Chevrolet Silverado / GMC Sierra. Service manual — part 1407

Fill Plug

Drain and fill plug leaks are usually caused by a loose plug. These leaks can by repaired by either
tightening the plug or by using an approved sealer on the threads on the plug.

Other leaks such as axle tube to differential carrier housing or porosity leaks require the
replacement of the rear axle housing.

LIMITED SLIP DIFFERENTIAL DIAGNOSIS

Limited Slip Differential Diagnosis

Step

Action

Values

Yes

No

1

Did you review the general description
and perform the necessary inspections?

-

Go to Step

2

Go to Diagnostic
Starting Point -
Locking/Limited
Slip Rear Axle

2

Measure the rotational force of the axle
using the following procedure:

1. Block the front wheels.

2. Raise and support the vehicle.

Refer to Lifting and Jacking the
Vehicle .

3. Remove the tire and wheel. Refer

to Tire and Wheel Removal and
Installation .

4. Using the J 28733-B Front/Rear

Spindle Remover, measure the
rotational force of the axle. See
Special Tools.

5. Repeat the procedure for the other

axle.

Does the force measure outside the
specified range?

22-271 N.m

(30-200 lb

ft)

Go to Step

3

System OK

3

Repair the rear axle.
Did you complete the repair?

-

Go to Step

4

-

2008 Chevrolet Silverado 1500

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

LOCKING DIFFERENTIAL DIAGNOSIS

1. Place the vehicle on a frame-contact hoist, allowing free rotation of the rear wheels.

2. Hold 1 wheel stationary. Slowly rotate the other wheel approximately 1/2 revolution per

second in both the forward and reversed directions. The wheel should rotate freely. The
differential is locking and is broken if both wheels attempt to turn together.

3. Raise the hoist to maximum height with 1 person in the vehicle.

4. Start the engine. Ensure that the engine is operating at low idle speed (warm engine).

5. Apply the service brake. Place the automatic transmission in drive. Depress the clutch and

place the transmission in first gear with a manual transmission.

6. Lock 1 rear wheel by pulling one parking brake cable from under the vehicle with the aid of

an assistant.

7. Release the service brakes or disengage the clutch slowly enough to start the free wheel

turning. The locked rear wheel remains stationary.

8. Increase the speed of the free wheel. The differential will lock, causing the rotating wheel to

stop or both wheels to turn at the same speed. The engine, if equipped with manual
transmission, may stall. In order to cause the differential to lock, you may need to accelerate
the engine until approximately 16 km/h (10 mph) is indicated on the vehicle speedometer. If
the indicated speed can be increased beyond 32 km/h (20 mph) without causing the
differential to lock, the unit is not functioning properly. Rapid release of the brakes or
clutch, or rapid acceleration of the engine, will invalidate the test.

9. Lock the opposite rear wheel and repeat the procedure.

LOCKING REAR AXLE DOES NOT LOCK

4

Operate the system in order to verify the
repair.
Did you correct the condition?

-

Go to Step

2

System OK

Checks

Action

Little or no preload on the
latching bracket

Replace the governor assembly and the latching bracket. Refer
to Locking Differential Disassemble (8.6, 9.5LD Axles)
and Locking Differential Cam Unit Disassemble (9.5 Inch
Axle).

Flyweights in the governor
assembly are stuck closed

Replace the governor assembly and the latching bracket. Refer
to Locking Differential Assemble (9.5 Inch Axle) and

Locking Differential Assemble (9.5 Inch Axle)

.

The drive teeth on the

Replace the cam plate, the governor assembly, and the latching

2008 Chevrolet Silverado 1500

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

LOCKING REAR AXLE LOCKS IN TURNS

governor or cam gear
assembly are broken

bracket. Refer to the following:

Locking Differential Disassemble (8.6, 9.5LD Axles)

Locking Differential Cam Unit Disassemble (9.5
Inch Axle)

Locking Differential Cleaning and Inspection

Locking Differential Cam Unit Assemble (8.6 Inch
Axle) or Locking Differential Cam Unit Assemble
(9.5 Inch Axle)

Locking Differential Adjustment (8.6 Inch Axle) or
Locking Differential Adjustment (9.5 Inch Axle)

Locking Differential Assemble (9.5 Inch Axle)

Broken clutch plates

Replace the clutch plates and the wave spring. Refer to the
following:

Locking Differential Disassemble (8.6, 9.5LD Axles)

Locking Differential Cam Unit Disassemble (9.5
Inch Axle)

Locking Differential Cleaning and Inspection

Locking Differential Cam Unit Assemble (8.6 Inch
Axle) or Locking Differential Cam Unit Assemble
(9.5 Inch Axle)

Locking Differential Adjustment (8.6 Inch Axle) or
Locking Differential Adjustment (9.5 Inch Axle)

Locking Differential Assemble (9.5 Inch Axle)

Checks

Action

The governor assembly is
tight in the case

Free up the governor assembly. Refer to Locking
Differential Disassemble (8.6, 9.5LD Axles) and Locking
Differential Assemble (9.5 Inch Axle).

Broken or weak governor
flyweight spring

Replace the governor assembly and the latching bracket. Refer
to Locking Differential Disassemble (8.6, 9.5LD Axles)
and Locking Differential Assemble (9.5 Inch Axle).

The flyweight in the

Replace the governor assembly and the latching bracket. Refer

2008 Chevrolet Silverado 1500

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

LOCKING REAR DRIVE AXLE CHATTERS IN TURNS

NOISE IN ADDITION TO NORMAL CLUTCH ENGAGEMENT

governor assembly is stuck
open

to Locking Differential Disassemble (8.6, 9.5LD Axles)
and Locking Differential Assemble (9.5 Inch Axle).

The cam plate or the
governor drive teeth are
broken

Replace the cam plate, the governor assembly, and the latching
bracket. Refer to the following:

Locking Differential Disassemble (8.6, 9.5LD Axles)

Locking Differential Cam Unit Disassemble (9.5
Inch Axle)

Locking Differential Cleaning and Inspection

Locking Differential Cam Unit Assemble (8.6 Inch
Axle) or Locking Differential Cam Unit Assemble
(9.5 Inch Axle)

Locking Differential Adjustment (8.6 Inch Axle) or
Locking Differential Adjustment (9.5 Inch Axle)

Locking Differential Assemble (9.5 Inch Axle)

Checks

Action

Lubricant is contaminated

Drain and flush the axle housing thoroughly. Refill with the
correct lubricant. Refer to Rear Axle Lubricant
Replacement (8.6 Inch Axle) or Rear Axle Lubricant
Replacement (9.5 Inch LD Axle) or Rear Axle Lubricant
Replacement (10.5 Inch Axle).

The clutch plates are
deteriorated

Replace the clutch plates. Refer to Locking Differential
Cam Unit Disassemble (9.5 Inch Axle) and Symptoms -
Locking/Limited Slip Rear Axle.

Checks

Action

The clutch plates are broken Replace the clutch plates. Refer to the following:

Locking Differential Disassemble (8.6, 9.5LD Axles)

Locking Differential Cam Unit Disassemble (9.5
Inch Axle)

Locking Differential Cleaning and Inspection

2008 Chevrolet Silverado 1500

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