-62-

!

CAUTION

FAILURE TO BACK OFF THE INNER ADJUSTING
NUT COULD CAUSE BEARING AND AXLE SPINDLE
OVERHEATING OR DAMAGE, WHICH COULD RESULT
IN THE WHEEL LOCKING UP OR COMING OFF DURING
VEHICLE OPERATION AND LEAD TO AN ACCIDENT,
INJURIES OR DEATH.

!

CAUTION

FAILURE TO TORQUE THE OUTER LOCKNUT
PROPERLY COULD CAUSE THE WHEEL END TO COME
OFF DURING VEHICLE OPERATION WHICH COULD
RESULT IN AN ACCIDENT, INJURIES OR DEATH.

-63-

Hubs/Drums/Bearings

8. Install cap with the O-ring and plug installed. Rotate the hub
and check the bearing adjustment. The allowable end play is
.001"-.010".

Axle & Suspension Installation
Responsibility for proper axle alignment lies with the axle installer.
The axle must be installed so that it will be parallel to the drive
axle(s) of the tractor. This will allow good vehicle control when
cornering, longer tire wear, and it will eliminate dog tracking.
Alignment can be determined by measuring from the center of
the trailer king pin to the center of each end of the axles. The
difference should not vary by more than ¹⁄₁₆". In the case of
multiple axles, the axles must also be in line with each other. The
difference between the centers of one axle and end centers of the
other axle must not vary more than ¹⁄₈".

!

CAUTION

Safety glasses should be worn at all times when
assembling or disassembling axles and their
components.
Dexter tubular axles are made of high strength steel for better
fatigue life and superior welding qualities. The round tubular axles
provide a uniform section modulus no matter how the beam is
rotated.

Axle Installation

Brake spiders are positioned and welded to specific requirements
at our factory. Welding the spider directly to the axle beam
provides a higher strength and more reliable brake attachment
over bolt-on versions.
In welding suspension components to a Dexter trailer axle,
extreme care must be exercised to obtain correct location and
ensure the spring seat load bearing surfaces are parallel to each
other. Any welding of additional attachments to the axle should be
approved by Dexter’s engineering department.

-64-

The suspension systems incorporated into Dexter axles are
designed to provide the trailer owner three basic functions:
1. Attach the axle to the trailer
2. Dampen the effects of road shock
3. Provide stability to the trailer
All Dexter suspension systems are available in single and multiple
axle configurations.

Slipper Leaf Springs
Slipper springs have an eye formed in one end only, with the other
end formed into a reverse curve. The attachment of these springs
is as follows:
1. The front eye is attached directly into the front hanger with a
bolt and nut.
2. The rear end of the spring is captured in the rear hanger or
equalizer with a “keeper bolt” that prevents the spring from
coming out when the trailer is jacked up for service.

Front
Hanger

Spring Eye
Bolts

U-Bolt

Center
Hanger

Spring Eye
Bolts

U-Bolt
Rear
Hanger

Tie Plate

Equalizer

Tie Plate

The articulation of this suspension occurs when the rear end of
each slipper spring slides against the wear surfaces provided in
the rear hangers or equalizers. This suspension is also available in
single and multiple axle configurations.

-65-

Suspensions

Suspension Systems

Inspection and Replacement
All the components of your suspension system should be visually
inspected least every 6,000 miles for signs of excess wear,
elongation of bolt holes, and loosening of fasteners. Whenever
loose or replaced, the fasteners in your suspension system
should be torqued as detailed in the charts at the end of this book
(Fastener Torque Values).
Worn spring eye bushings, sagging springs, or broken springs
should be replaced using the following method.

!

CAUTION

Do not lift or support the trailer on any part of the axle
or suspension system. Never go under any trailer unless
it is properly supported on jack stands which have been
rated for the load. Improperly supported vehicles can
fall unexpectedly and cause serious injury or death.
1. Support the trailer with the wheels just off the ground. Follow
the trailer manufacturer’s recommendations for lifting and
supporting the unit. Do not lift or place supports on any part
of the suspension system.
2. After the unit is properly supported, place a suitable block
under the axle tube near the end to be repaired. This block
is to support the weight of the axle only so that suspension
COMPONENTS can be removed.
3. Disassemble the U-bolts, nuts, and tie plates.

Suspensions

4. Remove the spring eye bolts and remove the spring and
place on a suitable work surface.
5. If the spring eye bushings are to be replaced, press out the
old bushing using a hydraulic shop press.

-66-

CAUTION

Be sure to wear safety glasses when removing or
installing force fitted parts. Failure to comply may result
in serious injury.
6. Lubricate the rubber bushing with liquid soap (not
petroleum.) Press the new bushing into the spring eye using
a hydraulic press.
7. Reinstall repaired or replaced components in reverse order.
Note: For multiple axle units, the weight of each axle must
be supported as outlined in Step 2 before disassembly of
any component of the suspension system.
If the equalizer or equalizer bushings must be replaced, follow
the instructions above for lifting and supporting the trailer unit and
then proceed as follows:
1. With both axles blocked up, remove the spring eyebolt,
keeper bolt, and equalizer bolt from the equalizer to be
repaired or replaced.
2. Press the old rubber bushing out of the equalizer using a
hydraulic press.
3. Lubricate the replacement bushing with liquid soap and
press into the equalizer.
4. Reassemble in reverse order.

