11. Raise the bottle jack until there is NO
CLEARANCE between the knuckle assembly and the bottom of the axle, slightly
lifting the axle.
12. Check the reading on the dial indicator. The
specification for vertical travel on the steering knuckle during assembly is 0.008" to 0.011".
13. If the clearance is above 0.011", loosen the socket head cap screws and push down on the
knuckle assembly until the proper vertical end play is achieved.
If the clearance is below 0.008", loosen the socket head cap screws and pull up on the
knuckle assembly until the proper vertical end play is achieved.
NOTE

The socket head cap screw comes with a pre-applied Loctite compound.
PRIOR TO INSTALLATION ENSURE THAT ALL RESIDUAL LOCTITE MATERIAL IS REMOVED FROM THE
MOUNTING BOLTS AND THE THREAD BORES IN THE UPPER STEERING KNUCKLE, AND NEW LOCTITE
277 OR EQUIVALENT IS APPLIED TO HELP ENSURE THAT THE BOLTS SUSTAIN THE PROPER TORQUE
REQUIREMENT. FAILURE TO DO SO CAN CAUSE LOSS OF VEHICLE CONTROL RESULTING IN PERSONAL
INJURY OR PROPERTY DAMAGE.

14. Remove one old socket head cap screw and replace with new socket head cap screw.
15. Remove second socket head cap screw and replace with new socket head cap screw. Tighten
both socket head cap screws to 188 ± 12 foot pounds torque.
16. Recheck the vertical end play with the dial indicator or a 0.010" feeler gauge, see Figure 9‑43.

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AIRTEK® for Tiffin Motorhome Chassis
17. Remove the brake spider bolts, they should thread out freely.
18. Remove the bottle jack and continue assembling the wheel ends.
IMPORTANT NOTE

It is critical to apply Loctite to the three brake spider bolts to ensure that these bolts sustain the
proper torque requirement of steering knuckle assembly.
19. Apply Loctite to the three brake spider bolts prior to installation into the brake spider. Tighten
bolts to 188 ± 12 foot pounds torque.
DO NOT GREASE KNUCKLES WITHOUT THE BRAKE SPIDER INSTALLED AND TIGHTENED TO PROPER
TORQUE. FAILURE TO DO SO CAN CAUSE COMPONENT DAMAGE RESULTING IN FAILURE AND LOSS OF
VEHICLE CONTROL, POSSIBLY CAUSING PERSONAL INJURY OR PROPERTY DAMAGE.

20. Install the tie rod end into the lower steering knuckle arm.
21. Tighten the castle nuts to 185 foot pounds torque then rotate the castle nut to the next
castle slot and install cotter pin.
22. Install the drag link into the steering arm and tighten to the vehicle manufacturer’s
­specifications.
23. Install new O-rings on the grease caps and lubricate O-rings with grease.
24. Install new grease caps. Note the grease caps on the STEERTEK NXT axle are threaded, tighten
to 60 ± 10 foot pounds torque. Allow 30 minutes for thread sealant to cure before greasing.
Install new grease zerk and tighten to a minimum of 15 foot pounds, see Figure 9-44.
FIGURE 9-44
Grease Zerk
Tightening Torque
minimum of 15 ft. lbs.
(20 Nm)

Grease Cap Threads
Tightening Torque
60 ± 10 ft. lbs.
(81 ± 14 Nm)
Grease Cap Threads
Tightening Torque
60 ± 10 ft. lbs.
(81 ± 14 Nm).

25. Install brakes, drums, wheels and tires.
26. Remove jack and safety stands.
27. Grease steering knuckles with the vehicle on the floor.
28. Remove the wheel chocks.

Component Replacement

54

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AIRTEK® for Tiffin Motorhome Chassis
TIE ROD END AND CROSS TUBE
NOTE

Hendrickson supplies different tie rod configurations. Prior to ordering find the part number on the
tie rod tube, refer to Hendrickson Technical Bulletin Literature No. SEU-0223 for additional information or contact Hendrickson Truck Parts (e‑mail: truckparts@hendrickson‑intl.com).

DISASSEMBLY

FIGURE 9-45

1. Chock the wheels.
2. Position the steer axle tires straight ahead.
3. Remove the cotter pin and castle nut.
4. Lightly tap the side of the Ackermann arm to
loosen the tie rod end from the Ackermann
arm, see Figure 9-45.

