Chevrolet 1980 Light Duty Truck Service Manual page 350

4C-2 FRONT WHEEL DRIVE
FRONT WHEEL, PIN IO N , DIFFERENTIAL SIDE A N D REAR WHEEL ROLLER BEARINGS
Road Test
Tire Noises
Engine or
Exhaust
Noises
Test for
Wheel Bearing
Noise
Test for
Differential
Bearing Noise
Test for
Pinion Bearing
Noise
Disassembly
Refer to Section 3C for hub, spindle and knuckle
removal and installation procedures.
1. Securely mount the axle assembly in a suitable
holding fixture.
2. If the vehicle is not equipped with RPO F76
freewheeling hubs, remove the hub cap and snap ring.
BEARINGS AND RACES
DIAGNOSIS
EXCESS IMOISE COMPLAINT
DIAGNOSTIC PROCEDURE
1. Check tires for irregular wear
2. Check tire pressure
3. Check lubricant level
4. Drive to warm-up rear axle
5. Test at various speeds in drive, float, coast and cornering
1. Change tire pressure to minimize noises
2. Drive over different road surfaces
3. Smooth black-top minimizes tire noise
4. Cross switch tires, if necessary
5. Snow tire treads and studs caused added noises
1. Drive slightly above speed where noise occurs, place transmission in neutral
2. Let engine speed drop to idle
3. Stop car
4. Run engine at various speeds
1. Drive car at low speed on a smooth road
2. Turn car to develop left and right motions, traffic permitting
3. Noise should change due to cornering loads
4. Jack-up wheels to verify roughness at wheels
1. Drive car at low speed on a smooth road
2. Constant low pitch bearing noise may be heard
3. Noise should not change in reversing turns
4. Noise pattern should vary with wheel speed
1. Roughness or whine noise should increase with speed
2. Noise pitch should be higher than differentials
3. Test on smooth road to minimize tire noises
4. Test at various speeds in drive, float, and coast
5. Rear pinion bearing noise may be louder on acceleration
6. Front pinion bearing noise may be louder on deceleration
7. Gear noises tend to peak in a narrow speed range
Fig. 4C-1--Bearing Diagnosis
3. Remove the drive gear and pressure spring. Place
a hand over the drive gear and use a screwdriver to pry the
gear out.
4. Remove the wheel bearing outer lock nut, lock ring,
and wheel bearing inner adjusting as outlined in Section 3C.
5. Remove the disc assembly outer wheel bearing and
the spring retainer plate.
LIG H T T R U C K S ER V IC E M ANUAL