING LOSS OF VEHICLE
CONTROL AND POSSIBLE PERSONAL INJURY OR PROPERTY DAMAGE.

6. Verify the 5⁄8" tie rod clamp bolt head does not contact the lower shock absorber mount at full
wheel cut, see Figure 7-4.
THE THREADED PORTION OF THE TIE ROD END MUST EXTEND PAST THE SLOTS INTO THE TIE ROD
CROSS TUBE, SEE FIGURE 7-4. FAILURE TO DO SO CAN CAUSE COMPONENT DAMAGE, LOSS OF
VEHICLE CONTROL AND POSSIBLE PERSONAL INJURY OR PROPERTY DAMAGE.

7. Check that the tie rod end is threaded correctly into the cross tube and is engaged deeper
than the end of the cross tube slot. The tie rod end must be visible the entire length of the
cross tube slot, see Figure 7-4.
FIGURE 7-4
5/8" Tie Rod Clamp Bolt
It is critical to check the 5/8" tie rod clamp
bolt head location to verify the clamp
fasteners have sufficient clearance away
from the lower shock mount at full wheel
cut. The fasteners must not contact the
lower shock mount.

Tie Rod Cross Tube Slots
It is critical to have the threaded
portion of the tie rod end extend past
the slots in the tie rod cross tube.

Threaded Portion
of the Tie Rod End

5/8" Tie Rod Clamp Locknut
Tightening Torque 68 ± 7 ft. lbs.

8. Check that grease zerks are installed. Replace a damaged grease zerk with a new one.
DO NOT USE THE FOLLOWING ITEMS OR METHODS TO CHECK FOR MOVEMENT OF THE TIE ROD
ASSEMBLY, WHICH CAN CAUSE DAMAGE TO COMPONENTS:
■■
■■

■■

A CROW BAR, PICKLE FORK OR 2 X 4.
ANYTHING OTHER THAN HANDS USED TO GRASP AND ROTATE THE CROSS TUBE ASSEMBLY (CAN
RESULT IN DAMAGE TO THE CROSS TUBE).
EXCESSIVE PRESSURE OR FORCE APPLIED TO THE TIE ROD ENDS OR THE JOINTS OF THE ASSEMBLY.

9. By hand or using a pipe wrench, with jaw protectors to avoid gouging the cross tube, rotate
the cross tube toward the front of the vehicle and then toward the rear. After rotating, center
the cross tube. If the cross tube will not rotate in either direction, replace both tie rod ends,
see Figure 7-5.

17730-311

15

Preventive Maintenance

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
FIGURE 7-5

10. Position yourself directly below the tie rod end. Using both hands, grab the assembly end as
close to the tie rod end as possible (no more than 6" or 152.4 mm). Apply hand pressure with
reasonable human effort vertically up and down in a push-pull motion several times (using
approximately 50‑100 pounds of force). Check for any movement or looseness at both tie rod
end locations, see Figure 7-6.
11. If there is any movement in the tie rod assembly, install a magnetic based dial indicator on the
tie rod arm, see Figure 7-7.
FIGURE 7-6

FIGURE 7-7

Push up and down in
a push-pull motion to
check any movement
or looseness

12. Set the dial indicator to zero.
13. Apply hand pressure with reasonable human effort vertically up and down in a push-pull
motion several times (using approximately 50‑100 pounds of force). Observe the reading on
the dial indicator.
14. If the reading is more than 0.060", replace both tie rod ends at the next service i­nterval.
15. If a tie rod end exhibits ≥ 0.125" of movement by hand, the vehicle should be removed immediately from use and the tie rod end be replaced.
NOTE

Preventive Maintenance

According to the Commercial Vehicle Safety Alliance (CVSA), the “out of service” criteria for front
steer axle tie rod assemblies on any commercial vehicle is: Any motion other than rotational
between any linkage member and its attachment point of more than 1⁄8" (3 mm) measured with
hand pressure only. (393.209(d)), (published in the North American Standard Out-of-Service
Criteria Handbook, April 1, 2006.)

