30S03T0 nvh principles and diagnosis 2004

1-15 Worksheet A at Workstation 1 Identifying Engine Noises On-Vehicle Student’s Answer Sheet .... 2-18 Worksheet B at Workstation 1 Identifying Vehicle Noise On-Vehicle Student’s Answer

vibration harshness

nvh principles and

diagnosis

student reference book

Appropriate service methods and proper repair procedures are essential for the safe, reliable operation of all motor vehicles,

as well as the personal safety of the individual doing the work This manual provides general directions for accomplishing service and repair work with tested, effective techniques Following them will help assure reliability.

There are numerous variations in procedures, techniques, tools and parts for servicing vehicles, as well as in the skill of the individual doing the work This manual cannot possibly anticipate all such variations and provide advice or cautions as to each Accordingly, anyone who departs from instructions provided in this manual must first establish that he compromises neither his personal safety nor the vehicle integrity by his choice of methods, tools or parts.

As you read through the procedures, you will come across NOTES, CAUTIONS, and WARNINGS Each one is there for a specific purpose NOTES give you added information that will help you to complete a particular procedure CAUTIONS are given to prevent you from making an error that could damage the vehicle WARNINGS remind you to be especially careful

in those areas where carelessness can cause personal injury The following list contains some general WARNINGS that you should follow when you work on a vehicle.

• Always wear safety glasses for eye protection.

• Use safety stands whenever a procedure requires you to

be under the vehicle.

• Be sure that the ignition switch is always in the OFF

position, unless otherwise required by the procedure.

• Set the parking brake when working on the vehicle If you

have an automatic transmission, set it in PARK unless

instructed otherwise for a specific service operation If

you have a manual transmission it should be in

RE-VERSE (engine OFF) or NEUTRAL (engine ON) unless

instructed otherwise for a specific service operation.

• Operate the engine only in a well-ventilated area to avoid

the danger of carbon monoxide.

• Keep yourself and your clothing away from moving parts

when the engine is running, especially the fan and belts.

• To prevent serious burns, avoid contact with hot metal parts such as the radiator, exhaust manifold, tail pipe, catalytic converter and muffler.

• Do not smoke while working on the vehicle.

• To avoid injury, always remove rings, watches, loose hanging jewelry, and loose clothing before beginning to work on a vehicle Tie long hair securely behind your head.

• Keep hands and other objects clear of the radiator fan blades Electric cooling fans can start to operate at any time by an increase in underhood temperatures, even though the ignition is in the OFF position Therefore, care should be taken to ensure that the electric cooling fan is completely disconnected when working under the hood.

The recommendations and suggestions contained in this manual are made to assist the dealer in improving his dealership parts and/or service department operations These recommendations and suggestions do not supersede or override the provisions of the Warranty and Policy Manual, and in any cases where there may be a conflict, the provisions of the Warranty and Policy Manual shall govern.

The descriptions, testing procedures, and specifications in this handbook were in effect at the time the handbook was approved for printing Ford Motor Company reserves the right to discontinue models at any time, or change specifications, design, or testing procedures without notice and without incurring obligation Any reference to brand names in this manual

is intended merely as an example of the types of tools, lubricants, materials, etc recommended for use Equivalents, if available, may be used The right is reserved to make changes at any time without notice.

WARNING: Many brake linings contain asbestos fibers When working on brake components, avoid breathing the dust Breathing

the asbestos dust can cause asbestosis and cancer.

Breathing asbestos dust is harmful to your health.

Dust and dirt present on car wheel brake and clutch assemblies may contain asbestos fibers that are hazardous to your health when made airborne by cleaning with compressed air or by dry brushing.

Wheel brake assemblies and clutch facings should be cleaned using a vacuum cleaner recommended for use with asbestos fibers Dust and dirt should be disposed of in a manner that prevents dust exposure, such as sealed bags The bag must be labeled per OSHA instructions and the trash hauler notified as to the contents of the bag.

