1. Servicing the Suspension System
Chapter 22
Servicing the Suspension System

2. Loaded Lower Ball Joint
22-1
Place a dial indicator on the lower control arm and vertically against the steering knuckle.

3. Loaded Lower Ball Joint
22-1
Place a pry bar under the tire and pry it upward, watching the dial indicator reading as you pry and release. Record the total amount of movement in the joint and compare to the manufacturer’s specifications.

4. Loaded Lower Ball Joint
22-1
Rock the tire in and out at the top, watching for any play in the upper ball joint and compare to specifications.

5. Loaded Upper Ball Joint
22-2
Obtain a properly sized block of wood to fit between the upper control arm and the frame. Place the block of wood between the upper control arm and frame, so it is secure.

6. Loaded Upper Ball Joint
22-2
Place a dial indicator on the upper control arm and vertically against the steering knuckle.

7. Loaded Upper Ball Joint
22-2
Place a pry bar under the tire and pry it upward, watching the dial indicator reading as you pry and release. Record the total amount of movement in the joint and compare to specifications.

8. Loaded Upper Ball Joint
22-2
Rock the bottom of the tire in and out, watching for any play in the lower ball joint and compare to specifications.

9. Ride Height
22-3
Refer to the manufacturer’s service information for correct measurement points and specifications.

10. Ride Height
22-3
Check for properly sized, matching, and inflated tires. Correct any issues found.

11. Ride Height
22-3
Check the vehicle for any nonstandard loads in the trunk or luggage area. Remove them temporarily while measuring ride height.

12. Ride Height
22-3
Measure from points specified, such as from frame to ground on all four corners of the vehicle, and compare measurements to specifications.

13. Ride Height
22-3
Inspect for bent components or a weak or broken spring if any measurements are not correct. If working with a torsion bar suspension, adjustment of ride height may need to be performed to correct the condition.

14. Inspecting the Shock Absorbers
22-4
Place your weight on a bumper and begin to bounce the vehicle until it reaches its maximum amount of travel produced by your weight. Stop bouncing at the bottom of the bounce. If the vehicle rebounds and compresses more than twice, replace the shock absorbers. If the shock absorbers are performing well, the vehicle will rebound once or one and a half times, then return to its original position.

15. Inspecting the Shock Absorbers
22-4
Pay particular attention to the top strut mounting during the bounce test. Place your hand on top of the mounting during the bounce test. Any noise or looseness in the mounting could indicate the need to replace the mount. While driving, the same test can be performed by stopping the vehicle suddenly from a very low speed. If the vehicle “bounces” up and down when coming to rest, you need to replace the shock absorbers.

16. Inspecting the Shock Absorbers
22-4
Visually inspect the shock absorber mounting points for security and corrosion, and note any wet looking patches on the sides of the shock absorbers. Slight dampness on the shock is typically normal, but a drip on the shock is not normal and indicates leaking.

17. Removing and Inspecting the Stabilizer Bar Bushings and Mount Brackets
22-5
Raise the vehicle on a hoist, or use a jack and place safety stands under the frame. Remove the bolts holding the stabilizer bar bushing mount brackets and inspect the brackets for cracks.

18. Removing and Inspecting the Stabilizer Bar Bushings and Mount Brackets
22-5
Remove the bushings by hand. Inspect the rubber in the bushings for cracks, brittleness, softness, or wear.

19. Removing and Inspecting Sway Bar Links
22-6
Raise the vehicle on a hoist, or use a jack and place safety stands under the frame. Remove the nut holding the stabilizer bar link.

20. Removing and Inspecting Sway Bar Links
22-6
Remove the link by hand.

21. Removing and Inspecting Sway Bar Links
22-6
Inspect the rubber link grommets for cracks, softness, brittleness, or wear. Repeat on the other link.

22. Replacing a Shock Absorber
22-7
Raise the vehicle on a lift, or raise it with a jack and support it with safety stands under the frame. Remove the upper bolts holding the shocks in place with a socket and box-end wrench.

23. Replacing a Shock Absorber
22-7
Remove the lower bolts holding the shock in place.

24. Replacing a Shock Absorber
22-7
Pull the shock out by hand. Repeat on the other side.

25. Inspecting SLA Suspension System Coil Springs and Spring Insulators
22-8
Measure ride height as in Skill Drill 22-3.

26. Inspecting SLA Suspension System Coil Springs and Spring Insulators
22-8
Inspect the coil springs and spring insulators for damage.

