Gear Noise, Analysis

Gear Howl and Whine

When disassembling the axle to diagnose and correct gear noise, it is assumed that the tires, exhaust, and trim items have first been checked and negated as possible causes.

The noises described under Road Test usually have specific causes that can be diagnosed by observation as the unit is disassembled. The initial clues are, of course, the type of noise heard on the road test and the driving conditions.

Knock

Knock, which can occur on all driving phases, has several causes. In most cases, one of the following conditions has occurred:

1. A gear tooth damaged on the driver's side is a common cause of the knock. This can usually be corrected by grinding the damaged area.

2. Knock is also characteristic of excessive end play in the axle shafts. Up to 0.762mm (0.030 inch) is allowed in most axles. The frequency of knock will be less because the axle shaft speed is slower than the driveshaft.

   NOTE: Be sure to measure the end play with a dial indicator, not by feel. A guess usually feels like far more end play than there actually is.

   On the integral axle, end play is allowable up to 0.762mm (0.030 inch). It is controlled by the C-washer that holds the shaft in the pocket of the side gear.