!

CAUTION

Be sure to wear safety glasses when removing or
installing force fitted parts. Failure to comply may result
in serious injury.

-67-

Suspensions

!

Suspension Replacement
1. Make sure springs are on straight. Align spring eyes to front
hanger. Insert spring eye bolts but do not torque at this
point.
2. Assemble springs into equalizer.
3. After leveling equalizer to frame, torque equalizer nuts
to values specified in Fastener Torque Specifications
(Replacement Parts/Kits section).
4. Torque spring eye bolts to values specified in Fastener
Torque Specifications (Replacement Parts/Kits section)
for rubber bushed suspension. Torque bronze bushed
suspension to snug fit only.

Torflex® Suspension

Suspensions

The Torflex® suspension system is a torsion arm type suspension
which is completely self contained within the axle tube. It attaches
directly to the trailer frame
Mounting Bracket
Axle Tube
using brackets which are
an integral part of the axle
assembly. The Torflex®
axle provides improved
Spindle
suspension characteristics
relative to leaf spring
axles, through the unique
Torsion Bar
arrangement of a steel
Torsion Arm
torsion bar surrounded by
four natural rubber cords
encased in the main structural member of the axle beam.
The spindle is attached to a lever, called the torsion arm, which
is fastened to the rubber encased bar. As load is applied, the bar
rotates causing a rolling/compressive resistance in the rubber
cords. This action provides the same functions as conventional
sprung axles with several operating advantages including
independent suspension.
Except for periodic inspection of the fasteners used to attach
the Torflex® axle to the vehicle frame, no other suspension

-68-

CAUTION
DO NOT WELD ON THE TORFLEX® BEAM. It has rubber
cords inside and the heat generated by welding could
damage the cords.

-69-

Suspensions

maintenance is required on Torflex® axles. They are, of course,
subject to the maintenance and inspection procedures regarding
brakes, hubs, bearings, seals, wheels, and tires, as outlined in this
manual.

Heavy Duty Suspension
System Axle Alignment
Alignment
For safe and efficient trailer operation, to prevent excessive tire
wear off-tracking and hard pulling, it is recommended that after a
short break-in period you have a qualified trailer mechanic check
the alignment.
To align a four (4) spring suspension, the track arms need to be
adjusted. There is one adjustable track arm (rod) on each axle;
typically on the road (left) side.
Loosen the clamp nuts at each end of the adjusting bolt so the
adjusting rod can rotate (see Figure 1). Align front axle with the
king pin or coupler and adjust rear axle parallel to the front axle.
Be sure to secure the clamps on the adjustable track arm after
alignment (see Figure 1).

Alignment Procedure (Figure 1)
Before taking axle alignment measurements, make sure the trailer
is unloaded and free the suspension of any binds by pushing the
trailer backwards and then pulling the trailer forward. While pulling
the trailer forward on a level floor, apply the brakes and release.
This will ensure that an adjustable undercarriage is in its rearmost
lock position. The trailer MUST be level from side to side as well
as from front to rear.

Suspensions

Note: Neither service nor parking brakes should be applied during
the measurement procedure.
Ensure the king pin or coupler is at the correct height. Use axle
end extenders (or remove outer wheels and any obstructions) to
achieve a straight line for measuring from king pin to the axle ends
or axle centers.
Proper tools for axle alignment inspection are:
•
•
•
•

Spring loaded kingpin extender with level or plum-bob.
Axle end extenders.
50 foot steel tape.
Optional; adjustable tram.
-70-

A means to measure axle center to axle center.
Optional; Extra adjustable track arm (rod) clamp bolts if
required.

Adjust Clamp Bolt / Nut
Tighten to 130-170 Ft. Lbs.

Adjust Clamp Bolt / Nut
Tighten to 130-170 Ft. Lbs.

Adjustable Track
Arm (Rod)

Figure 1

Measuring (Figure 2)
1. Lateral Centerline (E). Determine lateral centerline of trailer
body and axles by measuring distance E between trailer and
axle centerlines first, and correct so that distance E is ¹⁄₄" or
less for each axle.
2. Thrust Angle (A, B). Measure distances A (curbside) then
B (roadside) from the king pin or coupler to the front of the
axle extension or axle centers. These must be equal to
within 0.1 degree or ¹⁄₈" of each other (A = B ± ¹⁄₈"). Ensure
the lateral tension (pulling force) applied to the measuring
tape is the same for both A and B measurements. Use a
tensioning device scale or optical (laser) to ensure accuracy.
3. Scrub Angle (C, D). Measure distances C (curbside) then
D (roadside) between axles, measuring from front of axle
extension to front of axle extension, or axle center to center.
Adjust the rear axle so it aligns to the front axle. These also
must be equal to within ¹⁄₁₆" of each other (C = D ± ¹⁄₁₆"). This
measurement should be as close to zero as possible. The
smaller the offset, the lower the rolling resistance and the
better the fuel economy.