27. Lubricating Suspension and Steering Systems
22-10
Determine the location of lubricating points. Check the shop service manual to determine where the grease points are and the type of grease required. Also look to see if any aftermarket grease fittings are installed. If so, grease them.

28. Lubricating Suspension and Steering Systems
22-10
Clean each of the lubrication fittings and the grease gun nozzle by wiping them with a clean rag. You may need to remove a component’s plugs and temporarily install a lubrication fitting. After the component has been lubricated, reinstall the original plug.

29. Lubricating Suspension and Steering Systems
22-10
Push the grease gun nozzle fully over the fitting. It should snap into place. Add enough grease to see the seal or rubber boot rise slightly. Do not overfill a lubricated joint with grease.

30. Lubricating Suspension and Steering Systems
22-10
If the fitting is clean and will not take grease, remove the grease zerk and check for blockage. If found, the fitting must be replaced with a new fitting of the same size and angle, and the joint relubricated.

31. Lubricating Suspension and Steering Systems
22-10
Remove the nozzle from the fitting and wipe away any excess grease from it. Repeat the procedure until all the appropriate joints have been lubricated.

32. Lubricating Suspension and Steering Systems
22-10
After you have completed lubricating all the appropriate joints and cleaned off any excess grease, attach a static cling sticker to the windshield, or reset the maintenance reminder system. Lower the vehicle and remove it from the lifting device.

33. Inspecting the Strut Cartridge or Assembly
22-11
Bounce test each strut and check for lack of dampening, binding, or unusual noises.

34. Inspecting the Strut Cartridge or Assembly
22-11
Inspect the strut assembly for damage.

35. Inspecting the Strut Cartridge or Assembly
22-11
Inspect the top of the strut cartridge for leaks (a small amount of seepage is allowable for some vehicles).

36. Inspecting the Front Strut Bearing and Mount
22-12
With the vehicle on the ground, inspect the upper strut bearing mount for damage or wear.

37. Inspecting the Front Strut Bearing and Mount
22-12
With your hand safely on the top of the strut mount (not in any holes) have an assistant turn the steering wheel and feel for any roughness.

38. Inspecting the Front Strut Bearing and Mount
22-12
Lift the vehicle so that the weight is off the suspension. Inspect the upper strut mount for torn bushings or insulators. Also inspect the spring and any insulators.

39. Inspecting Leaf Springs
22-13
Raise the vehicle on a lift and support the rear axle with tall screw jack stands. Check to see if any of the leaves are cracked or broken and that the noise deadening inserts are positioned correctly between the leaves.

40. Inspecting Leaf Springs
22-13
Test the security of the spring center bolt, and make sure the U-bolts are tight.

41. Inspecting Leaf Springs
22-13
Check the condition of the bushings or mountings and the spring shackles by placing a lever between the frame and the eye of the spring and levering against the spring.

42. Inspecting Strut Rods and Bushings
22-14
Raise the vehicle on the hoist and inspect the strut rods and bushings for wear and cracking.

43. Inspecting Strut Rods and Bushings
22-14
Pry the strut rod front to back and check for excessive looseness.

44. Inspecting Strut Rods and Bushings
22-14
Pry the strut rod side to side and check for excessive looseness.

45. Inspecting Torsion Bar Suspension
22-15
Measure the ride height and compare to specifications.

46. Inspecting Torsion Bar Suspension
22-15
Raise the vehicle on a hoist and inspect the torsion bars for damage or excessive rust.

47. Inspecting Torsion Bar Suspension
22-15
If the ride height was out of specifications, readjust the torsion bars if possible. If still out of spec, inform your supervisor.

48. Preparing a Vehicle for a Wheel Alignment
22-16
Remove any heavy items from the trunk and passenger compartments.

49. Preparing a Vehicle for a Wheel Alignment
22-16
Check the size and condition of all four tires. Adjust the air pressure to specifications.

50. Preparing a Vehicle for a Wheel Alignment
22-16
Measure the vehicle’s ride height.

51. Preparing a Vehicle for a Wheel Alignment
22-16
Check the play of the steering wheel. Correct any excess play before undertaking the wheel alignment.