Lightly tap the side
of Ackermann arm to
loosen the tie rod end

5. Repeat Steps 3 and 4 to remove the other tie rod end.
6. Remove the cross tube and tie rod ends from the vehicle.
7. Mount the cross tube in a soft jaw vice.
8. Remove the hardware from the clamp on the cross tube.
9. Count the exposed threads on the tie rod end being replaced.
10. Remove the tie rod end from the cross tube.
DO NOT HEAT THE CROSS TUBE WITH A TORCH TO FACILITATE THE REMOVAL OF THE TIE ROD END. THE
USE OF SUCH HEAT CAN ADVERSELY AFFECT THE STRENGTH OF THE CROSS TUBE. A COMPONENT
DAMAGED IN THIS MANNER WILL RESULT IN LOSS OF WARRANTY, AND CAN RESULT IN THE AND LOSS
OF VEHICLE CONTROL, AND POSSIBLE PERSONAL INJURY OR PROPERTY DAMAGE.

11. If the opposing tie rod end is being replaced repeat Steps 8 through 10.
12. Inspect the cross tube for dents, cracks, or thread damage. Replace the cross tube if needed.

ASSEMBLY
1. Lubricate the new tie rod end threads with Anti-Seize.
NOTE

When installing the cross tube the thread direction of the tie rod ends are as follows:
■ A right hand threaded tie rod end will be installed into the right side Ackermann arm.
■ A left hand threaded tie rod end will be installed into the left side Ackermann arm.
2. Install the new tie rod end into the cross tube, leaving the same amount of threads exposed
that were counted on the failed tie rod end prior to removal.
THE THREADED PORTION OF THE TIE ROD END MUST EXTEND PAST THE SLOTS INTO THE TIE ROD
CROSS TUBE, SEE FIGURE 9-46. FAILURE TO DO SO CAN CAUSE COMPONENT DAMAGE, LOSS OF
VEHICLE CONTROL AND POSSIBLE PERSONAL INJURY OR PROPERTY DAMAGE.
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.

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Component Replacement

AIRTEK® for Tiffin Motorhome Chassis
FIGURE 9-46
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. (92 ± 9 Nm)

3. Replace the opposing tie rod end if necessary by repeating Steps 1 and 2.
DO NOT HEAT THE CROSS TUBE WITH A TORCH TO ROTATE THE CROSS TUBE IN THE TIE ROD END.THE USE
OF SUCH HEAT CAN ADVERSELY AFFECT THE STRENGTH OF THE CROSS TUBE. A COMPONENT DAMAGED
IN THIS MANNER WILL RESULT IN LOSS OF WARRANTY, AND CAN RESULT IN THE LOSS OF VEHICLE
CONTROL, AND POSSIBLE LOWER STEERING KNUCKLE PERSONAL INJURY OR PROPERTY DAMAGE.

4. If replacing opposing tie rod end is not necessary it is critical that the cross tube will rotate in
the opposing tie rod end.
5. Install the cross tube into the Ackermann arms.
6. Tighten the castle nuts to 185 foot pounds torque then rotate the castle nut to the next
castle slot and install cotter pin.
7. Grease tie rod ends. See Lubrication Chart for required lubricant in the Preventive Maintenance
Section of this publication.
8. Set the toe, see Toe Adjustment Procedure in the Alignment & Adjustments Section of this
publication.
9. Remove the wheel chocks.

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AIRTEK® for Tiffin Motorhome Chassis
SECTION 10

Front Wheel Alignment Specifications
AIRTEK FOR TIFFIN MOTORHOME CHASSIS
FRONT AIR MODULE SUSPENSION ALIGNMENT SPECIFICATION
CAMBER1

RANGE

DESIGN SPECIFICATION

MINIMUM

MAXIMUM

LEFT

0.00º ± 1.0º

-1.0º

+1.0º

RIGHT

- 0.25º ± 1.0º

-1.25º

+0.75º

CROSS

Max 2.0º

—

—

CAMBER NOTES:
1

The camber angle is not adjustable. Do not bend axle or otherwise try to adjust camber. If found out of ­specification, notify
Hendrickson Tech Services for further information.

CASTER1,2

RANGE

DESIGN SPECIFICATION

MINIMUM

MAXIMUM

LEFT

5º ± 1º

+4º

+6º

RIGHT

5º ± 1º

+4º

+6º

Max 1.0º

—

—

CROSS3
CASTER NOTES:
1

Caster is determined with the vehicle at specified ride height for air suspension or at rated load for mechanical suspension systems.
It is critical that the vehicle front and rear ride height is within specifications prior to performing a caster measurement or adjustment.
Refer to vehicle manufacturer’s ride height ­specifications and procedure.

2

In most cases actual vehicle caster is defined with the frame rails at zero slope. Refer to the vehicle manufacturer’s specifications
for correct frame rail slope. (Both the alignment surface and the vehicle’s frame rails should be level during execution of alignment
procedures). For vehicles with a positive frame rake (higher in rear) add the frame slope (in degrees) to the caster reading to
determine true vehicle caster.