16

17730-311

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
CLAMP GROUP RE-TORQUE INTERVAL
1. Clamp group hex bolts and axle collar hex cap bolts must be torqued to specification at
preparation for delivery.
2. Clamp group hex bolts and axle collar hex cap bolts must be re-torqued at 1,000 miles.
3. Thereafter follow the 6 month / 50,000 mile visual inspection and annual re-torque interval.
ENSURE CLAMP GROUP IS ALIGNED PROPERLY PRIOR TO TIGHTENING HARDWARE. FAILURE TO DO SO
CAN CAUSE LOSS OF VEHICLE CONTROL, PROPERTY DAMAGE OR PERSONAL INJURY.
FIGURE 7-8

4. Ensure that the clamp group is properly aligned
and the hex bolts are seated in the axle seat, and
the top pad is centered on the leaf spring, see
Figure 7-8.

FIGURE 7-9

5. Check for the signs of component or bolt
movement.
6. If signs of movement are present, disassemble
the clamp group fasteners, check for component
wear or damage and replace as necessary, then
install new clamp group fasteners and repeat
Steps 4 through 5.
7. Tighten the clamp group hex bolts evenly in 100
foot pounds increments to
600 ± 20 foot
pounds torque in the proper pattern to achieve
uniform bolt tension, see Figure 7-9.

STEERING KNUCKLE
CHECKING VERTICAL END PLAY (UP AND DOWN MOVEMENT)
The operating specification for vertical end play on the steering knuckle is 0.008" to 0.030".
1. Chock the rear tires to help prevent the
vehicle from moving.
2. Set the parking brakes.
3. Use a jack to raise the vehicle until both
tires are 1" off the ground.

FIGURE 7-10
Ensure the tip of
the dial indicator
is on the top of
the upper steering
knuckle and not
on the grease cap

4. Place a dial indicator on each side of the
axle as follows:
a. Index the wheels slightly (left or
right).
b. Place the magnetic dial indicator
base on the axle, see Figure 7-10.
c. Place the tip of the dial indicator on
the top of the upper steering knuckle
(not on the grease cap).
5. Set the dial indicator to “0” (zero).
6. Lower the jack.

17730-311

17

Preventive Maintenance

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
7. If vertical end play is greater than 0.030", or below 0.008" an adjustment of the upper knuckle
is necessary. If the vertical end play is:
■■ Greater
■■ Less

than 0.030", add shims until the proper vertical end play is achieved.
than 0.008", remove shims until the proper vertical end play is achieved.

8. Retighten the kingpin draw keys to

188 ± 12 foot pounds torque.

KINGPIN BUSHING WEAR
CHECKING STEERING KNUCKLE LATERAL MOVEMENT
NOTE

If one (1) bushing is worn or damaged, it is mandatory to replace both the upper and lower bushings on that knuckle assembly.
FIGURE 7-11
CHECKING UPPER KINGPIN BUSHING

FIGURE 7-12
CHECKING LOWER KINGPIN BUSHING

FIGURE 7-13

1. Chock the wheels to help prevent the vehicle
from moving. Set the parking brake.
2. Use a jack to raise the vehicle until the wheels
are off the ground. Support the vehicle with
safety stands.
3. CHECKING THE UPPER KINGPIN BUSHING.
Install the base of a dial ­indicator onto the
axle beam and place the tip against the steering knuckle, see Figure 7‑11.
4. Set the dial indicator to “0” zero.
5. Move the top of the tire in and out by applying reasonable constant pressure and then
release, see Figure 7-13.
6. Check the reading on the dial indicator. If the
dial indicator moves more than 0.015", the
upper bushing is worn or damaged. Replace
both bushings. Refer to the Kingpin Bushing
replacement procedure in the Component Replacement Section of this publication.
7. CHECKING THE LOWER KINGPIN BUSHING. Install a dial indicator so that the base is on the axle
and the indicator tip is against the inside of the bottom of the knuckle, see Figure 7-12.
8. Set the dial indicator to “0” zero.
9. Move the bottom of the tire in and out. If the dial indicator moves more than 0.015", the
lower bushing is worn or damaged. Replace both kingpin bushings. Refer to the Component
Replacement Section of this publication.
Preventive Maintenance

18

17730-311

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
SHOCK ABSORBER
NOTE

It is not necessary to replace shock absorbers in pairs if only one (1) shock absorber requires
replacement.
FIGURE 7-14

Hendrickson offers a long service life, premium shock
absorber for use on STEERTEK NXT High Capacity suspensions. If shock absorber replacement is necessary,
Hendrickson recommends that original Hendrickson shock
absorbers be replaced with identical Hendrickson Genuine
parts for servicing. Failure to do so will affect the suspension performance, durability, and will void the w
­ arranty.
Inspection of the shock absorber can be performed
by doing a heat test, and a visual inspection. For
instructions on shock absorber replacement see the
Component Replacement Section of this publication.

