System Mfgr’s Directions

Brakes Out of
Adjustment

Adjust Brakes

Air Lines
Kinked or Broken

Replace

Slack Adjuster
Broken

Repair or Replace

Air Chamber
Malfunction

Replace

Brakes Out of
Adjustment

Adjust

Excessive Drum Wear

Replace Drums

Excessive Lining Wear

Replace Linings

Oil Soaked Linings

Replace Linings

Overloaded Trailers

Use Proper Load

Air System Malfunction

Troubleshoot per
System Mfgr’s Directions

Wrong Size
Air Chamber

Use Correct Size Air
Chamber for Application

Worn Anchor Pin
Bushings or
Camshaft Bushings

Replace Bushings

Braking Systems - Air

Troubleshooting

Weak Brakes

Brake Adjustment
Not Correct

Adjust

Oil on Linings

Replace Linings

Wrong Brake
Component

Use Only Approved
Dexter Components

Harsh Brakes

-53-

Airtrbl.eps
9/19/95

Troubleshooting
SYMPTOM

Brake Lock-Up

CAUSES

REMEDIES

Cams Froze in
Park Position

Replace Camshaft
Bushings

Wrong Size
Air Chamber

Use Correct Size
Air Chamber

Incorrect Slack
Adjuster Length
Air System Timing
Malfunction

- Too Low Relay Valve
Crack Pressure
- Quick Release Valve
Malfunction

S-Cam Flipped Due to
Brake Lining Wear
Broken Return
Springs

Use Correct Length
Slack Adjuster
Troubleshoot
per
System Mfgr’s
Directions
Replace Linings,
Adjust
Determine Cause of
Breakage and Replace

Grease or Oil
on Linings

Replace Linings

Out of Round
or Cracked Drums

Turn or Replace
Drums

Linings Dragging Due to
Weak or Broken
Return Spring

Replace
Return Springs

Wrong Component in
Brake

Use Only Dexter
Approved COmponents

Bearing Adjustment

Re-adjust

Air System Malfunction
Sticky Valves, Dirt, etc.

Troubleshoot per
System Mfgr’s Directions

Improper Mounting of
Air Chamber and
Slack Adjuster

Mount per
Recommended
Procedure

Camshaft or Shoes
Frozen

Replace Bushing

Surging Brakes

Braking Systems - Air

Overheating Brakes

Airtrbl.e
9/19/9

-54-

Hub Removal
Whenever the hub equipment on your axle must be removed for
inspection or maintenance the following procedure should be
utilized.
1. Elevate and support the trailer unit per manufacturers’
instructions.

!

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.
2. Remove the wheel(s).
3. Remove the grease or oil cap by unscrewing it
counterclockwise while holding the hub stationary.
4. Bend the locking tang down from the outer spindle nut and
remove spindle nut.
5. Remove the tang washer and unscrew the inner spindle nut
(counterclockwise) and remove the spindle washer.
6. Remove the hub from the spindle, being careful not to allow
the outer bearing cone to fall out. The inner bearing cone
will be retained by the seal.
Note: A gear puller may be necessary to remove hub from
spindle.

Brake Drum Inspection
There are two areas of the brake drum that are subject to wear
and require periodic inspection. These areas are the drum surface
where the brake shoes make contact during stopping and the
armature surface where the magnet contacts (only in electric
brakes).
-55-

Hubs/Drums/Bearings

Hubs/Drums/Bearings

The drum surface should be inspected for excessive wear or
heavy scoring. If worn more than .020" oversized, or the drum
has worn out of round by more than .015", then the drum surface
should be re-machined. If scoring or other wear is greater than
.090" on the diameter, the drum must be replaced. When turning
the drum surface, the maximum rebore diameter for a 12¹⁄₄" brake
drum is 12.340".
For electric brakes only, the machined inner surface of the brake
drum that contacts the brake magnet is called the armature
surface. If the armature surface is scored or worn unevenly, it
should be refaced to a 120 micro inch finish by removing not
more than .030" of material. To ensure proper contact between
the armature face and the magnet face, the magnets should
be replaced whenever the armature surface is refaced and the
armature surface should be refaced whenever the magnets are
replaced.
Note: It is important to protect the wheel bearing bores from
metallic chips and contamination which result from drum turning or
armature refacing operations. Make certain that the wheel bearing
cavities are clean and free of contamination before reinstalling
bearing and seals. The presence of these contaminants will cause
premature wheel bearing failure.

