SSP Audi Noise Vibration Harshness

7/28/2019 SSP Audi Noise Vibration Harshness

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Service Training

Noise Vibration and Harshness

Self Study Programme NVH


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4ABLEOF#ONTENTS

I

#OURSE'OALS

)NTRODUCTION

4HEORY#HARACTERISTICSOF.OISE6IBRATIONAND(ARSHNESS.6('ENERATIONOF

.OISEAND6IBRATION3OUNDAND3OUND7AVES!UDIBLE2ANGEOF3OUND

.6(4ERMINOLOGY4YPESOF.OISE#OMPELLING&ORCEAND6IBRATING"ODY

6IBRATION6IBRATION4RANSFER0ATH6IBRATION/RDER4YPESOF6IBRATION

2IDE#OMFORT

$IAGNOSIS

'ETTING'OOD)NFORMATIONFROM3ERVICE!DVISORS4HE&OUR3TEPS$IAGNOSINGAND3OLVING#USTOMER#ONCERNS/THER)NFORMATION

3OURCES0RE2OAD4EST)NSPECTION2OAD4EST4IPS2OAD4ESTING

%NGINE6IBRATIONS%NGINE3PEED2ELATED6IBRATIONS4YPESOF%NGINE6IBRATIONS%NGINE

6IBRATION&ORMULA%NGINE!CCESSORY&ORMULA4YPESOF%NGINE.OISE

%XHAUST.OISE%NGINE&IRING&REQUENCY&ORMULA

6EHICLE3PEED6IBRATIONS

4IRESAND7HEELS4IRE6IBRATION&ORMULAS$RIVE3HAFT&REQUENCY&ORMULA$RIVEAND!XLE3HAFTS$RIVELINE6IBRATION4RANSMISSION.OISE

AND6IBRATIONS$IFFERENTIAL/PERATION$RIVELINE3NAP3USPENSION

#OMPONENTS3TEERING#OMPONENTS

4OOLS3IROMETER%6!))#HASSIS%!2/THER4OOLS

'LOSSARY.6(4ERMINOLOGY

$IAGNOSTIC&LOW#HART

+NOWLEDGE!SSESSMENT

4HE3ELF3TUDY0ROGRAMPROVIDESYOUWITHINFORMATION

REGARDINGDESIGNSANDFUNCTIONS

4HE3ELF3TUDY0ROGRAMISNOTAREPAIRMANUAL

&ORMAINTENANCEANDREPAIRWORKALWAYSREFERTOTHE

CURRENTTECHNICALLITERATURE

)MPORTANT.OTE

.EW


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#OURSE'OALS

#OURSE'OALS

4HISCOURSEWILLENABLEYOUTO

s )DENTIFYTHETERMINOLOGYUSEDINDIAGNOSING

.OISE6IBRATIONAND(ARSHNESS.6(

CONCERNS

s )DENTIFYTHEDIFFERENTTYPESOF.6(

s )DENTIFYTHESTEPSOFTHE.6(SYSTEMATIC

DIAGNOSTICAPPROACH

s )DENTIFYTHEROADTESTPROCEDURES

NECESSARYTOISOLATEANOISEORVIBRATION

s #ALCULATE.6(FREQUENCIESNECESSARYFOR

COMPONENTCLASSIlCATION

s )DENTIFYTESTEQUIPMENTANDTOOLSUSEDINDIAGNOSINGANDCORRECTING.6(CONCERNS

s )DENTIFYDIAGNOSEANDSPECIFYTHE

COMPONENTCAUSINGTHE.6(CONCERN


