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Chevrolet Silverado / GMC Sierra. Manual - part 1229
DRIVE AXLE - NOISE DIAGNOSIS
Unrelated Noises
Some driveline trouble symptoms are also common to the engine, transmission, wheel bearings,
tires, and other parts of the vehicle. Ensure cause of trouble actually is in the drive axle before
adjusting, repairing, or replacing any of its parts.
Non-Drive Axle Noises
A few conditions can sound just like drive axle noise and have to be considered in pre-diagnosis.
components
Floor mat interference with pedal
Lay mat flat in proper area
Dry or binding ball/fork pivots
Lubricate and align
components
Faulty clutch cable
Replace clutch cable
Noisy Clutch Pedal
Faulty interlock switch
Replace interlock switch
Self-adjuster ratchet noise
Lubricate or replace self-
adjuster
Speed control interlock switch
Lubricate or replace
interlock switch
Clutch Pedal Sticks Down
Binding clutch cable
See CLUTCH article
Springs weak in pressure plate
Replace pressure plate
Binding in clutch linkage
Lubricate and free linkage
Noisy
Dry release bearing
Lubricate or replace release
bearing
Dry or worn pilot bearing
Lubricate or replace bearing
Worn input shaft bearing
Replace bearing
Transmission Click
Weak springs in pressure
Replace pressure plate plate
Release fork loose on ball stud
Replace release fork
and/or ball stud
Oil on clutch disc damper
Replace clutch disc
Broken spring in slave cylinder
Replace slave cylinder
2008 Chevrolet Silverado 1500
GENERAL INFORMATION Trouble Shooting - Basic Procedures
The 4 most common noises are exhaust, tires, CV/universal joints and wheel trim rings.
In certain conditions, the pitch of the exhaust gases may e gear whine. At other times, it may be
mistaken for a wheel bearing rumble.
Tires, especially radial and snow, can have a high-pitched tread whine or roar, similar to gear
noise. Also, some non-standard tires with an unusual tread construction may emit a roar or whine.
Defective CV/universal joints may cause clicking noises or excessive driveline play that can be
improperly diagnosed as drive axle problems.
Trim and moldings also can cause a whistling or whining noise. Ensure none of these components
are causing the noise before disassembling the drive axle.
Gear Noise
A "howling" or "whining" noise from the ring and pinion gear can be caused by an improper gear
pattern, gear damage, or improper bearing preload. It can occur at various speeds and driving
conditions, or it can be continuous.
Before disassembling axle to diagnose and correct gear ke sure that tires, exhaust, and vehicle
trim have been checked as possible causes.
Chuckle
This is a particular rattling noise that sounds like a stick against the spokes of a spinning bicycle
wheel. It occurs while decelerating from 40 MPH and usually can be heard until vehicle comes to
a complete stop. The frequency varies with the speed of the vehicle.
A chuckle that occurs on the driving phase is usually caused ive clearance due to differential gear
wear, or by a damaged tooth on the coast side of the pinion or ring gear. Even a very small tooth
nick or a ridge on the edge of a gear tooth is enough the cause the noise.
This condition can be corrected simply by cleaning the gear tooth nick or ridge with a small
grinding wheel. If either gear is damaged or scored badly, the gear set must be replaced. If metal
has broken loose, the carrier and housing must be cleaned to remove particles that could cause
damage.
Knock
This is very similar to a chuckle, though it may be louder, and occur on acceleration or
deceleration. Knock can be caused by a gear tooth that is damaged on the drive side of the ring
2008 Chevrolet Silverado 1500
GENERAL INFORMATION Trouble Shooting - Basic Procedures
and pinion gears. Ring gear bolts that are hitting the carrier casting can cause knock. Knock can
also be due to excessive end play in the axle shafts.
Clunk
Clunk is a metallic noise heard when an automatic transmission is engaged in Reverse or Drive, or
when throttle is applied or released. It is caused by backlash somewhere in the driveline, but not
necessarily in the axle. To determine whether driveline clunk is caused by the axle, check the
total axle backlash as follows:
1. Raise vehicle on a frame or twinpost hoist so that drive wheels are free. Clamp a bar
between axle companion flange and a part of the frame or body so that flange cannot move.
2. On conventional drive axles, lock the left wheel to keep it from turning. On all models, turn
the right wheel slowly until it is felt to be in Drive condition. Hold a chalk marker on side
of tire about 12" from center of wheel. Turn wheel in the opposite direction until it is again
felt to be in Drive condition.
3. Measure the length of the chalk mark, which is the total axle backlash. If backlash is one
inch or less, drive axle is not the source of clunk noise.
Bearing Whine
Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by malfunctioning
pinion bearings. Pinion bearings operate at drive shaft speed. Roller wheel bearings may whine in
a similar manner if they run completely dry of lubricant. Bearing noise will occur at all driving
speeds. This distinguishes it from gear whine, which usually comes and goes as speed changes.
Bearing Rumble
Bearing rumble sounds like marbles being tumbled. It is usually caused by a malfunctioning wheel
bearing. The lower pitch is because the wheel bearing turns at only about 1/3 of drive shaft speed.
Chatter On Turns
This is a condition where the entire front or rear of vehicle vibrates when vehicle is moving. The
vibration is plainly felt as well as heard. Extra differential thrust washers installed during axle
repair can cause a condition of partial lock-up that creates this chatter.
Axle Shaft Noise
Axle shaft noise is similar to gear noise and pinion bearing whine. Axle shaft bearing noise will
normally distinguish itself from gear noise by occurring in all driving modes (Drive, cruise, coast
and float), and will persist with transmission in Neutral while vehicle is moving at problem speed.
2008 Chevrolet Silverado 1500
GENERAL INFORMATION Trouble Shooting - Basic Procedures
If vehicle displays this noise condition, remove suspect parts, replace wheel seals and install a
new set of bearings. Re-evaluate vehicle for noise before removing any internal components.
Vibration
Vibration is a high-frequency trembling, shaking or grinding condition (felt or heard) that may be
constant or variable in level and can occur during the total operating speed range of the vehicle.
The types of vibrations that can be felt in the vehicle can d into 3 main groups:
Vibrations of various unbalanced rotating parts of the vehicle.
Resonance vibrations of the body and frame structures caused by rotating of unbalanced
parts.
Tip-in moans of resonance vibrations from stressed engine or exhaust system mounts or
driveline flexing modes.
DRIVE AXLE - RWD TROUBLE SHOOTING
DRIVE AXLE (RWD) TROUBLE SHOOTING
NOTE:
This is GENERAL information. This article is not intended to be
specific to any unique situation or individual vehicle configuration.
The purpose of this Trouble Shooting information is to provide a list
of common causes to problem symptoms. For model-specific
Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING
articles available in the section(s) you are accessing. For
definitions of listed noises or sounds, see DRIVE AXLE - NOISE
DIAGNOSIS under POWERTRAIN.
CONDITION & POSSIBLE CAUSE
CORRECTION
Knocking or Clunking
Differential Side Gear Clearance
Check Clearance
Worn Pinion Shaft
Replace Pinion Shaft
Axle Shaft End Play
Check End Play
Missing Gear Teeth
Check
Differential/Replace
Gear
Wrong Axle Backlash
Check Backlash
Misaligned Driveline
Realign Driveline
Clinking During Engagement
2008 Chevrolet Silverado 1500
GENERAL INFORMATION Trouble Shooting - Basic Procedures
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