HEAT TEST
1. Drive the vehicle at moderate speeds on rough road
for minimum of fifteen minutes.
DO NOT GRAB THE SHOCK ABSORBER AS IT COULD POSSIBLY
BE HOT AND CAUSE PERSONAL INJURY.
2. Use an infrared thermometer to check the temperature of the shock absorber.This can also be performed
by carefully touching the shock absorber body below
the dust cover. Touch the frame to get an ambient r­eference, see Figure 7-14. A warm shock
absorber is acceptable, a cold shock absorber should be replaced.
3. To inspect for an internal failure, remove and shake the suspected shock absorber. Listen for
the sound of metal parts rattling inside. Rattling of metal parts can indicate that the shock
absorber has an internal failure.

VISUAL INSPECTION
FIGURE 7-15

Look for any of the potential problems shown in Figure 7-15 when doing a visual inspection.
Inspect the shock absorbers fully extended. Replace as necessary.
SHOCK ABSORBER VISUAL INSPECTION - UNACCEPTABLE CONDITIONS

Damaged upper or
lower mount

17730-311

Damaged upper or
lower bushing

Damaged dust cover
and / or shock body

19

Bent or dented shock
absorber

Improper intallation
Example: washer (if equipped
installed backwards

Preventive Maintenance

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
LEAKING VS. MISTING VISUAL INSPECTION
The inspection must not be conducted after driving in wet weather or a vehicle wash. The shock
absorber needs to be free from water. Many shock absorbers are often misdiagnosed as failures.
Misting is the process whereby very small amounts of shock absorber fluid evaporate at a high
­operating temperature through the upper seal of the shock absorber. When the “mist” reaches
the cooler outside air, it condenses and forms a film on the outside of the shock absorber body.
Misting is perfectly normal and necessary function of the shock absorber. The fluid which evaporates through the seal area helps to lubricate and prolong the life of the seal.
FIGURE 7-16

A shock absorber that is truly leaking and needs to be
replaced will show signs of fluid leaking in streams
from the upper seal. These streams can easily be seen
when the shock absorber is fully extended, underneath
the main body (dust cover) of the shock absorber.
Look for these potential problems when doing a visual
inspection. Inspect the shock absorbers fully extended.
Replace as necessary.
NOTE

The STEERTEK NXT High Capacity steer axle system is
equipped with a premium seal on the shock absorber,
however this seal will allow for misting to appear on
the shock absorber body (misting is not a leak and is
considered acceptable).
Inspect the shock absorber fully extended. A shock
absorber that is truly leaking will show signs of fluid leaking in streams from the upper seal.
These streams can easily be seen, underneath the main body (dust cover) of the shock absorber.
Replace as necessary.

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:
■■ Overall

Fast Wear (Miles per 32nd)

■■ Feather Wear
■■ Rapid

Shoulder Wear (One Shoulder Only)

■■ One-Sided Wear
■■ Diagonal Wear
■■ Cupping

Preventive Maintenance

20

17730-311

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
FIGURE 7-17

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.
FIGURE 7-18

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 ­misalignment such as excessive toe, drive axle misalignment,
worn, missing or damaged suspension components, bent tie rods or other chassis misalignment.
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.
If feather wear on both steer tires is in the same direction, drive axle or other chassis ­misalignment
is indicated. If one steer tire shows feather wear and the other steer tire has normal wear, a combination of toe and drive axle or chassis misalignment is indicated.
FIGURE 7-19

Rapid Shoulder Wear (One Shoulder Only) — Is defined as a tire worn on the edge of one shoulder, sometimes extending to inner ribs. It can progress to diagonal wipeout. For more information,
see TMC RP 219A publication, page 22.
This wear condition is usually caused by excessive toe or excessive camber. These conditions can
be created by a misaligned or bent axle and can also be caused by loose or worn wheel bearings.
To correct this type of rapid shoulder wear:
■■
Tires – Change direction of rotation of tire. If shoulder wear is severe, remove and retread.
■■