-71-

Suspensions

•
•

C
A

E
B
D
Figure 2

Adjusting
1. Loosen the adjustable track rod clamp bolts (Figure 1) and
turn the center rod to adjust as necessary per above.
2. After adjusting, tighten the adjustable track rod clamp nuts
(Figure 1) to proper torque. Recheck measurements and
readjust as needed.

Precautions
1. Always measure to the front axle ends for accurate
alignment.

Suspensions

2. Avoid measuring to rims, suspension brackets, hub cap,
vent holes, brake drums, etc. This can result in improper
alignment. For accurate measurements, use axle extenders.
3. Always align any succeeding axles with the front axle, not to
the kingpin or coupler.

Additional Suspension Maintenance Check
Track arms should be checked for clearance. If slack is found,
it should be repaired immediately since this indicates that there
is wear in the rubber bushing or track arm parts. Check the
adjustable track arm clamps for proper torque. Loose clamps will
-72-

Check leaf springs for broken leaves. Replace broken leaves
immediately to prevent the other leaves from being overloaded.
On taper leaf springs, be sure the plastic liner is serviceable and
on top of the spring. The liners between leaves should be in place
and serviceable.

Heavy Duty Suspension Torque Requirements

CAUTION
Before torquing equalizer bolts, level equalizers parallel
to main frame members. After initial break-in period (up
to 1,000 miles) and at least every 4 months thereafter;
all bolts and nuts should be checked to ensure
recommended torque is being maintained.

Minimum Torque Values for Bolts With
Clean Dry Threads
Torque Min
Ft. Lbs.

Torque Max
Ft. Lbs.

1¹⁄₈-7 UNC Nut
Oiled
Dry

565
765

615
815

1-8 UNC Nut

325

350

35

50

130

170

Description

Spring Keeper Nut
⁵⁄₈-18 UNF
Track Rod Clamp Nut
⁵⁄₈-18 UNF

-73-

Suspensions

cause wear on the adjusting threads and the suspension cannot
be kept in alignment. On leaf spring type suspensions, have the
trailer checked for axle alignment after two to three thousand
miles.

Wheels
Wheel Selection
Wheels are a very important and critical component of your
running gear system. When specifying or replacing your trailer
wheels it is important that the wheels, tires, and axle are properly
matched. The following characteristics are extremely important
and should be thoroughly checked when replacement wheels are
considered.
1. Bolt Circle. Many bolt circle dimensions are available and
some vary by so little that it might be possible to attach an
improper wheel that does not match the axle hub. Be sure to
match your wheel to the axle hub.
2. Capacity. Make sure that the wheels have enough
load carrying capacity and pressure rating to match the
maximum load of the tire and trailer.
3. Offset. This refers to the relationship of the center line of
the tire to the hub face of the axle. Care should be taken to
match any replacement wheel with the same offset wheel
as originally equipped. Failure to match offset can result in
reducing the load carrying capacity of your axle.
4. Rim Contour.

Wheels and Tires

!

CAUTION

Replacement tires must meet the same specifications
as the originals. Mismatched tires and rims may come
apart with explosive force and cause personal injury to
yourself or others. Mismatched tires and rims can also
blow out and cause you to lose control and have an
accident which can result in serious injury or death.

-74-

CAUTION

Do not attempt to repair or modify a wheel. Even minor
modifications can have a great effect. Do not install
a tube to correct a leak through the rim. If the rim is
cracked, the air pressure in the tube may cause the
pieces of the rim to explode with great force and can
cause serious injury or death.

Torque Requirements
It is extremely important to apply and maintain proper wheel
mounting torque on your trailer axle. Torque is a measure of
the amount of tightening applied to a fastener (nut or bolt) and
is expressed as length times force. For example, a force of 90
pounds applied at the end of a wrench one foot long will yield
90 Ft. Lbs. of torque. Torque wrenches are the best method to
assure the proper amount of torque is being applied to a fastener.

!

CAUTION

Wheel nuts or bolts must be tightened and maintained
at the proper torque levels to prevent loose wheels,
broken studs, and possible dangerous separation of
wheels from your axle, which can lead to an accident,
personal injuries or death.
Be sure to use only the fasteners matched to the cone angle
of your wheel (usually 60° or 90°.) The proper procedure for
attaching your wheels is as follows:
1. Start all bolts or nuts by hand to prevent cross threading.
2. Tighten bolts or nuts in the following sequence.
3. The tightening of the fasteners should be done in stages.
Following the recommended sequence, tighten fasteners
per wheel torque requirements diagram.

-75-

Wheels and Tires

!

4. Wheel nuts/bolts should be torqued before first road use
and after each wheel removal. Check and re-torque after
the first 50 miles and again at 100 miles. Check periodically
thereafter.

Wheel Torque Sequence
Torque
Min
Ft. Lbs.

Torque
Max
Ft. Lbs.

Description

Part No.

Application

⁵⁄₈-18 90° Cone Nut

006-109-00

Clamp Ring
033-052-01

190

210
Greased
Threads

³⁄₄-10 Hex Nut

006-117-00