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Suspension System Diagnosis and Repair.

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Presentation on theme: "Suspension System Diagnosis and Repair."— Presentation transcript:

1 Suspension System Diagnosis and Repair

2 Contents Suspension system diagnosis Shock absorber service
(8 Topics) Suspension system diagnosis Shock absorber service Suspension spring service Ball Joint service

3 Contents Suspension bushing service MacPherson strut service
Wheel 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 as the loose parts bang against the body

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 maximum two or three oscillations

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 shock 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 Unbolting the top and bottom of the shock
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 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 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 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 any other fittings provided 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 measure 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, watching for joint movement Compare 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 ball joint using a 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
Stabilizer bar and strut rod must be unbolted from the control arm Remove bolts passing through the bushings Remove the control arm Bushings are pressed or screwed into the control arm

46 Bushing Removal

47 Using a driver on a pressed-in bushing
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 Bushings may require preload with the weight of the vehicle on the wheels lower the vehicle before tightening control arm shaft nuts

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

51 Strut Removal

52 Remove the strut as a single unit. Note the alignment for reassembly
Strut Removal Remove the strut as a single unit. Note the alignment for reassembly

53 Strut Disassembly Use a spring compressor to remove the coil spring
After the spring is squeezed together, remove the upper mount assembly Release spring tension and lift the spring off the strut Inspect the parts for wear and bearing roughness Replace parts as necessary

54 Spring Compressors Portable Bench-mounted

55 Strut Assembly Inspection

56 Replacing a Strut Cartridge

57 Assembling the Strut Fit the strut into the compressor
Compress the spring Install the upper spring seat and mount assembly Release the spring compressor

58 Strut Assembly

59 Strut Installation Lift the strut into position in the upper body mount Attach the lower end of the strut to the steering knuckle or bearing support Align any reference marks Install the fasteners Install any other parts

60 Always torque fasteners to specs
Strut Installation Always torque fasteners to specs

61 When Alignment is Needed
After servicing ball joints, control arm bushings, strut rods, springs, strut assemblies, or other suspension parts, wheel alignment must be checked and adjusted Rapid tire wear or handling problems could occur if alignment is altered

62 Computerized Suspension Diagnosis

63 Computerized Suspension System

64 System Diagnosis Connect a scan tool to the diagnostic connector
Read any stored diagnostic trouble codes Check scan data for suspension-related operating values If any problems are noted, use pinpoint checks to isolate the source of the problem

65 Scan Tool Display A. Select the desired control module B. Choose a mode such as read codes C. Trouble code display

66 Scoping the output signal from a height sensor
Pinpoint Tests Scoping the output signal from a height sensor

67 Pinpoint Tests Voltage waveform from a height sensor. Voltage should rise and fall smoothly as the arm is moved

68 Height Sensor Service Sensor can fail mechanically due to worn parts, a bent arm, or broken parts Sensor may also fail electrically, ceasing to produce a normal signal Replacement is usually required

69 Height Sensor Replacement

70 Compressor Service A faulty compressor will not produce the air pressure needed to maintain the correct ride height Check the electrical connections and source voltage Connect a pressure gauge to the output hose fitting to measure pressure output If the pressure is not within specs, replace the compressor

71 Compressor Replacement

72 Electronically-Controlled Shock Service
When replacing the shocks, you may be able to transfer some of the electronic parts from the old units onto the new ones Do not install conventional shocks to save the customer money constant trouble codes might be set and vehicle safety could be adversely affected

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