If a vacuum bag suitable for asbestos is not available, cleaning should be done wet If dust generation is still possible, technicians should wear government approved toxic dust purifying respirators.

4 Vehicles serviced right on the first visit.

5. Service status provided within one minute of inquiry.

6. Vehicle ready at agreed upon time.

7. Thorough explanation of work done, coverages and changes.

1. Appointment available within one

day of the customer’s requested

service day.

2. Write-up begins within four minutes of

arrival.

3. Service needs courteously identified,

accurately recorded on Repair

Order, and verified with customer.

These seven service standards provide a process and product value that are

compelling reasons for owners to purchase and repurchase Ford or Lincoln-Mercury products These standards also help to attract new owners through favorable

testimonials and improved owner satisfaction.

Standard 4

“Fix It Right the First Time, on Time.”

The technician is the most important player when it comes to Standard #4.

Why

Customers tell us “Fixing It Right the First Time, on Time” is one of the reasons they would decide to return to a dealer to buy a vehicle and get their vehicles serviced.

Technician Training

It is our goal to help the technician acquire all of the skills and knowledge necessary to

“Fix it Right the First Time, on Time.” We refer to this as “competency.”

Dealer-to-Customer Service Standards:

WARM UP QUIZ Warm Up-1

NVH Warm Up Quiz Warm Up-1 Instructor’s Information Sheet Warm Up-1 Instructor’s Answer Sheet Warm Up-3

INTRODUCTION Intro-1

Introduction Intro-1 Evaluation Strategy Intro-1

DAY ONE: INTRODUCTION TO NVH 1-1

What is NVH? 1-2 Fundamentals of NVH 1-3 Definition of Vibration 1-8 Definition of Noise 1-13 Definition of Harshness 1-15 Worksheet A (at Workstation 1)

Identifying Engine Noises (On-Vehicle)

Student’s Answer Sheet 1-20

DAY ONE: NVH DIAGNOSTIC TOOLS AND EQUIPMENT 2-1

Vibration Diagnostic Tools 2-2 Noise Diagnostic Tools 2-18 Worksheet B (at Workstation 1)

Identifying Vehicle Noise (On-Vehicle)

Student’s Answer Sheet 2-29 Worksheet C (at Workstation 2)

Measuring Frequency and Amplitude (On-Vehicle)

Student’s Answer Sheet 2-33 Worksheet D (at Workstation 3)

Measuring Frequency (Bench)

Student’s Answer Sheet 2-37 Worksheet E (at Workstation 4)

NVH Terminology and Tools

Student’s Answer Sheet 2-41

DAY TWO: DIAGNOSIS OF NVH CONCERNS 3-1

Diagnostic Process 3-2 Diagnosis of Vibration Concerns 3-15 Worksheet F (at Workstation 1)

Diagnosing Vehicle Vibrations (On-Vehicle)

Student’s Answer Sheet 3-55 Worksheet G (at Workstation 2)

Diagnosing Vehicle Vibrations (On-Vehicle)

Student’s Answer Sheet 3-59 Worksheet H (at Workstation3)

Vibrate 5.0 (Bench)

Student’s Answer Sheet 3-63 Worksheet I (at Workstation 4)

Frequency Calculations (Navigation)

Student’s Answer Sheet 3-69 Diagnosis of Noise Concerns 3-73 Diagnosis of Harshness Concerns 3-78

DAY THREE Day Three-1

Worksheet J (at Workstation 1)

Diagnosing Vehicle Noise (On-Vehicle)

Student’s Answer Sheet Day Three-3 Worksheet K (at Workstation 2)

Diagnose A Vehicle Vibration (On-Vehicle)

Student’s Answer Sheet Day Three-7 Worksheet L (at Workstation 4)

Diagnosing Noise and Vibration Concerns (Navigation)

