Ford Falcon. Manual — part 19

100-04-48

Noise, Vibration and Harshness

100-04-48

DIAGNOSIS AND TESTING (Continued)

Test Step

Result / Action to Take

J10

CHECK THE DRIVETRAIN

Yes

WARNING:

If only one drive wheel is allowed to rotate, speed CHECK/TEST the drivetrain and driveline

must be limited to 55 km/h (34 mph) using the speedometer reading,

components. TEST the system for normal

since actual wheel speed will be twice that indicated on the

operation.

speedometer. Exceeding a speed of 55 km/h (34 mph) or allowing the

No

drive wheel to hang unsupported can result in tyre disintegration or

SUBSTITUTE known good wheel and tyre

differential failure, which can cause serious personal injury and

assemblies as necessary. TEST the system for

extensive vehicle damage.

normal operation.

Remove the rear wheel and tyre assemblies. Refer to Section 204-04
.

Secure the brake drums (if so equipped), by installing wheel hub bolt
nuts, reversed.

Carefully accelerate the drivetrain while checking for vibration.

Is the vibration present?

PINPOINT TEST K : CLUTCH VIBRATION

Test Step

Result / Action to Take

K1

CHECK ENGINE COMPONENTS FOR GROUNDING

Yes

NOTE:

Make sure the clutch is the cause of the vibration concern. The

REPAIR as necessary. TEST the system for

vibration should occur during clutch operation. The clutch can also be

normal operation.

difficult to engage or disengage. Eliminate all related systems before
checking the clutch components.

No

Go to K2.

NOTE:

Check the driveline angles and driveshaft runout before

disassembling the clutch system. Refer to Section 205-00 for the correct
driveline angle specifications.

Check the powertrain/drivetrain mounts, exhaust manifolds or other
engine components for grounding on the chassis.

Are any mounts or engine components grounded?

K2

CHECK THE ACCESSORY DRIVE BELT

Remove the accessory drive belt.

Yes

DIAGNOSE the accessory drive components.

Does the vibration stop with the accessory drive belt removed?

No

Go to K3.

K3

CHECK FOR LOOSE CLUTCH PRESSURE PLATE

BOLTS

Check for loose clutch pressure plate bolts. Inspect the clutch

Yes

pressure plate for damage or for material between the pressure plate

TIGHTEN the bolts to specifications or if

and flywheel.

damaged, INSTALL a new clutch pressure plate.
REFER to Section 308-01 . TEST the system for

Are there any loose bolts or damage?

normal operation.

No

Go to K4.

K4

CHECK THE CLUTCH DISC SPRINGS

Check for worn, broken or loose clutch disc springs.

Yes

INSTALL a new clutch disc. REFER to Section

Are the clutch springs worn, broken or loose?

308-01 . TEST the system for normal operation.

No

Go to K5.

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Noise, Vibration and Harshness

100-04-49

DIAGNOSIS AND TESTING (Continued)

Test Step

Result / Action to Take

K5

CHECK THE CLUTCH DISC SPLINES

Inspect the clutch disc splines for damage or wear.

Yes

INSTALL a new clutch disc. REFER to Section

Is there damage or wear?

308-01 . TEST the system for normal operation.

No

Go to K6.

K6

CHECK THE FLYWHEEL BOLTS

Check for loose flywheel bolts.

Yes

TIGHTEN the bolts to specifications. REFER to

Are the bolts loose?

Section 308-01 . TEST the system for normal
operation.

No

Go to K7.

K7

CHECK THE FLYWHEEL SURFACE

Inspect the flywheel surface for wear or damage. Check the flywheel

Yes

runout.

INSTALL a new flywheel. REFER to Section
303-01a for 2.0L Zetec engine or Section

Is there any damage or excessive wear?

303-01b for 3.0L (4V) engine. TEST the system
for normal operation.

No

Clutch system is normal. CONDUCT a diagnosis
on other suspect systems.

scored or forcibly damaged gear teeth and is usually

Component Tests

quite audible over the entyre speed range. The

Steering Gear Grunt/Shudder Test

second type of ring and pinion noise pertains to the

mesh pattern of the gear pattern. This gear noise can

1. Start and run the vehicle to operating

be recognized as it produces a cycling pitch or whine.

temperature.

Ring and pinion noise tends to peak in a narrow

2. Set engine idle speed to 1,200 rpm.

speed range or ranges, and will tend to remain

constant in pitch.

CAUTION: Do not hold the steering wheel

1. Raise and support the vehicle. Refer to Section

against the stops for more than three to five

100-02.

seconds at a time. Damage to the power

steering pump will occur.

2. Drain the axle lubricant. Refer to Section 205-02.

3. Rotate the steering wheel to the RH stop, then

3. Remove the carrier assembly or the axle housing

turn the steering wheel 90 degrees back from that

cover depending on the axle type. Refer to

position. Turn the steering wheel slowly in a 15 to

Section 205-02.

30 degree arc.

4. Inspect the gear set for scoring or damage.

4. Turn the steering wheel another 90 degrees. Turn

the steering wheel slowly in a 15 to 30 degree

arc.

5. Repeat the test with power steering fluid at

different temperatures.

6. If a light grunt is heard or a low (50-200 Hz)

shudder is present, this is a normal steering

system condition.

7. If a loud grunt is heard or a strong shudder is felt,

fill and purge the power steering system.

Checking Tooth Contact Pattern and

Condition of the Ring and Pinion

There are two basic types of conditions that will

produce ring and pinion noise. The first type is a howl

or chuckle produced by broken, cracked, chipped,

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Noise, Vibration and Harshness

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DIAGNOSIS AND TESTING (Continued)

8. A high, thick contact pattern that is worn more

5. In the following steps, the movement of the

toward the toe.

contact pattern along the length is indicated as

toward the “heel” or “toe” of the differential ring

Tooth contact pattern shown on the drive side

gear.

of the gear teeth.
The high contact pattern indicates that the

drive pinion is not installed deep enough into

the carrier.
The differential ring gear backlash is correct,

a thinner drive pinion shim is needed. A

decrease will move the drive pinion toward

the differential ring gear.

Item

Description

1

Heel

2

Toe

6. Apply a marking compound to a third of the gear

teeth on the differential ring gear. Rotate the

differential ring gear several complete turns in

9. A high, thin contact pattern that is worn toward

both directions until a good, clear tooth pattern is

the toe.

obtained. Inspect the contact patterns on the ring

gear teeth.

Tooth contact pattern shown on the drive side

of the gear teeth.

7. A good contact pattern should be centered on the

tooth. It can also be slightly toward the toe. There

The drive pinion depth is correct. Increase the

should always be some clearance between the

differential ring gear backlash.

contact pattern and the top of the tooth.

Tooth contact pattern shown on the drive side

of the gear teeth.

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Noise, Vibration and Harshness

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DIAGNOSIS AND TESTING (Continued)

10. A contact pattern that is worn in the center of the

differential ring gear tooth toward the heel.

Tooth contact pattern shown on the drive side

of the gear teeth.
The low contact pattern indicates that the

drive pinion is installed too deep into the

carrier.
The differential ring gear backlash is correct.

A thicker drive pinion shim is needed.

11. A contact pattern that is worn at the top of the

differential ring gear tooth toward the heel.

Tooth contact pattern shown on the drive side

of the gear teeth.
The pinion gear depth is correct. Decrease

the differential ring gear backlash.

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