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)NTRODUCTION

)NTRODUCTION

4HIS3ELF3TUDY0ROGRAMFOCUSESONVEHICLE

.OISE6IBRATIONAND(ARSHNESS.6(THEIRCAUSESANDDIAGNOSTICANDSERVICEPROCEDURES

TOLOCATEANDCORRECT.6(CONCERNS

-ODERNCARSANDTRUCKSUSEACOMBINATION

OFSYSTEMSTOPROVIDETHEDRIVERWITHTHE

SAFESTMOSTRESPONSIVEANDCOMFORTABLE

VEHICLEEVERBUILT4ODAYSDRIVERHASCOMETO

EXPECTASMOOTHANDQUIETRIDEINALLOPERATING

ENVIRONMENTS7HENVEHICLENOISEVIBRATION

ORRIDEHARSHNESSEXCEEDSTHEDRIVERS

EXPECTATIONSITISUPTOTHETECHNICIANTOCORRECTTHECAUSEOFTHECUSTOMERSCONCERN

6EHICLECOMPONENTSAREBEINGMANUFACTURED

USINGLIGHTERWEIGHTMETALS,IGHTERWEIGHT

METALSREDUCETHEOVERALLVEHICLEWEIGHTTHAT

REDUCEEMISSIONSANDIMPROVEFUELECONOMY

!STECHNOLOGIESDEVELOPSTRONGERANDMORE

LIGHTWEIGHTMETALSTHISTRENDWILLCONTINUE

,IGHTERVEHICLECOMPONENTSDONOTABSORB

NOISESANDVIBRATIONSASWELLASHEAVIER

COMPONENTS4HISLEADSTOANINCREASEIN.6(CONCERNS

$IAGNOSING.6(CONCERNSHASBEENDEVELOPED

INTOALOGICALANDALMOSTSCIENTIlCPROCEDURE

4HISCOURSEWILLPROVIDETHE!UDITECHNICIANWITH

CONCEPTSTOHELPUNDERSTANDANDDIAGNOSE.6(

CONCERNS


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4HEORY

'ENERATIONOF.OISEAND6IBRATION

!VIBRATINGOBJECTNORMALLYPRODUCESSOUNDAND

THATSOUNDMAYBEANANNOYINGNOISE)NTHECASEWHEREAVIBRATINGBODYISTHEDIRECTSOURCE

OFNOISESUCHASCOMBUSTIONCAUSINGTHE

ENGINETOVIBRATETHEVIBRATINGBODYORSOURCE

ISEASYTOlND)NOTHERCASESTHEVIBRATING

BODYMAYGENERATEASMALLVIBRATIONONLY

4HISSMALLVIBRATIONMAYCAUSEALARGERVIBRATION

ORNOISEDUETOTHEVIBRATINGBODYSCONTACT

WITHOTHERPARTS7HENTHISHAPPENSATTENTION

FOCUSESONWHERETHELARGEVIBRATIONORNOISE

OCCURSWHILETHEREALSOURCEOFTENESCAPESNOTICE

!NUNDERSTANDINGOFNOISEANDVIBRATION

GENERATIONASSISTSWITHTHETROUBLESHOOTING

PROCESS4HEDEVELOPMENTOFASMALLNOISE

INTOALARGERNOISEBEGINSWHENAVIBRATION

SOURCECOMPELLINGFORCEGENERATESAVIBRATION

2ESONANCEAMPLIlESTHEVIBRATIONWITHOTHER

VEHICLEPARTS4HEVIBRATINGBODYSOUND

GENERATINGBODYTHENRECEIVESTRANSMISSIONOF

THEAMPLIlEDVIBRATION