Hubs/Drums/Bearings

Bearing Inspection
Wash all grease and oil from the bearing cone using a suitable
solvent. Dry the bearing with a clean, lint-free cloth and inspect
each roller completely. If any pitting, spalling, or corrosion is
present, then the bearing must be replaced. The bearing cup
inside the hub must be inspected.
IMPORTANT: Bearings must always be replaced in sets of a cone
and a cup.

!

CAUTION

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

-56-

1. Place the hub on a flat work surface with the cup to be
replaced on the bottom side.
2. Using a brass drift punch,
carefully tap around the
small diameter end of the
cup to drive out.
3. After cleaning the hub
bore area, replace the
cup by tapping in with
the brass drift punch. Be
sure the cup is seated all
the way up against the
retaining shoulder in the
hub.
Replace only with bearings as specified in the Bearing
Replacement Chart.

Bearing Lubrication - Grease

CAUTION
Do not mix Lithium, calcium, sodium or barium complex
greases due to possible compatibility problems.
When changing from one type of grease to another,
it is necessary to ensure all the old grease has been
removed.
Grease should be replaced every 12,000 miles or 12 months. Prior
to repacking bearings, all old grease should be removed from the
wheel hub cavity and bearings. Bearings should be packed by
machine if possible. If a machine is unavailable, packing by hand
method is acceptable. The method to pack bearing cones is as
follows:
1. Place a quantity of grease onto the palm of your hand.

-57-

Hubs/Drums/Bearings

When replacing the bearing cup proceed as follows:

2. Press a section of the widest end of bearing into the outer
edge of the grease pile closest to the thumb forcing grease
into the interior of the bearing
between two adjacent rollers.
3. Repeat this while rotating the
bearing from roller to roller.
4. Continue this process until you
have the entire bearing completely
filled with grease.
5. Before reinstalling, apply a light
coat of grease onto the bearing
cup mating surface.

Bearing Lubrication - Oil

Hubs/Drums/Bearings

If your axles are equipped with oil lubricated hubs, then your
lubrication procedure is to periodically fill the hub with a high
quality hypoid gear oil to the level indicated on the clear plastic oil
cap. The oil can be filled through the rubber plug hole in the cap.
Oil should be replaced every 12 months or 12,000 miles.

-58-

Grease
Thickener Type
Dropping Point
Consistency
Additives
Viscosity Index

Lithium Complex
215°C (419°F) Minimum
NLGI No. 2
EP, Corrosion & Oxidation Inhibitors
80 Minimum

Approved Grease Sources
Chem Arrow
Chevron Texaco
Citgo

ConocoPhillips/
76 Lubricants/Kendall
Dexter Company
Exxon/Mobil Company

Fuchs
Great Plains Lubricants
Oil Center Research
of Oklahoma
Pennzoil-Quaker State
Company
Royal Mfg. Company
Shell

Valvoline

Arrow 2282
Chevron Ulti-Plex Grease EP #2
Texaco Starplex Moly MPGM #2
Lithoplex MP #2
Lithoplex CM #2
Mystik JT-6 Hi-Temp Grease #2
Multiplex RED #2
L427 Super Blu Grease
Lithoplex Red MP #2
Ronex, MP
Mobilith AW 2
Mobil I Synthetic Grease
Renolit Uniwrl 2
Lithium Complex EP #2
Liquid-O-Ring No, 167L
Synthetic Red Grease
Royal 98 Lithium Complex EP #2
Gadus S3 V220C
Gadus S5 V220
Rotella Heavy Duty Lithium
Complex #2
Valvoline Multi-Purpose GM
Valvoline Durablend

-59-

Hubs/Drums/Bearings

Recommended Wheel Bearing
Lubrication Specifications

Oil
SAE 90, SAE 80W-90, SAE 75W-90

Approved Oil Sources
Ashland Oil
CITGO Petroleum Co.

Conoco
Exxon Company USA
Industrial Oils Unlimited
Kendall Refining Co.
Lubriplate Division/
Fiske Brothers Refining
MFA Oil Company
Mobil Oil Corporation
Phillips 66 Petroleum

Hubs/Drums/Bearings

Pennzoil Products Co.

