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Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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2009Pearson
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OBJECTIVES:
After studying Chapter 73, the reader should
be able to:

•
•
•

Prepare for Suspension and Steering (A4) ASE certification
test content area “C” (Related Suspension and Steering
Service).

Discuss the various types, designs, and parts of automotive
antifriction wheel bearings.
Describe the symptoms of defective wheel bearings.

Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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OBJECTIVES:
After studying Chapter 73, the reader should
be able to:

•
•

•

Explain wheel bearing inspection procedures and causes of
spalling and brinelling.
List the installation and adjustment procedures for front
wheel bearings.
Explain how to inspect, service, and replace rear wheel
bearings and seals.

Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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2009Pearson
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KEY TERMS:
antifriction bearings • axial load

ball bearings • brinelling
cage • C-lock axle • cone • cup
dynamic seals
garter spring • GC-LB • grease • grease seal
inner ring
National Lubricating Grease Institute (NLGI)
Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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KEY TERMS:
outer ring
radial load • retainer plate-type axle • roller bearings
spalling • static seal

tapered roller bearings

Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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2009Pearson
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ANTIFRICTION BEARINGS
Bearings allow the wheels of a vehicle to rotate and still support
the weight of the entire vehicle. Antifriction bearings use rolling
parts inside the bearing to reduce friction. Four styles of rolling
contact bearings include ball, roller, needle, and tapered roller
bearings, as shown here.

Figure 73–1 Rolling contact bearings include (left to
right) ball, roller, needle, and tapered roller.

Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

Continued
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All four styles convert sliding friction into rolling motion. All of the
weight of a vehicle or load on the bearing is transferred through the
rolling part. In a ball bearing, all of the load is concentrated into
small spots where the ball contacts the inner and outer race (rings).

Figure 73–2 Ball bearing point
contact.

Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition

By James D. Halderman

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Ball Bearings Hardened steel balls between the inner and outer
race to reduce friction in ball bearings . They cannot support the
same weight as roller bearings, however, there is less friction in
ball bearings and they generally operate at higher speeds.
Ball bearings can control thrust movement of an axle shaft
because the balls ride in grooves on the inner and outer races.
The groove walls resist lateral movement of the wheel on the
spindle. The most frequent use of ball bearings is at the rear
wheels of a rear-wheel-drive vehicle with a solid rear axle.
These bearings are installed into the axle housing and are often
press fitted to the axle shaft. Many front-wheel-drive vehicles use
sealed double-row ball bearings as a complete sealed unit and are

nonserviceable except as an assembly. See Figure 73–3.
Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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Figure 73–3 Radial load is the vehicle weight pressing on the wheels. The thrust load occurs as
the chassis components exert a side force during cornering.

Continued
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Roller Bearings Rollers between the inner and outer race to
reduce friction allow roller bearings a greater (longer) contact
area that can support heavier loads than a ball bearing.

Figure 73–4
Roller bearing line contact.

A needle bearing is a type of roller bearing that uses smaller rollers
called needle rollers. The clearance between the diameter of the
ball or straight roller is manufactured into the bearing to provide
the proper radial clearance and is not adjustable.
Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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Tapered Roller Bearings
The most commonly used
automotive bearing is the
tapered roller bearing.

By design, this bearing can
withstand radial loads (up
and down) as well as axial
loads (thrust) in one
direction.
Figure 73–5 A tapered roller bearing
will support a radial load and an
axial load in only one direction.

Not only is the bearing

itself tapered, but the
rollers are also tapered.
Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
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Many non-drive-wheel bearings use tapered roller bearings. The
taper allows more weight to be handled by the bearings because the
weight is directed over the entire length of each roller rather than
concentrated on a small spot, as with ball bearings.
The rollers are held in place by a cage between the inner race
(called the inner ring or cone) and the outer race (also called the
outer ring or cup). Tapered roller bearings must be loose in the
cage to allow for heat expansion. Tapered roller bearings should

always be adjusted to allow for heat expansion.
On non-drive-axle vehicle wheels, the cup is tightly fitted to the
wheel hub and the cone is loosely fitted to the wheel spindle.
New bearings come packaged with the rollers, cage, and inner race
assembled together wrapped with moisture-resistant paper. See
Figure 73–6.
Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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Figure 73–6 Many tapered roller bearings use a plastic cage to retain the rollers.

Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition

By James D. Halderman

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Inner and Outer Wheel Bearings Many rear-wheel-drive
vehicles use an inner and an outer wheel bearing on the front
wheels.
The inner wheel bearing is always the larger bearing because it is
designed to carry most of the vehicle weight and transmit the
weight to the suspension through to the spindle.
Between the inner wheel bearing and the spindle, there is a grease
seal, which prevents grease from getting onto the braking surface
and prevents dirt and moisture from entering the bearing.
See Figure 73–7.

