Transmission and Drivetrain: Testing and Inspection

Certain rear axle and driveline concerns are also common to the engine, transmission, wheel bearings, tires and other parts of the vehicle. For this reason, make sure the cause of the trouble is in the rear axle before adjusting, servicing or replacing any of the parts.
Rear axle concerns can be diagnosed and corrected quickly by following the proper procedures. Being able to perform a good diagnosis is necessary in order to eliminate guesswork and save time.
This section defines various possible rear axle conditions and tests for identifying the cause and the service procedure. The four rear axle conditions that will be reviewed are:
1. Leakage conditions:
a. rear axle drive pinion seal
b. drive pinion nut
c. inner wheel bearing oil seals
d. casting porosity
e. weld leaks
f. rear axle housing vent
2. Vibration conditions:
a. tires
b. driveline angle
c. axle shaft runout
d. drive pinion stem and rear axle universal joint flange
3. Noise conditions:
a. non-axle noise
b. axle noise
(1) gear noise
(2) chuckle
(3) knock
(4) clunk
(5) bearing whine
(6) chatter on corners
(7) click at engagement
(8) axle shaft noise
c. bearing rumble
4. Inoperative conditions:
a. Broken pinion stem
b. Broken welds
c. Wheel bearing malfunctions
d. Axle lockup
The diagnostic material also deals with symptom analysis which aids the technician in discovering the original cause of a concern repeat service can be avoided. However, the purpose of this section is to provide information on service steps of special importance.