Noise Diagnosis - Front Suspension

DEFINITION: Any noise emitted from the front of the vehicle that is induced by VEHICLE SPEED or DRIVING TERRAIN as related to the front suspension.

1. Did you review the General Description and perform the necessary inspections? If so, go to next step. If not, see SYMPTOMS - SUSPENSION GENERAL DIAGNOSIS  .
   NOTE: Compare this vehicle to an identical vehicle in order to determine if the customer's concern is a normal operating characteristic of the vehicle.
2. Attempt to duplicate the noise. Road test the vehicle. Is the front suspension noisy? If so, go to next step. If not, system is OK.
3. Shift the transmission into Park. Turn the ignition off. Bounce the front of the vehicle in order to duplicate the noise. Is the noise present? If so, go to next step. If not, go to step  5 .
4. Bounce the front of the vehicle. Use J-39570 Chassis Ear in order to locate the source of the noise. Repair or replace the suspect components as necessary. After repairs are complete, go to step  25 .
   Fig 1: Identifying J-35970 Chassis Ear

   Courtesy of GENERAL MOTORS CORP.
5. Raise and support the vehicle. Refer to LIFTING AND JACKING THE VEHICLE  . Inspect all of the front suspension components for any damage. Are any components damaged? If so, go to next step. If not, go to step  7 .
6. Repair any damaged components. Did you complete the repair?  25 .
7. Inspect the tires for proper inflation. Refer to TIRE INFLATION PRESSURE SPECIFICATIONS  . Correct the tire inflation pressure as necessary. Inspect the tires for unusual wear. Refer to TIRE DIAGNOSIS - IRREGULAR OR PREMATURE WEAR in TIRES AND WHEELS . Does either tire exhibit unusual tread wear? If so, go to next step. If not, go to step  10 .
8. Rotate the tires. Road test the vehicle. Is the noise now emitted from the rear of the vehicle? If so, go to next step. If not, go to step  10 .
9. Replace the tires that are causing the noise. After repairs are complete, go to step  25 .
10. Ensure that the ball joints and steering linkage are lubricated, if applicable. Lubricate/replace as necessary. Did you service any components? If so, go to step  25 . If not, go to next step.
11. Ensure that all of the wheel nuts are tightened to 140 N.m (103 lb ft). Tighten as necessary. Did you tighten any wheel nuts? If so, go to step  25 . If not, go to next step.
12. Use your hands in order to push and pull the strut. Is the strut loose? If so, go to next step. If not, go to step  15 .
13. Inspect the strut fasteners for the correct fastener tightening specification. Tighten as necessary to 85 N.m (63 lb ft). Use your hand to push and pull the strut. Is the strut loose? If so, go to next step. If not, go to step  25 .
14. Replace the loose or worn strut components. Refer to STRUT, STRUT COMPONENT AND/OR SPRING REPLACEMENT in FRONT SUSPENSION . After repairs are complete, go to step  25 .
15. Use your hands in order to push and pull on the stabilizer shaft. Is the stabilizer shaft loose? If so, go to next step. If not, go to step  20 .
16. Inspect all of the stabilizer shaft fasteners. Tighten to 85 N.m (63 lb ft) as necessary. Use your hands in order to push and pull on the stabilizer shaft. Is the stabilizer shaft loose? If so, go to next step. If not, go to step  25 .
17. Observe the location of the stabilizer shaft looseness. Is the looseness observed at the stabilizer shaft links? If so, go to next step. If not, go to step  20 .
18. Replace the stabilizer shaft links. Refer to STABILIZER SHAFT LINK REPLACEMENT in FRONT SUSPENSION . After repairs are complete, go to step  25 .
19. Replace the stabilizer shaft insulators and/or brackets. Refer to STABILIZER SHAFT INSULATOR REPLACEMENT in FRONT SUSPENSION . After repairs are complete, go to step  25 .
20. Inspect the control arms for looseness or movement. Is any looseness or movement observed? If so, go to next step. If not, go to step  23 .
21. Inspect the control arm fasteners for the correct fastener tightening specification. Tighten to 113 N.m (83 lb ft) as necessary. Inspect the control arm for looseness. Is the control arm loose? If so, go to next step. If not, go to step  25 .
22. Replace any worn or loose control arm bushings. Refer to LOWER CONTROL ARM BUSHINGS REPLACEMENT in FRONT SUSPENSION . After repairs are complete, go to step  25 .
23. 1. Start the engine with the drive wheels off of the ground.
    2. Shift the transmission into Drive.
       WARNING: Do not spin the drive wheels faster than 55 km/h (35 mph) as indicated by the speedometer. This limit is necessary because the speedometer indicates only one half of the actual wheel speed when one drive wheel is spinning and the other drive wheel is stopped. Personal injury and damage may result from high speed spinning.
       CAUTION: This step will require the assistance of another person to maintain the drive train speed. Do not use the cruise control to maintain the drivetrain speed.
    3. Increase the drive wheel speed until the noise is at the most audible level.
       CAUTION: Do not allow the J-39570 Chassis Ear to contact any moving components.
    4. Use a J-39570 Chassis Ear in order to locate the source of the noise. See Fig 1 .
    Does either wheel bearing exhibit noise? If so, go to next step. If not, go back to step  8 .
24. Replace the wheel bearings. Refer to WHEEL BEARING/HUB REPLACEMENT - FRONT in FRONT SUSPENSION . After repairs are complete, go to next step.
25. Operate the vehicle in order to verify the repair. Did you correct the condition? If so, system is OK. If not, go back to step  3 .