Continued

Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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Figure 73–7 Non-drive-wheel hub with inner and outer tapered roller bearings. By angling the
inner and outer in opposite directions, axial (thrust) loads are supported in both directions.

INNER WHEEL BEARING

SPINDLE

OUTER WHEEL BEARING

Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition

By James D. Halderman

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Standard Bearing Sizes Bearings use standard dimensions for
inside diameter, width, and outside diameter. The standardization
of bearing sizes helps interchangeability.
The dimensions that are standardized include bearing bore size
(inside diameter), bearing series (light to heavy usage), and
external dimensions. When replacing a wheel bearing, note the
original bearing brand name and number.
Replacement bearing catalogs usually have cross-over charts from
one brand to another. The bearing number is usually the same
because of the interchangeability and standardization within the
wheel bearing industry.


Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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Sealed Front-Wheel-Drive Bearings Most front-wheel-drive
(FWD) vehicles use a sealed nonadjustable front wheel bearing.
This type of bearing can include either two preloaded tapered roller
bearings or a double row ball bearing. This type of sealed bearing is
also used on the rear of many front-wheel-drive vehicles.
Double row ball bearings are often used because of their reduced
friction and greater seize resistance.
See Figures 73–8 and 73–9.

Continued

Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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Figure 73–8
Sealed bearing and hub assemblies are used on the front and rear wheels of many vehicles.

Continued
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Figure 73–9 Sealed bearing and hub assemblies are serviced as a complete unit as shown.
This assembly includes the wheel speed sensor.

Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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BEARING GREASES
Grease is an oil with a thickening agent to allow it to be installed
in places where a liquid lubricant would not stay. Greases are
named for their thickening agent, such as aluminum, barium,
calcium, lithium, or sodium

Grease Additives Commonly used additives in grease include:
Antioxidants
Antiwear agents
Rust inhibitors
Extreme pressure (EP) additives as sulfurized fatty oil or chlorine
Grease contains a dye to not only provide product identification
but to give a consistent color. A solid such as molybdenum
disulfide (moly), or graphite acts as an antiseize additive. Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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What Do Different Grease Colors Mean?
Nothing. According to grease manufacturers, grease is colored for identification,
marketing, and for consistency color reasons.
• Identification. The color is often used to distinguish one type of
grease from another within the same company. Blue grease from
one company may be totally different from the blue grease produced
or marketed by another company.
• Marketing. According to grease manufacturers, customers tend to
be attracted to a particular color of grease and associate that color
with quality.
• Consistency of color. All greases are produced in batches, and the
color of the finished product often varies in color from one batch to
another. By adding color to the grease, the color can be made
consistent.
Always use the grease recommended for the service being performed.
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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Vehicle manufacturers specify the type and consistency of grease
for each application. The tech should know what the specs mean.
NLGI Classification The National Lubricating Grease Institute
(NLGI) uses the penetration test as a guide to assign the grease a
number. Low numbers are very fluid and higher numbers are more
firm or hard. See the chart below.

See the chart on
Page 871 of your
textbook.

Continued
Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
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Grease is also classified according to quality. Wheel bearing
classifications include the following:

GA—mild duty
GB—moderate duty
GC—severe duty, high temperature
(frequent stop and go service)
GC indicates the highest quality. Chassis grease, used to lubricate
steering and suspension components, include the following:
LA—mild duty (frequent relubrication)
LB—high loads (infrequent relubrication)
LB indicates the highest quality. Most multipurpose greases are
labeled with both wheel bearing and chassis grease classifications
such as GC-LB.

Continued


Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

©©2008
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More rolling bearings are destroyed by overlubrication than
underlubrication because heat generated in bearings cannot be
transferred easily to the air through the excessive grease.
Bearings should never be filled beyond one-third to one-half of their
grease capacity by volume
Smoking Can Kill You
Some greases contain polymers such as Teflon® that turn to a deadly gas
when burned. Always wash your hands thoroughly after handling grease
that contains these ingredients before smoking. If some of the grease is on
the cigarette paper and is burned, these polymers turn into nitrofluoric acid
—a deadly toxin.


Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition
By James D. Halderman

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SEALS
Seals are used in all vehicles to keep lubricant, such as grease, from
leaking out and to prevent dirt, dust, or water from getting into the
bearing or lubricant. Two general applications of seals
are static and dynamic.
Static seals are used between two surfaces that do not move.
Dynamic seals are used to seal between two surfaces that move.
Wheel bearing seals are dynamic type seals that must seal between
rotating axle hubs and the stationary spindles or axle housing.


Continued
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