Chevrolet Light Duty Truck 1973, Service Manual

Page: 259 / 979

REAR S U S P E N S IO N A N D DRIVE LINE 4 -3 5
6
. Lubricate the cavity between the seal lips with a high
melting point bearing lubricant.
7. Install a new pinion oil seal into the bore, using
J-24434 for Chevrolet 10-1/2” axles, J-24384 for Dana
10-1/2" axles, and J-22281 for 12-1/4" axles. Be sure
seal bottoms against shoulder in bore.
8
.
For 12-1/4" axles,
install the bearing retainer to the
carrier.
9. Reinstall the companion flange, pinion nut and pro­
peller shaft.
CAUTION:
See CAUTION on page 1 of this
section, regarding the above fasteners.
Fig. 77—Pinion O il Seal—12-1/4” A xle
DIFFERENTAIL D IA G N O S IS
STANDARD DIFFERENTIAL
Noise
The most essential part of rear axle service, as with any
mechanical repair, is proper diagnosis of the problem, and, in
axle work one of the most difficult areas to diagnosis is noise.
Locating a broken axle shaft, or broken differential gear,
presents little or no problem, but, locating and isolating axle
noise can be an entirely different matter.
Fig. 78—Noise Level
Degree of Noise
Any gear driven unit, and especially an automotive drive
axle where engine torque multiplication occurs at a 90°
turn in the drive line, produces a certain amount of
noise. Therefore, an interpretation must be made for
each vehicle to determine whether the noise is normal or
if a problem actually exists. A normal amount of noise
must be expected and cannot be eliminated by
conventional repairs or adjustment. See figure 78.
Acceptable noise can be defined as a slight noise heard
only at a certain speed or under unusual or remote
conditions. For example, this noise tends to reach a
"peak" at speeds from 40 to 60 miles per hour
depending on road and load conditions, or on gear ratio
and tire size. This slight noise is in no way indicative of
trouble in the axle assembly.
Drive line noises may baffle even the best diagnostician.
Vehicle noises coming from tires, transmission, propeller
shaft, universal joints, and front or rear wheel bearings,
are often mistaken for axle noise. Such practices as:
raising tire pressure to eliminate tire noise (although this
will not silence tread noise of mud and snow tires),
listening for the noise at varying speeds and road
surfaces, on drive, float, and coast conditions will aid in
locating the source of alleged axle noises. Thus, every
effort should be made to isolate the noise to a specific
drive line component instead of making a random guess
that could be a costly waste of time.
LIGHT DUTY TRUCK SERVICE MANUAL