2 OBJECTIVES After studying Chapter 14, the reader will 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.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.
4 ANTIFRICTION BEARINGS PURPOSE AND FUNCTION 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.
5 ANTIFRICTION BEARINGS PURPOSE AND FUNCTION FIGURE 14–1 Rolling contact bearings include (left to right) ball, roller, needle, and tapered roller.
6 ANTIFRICTION BEARINGS PURPOSE AND FUNCTION FIGURE 14–2 Ball bearing point contact.
7 ANTIFRICTION BEARINGS BALL BEARINGS Ball bearings use hardened steel balls between the inner and outer race to reduce friction.While ball bearings cannot support the same weight as roller bearings, 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.
8 ANTIFRICTION BEARINGS BALL BEARINGS FIGURE 14–3 Radial load is the vehicle weight pressing on the wheels. The thrust load occurs as the chassis components exert a side force during cornering.
9 ANTIFRICTION BEARINGS ROLLER BEARINGS Roller bearings use rollers between the inner and outer race to reduce friction.A roller bearing having a greater (longer) contact area can support heavier loads than a ball bearing.FIGURE 14–4 Roller bearing line contact.
10 ANTIFRICTION BEARINGS TAPERED ROLLER BEARINGS The most commonly used automotive wheel bearing is the tapered roller bearing.Not only is the bearing itself tapered, but the rollers are also tapered.By design, this type of bearing can withstand radial loads (up and down) as well as axial loads (thrust) in one direction.FIGURE 14–5 A tapered roller bearing will support a radial load and an axial load in only one direction.
11 ANTIFRICTION BEARINGS TAPERED ROLLER BEARINGS FIGURE 14–6 Many tapered roller bearings use a plastic cage to retain the rollers.
12 ANTIFRICTION BEARINGS INNER AND OUTER WHEEL BEARINGS Many rearwheel-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.
13 ANTIFRICTION BEARINGS INNER AND OUTER WHEEL BEARINGS FIGURE 14–7 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.
14 ANTIFRICTION BEARINGS STANDARD BEARING SIZES Bearings use standard dimensions for inside diameter, width, and outside diameter.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.
15 ANTIFRICTION BEARINGS 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
16 ANTIFRICTION BEARINGS SEALED FRONT-WHEEL-DRIVE BEARINGS FIGURE 14–8 Sealed bearing and hub assemblies are used on the front and rear wheels of many vehicles.
17 ANTIFRICTION BEARINGS SEALED FRONT-WHEEL-DRIVE BEARINGS FIGURE 14–9 Sealed bearing and hub assemblies are serviced as a complete unit as shown. This assembly includes the wheel speed sensor.