Driveline Module Assembly Noise

The most important part of driveline module service is properly identifying the cause of failures and noise complaints. The cause of most driveline module failures is relatively easy to identify. The cause of driveline module noise is more difficult to identify.

If vehicle noise becomes intolerable, an effort should be made to isolate the noise. Many noises that are reported as coming from the driveline module may actually originate at other sources. For example:

• Tires
• Road surfaces
• Wheel bearings
• Engine
• Transmission
• Exhaust
• Propeller shaft (vibration)
• Vehicle body (drumming)

Driveline module noises are normally divided into two categories: gear noise or bearing noise. A thorough and careful inspection should be completed to determine the actual source of the noise before replacing the driveline module. Other sources of noise from the rear driveline module are the pump, actuator, and low hydraulic fluid level.

The rubber mounting bushings help to dampen-out driveline module noise when properly installed. Inspect to confirm that no metal contact exists between the driveline module case and the body or suspension cradle. The complete isolation of noise to one area requires expertise and experience. Identifying certain types of vehicle noise baffles even the most capable technicians. Often such practices as:

• Increase tire inflation pressure to eliminate tire noise.
• Listen for noise at varying speeds with different driveline load conditions
• Swerving the vehicle from left to right to detect wheel bearing noise.

All driveline module assemblies produce noise to a certain extent. Slight carrier noise that is noticeable only at certain speeds or isolated situations should be considered normal. Carrier noise tends to peak at a variety of vehicle speeds. The pump and actuator may be audible in certain situations that may be normal. Noise is NOT ALWAYS  an indication of a problem within the carrier or rear driveline module components.