Modern Automotive Technology

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

2. Chapter 66 Tire, Wheel, and Wheel Bearing Service

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

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

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

6. 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

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

8. Tire Impact Damage Typical damage found on used tires

9. Tire Wear Patterns

10. 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

11. Tire Inflation Pressure

12. 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

13. Causes of Tire Vibration

14. 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

15. 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

16. Wheel Cover Removal and Installation

17. Wheel Cover Removal Pry between the wheel and coverat four alternating points

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

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

20. 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

21. Tire Service Tools

22. 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)

23. Tire Rotation Patterns

24. 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

25. Torquing Lug Nuts Torque nuts to specifications in a crisscross pattern

26. 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

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

28. 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)

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

30. 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)

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

32. Wheel Balance • 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

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

34. Dynamic Imbalance Heavy spot is to one side of thetread or on the sidewall

35. 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

36. Wheel Balancing Weights are often kept on thebalancing machine

37. 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

38. Wheel Balancing

39. 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

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

41. 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

42. Bubble Balancer Wheel and tire assembly is mounted on the machine

43. Bubble Balancer Add weights until the bubble is centered

44. 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

45. Off-Car Balancer

46. 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

47. 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

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

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

50. 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