52. Preparing a Vehicle for a Wheel Alignment
22-16
Bounce each corner of the vehicle to check the correct functioning of the shock absorbers.

53. Preparing a Vehicle for a Wheel Alignment
22-16
With the vehicle raised, inspect all suspension and steering components, including the wheel bearings. Repair or replace all damaged or worn suspension components.

54. Preparing a Vehicle for a Wheel Alignment
22-16
Position the vehicle on the wheel alignment ramp, making sure the front tires are positioned correctly on the turntables.

55. Preparing a Vehicle for a Wheel Alignment
22-16
Position the rear wheels on the slip plates or rear turntables.

56. Preparing a Vehicle for a Wheel Alignment
22-16
Attach the wheel units of the wheel alignment machine.

57. Performing Four-Wheel Alignment
22-17
Position the vehicle on the frontend rack. Raise the vehicle to a comfortable working level, and set the rack on its mechanical locks to provide a level surface.

58. Performing Four-Wheel Alignment
22-17
Raise the vehicle with the air jacks on the alignment rack.

59. Performing Four-Wheel Alignment
22-17
Attach sensors and compensate each one.

60. Performing Four-Wheel Alignment
22-17
Pull the lock pins from the slip plates and turntables.

61. Performing Four-Wheel Alignment
22-17
Lower the vehicle as instructed by the machine. Install a brake pedal depressor.

62. Performing Four-Wheel Alignment
22-17
Perform a caster sweep by selecting caster sweep on the machine and turning the wheel the number of degrees on the turntables as designated by the machine.

63. Performing Four-Wheel Alignment
22-17
Take the alignment readings and compare them to the vehicle manufacturer’s specifications.

64. Performing Four-Wheel Alignment
22-17
Prepare to adjust rear caster, camber, and toe, if possible, by loosening the eccentric bolts.

65. Performing Four-Wheel Alignment
22-17
Adjust front caster and camber by turning the eccentric bolts attaching the control arm until alignment is within specifications.

66. Performing Four-Wheel Alignment
22-17
Install a steering wheel holder to center the steering wheel.

67. Performing Four-Wheel Alignment
22-17
Adjust front toe by lengthening or shortening the tie-rod assemblies until toe is within specifications. Tighten the lock nuts on the tie-rod assemblies. Test-drive the vehicle to make sure the repair was successful.

68. Checking SAI and Included Angle
22-18
Position the vehicle on the alignment rack. Attach the wheel sensors on the vehicle to the locations specified by the sensor manufacturer, and compensate.

69. Checking SAI and Included Angle
22-18
Follow the alignment machine instructions for taking the SAI measurements, and compare them to the vehicle manufacturer’s specifications. Typically, the SAI reading will require a caster sweep to be performed. SAI is a nonadjustable angle. No changes can be made; the angle will help the technician to verify that suspension components are bent.

70. Checking SAI and Included Angle
22-18
Calculate the included angle, if the alignment machine doesn’t, by adding the camber reading of each wheel to the SAI of each wheel, and compare to specifications. Remember that if camber is a negative number, you will need to subtract the camber from the SAI to get the included angle.

71. Checking Rear Wheel Thrust Angle
22-19
Position the vehicle on the alignment rack. Attach the wheel sensors on the vehicle to the locations specified by the sensor manufacturer, and compensate.

72. Checking Rear Wheel Thrust Angle
22-19
Thrust angle can be indicated on most alignment machines, although you may have to go to a special screen. Take the thrust angle reading, and compare it to the vehicle manufacturer’s specifications.

73. Checking Front and/or Rear Cradle Alignment
22-20
Position the vehicle on the alignment rack. Attach the wheel sensors on the vehicle, and compensate. Take the alignment readings and compare to the specifications. If camber and caster are incorrect and not adjustable, check for bent parts.

74. Checking Front and/or Rear Cradle Alignment
22-20
If the parts are not bent, check the positioning of the cradle. Loosen cradle bolts and shift in the necessary direction to correct alignment angles.

75. Checking Front and/or Rear Cradle Alignment
22-20
If adjustment is still not possible, check for a bent cradle or cradle mounting points by measuring from fixed points on one side, compared to the same points on the other side. If they are different, the cradle needs adjusting.