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

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

2. Chapter 68 Suspension System Diagnosis and Repair

3. Contents • Suspension system diagnosis • Shock absorber service • Suspension spring service • Ball joint service • Suspension bushing service • MacPherson strut service • When alignment is needed • Computerized suspension diagnosis

4. Suspension System Diagnosis • Symptoms of suspension system problems: • abnormal noises • tire wear • steering wheel pull • front end shimmy

5. Diagnosing the Suspension System • Gather information from the customer or service writer • Inspect the parts that could cause the problems indicated • If necessary, road test the vehicle to verify the complaint

6. Suspension System Problems

7. Front Suspension System

8. Shock Absorber Service • Worn shock absorbers will cause a vehicle to ride poorly • When the tire strikes a bump, a bad shock will not dampen spring oscillations • Loose or damaged shock absorbers may produce a loud clanking noise

9. Checking Shock Absorber Condition • Perform a visual inspection for damage, rubber bushing wear, or oil leakage • Perform a shock absorber bounce test • push down on one corner of the vehicle • release the body • count the number of times the body rebounds • one or two rebounds is acceptable

10. Replacing the Shocks • Raise the vehicle on a lift • Remove the wheels • Support the control arms or axle housing with a jack or jack stand • Remove the old shock absorbers • Install the new shocks • Install the wheels and torque to specs

11. Replacing the Shocks Support the control arm to prevent the spring from forcing parts down violently

12. Replacing the Shocks Unbolting the top and bottom of the shock

13. Air- and Gas-Charged Shock Service • Gas-filled shocks require replacement when faulty • Air shocks may be repairable • Air leakage may occur at air lines, an air valve, or the shocks themselves • To test, wipe on a soap-and-water solution, watching for bubbles that indicate leakage

14. Suspension Spring Service • Spring fatigue allows a vehicle’s body to settle, lowering the curb height • changes the control arm position • misalignment results • Fatigue can occur after prolonged service

15. Measuring Curb Height • Place the vehicle on a level surface • Measure from a specified point on the frame, body, or suspension down to the floor • Compare the distance to specifications • If the curb height is too low, spring replacement or torsion bar adjustment will be necessary

16. Curb Weight • Weight of the vehicle with a full tank of fuel and no passengers or luggage • Vehicle should be at curb weight when measuring curb height • remove everything from the trunk except the spare tire and jack

17. Coil Spring Compressor • Squeezes the coils closer together • Reduces the length of the spring

18. Coil Spring Compressor Coil spring compressor kit

19. Coil Spring Removal • Raise the vehicle on a lift • Support the control arm or axle housing • Remove the shock absorber • Install the spring compressor and compress the spring

20. Coil Spring Removal If necessary, separate the lower or upper ball joint using a separator tool

21. Coil Spring Removal • Remove any components that could be damaged when the control arm is lowered: • brake line, strut rod, steering linkage • Pull the spring and the compressor out as a unit

22. Coil Spring Installation • Compress the new spring • Slip the spring into place and position the coil ends in the same location as the old spring • Reassemble the ball joint and other components • Unscrew the spring compressor while guiding the coil into place • Install the wheels and lower the vehicle

23. Rear Coil Springs Lower the axle after unbolting the shocks—the coils will simply fall out

24. Leaf Spring Service • Service usually involves spring or bushing replacement • Place jack stands under the frame • Use a floor jack to raise the weight of the rear axle off the leaf spring • Remove the U-bolts that clamp around the middle of the spring and the axle

25. Leaf Spring Service • Slide the through-bolts out of the spring • Remove the old leaf spring • Install the new leaf spring • Reassemble and lower the vehicle

26. Spring Bushing Replacement Replacing a worn bushing with a driving tool

27. Torsion Bar Service • Most torsion bars are adjustable • Replacement is not generally needed unless a torsion bar breaks • When the curb height is too low, tension must be increased to raise the vehicle

28. Torsion Bar Suspension

29. Ball Joint Service • Worn ball joints cause the steering knuckle and wheel assembly to be loose on the control arms • Clunking or popping sounds might be heard when turning or driving over bumps

30. Ball Joint Lubrication • Wear is usually a result of improper lubrication or prolonged use • If dry, the joints can wear out quickly • Grease fittings or lube plugs may be provided • lubricate the joints with a grease gun at regular intervals • Many late-model ball joints are sealed units that do not require lubrication

31. Ball Joint Lubrication Replace lube plugs with grease fittings

32. Ball Joint Lubrication Grease the ball joints and other fittings regularly Only install enough grease to fill the boot

33. Checking Ball Joint Wear • Two methods of checking ball joint condition are commonly used: • ball joint wear indicator • measuring the play in the ball joint

34. Ball Joint Wear Indicator • Part of the ball joint • Inspect when the weight of the vehicle is on the wheels • A shoulder around the grease fitting will recede into the joint as it wears • When the shoulder recedes below the surface, replace the joint

35. Ball Joint Wear Indicator

36. Measuring Ball Joint Play • Jack up the vehicle • weight must be removed from the joint • Physically move the control arm and tire assembly • Use a pry bar while watching for joint movement • Compare the movement to specifications

37. Measuring Ball Joint Play Lift points for different suspension systems

38. Measuring Ball Joint Play

39. Ball Joint Removal • Raise the vehicle on a lift • Support the control arm • Remove the shock absorber • Install a coil spring compressor on the spring, if necessary • Remove the nut securing the ball joint to the steering knuckle • Separate the knuckle from the joint

40. Ball Joint Replacement(Press-fit) Remove and install the ball joint usinga ball joint driver

41. Ball Joint Replacement(Riveted) Drill out the rivet heads Drive out the old rivets Bolt on the new ball joint

42. Ball Joint Replacement • If the ball joint is screwed into place, use a large wrench to unscrew the old ball joint • Clean the threads in the control arm • Torque the new joint to specifications • Reassemble the vehicle • Remove the spring compressor, if used • Lower the vehicle

43. Suspension Bushing Service • Rubber bushings are commonly used on the inner ends of the control arms • Bushings should be checked periodically for wear • Worn bushings can let the control arms move sideways, causing tire wear and steering problems

44. Checking Bushing Wear • Try to move the control arm against normal movement • Watch the bushings • If the arm moves in relation to its shaft, the bushings are worn and must be replaced

45. Bushing Removal • Procedures vary, refer to a service manual • The stabilizer bar and strut rod must be unbolted from the control arm • Remove the bolts passing through the bushings • Remove the control arm • Bushings are pressed or screwed into the control arm

46. Bushing Removal

47. Bushing Replacement Using a driver on a pressed-in bushing

48. Bushing Replacement With this design, nuts are used to force new bushings into the control arm

49. Bushing Replacement • Reinstall the control arm • Torque all bolts properly • Install the ball joint cotter pin and other components • The bushings may require preload with the weight of the vehicle on the wheels • lower the vehicle before tightening the control arm shaft nuts

50. MacPherson Strut Service • The most common problem is worn strut shock absorbers • the seals inside the strut can begin to leak • dampening is reduced • vehicle ride is affected