Component Tests and General Diagnostics

Gear Howl and Whine

Howling or whining of the ring gear and drive pinion are due to an incorrect gear pattern, gear damage or incorrect bearing preload.

Bearing Whine

Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by worn/damaged pinion bearings. Bearing noise occurs at all driving speeds. This distinguishes it from gear whine which is speed dependent.

As noted, pinion bearings make a high-pitched, whistling noise, usually at all speeds. If however there is only one pinion bearing that is worn/damaged, the noise may vary in different driving phases.

A wheel bearing noise can be mistaken for a pinion bearing noise.

Knock

Knock, which can occur on all driving phases, has several causes including damaged teeth or gearset.







A gear tooth damaged on the drive side is a common cause of the knock.

Bearing Rumble

Bearing Rumble is usually caused by a worn/damaged wheel bearing. The lower pitch is because the wheel bearing turns at only about one-third of the driveshaft speed. Wheel bearing noise may also be high-pitched, similar to gear noise, but will be evident in all four driving modes.