3

The cross caster angle is not adjustable – Do not bend axle or otherwise try to adjust cross caster. If found out of specifications
notify Hendrickson Tech Services for further information. Changes to caster can be attained by using caster shims as p­ rovided by
the vehicle manufacturer or chassis and body manufacturer. Caster shims must match, side to side, to reduce uneven loading to the
suspension components. The use of two different angle caster shims will not correct cross caster.

4

Example of caster adjustment: 2.5º RH / 3º left hand, would require one, 1.0 shim on each side to increase caster and achieve
3.5° RH / 4.0° left hand, which is in specification. Do not attempt to use uneven shims.

Hendrickson recommends following TMC2 practices:

RANGE

DESIGN SPECIFICATION¹
TOTAL TOE2

1/16"

± 1/32" (0.06" ± 0.03")

MINIMUM

MAXIMUM

1/32"

3/32"

(0.03")

(0.09")

TOE-IN NOTES:
1

Toe-in is to be set and adjusted in the normal vehicle unladed configuration. Actual vehicle curb weight on the ground. Toe should be
checked at the tires front and rear tread center, at a distance above ground equal to the tire’s rolling radius.

2

In most instances total toe is set by the vehicle manufacturer or body builder. Consult the vehicle manufacturer for specifications.

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AIRTEK® for Tiffin Motorhome Chassis
SECTION 11

Troubleshooting Guide
AIRTEK with STEERTEK NXT Axle for Tiffin Motorhome Chassis
TROUBLESHOOTING GUIDE
CONDITION

Worn or damaged kingpins
and kingpin bushings

Vibration or shimmy of front
axle during operation

Excessive wear on tires or
uneven tire tread wear

Vehicle is hard to steer

Tie rod ends are worn and
require replacement

Troubleshooting Guide

POSSIBLE CAUSE

CORRECTION

Dirt in system– contaminated lubricant

Polish and inspect kingpin, replace bushing and seals,
then follow specified lubrication procedures

Incorrect lubricant

Lubricate axle with specified lubricant

Axle not lubricated at scheduled frequency

Lubricant axle at scheduled frequency

Incorrect lubrication procedures

Use correct lubrication procedures

Lubrication interval not compatible with
operating conditions

Change lubrication interval to match operating
conditions

Worn or missing seals

Replace worn or missing seals

Caster out of specification

Set proper ride height then adjust caster to specification

Wheels and / or tires out of balance

Balance or replace wheels and / or tires

Worn shock absorbers

Replace shock absorbers

Broken engine mount

Replace engine mount

Wheel bearing adjustment

Adjust wheel bearing to the vehicle manufacturers
specifications.

Tires have incorrect air pressure

Adjust tire pressure to manufacturer’s specification.

Tires out of balance

Balance or replace tires

Incorrect tandem axle alignment

Align tandem axles

Incorrect toe setting

Adjust toe-in to manufacturer’s specification

Incorrect steering arm geometry

Repair steering system as necessary

Worn kingpin bushings

Replace kingpin bushings

Excessive wheel bearing end play

Check specified wheel nut torque, replace worn or
damaged wheel bearings

Wheel bearing adjustment

Adjust wheel bearing to the vehicle manufacturers
specifications.

Low pressure in the power steering system

Repair power steering system

Steering linkage needs lubrication

Lubricate steering linkage

Steering knuckles are binding

Check vertical clearance

Incorrect steering arm geometry

Repair steering system as necessary

Caster out of specification

Set proper ride height per the vehicle manufacturer’s
instructions,then adjust caster to specification

Tie rod ends hard to move

Replace tie rod ends

Worn thrust bearing

Replace thrust bearing

Steering gear box internal problem

Perform steering gear trouble shooting procedures per
steering gear manufacturing guidelines.

Tie rod ends need lubrication

Lubricate tie rod end. Make sure lubrication schedule is
followed.

Severe operating conditions

Increase frequency of inspection and lubrication
intervals

Damaged boot on tie rod end

Replace tie rod end

58

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AIRTEK® for Tiffin Motorhome Chassis

AIRTEK with STEERTEK NXT Axle for Tiffin Motorhome Chassis
TROUBLESHOOTING GUIDE
CONDITION
Bent or broken tie rod cross
tube, tie rod end ball stud or
tie rod end
NOTE:
Damaged components
require replacement

Worn or broken steering ball
stud

Suspension has harsh or
bumpy ride

Restricted steering radius

Vehicle leans

Vehicle wanders

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POSSIBLE CAUSE

CORRECTION

Pump / gear relief valve pressure setting exceeds
system specifications

Adjust power steering system to manufacturer’s
specified pressure

Steering gear poppets improperly set or
malfunctioning

Check for proper operation or adjust poppets to OEM
specifications

Axle stops improperly set

Set axle stops to OEM specifications

Severe duty cycle service

Increase frequency of inspection and lubrication
intervals