Chevrolet Silverado / GMC Sierra. Service manual — part 1319

11

Carrier Housing

12

Output Shaft Seal Assembly

13

Output Shaft

14

Drain Plug Assembly

15

Drain Plug Washer

16

Fill Plug Assembly

17

Fill Plug O-ring Seal

18

Carrier Locator Pin

19

Vent Connector

20

Differential Case

21

Ring Gear

22

Output Shaft Bearing Assembly

23

8-Point Lock Ring

24

Sleeve and Insert Assembly

25

Differential Side Bearing Assembly

26

Differential Cross Pin Lock

27

Differential Pinion Thrust Washer

28

Differential Pinion Gear

29

Differential Side Gear Washer

30

Differential Side Gear

31

Output Shaft Snap Ring

32

Differential Pinion Gear

33

Differential Pinion Gear Thrust Washer

34

Differential Side Gear

35

Differential Side Gear Washer

36

Differential Cross Pin

37

Ring Gear Bolt

38

Output Shaft Bearing Assembly

39

8-Point Lock Ring

40

Sleeve and Insert Assembly

41

Differential Side Bearing Assembly

42

Carrier Gasket

43

Carrier Cover

44

Tube Locator Pin

45

Inner Output Shaft Thrust Washer

46

2008 Chevrolet Silverado 1500

2008 Driveline/Axle Front Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

DIAGNOSTIC INFORMATION AND PROCEDURES

DIAGNOSTIC STARTING POINT - FRONT DRIVE AXLE

Begin the system diagnosis by reviewing the system Description and Operation. Refer to Front
Drive Axle Description and Operation. Reviewing the Description and Operation information
will help you determine the correct symptom diagnostic procedure when a malfunction exist.
Reviewing the Description and Operation information will also help you determine if the
condition described by the customer is normal operation. Refer to Symptoms - Front Drive
Axle in order to identify the correct procedure for diagnosing the system and where the
procedure is located.

SYMPTOMS - FRONT DRIVE AXLE

Before beginning diagnosis, review the system description and operation in order to familiarize
yourself with the system functions. Refer to Front Drive Axle Description and Operation.

Noise Diagnosis

Any gear-driven unit produces a certain amount of noise that is normal and that conventional
repairs or adjustment cannot eliminate. Slight noise that is heard only at a certain speed or under
unusual or remote conditions is acceptable. For example, this noise tends to reach a peak at

Inner Output Shaft Bearing Assembly

47

Inner Output Shaft

48

Carrier Bolt

49

Shifter Spring

50

Shifter Fork

51

Shifter Fork Rod

52

Tube Bolt

53

Shift Actuator Assembly

54

Output Shaft Seal Assembly

55

Output Shaft Bearing Assembly

56

Tube

57

Tube Gasket

58

Output Shaft Locator Thrust Washer

59

Output Shaft Thrust Washer

60

Output Shaft Snap Ring

61

Shifter Sleeve

2008 Chevrolet Silverado 1500

2008 Driveline/Axle Front Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

speeds from 60-100 km/h (40-60 mph) depending upon road and load conditions, or upon gear
ratio and tire size. Noise of this kind does not indicate trouble in the axle assembly.

When an axle is suspected of being noisy, make a thorough test in order to determine whether the
noise originates in the tires, road surface, wheel bearings, engine, transmission, propeller shaft, or
axle assembly.

Classifying the Symptom

Front Drive Axle symptoms can usually be classified into the following categories:

Leaks

Noises

Vibrations

Leak and noise related symptoms are diagnosed within the Front Drive Axle section. For
vibration related symptoms, refer to Diagnostic Starting Point - Vibration Diagnosis and
Correction .

Visual/Physical Inspection

Inspect the system for loose or missing fasteners.

Inspect the system for loose or leaking components.

Inspect the system for obvious damage or conditions which may cause the symptom.

Symptoms List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom.

Front Drive Axle Noises

Noisy in Drive

Noisy When Coasting

Intermittent Noise

Constant Noise

Noisy on Turns

Front Axle Lubricant Leak Diagnosis

FRONT DRIVE AXLE NOISES

2008 Chevrolet Silverado 1500

2008 Driveline/Axle Front Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Gear Noise

Gear noise or whine is audible from 32-89 km/h (20-55 mph) under 4 driving conditions:

Drive-Acceleration or heavy pull

Road Load-Vehicle driving load or constant speed

Float-Using enough throttle to keep the vehicle from driving the engine, the vehicle slows
down gradually but the engine still pulls slightly.

Coast-Throttle is closed and the vehicle is in gear.

Gear noise most frequently has periods where the noise is more prominent, usually between 48-64
km/h (30-40 mph) and 80-85 km/h (50-53 mph). Gear whine is corrected by ring and pinion gear
replacement or adjustment, depending on the mileage of the gear set.

Bearing Noise

Faulty bearings produce a rough growl or grating sound, rather than the whine typical of gear
noise. Bearing noise (hum) will pulsate at a constant vehicle speed. This indicates a bad pinion or
a bad front axle side bearing. This noise can be confused with front wheel bearing noise. Inspect
and replace the bearings and the affected components as required.

Front Wheel Bearing Noise

A rough front wheel bearing produces a noise which continues with the vehicle coasting at low
speed and the transmission in neutral. The noise may diminish some when the brakes are gently
applied. The noise may also change when performing side-to-side maneuvers with the vehicle.

A rough and/or noisy wheel bearing can be heard by spinning the wheels by hand and listening at
the hubs for the noise. Inspect and replace the bearings and the affected components as needed.

Knock at Low Speeds

A low speed knock can be caused by a differential case side gear bore that has worn oversize.
Inspect the side gears and the differential case assembly and replace the components as necessary.

Backlash Clunk

Excessive backlash clunk under acceleration or de-acceleration can be caused by any of the
following:

Worn differential pinion shaft

Worn differential pinion and/or side gear teeth

2008 Chevrolet Silverado 1500

2008 Driveline/Axle Front Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado