What a Long Strange Journey It’s Been – the title of the Grateful Dead’s second compilation album – has long been used to describe any odd path in life, from stories of personal growth to the histories of great people of business. It may be applied to the popularity of 4WD/AWD vehicles. Four-wheel drive has been around for 100 years, but it took some strange turns to evolve from a drive-system for heavy vehicles to an absolute necessity for new vehicle buyers.
WWII contributed in the form of the much-loved Jeep that was at home in both the muddy fields of Europe and those in the US, along with dusty, near-impassible trails across the country. But it took efforts from smaller players, like Subaru which made AWD mainstream and the oddball AWD AMC Eagle, to capture the public’s full attention. From there, a buying movement away from cars and into trucks and SUVs where 4WD/AWD was usually an option, only drove the popularity of these systems. The advent of crossovers made them a normal part of the automotive landscape.
The public decided 4WD/AWD tech was a worthy investment that kept them safer and their vehicles further out of harm’s way. There’s plenty of truth to that, but these vehicles are far from accident free. American drivers have a tendency to push such technology to its limits, oftentimes foolish limits such as caution-free driving on icy roads where 4WD/AWD may be ineffective. Then there are accidents that can’t be avoided because they’re the fault of the other guy/gal. Whatever the case, odds are you see plenty of 4WD/AWD drive vehicles come through your doors.
Repairing these systems has become an increasingly challenging endeavor. This is especially true with AWD, since AWD systems tend both to incorporate more electronic components and use automatic/part-time versions requiring more input from sensors and others electronics. (Also, 4WD systems tend to be more robust and hold up better in many collisions.) Repairing these systems can involve some intense diagnosis and post-repair checks to ensure the work is done thoroughly. Use the following directions supplied by GM to guide your work on AWD.
All-Wheel Drive System Functional Inspection
The following steps for a 2020 Chevrolet Trax (the small GM crossover) should be performed and after a repair to test the AWD and determine that it is working properly.
Check the rear axle activation and operation by positioning the four wheels off the ground. Then, start the vehicle fully applying the parking brake and selecting the drive position.
Caution: To avoid rear differential damage, do not exceed 20 percent accelerator pedal application or apply throttle for more than 5 seconds while the parking brake is applied.
1. Lift the vehicle.
2. Ask another tech or helped to lightly depress the accelerator pedal.
3. Watch the rear wheels. They will rotate slightly as the drive line winds-up. This indicates the AWD is functioning.2020 Chevy Traverse
Tracing the source of a ratcheting noise during AWD engagement – Replacing the propeller shaft
Some AWD damage may not turn up until you’re able to test drive the vehicle. As always, you should perform a full diagnostic of the vehicle and look for any sensor issues. Some problems still aren’t going to reveal themselves until a vehicle’s wheels hit the streets.
The following steps outline tracing the source of a clicking/ratcheting noise to a damaged propeller shaft and then replacing the part on a 2020 Chevy Traverse.
Note that a clicking or ratcheting noise that is heard during AWD engagement or dis-engagement often is related to the AWD disconnect components internal to the power transfer unit. A single light click noise that is heard during AWD engagement is a normal operating characteristic of the vehicle.
Diagnosis
1. Compare the noise to a similar vehicle to see if a normal condition.
2. Note specifics such as, vehicle speed, road conditions, whether the noise is present on acceleration, deceleration, coast, turns or other specifics. Also note if the noise is present in 2WD, AWD-Sport, AWD-off road, or AWD-trailer (model dependent) mode.
3. Identify the source of the noise using chassis ears and refer to the appropriate service manual section.
4. If the source of the noise is the power transfer unit, inspect for the correct fluid level. Refer to GM’s Power Transfer Unit Case Fluid Replacement documentation.
5. Inspect the drain plug for large metal deposits. Small metal flakes and fine metal dust on the plug magnet are to be considered normal.
6. Inspect for a broken propeller shaft-to- power transfer unit retaining ring. Use the following steps to perform the repair.
Two-Piece Propeller Shaft Replacement
Special Tools
- DT-51329-A Drive Shaft Remover Adapter
- GE-2619-A Slide Hammer
Equivalent regional tools: Refer to GM’s documentation on Special Tools
Removal Procedure
- Raise and support the vehicle.
- Using a paint pen or a suitable marker, mark the relationship of the propeller shaft to the differential carrier assembly. This will be used as a visual reference for proper engagement location after re-installation.
- Using a paint pen or a suitable marker, mark the relationship of the propeller shaft to the power transfer unit. This will be used as a visual reference for proper engagement location after re-installation.
- Support the front of the differential carrier assembly with a jack stand.
- Lower the front of the differential carrier assembly to provide additional clearance between the propeller shaft and the fuel tank.
Caution: Use only the GM Special Tools Specified to remove the Propeller Shaft from the Differential Carrier Assembly. Prying on these components with any other tools may cause damage to either part which will result in improper performance or future failure.
- Note the correct location of the propeller shaft service groove prior to installing the DT-51329-A Drive Shaft Remover Adapter.
Caution: When removing the propeller shaft, DO NOT pry against the rear differential module slinger. Prying against the rear differential module slinger may cause damage to the slinger, which will result in unnecessary replacement of the rear differential module slinger.
Note: The 5/16 - 18 x 3.5 in. bolts included with the tool are to be used for this application.
- Install the DT-51329-A Drive Shaft Remover Adapter at the service groove located on the propeller shaft.
- Install the GE-2619-A Slide Hammer to the DT-51329-A Drive Shaft Remover Adapter.
- Using the GE-2619-A Slide Hammer and the DT-51329-A Drive Shaft Remover Adapter, separate the propeller shaft from the rear differential carrier assembly.
- Remove the GE-2619-A Slide Hammer and the DT-51329-A Drive Shaft Remover Adapter.
- Using a suitable jack stand, support the propeller shaft.
- Note the correct location of the propeller shaft service groove prior to installing the DT-51329-A Drive Shaft Remover Adapter.
Caution: When removing the propeller shaft, DO NOT pry against the power transfer unit. The power transfer unit will be damaged if it is pried against, which will result in unnecessary replacement of the power transfer unit.
Note: The 5/16” - 18 x 3.5” bolts included with the tool are to be used for this application.
Install the DT-51329-A Drive Shaft Remover Adapter at the service groove located just forward of the propeller shaft bearing bracket.Caution: Use only the GM Special Tools Specified to remove the Propeller Shaft from the Differential Carrier Assembly. Prying on these components with any other tools may cause damage to either part which will result in improper performance or future failure.
- Using the GE-2619-A Slide Hammer and the DT-51329-A Drive Shaft Remover Adapter, separate the propeller shaft from the power transfer unit.
- Remove the GE-2619-A Slide Hammer and the DT-51329-A Drive Shaft Remover Adapter.
- Remove the Rear Propeller Shaft Bearing Bracket Bolt.
Caution: When servicing the propeller shaft, support both ends of the propeller shaft evenly to limit the movement of propeller shaft joints to a maximum of 10 degrees. Do not let the propeller shaft hang unsupported at any time, as it will cause damage to the propeller shaft boots
Note: Due to the weight and length of the propeller shaft, not allowing excessive movement of the joints may be difficult during removal and installation. It is recommended to use the aid of an assistant to remove and install the propeller shaft.
- Remove the Propeller Shaft.
- Remove and discard the Propeller Shaft to Differential Carrier Interface Retainer.
- Remove and discard the O-Ring at the Differential Carrier Assembly.
- Remove and discard the Power Transfer Unit Propeller Shaft Retainer.
- Remove and discard the Power Transfer Unit Propeller Shaft Seal.
Installation Procedure
- Tighten the Differential Carrier Front Bolt referring to GM’s Differential Carrier Assembly Replacement documentation.
- Install the new Power Transfer Unit Propeller Shaft Seal.
Note: Walk on the retaining ring over the nose of the shaft to avoid distortion.
- Install the new Propeller Shaft to Differential Carrier Interface Retainer.
Caution: When servicing the propeller shaft, support both ends of the propeller shaft evenly to limit the movement of propeller shaft joints to a maximum of 10 degrees. Do not let the propeller shaft hang unsupported at any time, as it will cause damage to the propeller shaft boots
Note: Due to the weight and length of the propeller shaft, not allowing excessive movement of the joints may be difficult during removal and installation. It is recommended to use the aid of an assistant to remove and install the propeller shaft.
