alignment. 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.
Also see vehicle manufacturer’s applicable publications for other preventive maintenance
­requirements.

Towing Procedures

12

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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 chart below.
STEERTEK NXT High Capacity Greasing and Lubrication Specifications
Component

Kingpin
Bushings

Greasing Interval

Grease

Tie Rod Ends

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

Drag Link

Refer to Vehicle Manufacturer

Threaded Pin Every 3 months

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: L ubrication 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 chart 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:
a. Remove the grease zerk
b. Inspect the threaded grease zerk hole
in the tie rod end and remove any
obstructions

Dust Boot
Boot Crimp

Zerk Fitting

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 End Inspection
Inspection Procedure
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

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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 mount at full wheel
cut. The fasteners must not contact the lower shock 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 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
Ackermann 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

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.)

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.

Preventive Maintenance

16

17730-311

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
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.

1" Clamp Group Hex Bolt
Tightening Torque at
the Bolt Head
600 ± 20 ft. lbs.

5. Check for the signs of component or bolt
movement.

Figure 7-9

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.

IMPORTANT
Ensure that Clamp
Group Assembly
is properly aligned

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.

1" Axle Collar Bolt
Tightening Torque
800 ± 20 ft. lbs.

Shock Absorber Inspection
Figure 7-10

To help determine component replacement an 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. It is not necessary to replace
shock absorbers in pairs if one shock absorber requires
replacement.

Heat Test
1. Drive the vehicle at moderate speeds on rough road
for minimum of fifteen minutes.
DO NOT GRAB THE SHOCK as it could POSSIBLY 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 body below the dust
cover. Touch the frame to get an ambient reference,
see Figure 7-10. 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. Listen for the sound of metal
parts rattling inside. Rattling of metal parts can indicate that the shock has an internal failure.
4. To inspect for an internal failure, remove and shake the suspected shock. Listen for the sound
of metal parts rattling inside. Rattling of metal parts can indicate that the shock has an internal failure.

17730-311

17

Preventive Maintenance

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
Visual Inspection
Figure 7-11

Look for these potential problems when doing a visual inspection. Inspect the shock absorbers
fully extended. Replace as necessary.
SHOCK ABSORBER VISUAL INSPECTION - UNACCEPTABLE CONDITIONS

Leaking vs. Misting Shock visual inspection
The inspection must not be conducted after driving in wet weather or a vehicle wash. Shocks
needs to be free from water. Many shocks are often misdiagnosed as failures. Misting is the
process whereby very small amounts of shock fluid evaporate at a high o­ perating temperature
through the upper seal of the shock. When the “mist” reaches the cooler outside air, it condenses
and forms a film on the outside of the shock body. Misting is perfectly normal and necessary function of the shock. The fluid which evaporates through the seal area helps to lubricate and prolong
the life of the seal.
Figure 7-12

A shock 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 is fully extended, underneath the main body
(dust cover) of the shock. Look for these potential problems when doing a visual inspection. Inspect the shock
absorbers fully extended. Replace as necessary.
NOTE

The STEERTEK NXT systems are equipped with a premium seal on the shock, however this seal will allow for
misting to appear on the shock body (misting is not a
leak and is considered acceptable).
If the shock is damaged install new shock absorber as
detailed in the Component Replace­ment section of this
publication.

Preventive Maintenance

18

17730-311

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
Steering Knuckle Inspection
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".
Figure 7-13

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.

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 7-13.
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.
7. If vertical end play is greater than 0.030", or below 0.008" an adjustment of the upper knuckle
is necessary.
8. ■ If the vertical end play is greater than 0.030", add shims until the proper vertical end play
is achieved.
■■

If the vertical end play is less than 0.008", remove shims until the proper vertical end play
is achieved.

9. Retighten the kingpin draw keys to

188 ± 12 foot pounds torque.

Kingpin Bushing Inspection
Inspection Procedure (Steering knuckle lateral movement)
Figure 7-14
CHECKING UPPER KINGPIN BUSHING

17730-311

19

Figure 7-15
CHECKING LOWER KINGPIN BUSHING

Preventive Maintenance

STEERTEK NXT High Capacity Steer Axle System for Fire and Rescue Vehicles
Figure 7-16

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 7‑14.
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 7-16.
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 7-15.
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.
NOTE

If one bushing is worn or damaged, it is mandatory to replace both the top and bottom bushings
on that knuckle assembly.

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:

Preventive Maintenance

■■ Overall Fast Wear (Miles per 32nd)
■■ Feather Wear

■■ One-Sided Wear
■■ Diagonal Wear

■■ Rapid Shoulder Wear (One Shoulder Only)

■■ Cupping

20

17730-311

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

Figure 7-18

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.
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.
■■ Vehicle – Diagnose misalignment and / or mechanical condition and correct.

Figure 7-20

One-sided wear — Is excessive wear on one side of tire extending from the shoulder towards
the center of the tread. For more information, see TMC RP 219A, page 26.
One-sided wear is usually caused by improper alignment, worn kingpins, loose wheel bearings,
excessive camber, excessive axle loads, non-parallel axles, or non-uniform tire and wheel assembly caused by improper bead seating or bent wheel.
To correct one-sided wear:
■■ Tires – Depending on severity, rotate tires to another axle position or, if worn to minimum tread

depths, submit for possible retreading.