Modern Automotive Technology PowerPoint for by Russell Krick Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois

Chapter 66 Tire, Wheel, and Wheel Bearing Service

Contents Tire, wheel, and wheel bearing diagnosis (8 Topics) Tire, wheel, and wheel bearing diagnosis Wheel cover removal and installation Tire maintenance Measuring tire and wheel runout

Contents Wheel balance Mounting and dismounting tires Tire puncture repair Wheel bearing service

Tire, Wheel, and Wheel Bearing Diagnosis Problems usually show up as vibrations, abnormal tread wear patterns, steering wheel pull, abnormal noises, and other symptoms

Diagnosing Tire Problems Inspect the tires for problems Check both sidewalls and the tread area If necessary, road test the vehicle to verify the customer complaint Make sure the symptoms are not being caused by steering, suspension, or front wheel alignment problems

Wiggle the tire to check for dry, rough, or loose wheel bearings Inspecting the Tires Wiggle the tire to check for dry, rough, or loose wheel bearings

Typical damage found on used tires Tire Impact Damage Typical damage found on used tires

Tire Wear Patterns

Tire Inflation Problems Correct tire inflation is important to the service life of a tire assures the full tire tread contacts the road Underinflation wears the outer edges of the tread sidewalls flex, building up heat Overinflation wears the center of the tread produces a rough ride

Tire Inflation Pressure

Tire Vibration Problems When one of the front tires is vibrating, it may be felt in the steering wheel When one of the rear tires is vibrating, it will be felt in the center and rear of the car

Causes of Tire Vibration

Tire Noise “Thumping” sound caused by ply separation “Whine” due to abnormal tread wear When these noises occur, inspect the tire for an out-of-round condition or tread cupping these conditions require replacement

Wheel Bearing Noise Produced by a dry, worn wheel bearing When balls or rollers are damaged from lack of lubrication, they may emit a humming or growling sound Checking the bearings: raise the vehicle on a lift rotate the tire by hand feel and listen for bearing roughness wiggle the tire to check for looseness

Removal and Installation Wheel Cover Removal and Installation

Pry between the wheel and cover at four alternating points Wheel Cover Removal Pry between the wheel and cover at four alternating points

Wheel Cover Installation Hold the wheel cover in place with the valve stem sticking through the cover

Tire Maintenance Maintenance procedures include periodic inspection, inflation pressure checks, and tire rotation These maintenance steps help ensure safety and longer tire life

Checking Tire Inflation Pressure Remove the valve stem cap Press the tire gauge squarely over the stem Compare the reading to the maximum pressure printed on the tire sidewall or in the operator’s manual Adjust the pressure as necessary Reinstall the cap

Tire Service Tools

Rotating Tires Ensures maximum tire life The front and rear tires wear differently Rotation helps even out tire wear Tires are rotated at specific intervals, such as every 3000 miles (5000 km)

Tire Rotation Patterns

Torquing Lug Nuts Torque is very important, especially on vehicles with mag wheels and lightweight hubs Overtorquing can cause wheel and hub distortion, or brake pulsation Undertorquing might allow the lug nuts to loosen and the wheel to fall off

Torque the nuts to specifications in a crisscross pattern Torquing Lug Nuts Torque the nuts to specifications in a crisscross pattern

Replacing Lug Studs Lug studs can become stripped or worn Force out the old stud with a pressing tool To install new studs, use flat washers and a lug nut Draw the new stud into place by tightening the nut on the washers If the hub is removed from the vehicle, a hydraulic press can be used

Measuring Tire and Wheel Runout Tire runout Wheel runout caused by ply separation or manufacturing defect Wheel runout caused by impact damage or incorrect welding of the spider and rim

Lateral Runout Side-to-side movement of a wheel or tire Maximum for a tire 0.090" (2.0 mm) Maximum for a wheel 0.045" (1.0 mm)

Measuring Lateral Runout Mount a dial indicator with the stem against the sidewall and side of the rim. Check the reading at several points.

Radial Runout Difference in radius from the center axis of rotation (out or round) Maximum for a tire 0.060" (1.5 mm) Maximum for a wheel 0.035" (0.9 mm)

Measuring Radial Runout Mount a dial indicator with the stem against the tread and the lip of the rim. Check the reading at several points.

Wheel Balance Improper wheel balance is a common cause of tire and steering wheel vibration When one side of a tire is heavier than the other, centrifugal force tries to throw the heavy side outward when the tire is rotating

Caused by a heavy spot located in the center of the tire tread Static Imbalance Caused by a heavy spot located in the center of the tire tread

The heavy spot is to one side of the tread or on the sidewall Dynamic Imbalance The heavy spot is to one side of the tread or on the sidewall

Wheel Balancing Wheels are balanced by adding wheel weights Most weights are press-fit onto the wheel Weights for some mag wheels stick onto the wheel with an adhesive backing

Weights are often kept on the balancing machine Wheel Balancing Weights are often kept on the balancing machine

Wheel Balancing Static balancing Dynamic balancing add weights opposite the heavy area of the wheel if a large amount is needed, add half to the inside and half to the outside of the wheel Dynamic balancing add weights exactly where needed the dynamic balancing machine will indicate where weight must be added

Wheel Balancing

On-Car Balancing Follow the equipment operating instructions Wear eye protection Remove rocks and debris from the tread Place the vehicle on a jack stand When using the engine to spin the drive wheels, do not exceed 35 mph (40 to 56 km/h) when one wheel is on the floor, the free wheel will turn at twice the indicated speed

With a limited-slip differential, raise both rear wheels off the floor On-Car Balancing With a limited-slip differential, raise both rear wheels off the floor

