Modern Automotive Technology

© Goodheart-Willcox Co., Inc.

by

Russell Krick

Publisher

The Goodheart-Willcox Co., Inc.Tinley Park, Illinois



Tire, wheel, and wheel bearing diagnosis

Wheel cover removal and installation Tire maintenance Measuring tire and wheel runout

(8 Topics)


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


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


Inspecting the Tires

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


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 corners 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



Wheel Cover Removal

Pry between the wheel and coverat four alternating points


Wheel Cover Installation

Hold the wheel cover in place with the valve stem sticking through the cover


Maintenance procedures include periodic inspection, checking inflation pressure, and tire rotation

These maintenance steps help ensure safety and longer tire life


Checking Tire Inflation Pressure

Remove valve stem cap Press the tire gauge squarely over the

stem Compare reading to the maximum

pressure printed on the tire sidewall or operator’s manual

Adjust as necessary Reinstall the cap


Tire Service Tools


Rotating Tires

Ensures maximum tire life Front and rear tires wear differently Rotation helps even out tire wear Tires are rotated at 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


Torquing Lug Nuts

Torque 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


Tire 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

.090” (2.0 mm)

Maximum for a wheel .045” (1.0 mm)


Measuring Lateral Runout

Mount a dial indicator with the stem against the sidewall and side of the rim.

Check reading at several points


Radial Runout

Difference in radius from the center axis of rotation (out or round)

Maximum for a tire .060” (1.5 mm)

Maximum for a wheel .035” (0.9 mm)


Measuring Radial Runout

Mount a dial indicator with the stem against the tread and the lip of the rim.

Check reading at several points


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


Static Imbalance

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


Dynamic Imbalance

Heavy spot is to one side of thetread or on the sidewall


Wheel Balancing

Wheels are balanced by adding wheel weights

Most are press-fit onto the wheel Weights for mag wheels stick onto the

wheel with an adhesive backing


Weights are often kept on thebalancing machine

Wheel Balancing


Static 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 dynamic balancing machine will indicate

where weight must be added

Wheel Balancing


Wheel Balancing


On-car Balancing Follow equipment operating instructions Wear eye protection Remove rocks and debris from tread Place 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


On-car Balancing

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


Wheel Balancers Wheel balancing machine that 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 static or dynamic balance


Bubble Balancer

Wheel and tire assembly is mountedon the machine


Bubble Balancer

Add weights until the bubble is centered


Off-Car Balancer Wheel and tire assembly is mounted on

the machine and rotated 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 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


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


Tire Changing Machine

Power head turns the bar to force the beads over the rim


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 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 tire pressure to recommended limits


Automated Tire Changer

Uses a rubber wheel to force the bead back over

the wheel


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


Repairing a Leak

Use a stitcher tool to bond the patchto 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 air pressure to at least 15 psi (103 kPa)

Broken strands in steel belts indicate damage and could puncture the patch


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


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 bearing catches on the nut, the grease seal and inner wheel bearing will pop out

Wipe the bearings and races clean

Wheel Bearing Removal


Bearing Inspection

Wash and dry the bearings


Bearing Inspection

Bearing and race problems


Bearing Replacement

Bearing and race are replaced as a set. Drive out the old race


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 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


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(Driving Wheels)


Remove the caliper and hang it to one side

Unbolt the brake disc from the hub Remove the steering knuckle and hub

assembly



Using a puller to remove the hub from a steering knuckle



Remove the old bearing using a driver or hydraulic press



Wheel Bearing Installation

Install new bearings and a grease seal



Press the hub into the steering knuckle



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


Using a Press


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 nonserviceable units fail, 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 service manual procedures

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Modern Automotive Technology