#HARACTERISTICSOF.OISE6IBRATION(ARSHNESS

.OISEISDElNEDASANYUNPLEASANTORUNEXPECTEDSOUNDCREATEDBYAVIBRATINGOBJECT

6IBRATIONISDElNEDASANYOBJECTIONABLE

REPETITIVEMOTIONOFANOBJECTBACKANDFORTHOR

UPANDDOWN

(ARSHNESSISDElNEDASANAGGRESSIVE

SUSPENSIONFEELORLACKOFhGIVEvINRESPONSETO

ASINGLEINPUT


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4HEORY

3OUNDSAND3OUND7AVES

!SOUNDWAVESCYCLEPERIODFREQUENCYAND

AMPLITUDEDETERMINETHEPHYSICALQUALITIESOFTHESOUNDWAVE4HEPHYSICALQUALITIESOFSOUNDARE

s !UDIBLERANGEOFSOUND

s 0ITCH

s )NTENSITY

!LLPEOPLEHAVEDIFFERENTCAPABILITIESFORHEARING

SOUND3OMEPEOPLEMAYNOTHEARSOUNDS

THATOTHERPEOPLECANHEAR+EEPTHESEFACTSINMINDWHILEDIAGNOSINGNOISECONCERNS-OST

CUSTOMERSBECOMETUNEDINTOANOISEAFTER

HEARINGITREPETITIVELY

7HENDIAGNOSINGAVEHICLEITMAY

BEBENElCIALTOHAVETHECUSTOMER

REPRODUCETHENOISEDURINGAROADTEST

!UDIBLE2ANGEOF3OUND

&ORSOUNDTOBEHEARDTHERESULTINGACOUSTIC

WAVEMUSTHAVEARANGEOFTO(Z

WHICHISTHEAUDIBLERANGEOFSOUNDFORHUMANS

7HILEMANYVEHICLENOISESARECAPABLEOFBEING

HEARDSOME.6(NOISESARENOTINTHEAUDIBLE

RANGE

,OWSPEEDDRONINGISANEXAMPLEOFALOW

FREQUENCY.6(CONCERNTHATMAYHAVE

COMPONENTSNOTINTHEAUDIBLERANGE4HIS

CONDITIONEXERTSPRESSUREONTHEDRIVERS

EARDRUMANDCANBEEXTREMELYUNCOMFORTABLE

/NTHEOTHERENDOFTHEAUDIBLERANGEOFVEHICLE

NOISESAREWINDNOISEANDBRAKESQUEAKING

4HEHIGHFREQUENCIESOFTHESE.6(CONCERNS

PRODUCEAHIGHPITCHEDNOISETHATCANBE

EXTREMELYANNOYING4HElGUREBELOWILLUSTRATES

THEAUDIBLERANGEOFAUTOMOTIVENOISES

-AXIMUM!UDIBLE,EVEL

!VERAGE!UDIBLE,EVEL

-INIMUM!UDIBLE,EVEL

3/5.$,%6%L).4%.3)49D"

&2%15%.#9(Z

K K K


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4HEORY

#YCLE

#YCLEISTHEPATHAWAVETRAVELSBEFORETHEWAVE

BEGINSTOREPEATTHEPATHAGAIN)FAN!LTERNATING

#URRENT!#SINEWAVEBEGINSAPATHATZERO

VOLTSTHEWAVECOMPLETESONECYCLEWHENIT

RETURNSTOZEROVOLTSFROMAPOSITIVEVOLTAGE

&REQUENCY

&REQUENCYISTHENUMBEROFCOMPLETECYCLES

THATOCCURINONESECOND3OUNDANDVIBRATION

WAVESAREMEASUREDIN(ZOR#YCLES0ER

3ECOND#03/NE(ZISEQUALTOONE#03

" " " " " " "