Wheel Balancers A wheel balancing machine is used to determine which part of a wheel assembly is heavy Bubble balancer static balance Off-car balancer static or dynamic balance On-car balancer

The wheel and tire assembly is mounted Bubble Balancer The wheel and tire assembly is mounted on the machine

Add weights until the bubble is centered Bubble Balancer Add weights until the bubble is centered

Off-Car Balancer The wheel and tire assembly is mounted on the machine and rotated The machine will indicate where weights should be added After adding weights, spin the tire again to check for vibration

Off-Car Balancer

On-Car Balancer Provides an electric motor to spin the wheel and tire assembly An electronic pickup or hand-operated device is used to determine where weights are needed Balances the wheel cover, brake disc, and lug nuts along with the tire and wheel

Mounting and Dismounting Tires A tire changing machine is used to force the tire on and off the wheel prevents tire or rim damage reduces the labor required

Power head turns the bar to force the beads over the rim Tire Changing Machine Power head turns the bar to force the beads over the rim

Applies tremendous force to stretch the tire bead on and off the wheel Tire Changing Machine Applies tremendous force to stretch the tire bead on and off the wheel

Safe Work Practices Wear eye protection Keep your fingers out of the way Never mount a tire on a rim that is not smooth and clean Always lubricate the bead and wheel flange with the proper lubricant Only inflate a tire on the machine, or in a safety cage as recommended

Safe Work Practices Stand away from the tire when adding air; a loud “pop” sound will indicate when the beads seat Do not exceed 40–50 psi (276–345 kPa) when initially inflating a tire After inflation, install the core and reduce the tire pressure to the recommended limits

Automated Tire Changer Uses a rubber wheel to force the bead back over the wheel

Tire Puncture Repair Repairs must be made carefully Improper repair could result in a tire failure and an accident

Finding a Leak Inflate the tire with air Place the tire in a drum of water, or wet the tire with a water hose Look for air bubbles forming on the tire or around the bead at the rim Bubbles indicate leakage Mark the leak with a crayon or chalk

Repairing a Leak Remove the tire from the rim Inspect the inside of the tire carefully Fill the injury using a recommended plug or liquid sealant Select a patch that extends well beyond the damaged area

Repairing a Leak Scuff the area that the patch will cover Apply the proper cement to the inner liner Remove the covering from the adhesive side of the patch and carefully place it on the inner liner

Use a stitcher tool to bond the patch to the inner liner Repairing a Leak Use a stitcher tool to bond the patch to the inner liner

Tire Repair Practices Always dismount the tire and patch the inner liner Never repair sidewalls or tires with punctures larger than 1/2" (13 mm) When removing an object from the tire, reduce the air pressure to 15 psi (103 kPa) or lower Broken strands in steel belts indicate serious damage and could puncture the patch

Wheel Bearing Service Wheel bearings are normally filled with grease If the grease dries out, the bearing will fail Some bearings are serviceable Some bearings are sealed units

Nondriving Wheel Bearing Assembly

Wheel Bearing Removal (Nondriving Wheels) Raise the vehicle on a lift Remove the wheel, grease cap, cotter pin, adjusting nut, and safety washer Pull out the outer wheel bearing

Wheel Bearing Removal Screw the nut back on the spindle Slide the hub outward when the inner bearing catches on the adjusting nut, the grease seal and inner wheel bearing will pop out Wipe the bearings and races clean

Wash and dry the bearings Bearing Inspection Wash and dry the bearings

Bearing and race problems Bearing Inspection Bearing and race problems

The bearing and race are replaced as a set Bearing Replacement The bearing and race are replaced as a set Drive out the old race

To install a new race, use a driving tool Bearing Replacement To install a new race, use a driving tool

Greasing the Bearings Pack the bearing with high-temperature wheel bearing grease Use a packer or grease it by hand Make sure the grease is worked completely through each bearing cage and around every ball or roller

Greasing the Bearings

Bearing Installation Place the inner bearing in its race Install the new grease seal in the hub Wipe the spindle clean Slide the hub into position Install the outer bearing Install the safety washer and adjusting nut adjust the nut as described in the manual

Typical Bearing Adjustment

Driving Hub and Wheel Bearing Assembly

Wheel Bearing Removal (Driving Wheels) Loosen the wheel lug nuts and spindle nut Raise the vehicle on a lift Remove the lug nut or bolts, the wheel, and the axle nut

Wheel Bearing Removal Remove the caliper and hang it to one side Unbolt the brake disc from the hub Remove the steering knuckle and hub assembly

Use a puller to remove the hub from a steering knuckle Wheel Bearing Removal Use a puller to remove the hub from a steering knuckle

Remove the old bearing using a driver or hydraulic press Wheel Bearing Removal Remove the old bearing using a driver or hydraulic press

Wheel Bearing Installation Install the new bearings and a grease seal

Wheel Bearing Installation Press the hub into the steering knuckle

Wheel Bearing Installation

Wheel Bearing Installation Install the steering knuckle assembly Install the brake disc, caliper, and other components Tighten the spindle nut and lug nuts to specifications Stake the spindle nut or install a cotter pin as required Lower the vehicle

Spindle Nut Retainers

Servicing Rear Wheel Bearings (Front-Wheel-Drive) Two types of rear wheel bearings are used: serviceable nonserviceable (sealed units)

Rear Hub Assembly (Front-Wheel-Drive) This unit is not serviceable

Bearing and Hub Replacement When a nonserviceable unit fails, the bolts holding the bearing and hub to the axle or control arm must be removed When installing the new assembly, torque the bolts to specifications New fasteners may be specified

Wheel Bearing Service When a serviceable wheel bearing is used, it can be disassembled and packed with grease Follow the service manual procedures