Dodge dakota 2002 Service Manual page 119

3 - 46 FRONT AXLE - 9 1/4 AA
FRONT AXLE - 9 1/4 AA (Continued)
heard during a coast, the front pinion bearing is the
source.
Worn or damaged differential bearings usually pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differen-
tial bearing noise is also constant and varies only
with vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn
U-joint or by worn side-gear thrust washers. A worn
pinion shaft bore will also cause low speed knock.
VIBRATION
Vibration at the front/rear of the vehicle is usually
caused by:
• Damaged drive shaft.
• Missing drive shaft balance weight(s).
• Worn or out of balance wheels.
• Loose wheel lug nuts.
• Worn U-joint(s).
Condition
Wheel Noise
Axle Shaft Noise
• Loose/broken springs.
• Damaged axle shaft bearing(s).
• Loose pinion gear nut.
• Excessive pinion yoke run out.
• Bent axle shaft(s).
Check for loose or damaged front end components
or engine/transmission mounts. These components
can contribute to what appears to be a vibration. Do
not overlook engine accessories, brackets and drive
belts.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged) can be caused by:
• High engine idle speed.
• Transmission shift operation.
• Loose engine/transmission/transfer case mounts.
• Worn U-joints.
• Loose spring mounts.
• Loose pinion gear nut and yoke.
• Excessive ring gear backlash.
• Excessive side gear to case clearance.
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the vehi-
cle on a hoist with the wheels free to rotate. Instruct
the helper to shift the transmission into gear. Listen
for the noise, a mechanics stethoscope is helpful in
isolating the source of a noise.
DIAGNOSTIC CHART
Possible Causes
1. Wheel loose.
2. Faulty, brinelled wheel bearing.
1. Misaligned axle tube.
2. Bent or sprung axle shaft.
3. End-play in pinion bearings.
4. Excessive gear backlash
between the ring gear and pinion.
5. Improper adjustment of pinion
gear bearings.
6. Loose pinion yoke nut.
7. Scuffed gear tooth contact
surfaces.
Correction
1. Tighten loose nuts.
2. Replace bearing.
1. Inspect axle tube alignment.
Correct as necessary.
2. Inspect and correct as necessary.
3. Refer to pinion pre-load
information and correct as
necessary.
4. Check adjustment of the ring
gear and pinion backlash. Correct
as necessary.
5. Adjust the pinion bearings
pre-load.
6. Tighten the pinion yoke nut.
7. Inspect and replace as
necessary.
DR