Ford Mustang (1999-2004) Service Manual: Chuckle
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 inch), install a new gearset.
To check the 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 ring gear and pinion.

If metal has broken loose, the axle housing must be cleaned to remove particles that will cause damage. At this time, any other new parts in the axle housing must also be installed, if necessary.
Bearing Whine
Bearing whine is a high-pitched sound similar to a whistle. It is usually
caused by worn/damaged
pinion bearings, which are operating at driveshaft speed. Bearing noise occurs
at all driving speeds. ...
Knock
Knock, which can occur on all driving phases, has several causes including
damaged teeth or gearset.
In most cases, one of the following conditions will occur:
1. A gear tooth damaged on the drive s ...
Other materials:
Removal
1. Remove the upper intake manifold. For additional information, refer to
Upper Intake Manifold in
this section.
2. Partially drain the cooling system. For additional information, refer to
Section.
3. Relieve the fuel system pressure. For additional i ...
Electronic Leak Detection
Special Tool(s)
H10PM Refrigerant Leak
Detector With Battery
216-00001 or equivalent
CAUTION: Good ventilation is necessary in the area where electronic A/C
leak testing is to
be carried out. If the surrounding air is contaminated with refri ...
Pressure Plate Check
1. Check the clutch pressure plate surface for scoring, cracks or
discoloration. Minor scratches or
discoloration should be removed with a fine emery cloth.
2. Measure the flatness of the clutch pressure plate surface with a
straightedge and a feeler
g ...
