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3 -3 4 FRONT SU S PEN SIO N
FRONT WHEEL, PINION, DIFFERENTIAL SIDE AND 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
iNoise
DIAGNOSIS
EXCESS NOISE C O M PLA IN T
D IAG NO STIC 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
.
Front pinion bearing noise may be louder on deceleration
6
7.
Gear noises tend to peak in a narrow speed range
Fig. 47—Bearing Diagnosis
LIGHT DUTY TRUCK SERVICE MANUAL
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