Student’s Answer Sheet Day Three-11

NVH GLOSSARY Glossary-1 APPENDIX Appendix-1

“Write-Up” Job Aid Appendix-1 Courtesy Inspection Appendix-3 NVH Diagnostic Guide Appendix-5 Frequency and RPM Calculations Appendix-7 Day One – Homework Appendix-9 Day Two – Homework Appendix-11

NVH WARM UP QUIZ STUDENT’S ANSWER SHEET

NAME:

1 Harshness is a term commonly used to describe:

A a hard steering condition due to lack of power steering fluid

B an unpleasant sound found to be abnormal to the vehicle’s characteristics

C a firmer than usual response from the suspension system

D none of the above

2 Which of the following modes is used to monitor engine RPM with a New Generation Star (NGS) Tester?

A Output State Commands

B Retrieve and Clear Continuous Memory

C On Demand Self Test

D PID/Data Monitor and Record

3 Every time a vibrating component goes through its complete range of motion and returns to the startingpoint is called a:

B the frequency of a repetitive vibration

C the origin of a noise

D only the frequency of a noise

5 Which of the following is critical for vibration diagnosis?

A vibration frequency

B engine RPM

C vehicle speed

D all of the above

6 The number of times an engine fires a cylinder with each crankshaft revolution is equal to:

A One-half the number of cylinders

NVH WARM UP QUIZ STUDENT’S ANSWER SHEET (Continued)

7 Which of the following terms indicates the actual amount of component movement during a vibration?

A frequency

B amplitude

C pitch

D cycle

8 Which of the following is the correct order of vibration transfer path

A Conductor to Reactor to Originator

B Reactor to Conductor to Originator

C Originator to Conductor to Reactor

D Originator to Reactor to Conductor

9 Runout and imbalance conditions are affected mostly by:

A speed

B torque

C power

D all of the above

10 To interrupt the transmission of a normal engine vibration from reaching the passenger compartment, atechnician would:

A eliminate the originator of the vibration

B repair the engine vibration

C replace or realign faulty conductors of the vibration

D all of the above

11 Two high spots on a tire rotating 10 times a second has a _ order vibration of 20 Hz

A first

B second

C third

D half

NVH WARM UP QUIZ STUDENT’S ANSWER SHEET (Continued)

13 What is the ChassisEAR? How does it operate?

14 How do you get engine rpm readings from the New Generation Star Tester (NGS)?

_

15 Define noise Define vibration Define harshness

_

Before getting into the basic concepts of Noise, Vibration, and Harshness (NVH), it is necessary to understandwhy these concepts are important They are the building blocks in learning how to diagnose certain concerns Forexample, you first need to understand what frequency is and why it is significant before you can use it to

diagnose a concern You can record the frequency using tools, but if you do not understand the concept, it will nothelp you in your diagnosis You need to know why you are collecting the test data as well as what data to collect.Once you know why you are collecting it, it is much easier to analyze it to diagnose a concern

There are basically three things you need to know to pinpoint an NVH concern:

Another thing to remember is that the three most important pieces of test data required to diagnose a concern are

as follows:

The importance of frequency, RPM, and vehicle speed at which the concern is evident will be reinforced

throughout the course You will be taught how to use specific tools to obtain this data and how to use it to

Before getting into the basic concepts of Noise, Vibration, and Harshness (NVH), it is necessary to understandwhy these concepts are important They are the building blocks in learning how to diagnose certain concerns Forexample, you first need to understand what frequency is and why it is significant before you can use it to

diagnose a concern You can record the frequency using tools, but if you do not understand the concept, it will nothelp you in your diagnosis You need to know why you are collecting the test data as well as what data to collect.Once you know why you are collecting it, it is much easier to analyze it to diagnose a concern

There are basically three things you need to know to pinpoint an NVH concern:

Another thing to remember is that the three most important pieces of test data required to diagnose a concern are

as follows:

The importance of frequency, RPM, and vehicle speed at which the concern is evident will be reinforced

throughout the course You will be taught how to use specific tools to obtain this data and how to use it to

TECHNICIAN OBJECTIVES

WHAT IS NVH?

