GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 SLS 🢒 Preface 🢒 Cautions and Notices 🢒 Vibration Analysis - Driveline

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Generally, vibration will duplicate during repair; but the vibration you felt is either not severe or much worse than the vibration you felt during driving. This is normal. Driveline - order vibration may be present as a result of components imbalance. Service - Stall Test can help to determine which component need repair or replacement.

    2.

  2. If the vehicle's vibration frequency is equal to driveline's first order rotation speed, and this vibration which did not duplicate during vehicle testing in Service - Stall, may be produce by internal components of rear axle. If the vibration is eliminated during the repair, but re- occurs during driving, this may be the cause of the vibration.

Step

Action

Yes

No

1

Has the Vibration Analysis - Road Testing table been completed?

Go to Step 2

Go to Vibration Analysis - Road Testing

2

Did you record frequency data from J 38792-A Electronic Vibration Analyzer (EVA) 2 during the Vibration Analysis - Road Testing procedure?

Go to Step 3

Go to Step 5

3

Based on the Vibration Analysis - Road Testing, is the concern related with driveline first order?

Go to Step 6

Go to Step 4

4

Based on the Vibration Analysis - Road Testing, is the concern related with driveline second order?

Go to Step 21

Go to Step 5

5

Based on the Vibration Analysis - Road Testing table, is the concern from the noise unfelt?

Go to Vibration Diagnostic Aids

Go to Vibration Analysis - Road Testing

6
    • Inspect the drive shafts for dents, damage, missing weights, and/or undercoating.
    • Inspect the U-joint for excessive wear, looseness, and/or damage.
    • Inspect the drive shaft support bearing for damaged rubber components, worn bearings, and/or a deformed or cracked bracket.

Does any of the components exhibit the above conditions listed?

Go to Step 7

Go to Step 8

7

Replace the components if necessary. Refer to Rear Propeller Shaft Replacement .

Did you complete the heavy repair or replacement?

Go to Step 28

--

8

Attempt to duplicate the vibration in the stall. Refer to Vibration in Service-Stall Test (Non-Torque Sensitive) .

Were you able to duplicate the vibration?

Go to Step 10

Go to Step 9

9

Perform Vibration in Service-Stall Test (Torque Sensitive) .

Were you able to duplicate the vibration?

Go to Diagnostic Starting Point - Rear Drive Axle

Go to Vibration Diagnostic Aids

10
  1. Support the vehicle with the hoist and have an assistant drive the vehicle at the speed of vibration concern, and you perform the following steps at the same time.

    2. Use very slight force to fix J 38792-A sensor to the bottom of the transmission mounting bracket. Record the vibration amplitudes displayed on J 38792-A .

  2. Use very slight force to fix the J 38792-A sensor to rear drive axle pinion housing bottom. Record the vibration amplitudes displayed on J 38792-A .
  3. Determine the maximum amplitude shown on J 38792-A between the two locations.

Is the operation completed?

Go to Step 11

--

11

Was the vibration most evident under the transmission support?

Go to Step 12

Go to Step 14

12
  1. Inspect the front drive shaft coupling assembly for excessive wearing, loose and/or damage.
  2. Inspect the U-joint for excessive wear, looseness and/or damage.

Does any of the components exhibit the above conditions listed?

Go to Step 13

Go to Step 15

13
  1. Replace components as necessary, refer to the following procedures:
  2. Perform Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 15

Go to Step 28

14

Was the vibration most significant under the drive shaft support bearing?

Go to Step 15

Go to Step 17

15
  1. Inspect the U-joint for excessive wear, looseness, and/or damage.
  2. Inspect the drive shaft support bearing for damaged rubber components, worn bearings, and/or deformed or cracked bracket.

Does any of the components exhibit the above conditions listed?

Go to Step 16

Go to Step 17

16
  1. Replace the components if necessary. Refer to Rear Propeller Shaft Replacement .
  2. Perform the Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 17

Go to Step 28

17
  1. Inspect the rear drive shaft coupling assembly for excessive wearing, looseness, and/or damage.
  2. Inspect the rear drive axle shock absorber bushings for excessive wear and/or damage.

Does any of the components exhibit the above conditions listed?

Go to Step 18

Go to Step 19

18
  1. Replace the components if necessary. Refer to the following procedures:
  2. Perform Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 19

Go to Step 28

19

Visually inspect the rear axle pinion flange for damage.

Is there any damage visible on the rear drive axle pinion flange?

Go to Step 20

Go to Step 25

20
  1. Replace the pinion flange. Refer to Drive Pinion Collar .
  2. Perform Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 25

Go to Step 28

21
    • Inspect the drive shafts for dents, damage, missing weights, and/or undercoating.
    • Inspect the U-joint for excessive wear, looseness, and/or damage.
    • Inspect the drive shaft support bearing for damaged rubber components, worn bearings, and/or a deformed or cracked bracket.

Does any of the components exhibit the above conditions listed?

Go to Step 22

Go to Step 23

22
  1. Replace the components if necessary. Refer to Rear Propeller Shaft Replacement .
  2. Perform the Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 23

Go to Step 28

23

Measure the drive shaft angles. Refer to Driveline Working Angles Measurement .

Did the drive shaft angles need adjustment?

Go to Step 24

Go to Step 27

24
  1. Adjust the drive shaft angles. Refer to Driveline Working Angles Adjustment .
  2. Perform the Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 27

Go to Step 28

25

Balance the drive shaft. Refer to Driveline System Balance Adjustment .

Does the driveline system need to be balanced?

Go to Step 26

Go to Vibration Diagnostic Aids

26

Perform the Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 27

Go to Step 28

27

Replace the drive shaft. Refer to Rear Propeller Shaft Replacement

Is the replacement complete?

Go to Step 28

--

28
  1. Install or connect any components that were removed or disconnected during diagnosis.
  2. Perform the Vibration - Road Testing table. Refer to Vibration Analysis - Road Testing .

Is the vibration still present?

Go to Step 3

System OK