!"!"#

.6(4ERMINOLOGY

)NOTHERWORDSTHEWAVECOMPLETESONECYCLE

BYTRAVELINGTHEPATHFROMANEGATIVEVOLTAGETO

ZEROVOLTSTHENTOAPOSITIVEVOLTAGEANDTHEN

BACKTOZEROVOLTS

4HESOUNDWAVEINTHElGUREBELOWHASA

FREQUENCYOF(ZBECAUSEITCOMPLETESSEVEN

#034HEFREQUENCYOFASOUNDORVIBRATIONCAN

AIDINTROUBLESHOOTINGAN.6(CONCERN

4HEREARECOMMONTERMSUSEDWHENDISCUSSING

AN.6(CONCERN4HEFOLLOWINGTERMSANDGRAPHICSWILLHELPWHENDISCUSSING.6(WITH

OTHERPEOPLEWITHATECHNICALBACKGROUND


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4HEORY

0ITCH

0ITCHISTHEPHYSICALQUALITYOFSOUNDTHATRELATES

TOTHEFREQUENCYOFTHEWAVE)NCREASINGTHE

FREQUENCYOFASOUNDINCREASESTHEPITCHOFTHESOUND)FFREQUENCYDECREASESPITCHALSO

DECREASES

,ISTENINGTOANACCESSORYDRIVEBELTSQUEAKING

ISANEXAMPLEOFAHIGHPITCHEDHIGHFREQUENCY

TYPEOFNOISE!HIGHPITCHEDHIGHFREQUENCY

NOISEISIRRITATINGTOMOSTPEOPLE

!ROLLERBEARINGTHATMAKESNOISEISANEXAMPLE

OFALOWPITCHEDLOWFREQUENCYTYPEOFNOISE

(IGH&REQUENCY(IGH0ITCH

,OW&REQUENCY,OW0ITCH4)-%

!-0,)45$%

!MPLITUDE

!MPLITUDEREFERSTOTHEVERTICALMEASUREMENT

BETWEENTHETOPANDTHEBOTTOMOFAWAVE

4WOWAVESCANHAVETHESAMEFREQUENCYBUT

DIFFERINAMPLITUDE!MPLITUDEISTHEQUANTITY

ORAMOUNTOFENERGYPRODUCEDBYAVIBRATING

COMPONENT

-AXIMUM

-INIMUM

0ITCH

!MPLITUDE


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4HEORY

(IGH!MPLITUDE(IGH)NTENSITY

,OW!MPLITUDE,OW)NTENSITY

4)-%

!-0,)45$%

3OUND)NTENSITY

3OUNDINTENSITYISTHEPHYSICALQUALITYOFSOUND

THATRELATESTOTHEAMOUNTANDDIRECTIONOFTHE

mOWOFACOUSTICENERGYATAGIVENPOSITION4HElGUREILLUSTRATESTWOSOUNDWAVESWITH

THESAMEFREQUENCYBUTDIFFERENTAMPLITUDES

DIFFERENTINTENSITYLEVELS

3OUNDINTENSITYISMEASUREDINDECIBELS

!DECIBELISAUNITFOREXPRESSINGRELATIVE

DIFFERENCEINPOWERBETWEENACOUSTICSIGNALS

3OUNDSGREATERTHANDECIBELSAREDANGEROUS

TOHUMANHEARING

$IFFERENCESINPITCHTHESOURCEOFEACHSOUND

ORTHEPERSONWHOHEARSTHESOUNDCANCREATE

THEPERCEPTIONTHATTWOSOUNDSOFTHESAME

INTENSITYHAVEDIFFERENTLEVELSOFLOUDNESS


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4HEORY

2ESONANCE

2ESONANCEISTHETENDENCYOFASYSTEMTO

RESPONDTOACOMPELLINGFORCEOSCILLATINGATOR

NEARTHENATURALFREQUENCYOFTHESYSTEM!LLOBJECTSHAVENATURALFREQUENCIESANDEXPERIENCE

MAXIMUMRESPONSEATTHEPOINTOFRESONANCE

4HENATURALFREQUENCYOFATYPICALAUTOMOTIVE

FRONTSUSPENSIONISINTHETO(ZRANGE4HIS

ISDESIGNEDFORRIDEANDHANDLINGCONSIDERATIONS

!SSEENINTHElGURETHESUSPENSIONSNATURAL

FREQUENCYISTHESAMENOMATTERWHATTHE

VEHICLESPEED!STHETIRESPEEDINCREASES

ALONGWITHTHEVEHICLESPEEDTHEDISTURBANCE

CREATEDBYTHEUNBALANCEDTIREINCREASESIN

FREQUENCY%VENTUALLYTHEFREQUENCYOFTHE

UNBALANCEDTIREINTERSECTSWITHTHENATURAL

FREQUENCYOFTHESUSPENSIONCAUSINGTHE

SUSPENSIONTOVIBRATE4HISINTERSECTIONPOINTIS

CALLEDTHERESONANCE

