• When the differential is noisy or is suspected of being damaged, first make sure the noise is not any of the following: road noise, tire noise, front bearing noise, transmission and engine noise, driveshaft and u-joint noise.
  • If tests show that the differential or rear axle is noisy, the noise is most likely coming from one of several bad parts. these include the rear wheel bearings, differential side gear and pinion, side bearing, or ring and pinion gear.
  • A knock or clunk is caused by excessive wear or loose or broken parts. A knock is a repetitious rapping sound that occurs during all phases of driving but is most noticeable during acceleration and deceleration when the gears are loaded.
  • A clunk is a sharp, loud noise caused by one part hitting another. Unlike a knock, a clunk can be felt as well as heard. Clunks are generally caused by loose parts striking each other.
  • Limited slip clutch packs or cones that need servicing might be heard as a chatter or a rapid clicking noise that creates a vibration in the vehicle. Chattering is usually noticed when rounding a corner. A change of differential lubricant and adding friction modifier to the fluid sometimes corrects this problem. After draining the oil, replace it with the manufacturer's suggest friction modifier and lubricant. Road test the vehicle again.
  • To make sure that the noise heard during the test drive is coming from the differential, stop the vehicle and shift the transmission into neutral. Run the engine at various rpm levels. If the noise is heard during this procedure, it is caused by a problem somewhere other than in the differential.