Dodge 2000 DURANGO Service Manual page 84

3 - 34 C205F AXLE
DIAGNOSIS AND TESTING (Continued)
Condition
Axle Noise
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, tooth contact, worn/damaged
gears, or the carrier housing not having the proper
offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are accelera-
tion, deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate the vehicle to the speed range where the noise is
the greatest. Shift out-of-gear and coast through the
peak–noise range. If the noise stops or changes
greatly:
• Check for insufficient lubricant.
• Incorrect ring gear backlash.
• Gear damage.
Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight–ahead driving when the gears
are unloaded. The side gears are loaded during vehi-
cle turns. A worn pinion mate shaft can also cause a
snapping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion bearings can
all produce noise when worn or damaged. Bearing
noise can be either a whining, or a growling sound.
Pinion bearings have a constant–pitch noise. This
noise changes only with vehicle speed. Pinion bearing
noise will be higher pitched because it rotates at a
Possible Causes
1. Insufficient lubricant.
2. Improper ring gear and pinion
adjustment.
3. Unmatched ring gear and pinion.
4. Worn teeth on ring gear and/or
pinion.
5. Loose pinion bearings.
6. Loose differential bearings.
7. Mis-aligned or sprung ring gear.
8. Loose differential bearing cap
bolts.
9. Housing not machined properly.
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
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 rear of the vehicle is usually
caused by a:
• Damaged drive shaft.
• Missing drive shaft balance weight(s).
• Worn or out–of–balance wheels.
• Loose wheel lug nuts.
• Worn U–joint(s).
• Loose/broken springs.
Correction
1. Fill differential with the correct
fluid type and quantity.
2. Check ring gear and pinion
contact pattern.
3. Replace gears with a matched
ring gear and pinion.
4. Replace ring gear and pinion.
5. Adjust pinion bearing pre-load.
6. Adjust differential bearing
pre-load.
7. Measure ring gear run-out.
Replace components as necessary.
8. Inspect differential components
and replace as necessary. Ensure
that the bearing caps are torqued
tot he proper specification.
9. Replace housing.
DN