Unit II Wheel Bearings and Seal Service f2012 student notes (1).pptx

Unit II Wheel Bearings and Seal Service

Wheel Bearing and Seal Service Objectives

• Discuss the various types, designs of automotive antifriction bearings

• Describe the symptoms of defective wheel bearings • Explain wheel bearing inspection procedures and causes of

bearing failure• List the installation and adjustment procedures for both front

and rear wheel bearings• Explain how to inspect, service and replace rear wheel

bearings and seals

Wheel Bearings and Seal Service• Function of the wheel bearing is to support a

moving load with a minimum amount of friction

• Bearings allow the wheels to rotate while supporting the weight of the entire vehicle

Wheel Bearing Loading

• Axial loading is when the load is parallel to the shaft that supports the bearing(side to side)

• Radial loading is when the load is perpendicular to the shaft(up and down)

• Combination loading uses both axial and radial loading

Bearing Types

• Friction- have no moving parts, components slide past each other (ex. Engine bearing, pilot bushings)

• Anti –Friction- allow for movement between components with reduced friction, components are supported by either ball, roller or needle bearings

Bearing Types

Anti Friction Bearing Types

Anti Friction Bearing Types

• Ball bearings- used on drive ales, can support both axle and radial loads, low friction and high speed use

• Straight roller-used on rear axles or rear wheel drive cars ( C-lock style), support radial loads only, no axial load support

• Spherical Roller- used on front drive axles, supports radial and axial loads

Anti Friction Bearing Types

• Tapered Roller- most commonly used wheel and axle bearing, usually used on non drive axles can support radial and axial loads well

• Needle bearing- used on u-joints and transmissions, can support axial loads or radial loads but not both in one application

Ball Bearing

• Little friction• Axial load capabilities• Limited radial load

capabilities

Tapered Roller Bearing

• Limited use on front wheel drive vehicles

• Widely used on rear wheel drive front bearing hubs

Tapered Roller Bearing

Straight Roller Bearing

• Increased friction• Radial load

capabilities• No axial load

capabilities

Straight Roller Bearing

Spherical Roller Bearing

• Located on drive axle• Radial load

capabilities• Moderate axial loads

Needle Bearings

• Used in transmissions and U-joints

• Radial load capabilities

• No axial load capabilities

Needle Thrust Bearing

• Axial load capabilities• No radial load

capabilities

Nomenclature

Nomenclature

Bearing Service

• Types of Failure:– 1. Spalling or Indentations – hardened metal

surface flakes off. Causes: – dirt, heat, overloading, lack of lube, metal fatigue, incorrect hardness

Bearing Service

• 1. Brinelling – lines or indentations in the races that match the rollers. Causes: - extreme load, vibration, lack of movement

Bearing Service

• 3. Smearing – damage to inner or outer races caused by spinning of the race or contaminants between the race and spindle or hub

• 4. Galling – damage to the end of the rollers, similar to spalling but more severe. Caused by overloading or lack of lubrication, dirt.

Bearing Service

• 5. Stains or discoloration- not usually a problem unless the bearing is blue from heat

• 6. Cage damage- usually caused during servicing

• 7. Normal wear- dull grayish color

Bearing Wear Patterns

Bearing Wear Patterns

Bearing Wear Patterns

Bearing Wear Patterns

Bearing Failure Diagnosis

• 1. Noise – growling, humming– A. Tires (noise changes with road surface)– B. Bearings (noise remains constant over different road

surfaces)• 2. Vibration– A. Tires (speed dependent)– B. Bearings (loose wheel bearings can cause brake

pulsation and steering wheel roughness) – C. Driveline (speed and load dependent)

Bearing Failure Diagnosis

• 3. Locate growl either front or rear– May need to raise front or rear axles to isolate

• 4. Determine left or right side of vehicle, inner or outer wheel bearing by making gentle turns to the right or left– Putting load to one side while turning (outside

bearing will make the most noise)

Servicing (repacking)

• 1. When– A. Every 2 years or 24,000 miles– B. Brake job– C. Wheel alignment

• 2. Disassemble and Cleaning– A. Clean in clean solvent– B. Air dry– C. Clean again– D. Air dry again– E. Inspect for defects as discussed

• NOTE: Do NOT Air Spin!

Adjustment of Tapered Roller Bearings

• 1. If equipped with a castle nut (GM)– A. While rotating the hub, tighten the spindle nut

to 20 ft/lbs– B. Back off the nut ½ turn– C. Finger tighten to set end play (.001”-.005”)– D. Install cotter pin and recheck end play

Adjustment of Tapered Roller Bearings

• 2. If equipped with a hex nut and lock cover (Ford & Chrysler)– A. While rotating the hub, torque the spindle nut

to 20 ft/lbs– B. Back of spindle nut ½ turn– C. Finger tighten nut to 10-15 in/lbs– D. Install lock cover and cotter pin

Seal Service

• Function: keep the lubricant in and the dirt out

• Types:– A. O-ring– B. Lip type

Seal Service

• Installation– A. O-ring seals use distortion of the seal to keep

the lubricant in and dirt out– B. Replacement o-rings must match od, id, and

width to form a correct seal– C. Lubricate before installation– D. Lip seals must have the lip of the seal facing

the lubricant

Seal Service

– E. Must match od, id and width– F. Use correct installation technique– G. Lubricate properly

Axial Bearing Seals

Wheel Bearing Seals

Wheel Bearing Seals