Symptom Chart - NVH: Chuckle

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Chuckle that occurs on the coast driving phase is usually caused by excessive clearance between the differential gear hub and the differential case bore.

Damage to a gear tooth on the coast side can cause a noise identical to a chuckle. A very small tooth nick or ridge on the edge of a tooth can cause the noise.

Clean the gear tooth nick or ridge with a small grinding wheel. If the damaged area is larger than 3.2 mm (1/8 in), install a new gearset.

To check the differential ring gear and pinion, 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.

If either gear is scored or damaged badly, install a new differential ring gear and pinion.

Fig 1: Locating Damaged Ring Gear

Courtesy of FORD MOTOR CO.

If metal has broken loose, the differential housing must be cleaned to remove particles that will cause damage. At this time, any other damaged parts in the differential housing must also be discarded and new parts installed.