Chevrolet 1980 Light Duty Truck Service Manual page 336

4B-10 REAR AXLE
Problem
1. Noise is the same in drive or coast
2. Noise changes on a different type of road
3. Noise tone lowers as car speed is lowered
4. Similar noise is produced with car standing
and driving
5. Vibration
6. A knock or click approximately every two
revolutions of rear wheel
7. Noise most pronounced on turns
8. A continuous low pitch whirring or scraping
noise starting at relatively low speed
9. Drive noise, coast noise or float noise
10. Clunk on acceleration or deceleration
11. Grunt on stops
12. Groan in Forward or Reverse
13. Chatter on turns
14. Clunk or knock on rough road operation
A GENERAL DIAGNOSTIC PROCEDURE FOR
ISOLATING REAR AXLE NOISE PROBLEMS
Fig. 4B-1 1-Diagnosis of Noise Problems
Cause
1. a) Road noise
b) Tire noise
c) Front wheel bearing noise
2. a) Road noise
b) Tire noise
3. Tire noise
4. a) Engine noise
b) Transmission noise
5. a) Rough rear wheel bearing
b) Unbalanced or damaged propeller shaft
c) Tire unbalance
d) Worn universal joint in propeller shaft
e) Mis-indexed propeller shaft at companion
flange
f) Companion flange runout too great
6. A brinelled rear wheel bearing
7. Differential side gear and pinion
8. Pinion bearing
9. Ring and pinion gear
10. Worn differential cross shaft in case
11. No grease in propeller shaft slip yoke
12. Wrong lube in differential
13. a) Wrong lube in differential
b) Clutch plates worn
14. Excessive end play of axle shafts to differential
cross shaft
LIG H T T R U C K S ER V IC E M AN UAL