Noise Conditions

- Gear noise is typically a howling or whining of the ring gear and pinion due to an improper gear pattern, gear damage or improper bearing preload. It can occur at various speeds and driving conditions or it can be continuous.
- Chuckle is a particular rattling noise that sounds like a stick against the spokes of a spinning bicycle wheel. It occurs while decelerating from 64 km/h (40 mph) and can usually be heard all the way to a stop. The frequency varies with vehicle speed.
- Chuckle that occurs on the driving phase is usually caused by excessive clearance due to differential gear wear or by a damaged tooth on the coast side of the pinion or ring gear.
- Knock is very similar to chuckle, though it may be louder and occurs on acceleration or deceleration. The teardown will disclose what service is required.
- Chatter on corners occurs when the whole rear end vibrates only when the vehicle is moving. The vibration is plainly felt as well as heard. In conventional axles, extra differential thrust washers cause a condition of partial lockup that creates this chatter. Chatter noise on Traction-Lok(R) axles can usually be traced to erratic movement between adjacent clutch components and can sometimes be corrected with a lubricant change and the addition of Additive Friction Modifier C8AZ-19B546-A or equivalent meeting Ford specification EST-M2C118-A.
- Click at engagement is a condition when the axle produces a slight noise, distinct from a clunk, that happens in REVERSE or DRIVE engagement. Check for the presence of a pinion oil slinger.
- Rear hub noise is similar to gear noise and pinion bearing whine. However, rear hub bearing noise will normally distinguish itself from gear noise by occurring in all driving modes (drive, coast and float) and will persist with transmission in NEUTRAL while vehicle is moving at problem speed. If vehicle displays this noise condition upon ride evaluation, inspect the rear hub for looseness (proper torque on hub nut), side-to-side play and leakage of grease. Correct as necessary. Reevaluate vehicle for noise before removing any internal rear hub components.
- Boom occurs when ring gear teeth have a back lash variation of more than 0.10 mm (0.004 inch).

Any damage to a gear tooth on the coast side can cause a noise identical to chuckle. Even a very small tooth nick or ridge on the edge of a tooth is enough to cause the noise.

This condition can be corrected and the noise eliminated by cleaning up the gear tooth nick or ridge with a small grinding wheel. If the cleaned up or damaged area is larger than 3.2 mm (118 inch), replace the gearset.

If either gear is scored or damaged badly, the gearset must be replaced. Also, if there is metal broken loose, the carrier and housing must be cleaned to remove particles that could cause damage later. Any other damaged parts in the axle must be replaced.

To check the gearset, remove as much lubricant as possible from the gears with clean solvent. Wipe the gears dry or blow them dry with compressed air. Look for scored or damaged teeth. Also, look for cracks or other damage.