The letters NVH stand for Noise, Vibration, and Harshness Anynoise, vibration, or harshness that is irritating or annoying to theowner of a vehicle is an NVH concern

In dealing with these concerns, it is important that you understand themeaning of the terms used to describe NVH complaints

component moves back and forth or up and down consistently

vehicle’s operating characteristics

describe a firmer than usual response from the suspension system.Harshness also describes a perceived lack of suspension

compliance (or “give”)

FUNDAMENTALS OF NVH Frequency

Frequency and Cycle

Most vibrations consist of movements back and forth or up and downthat repeat as long as the causal conditions exist Every time thevibrating component goes through its complete range of motion andreturns to the starting point is called a cycle The rate at which thesecycles occur within a given time is called the frequency Frequency isusually measured in cycles per second (cps) The term Hertz (Hz) isalso used as a measurement of frequency One cps equals oneHertz (Hz)

The NVH concern of steering wheel nibble can demonstratefrequency As the steering wheel oscillates from left to right, it repeatsthe movement over and over The number of times the steering wheelgoes through this range of motion in one second is its frequency A

ONE CYCLE

1 SEC.

NVH002-A

NVH060-A

0 5 10 20

POINT OF RESONANCE

CAR SPEED

FREQUENCY CPS

SUSPENSION FREQUENCY

PROBLEM SPEED

UNBALANCED TIRES COMPELLING FORCE

Point of Resonance

Resonant frequency refers to the frequency of the applied force on

an object that results in the greatest vibration This point is where thenatural frequency of the object and the frequency of the applied forcemeet

The natural frequency refers to the frequency range during which anobject tends to vibrate Natural frequency varies depending on thematerial composition, mass, and size of an object Two identicallooking objects with different material composition will have differentnatural frequencies and a different resonant frequency when actedupon by an identical applied force

For example, a suspension system of a particular vehicle may have anatural frequency of 15 Hz which will remain constant at any speed.Suppose that this same vehicle has an unbalanced tire As the tirespeed increases, so does the frequency of the force created by theunbalance At some point, the frequency of the force created by thetire imbalance will be the same as the natural frequency of thesuspension system, causing the suspension system to vibrate This isthe point of resonance, or the resonant frequency

Amplitude of Vibration

The term amplitude, when applied to vibration, indicates the actualamount of component movement An extreme vibration has a highamplitude, and a mild vibration has a low amplitude

Referring back to the NVH concern of steering wheel nibble,amplitude can be demonstrated by the amount of steering wheelmovement The more the steering wheel moves, the higher theamplitude of the vibration causing the concern

TIME

Sound is the result of the disturbance of air caused by a vibration Thephysical movement of vibration causes pressure variations in the airthat may be detected by the ear, if they are within normal hearingrange (The normal range of human hearing is 20-20,000 Hz.) Forexample, striking a tuning fork causes it to vibrate The vibrationscreate air pressure variations, or waves, that we hear as sound

Pitch

Pitch

Pitch is the physical quality of sound (or noise) that relates to thefrequency of its vibration Increasing the frequency of a soundincreases the pitch of the sound If frequency decreases, pitchalso decreases Simply speaking, pitch refers to the highness orlowness of a sound

HIGH FREQUENCY: HIGH PITCH

INTENSITY

LOW FREQUENCY: LOW PITCH

TIME

NVH004-A

Intensity

Intensity is the physical quality of sound (or noise) that relates tothe strength of the sound’s vibration The illustration shows twosound waves with the same frequency, but with different intensitylevels (amplitudes) Intensity is measured in decibels

LOW AMPLITUDE: LOW INTENSITY

INTENSITY

HIGH AMPLITUDE: HIGH INTENSITY

TIME

NVH005-A

DEFINITION OF VIBRATION

Vibration is a shaking or trembling that can be felt by thecustomer when an object/component moves back and forth or upand down consistently Abnormal vibrations usually occur undercertain vehicle operating conditions