Oil Center Research
Sun Refining and
Marketing Company
Shell Oil Company

Texaco Oil Company
Troco Division/
Royal Manufacturing
Union Oil Company

Valvoline Dura Blend
Valvoline Power Lube
CITGO Premium Gear Oil MP
Mystik JT-7
Mystik Power Lube
Universal Gear Lubricant 80W-90
Gear Oil GX 80W-90
Super MP Gear Oil 80W-90
Kendall NS-MP Hypoid Gear Lube
Lubriplate APG 90
Multi-Purpose Gear Oil 80W-90
Mobilube SHC
Mobil 1 Synthetic Gear Lube
Superior Multi-Purpose Gear Oil
Philguard Gear Oil
Philsyn Gear Oil
Gear Plus 80W-90 GL-5
Gear Plus Super 75W-90
Gear Plus Super EW 80W-90
Multi-Purpose 4092 Gear Lube
Liquid-O-Ring 750 GX
Sonoco Ultra
Sonoco Dura Gear
Spirax A
Spirax G
Spirax HD
Spirax S
Multigear EP
Multigear SS
Multigear Select Gear Oil
Unocal MP Gear Lube
76 Triton Syn Lube EP
-60-

Whenever the hub is removed,
inspect the seal to assure that it
is not nicked or torn and is still
capable of properly sealing the
bearing cavity. If there is any
question of condition, replace the
seal. Use only the seals specified
in the Seal Replacement Chart.

Bad Seal: Nicks and Tears
(REPLACE SEAL)

To replace the seal:
1. Pry the seal out of the hub with a seal removal tool or a
screwdriver. Never drive the seal out with the inner bearing
as you may damage the bearing.

2. Apply a sealant similar to PERMATEX® High-Temp Red
RTV Silicone Gasket to the outside of the seal. Use only
enough to provide a thin coat to prevent any excess from
contaminating the rubber lip(s) of the seal. It is okay to apply
a slight amount of lube to the inner rubber lip(s) to aid with
installing onto the spindle.
Note: No sealant should be used if the outside of the seal is
rubber coated. For these type of seals it is recommended to
apply a thin coat of oil to the outside rubber.
3. Clean the seal journal of the spindle to inspect for nicks or
roughness. Use a file to remove any burrs from the leading
edge or shoulder area. Clean the journal area with very fine
emery cloth. Any presence of deep gouges or scratches in
this area may cause seal failure allowing lubricant to leak
out of the hub.
4, Clean the seal bore in the hub and inspect for any nicks,
gouges, or scratches that may prevent the seal from
retaining the bearing lubricant inside the hub.
5. Orient the seal properly. Many oil bath seals will be marked
AIR SIDE on the side of the seal to facing out of the hub
after installation.
6. Install new seal into place using a seal driver or seal
installation tool of proper size. It is important that any seal

-61-

Hubs/Drums/Bearings

Seal Inspection and Replacement

installation tool contact the outer ring of the seal casing. If
no seal driver is available, use a clean block of wood. It is
critical that the seal be driven in evenly and straight. NEVER
hammer directly on the seal.
7. The seals will be pressed flush to the back surface of the
hub in the 9K-10K General Duty axle product line. The seals
in the 10K through 15K axles need to be installed so that
the airside face of the seal is approximately ¹¹⁄₁₆" from the
inner bearing cone. It is NEVER necessary to bottom out the
seal for proper installation. Driving the seal in too deep may
damage the seal and may come in contact with the inner
bearing preventing it from rotating freely.
8. Proper installation will maintain the seal flatness in the hub
within .010”. A seal that is cocked too much inside the hub
will be more likely to leak.

Installation/Adjustment
For ABS installation:
1. Assure that the ABS sensor is pushed fully into its retainer
clip (sensor tip is as far outboard as possible).

Hubs/Drums/Bearings

2. Install hub and drum squarely to the spindle centerline so
that the exciter ring inside the drum will contact the sensor
tip and push it back to the proper sensor to exciter ring
running clearance (gap should not exceed ¹⁄₁₆" inch).
For non-ABS installation, begin with step 3:
3. Install the bearing and washer into the hub. Thread on the
inner nut, rotate the hub and tighten the nut to 100 Ft. Lbs.
of torque.
4. Loosen the nut to remove preload torque, do not rotate hub.
5. Hand tighten the nut, then back it off ¼ to ³⁄₈ turn.
6. Place the tang washer on the spindle and bend two tangs
inward over the nut. This will keep the inner nut from turning
while torque is applied to the outer nut.
7. Install the outer nut and torque it to 100-175 Ft. Lbs. Ensure
that the inner nut does not turn. Bend two tangs from the
tang washer over the outer nut flats to secure.