- Using a suitable jack stand, support the propeller shaft.
Note: When installing the propeller shaft to the differential carrier assembly, align the balance index paint mark on the propeller shaft to the paint mark on the differential carrier assembly shield/slinger.
- Install the propeller shaft so that it aligns with the reference mark at the differential carrier assembly.
- Install the propeller shaft so that it aligns with the reference mark at the power transfer unit.
Caution: Refer to GM’s Fastener Caution document.
- On the Rear Propeller Shaft Bearing Bracket Bolt, install and tighten at 58 Y (43 lb ft).
- Conduct a retention check on the propeller shaft front and rear interface. Place your hands around the propeller shaft tube just behind the interface and lightly pull on the propeller shaft tube without using leverage or body weight. For rear, place hands around the rear CV joint and pull without using leverage or body weight. The intention is to check that the retaining ring snapped into position, not to forcefully remove a correctly installed propeller shaft.
- Remove the support and lower the vehicle.
Rear Wheel Bearing and Hub Replacement (AWD)
Use the following directions to remove and replace the rear wheel bearing and hub on a 2020 Chevrolet Traverse AWD. Note that this procedure differs for the AWD version of the Traverse, something you’ll want to keep in mind when working on such vehicles.
Removal Procedure
- Raise and support the vehicle referring to GM’s Lifting and Jacking the Vehicle documentation.
- Remove the rear tire and wheel assembly referring to GM’s Tire and Wheel Removal and Installation documentation.
- Remove the rear wheel speed sensor at the rear suspension knuckle referring to GM’s Rear Wheel Speed Sensor Replacement documentation.
- Remove the rear brake rotor referring to GM’s Rear Brake Rotor Replacement documentation.
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Separate the appropriate rear wheel drive shaft from the affected rear wheel hub:
- Refer to GM’s Rear Wheel Drive Shaft Replacement - Left Side documentation.
- Refer to GM’s Rear Wheel Drive Shaft Replacement - Right Side documentation.
Remove and discard the Rear Wheel Hub Bolt.
- Remove Rear Wheel Hub.
Installation Procedure
Note: Avoid applying grease to any other machined surface, holes or threads. Ensure the drain channel at the bottom of the bore is not blocked with grease or debris.
- Apply grease evenly and ensure complete coverage to the knuckle bearing pilot bore only. Refer to GM’s Adhesives, Fluids, Lubricants, and Sealers documentation.
- Install the Rear Wheel Hub.
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Due to the unknown shelf life of the adhesive patch, prepare the NEW rear wheel hub bolts as follows:
- Remove all traces of the adhesive patch from the bolts and the mating threads using the appropriate tools.
- Clean the threads of the bolts and mating threads with denatured alcohol or equivalent and allow to dry.
- Apply thread locking adhesive to the bolts.
- Ensure there are no gaps in the thread locking adhesive once applied to the bolt. Caution: This vehicle is equipped with torque-to-yield or single use fasteners. Install a NEW torque-to-yield or single use fastener when installing this component. Failure to replace the torque-to-yield or single use fastener could cause damage to the vehicle or component.
Caution: Refer to GM’s Fastener Caution documentation.
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Install and tighten the Rear Wheel Hub Bolt.
- First Pass: 100 Y (74 lb ft)
- Final Pass: (15 - 30 degrees)
- Install the rear wheel drive shaft to the rear wheel hub:
- Refer to GM’s Rear Wheel Drive Shaft Replacement - Left Side document.
- Refer to GM’s Rear Wheel Drive Shaft Replacement - Right Side document.
6. Install the Rear Brake Rotor using GM’s Rear Brake Rotor Replacement documentation.
7. Install the Rear Wheel Speed Sensor at the Rear Suspension Knuckle using GM’s Rear Wheel Speed Sensor Replacement documentation.
8. Install the rear tire and wheel assembly using GM’s Tire and Wheel Removal and Installation documentation.
- Remove the support and lower the vehicle.