There are three types of vibrations:

been removed For example, a tire hitting a pothole willcontinue to vibrate after the initial impact has passed

force that initiated the vibration remains For example, anunbalanced driveshaft only causes a vibration as long as it isrotating Another example would be an unbalanced tire, whichwould stop vibrating when it stops rotating Forced vibrationsare the most common type dealt with in automotive

applications

force that is felt in the floor and seats of the vehicle This type

of vibration is most noticeable during hard acceleration and isamplified by the application of torque

Under normal circumstances, a rotating component will not produce anoticeable vibration However, if the component has improper weightdistribution (imbalance) or is rotating in an eccentric pattern (out-of-round or bent), then a vibration may be produced If the frequencyand amplitude of the vibration can be measured, then those

characteristics along with the vehicle speed and engine RPM at whichthe vibration occurs, can be matched with components that wouldlikely cause the vibration at that particular speed This procedure canhelp find the source quickly and accurately

Vibration Transfer Path

Vibration Transfer Path

Damaged or worn engine and body mounts or a grounded exhausthanger are components that could transmit (conduct) a normal enginevibration (originator) into the passenger compartment (reactor) as

Vibration Dampers

Vibration dampers are used to dampen vibrations at the originator,transfer path and/or reactor There are three types of vibration

dampers:

to cancel out original vibration

frequency This changes the frequency at which the object/component will vibrate

Order of Vibration

First and Second Order

Rotating components with more than one abnormal condition maygenerate more than one vibration per revolution For example, a tirewith one high spot would cause one vibration per revolution Thiswould be called a first order vibration A tire with two high spotswould create two vibrations per revolution This would be called asecond order vibration This concept is important to remember whenthe measured frequency of a vibration does not seem to

coordinate with any of the likely origins For example, it would benecessary to divide the frequency of a second order vibration bytwo to identify the originating component

NVH007-A

Normal Engine Order Vibration

Engines have vibrations created by firing frequency Firingfrequency refers to the force created by the engine each time acylinder fires The force of the combustion creates one pulse, andthe cylinders firing in order create a normal vibration The

frequency of these vibrations is dependent on the number ofcylinders in the engine

For example, six-cylinder engines fire half of its cylinders witheach crankshaft revolution This results in a third order vibration

A fourth order vibration would be common with eight-cylinderengines since four cylinders fire with each crankshaft revolution

DEFINITION OF NOISE

Generally, specific primary noises can be associated with a certainportion of the vehicle, such as the engine, driveline, axle, brakes, orbody components However, there are times when a noise will sound

as though it is coming from one area, but it is actually a secondarynoise, being produced by a completely unrelated component Roofracks are a classic example of this situation Many times, the air flowaround the rack will produce a sound that can be easily mistaken forgear howl from the drive axle Unless you are aware of theseconditions, an incorrect diagnosis could be made

In still other conditions, a noise will telegraph through the body Inthis case, for example, you may hear a chirping noise in the area ofthe instrument panel, only to find that the noise is being produced inthe rear brakes The sound has traveled, or telegraphed, through theparking brake cables This is a situation where following a strict roadtest procedure will help to locate the cause since the noise willonly occur when the brakes are applied or released

Noise Transfer Path

When a vibration produces a noise, the vibration can betransmitted from the originator, through the conductor, and on tothe reactor where the noise is heard by the customer The transferpath for a noise that is generated by a vibration is identical to avibration’s transfer path For example, if the steering system(originator) is producing an abnormal vibration, the suspensionsystem (conductor) can transmit the vibration to the instrumentpanel (reactor) where a noticeable squeak is heard

Noises that are produced by wind, turbulence, and air leaks areindependent from noises produced by moving components Manywind noises are caused by air escaping from the vehicle Turbulencecreated by loose or protruding moldings, or by gaps between rubberseals, moldings, and drip rails, can produce wind noise Wind noise iscovered in-depth in a separate course

Normal Noise

A gear-driven unit, especially an automotive drive axle, will produce

a certain amount of noise Some noise is normal and may be audible

at certain speeds or under certain driving conditions The noise is notharmful but is disturbing to the owner This is also true of Traction-Lok axles A slight chatter may be heard during low-speed turns,which is nothing more than the clutches doing their job

In dealing with these noise related concerns, it is important that youknow what is normal and that you explain why it is normal to theowner This can often be accomplished with a comparison drive in aknown normal vehicle In most cases, after you explain the condition,the owner will accept the fact that the noise will be there

After you have determined that a problem exists, the symptom must

be diagnosed and the cause repaired

DEFINITION OF HARSHNESS

Harshness is a concern that is related to the customer’s perception orexpectation of a vehicle’s ability to absorb vibrations caused by roadimperfections

Harshness is usually due to:

suspension components that cannot move within their normal range

of motion, or that have lost their isolating grommets or bearings

heavy-duty springs and shocks

harsh ride

Normal Harshness

Different vehicles have differing levels of ride quality A customermay perceive that the ride of a vehicle is harsh, when in reality it is anormal operating characteristic of the vehicle

For example, a customer who drives a utility vehicle may expect thesame ride quality as a luxury car, not realizing that the utilityvehicle’s normal ride quality is harsher than a luxury vehicle Thiswould be an example of normal harshness and comparison to a knowngood vehicle could resolve this concern for the customer

NOTES

NOTES

NOTES

NOTES

WORKSHEET A (AT WORKSTATION 1) IDENTIFYING ENGINE NOISES (ON-VEHICLE)

STUDENT’S ANSWER SHEET

NAME:

DIRECTIONS: Answer the following questions while using the ChassisEAR on a classroom vehicle.

1 What components of the ChassisEAR are color-coded?

A

B

2 Listen to the engine and identify normal engine noises without using the ChassisEAR

3 Compare the sounds on each channel of the ChassisEAR

4 What channel of the ChassisEAR is detecting fuel injector noise?

5 Record the component and the color of the ChassisEAR microphone attached to the component

VIBRATION DIAGNOSTIC TOOLS

There are several diagnostic tools that can be used to identifyvibrations These tools can be very helpful in isolating problems andmaking your diagnosis easier In this section, we will describe thesetools and equipment

The sirometer operates on the principle of resonant frequency As thelength of the scrolled wire changes, so does its natural frequency.Once the scrolled wire's natural frequency matches the vibratingcomponent’s natural frequency, this is the point of resonance (or itsresonant frequency) It is at this point that the scrolled wire willvibrate with the highest amplitude.

NVH051-A

Sirometer

Hz RPM

Reed Tachometer

Reed Tachometer

A reed tachometer is used to identify the frequency of a repetitivevibration Some reed tachometers measure vibration frequency incycles per second (Hz), others in revolutions per minute (RPM) Theonly difference between the two is face plate labeling since RPMvalues can be calculated from Hz values by multiplying by 60 Thereed tachometer contains several reeds, each tuned to vibrate orresonate at a different frequency The reeds range from 10 to 80 Hz or

600 to 4800 RPM, so the reed tachometer will only identify vibrationswithin this range A knob located on the side of the reed tachometer isused during transportation to protect the reeds from excessive

vibration When the knob is turned, the reeds are held in place Theknob also serves as a reset to dampen out the reeds to obtain a betterreading

Electronic Vibration Analyzer (EVA)

of vibrations Accurately obtaining these characteristics of a vibrationcan significantly reduce vehicle service time This section explains theoperation of the EVA and contains important information to assist indiagnosing customer NVH concerns

The EVA includes the following components:

Electronic Vibration Analyzer (EVA) Features

Display screen

The display screen on the EVA unit is a liquid crystal display thatprovides output messages to the operator It also provides informationabout vibration frequency and strength, for the three strongest

vibrations The display screen also provides instruction messages forunit operation