-0(

(Z

0OINTOF2ESONANCE

#OMPE

LLING&

ORCE

6IBRATION3PEED

3USPENSION&REQUENCY

4HEAMPLITUDEOFAVIBRATIONISGREATESTATTHE

POINTOFRESONANCE!LTHOUGHTHEVIBRATIONCAN

BEFELTABOVEANDBELOWTHEPROBLEMSPEEDITISMOSTPROMINENTATTHEPOINTOFRESONANCE

2ESONANCEEXPLAINSWHYATIREVIBRATIONOCCURS

ATCERTAINVEHICLESPEEDS)FTHEVEHICLEgS

SUSPENSIONHASANATURALFREQUENCYOF(Z

THESUSPENSIONWILLTRANSMITORRESONATETHE

VIBRATIONATSPEEDSINTHE(ZRANGE4HE

VEHICLEWILLVIBRATEATMPHMPHAND

MPHBECAUSETHESESPEEDSCAUSEATIRE

VIBRATIONTORESONATETHROUGHTHESUSPENSION

INTOTHEVEHICLE


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4HEORY

4YPESOF.OISE

4HERECANBEMANYTYPESOFNOISECONCERNSON

AVEHICLE4HECLASSIlCATIONOFNOISESASSISTSTHETECHNICIANINTROUBLESHOOTINGANDREPAIRINGTHE

CUSTOMERSVEHICLE

.OISEISANUNPLEASANTORUNEXPECTEDSOUND

CREATEDBYAVIBRATINGOBJECT)NTERPRETATIONPLAYS

ALARGEROLEINDElNINGNOISECHARACTERISTICS

4ERMSUSEDTODESCRIBENOISEINCLUDE

s $RONING

s "EAT

s 2OADNOISE

s "RAKESQUEAL

4HEFREQUENCYOFNOISEVIBRATIONSISMUCHHIGHER

THANTHATWHICHCANONLYBEFELTOFTENRANGING

BETWEENAND(Z#ERTAINNOISESCAN

BEASSOCIATEDWITHTHECOMPONENTSYSTEMS

OFAVEHICLESUCHASTHEENGINEDRIVELINEAXLE

BRAKESORBODYCOMPONENTS

)NOTHERSITUATIONSANOISECANTELEGRAPH

THROUGHTHEBODYOFAVEHICLE&OREXAMPLE

ACHIRPINGNOISEMAYBEHEARDINTHEAREAOF

THEINSTRUMENTPANELWHENINFACTITISBEING

PRODUCEDBYTHEREARBRAKES4HESOUNDHAS

TRAVELEDORTELEGRAPHEDTHROUGHTHEPARKING

BRAKECABLES&OLLOWINGASYSTEMATICAPPROACH

WHENTROUBLESHOOTINGAN.6(CONCERNHELPSTO

LOCATETHECAUSEANDCORRECTTHECONDITION

.OISECANBEANNOYINGTOSOMEPEOPLEWHILE

OTHERSlNDITACCEPTABLE!UTOMOTIVENOISESCANBEAUDIBLEATCERTAINSPEEDSORUNDER

CERTAINDRIVINGCONDITIONS!GEARDRIVENUNIT

SUCHASANAUTOMOTIVEDRIVEAXLEPRODUCESA

CERTAINAMOUNTOFNOISE)NDEALINGWITHTHESE

CONCERNSITISIMPORTANTTOKNOWWHATANORMAL

CONDITIONISANDEXPLAINITTOTHECUSTOMERIN

TERMSTHEYCANUNDERSTAND

4RYINGTOREPAIRANORMALVEHICLECONDITIONCAN

BEFRUSTRATING$ESPITEGOODINTENTIONSAN

ATTEMPTEDREPAIRCANALSOBECOMEALIABILITYIF

LEGALACTIONISINITIATED


12/70

4HEORY

$RONING

4HESENSATIONPEOPLEEXPERIENCEWHENDRIVING

INTOATUNNELATHIGHSPEEDORCLIMBINGTOA

HIGHALTITUDEISAFEELINGOFEARDISCOMFORT4HEEARDRUMSFEELASIFTHEYAREBEINGFORCEDIN

OROUTDUETOSUDDENCHANGESINATMOSPHERIC

PRESSURE!NUNPLEASANTDRONINGCAUSESA

SIMILARSENSATIONDUETOLARGEmUCTUATIONSOFAIR

PRESSUREINTHECAR

!CUSTOMERMAYREFERTOUNPLEASANTDRONING

NOISESASHUMMINGNOISES4HEREARETHREE

TYPESOFUNPLEASANTDRONING

s ,OWSPEED

s -IDDLESPEED

s (IGHSPEED

5NPLEASANTDRONINGATLOWANDMIDDLESPEED

DRIVINGISALONGDURATIONLOWPITCHEDNOISETHAT

ISNONDIRECTIONAL)TISHARDTOHEARANDFEELSLIKEPRESSUREINTHEEARS

&EELINGASMALLAMPLITUDEVIBRATIONISCOMMON

WITHLOWANDMIDDLESPEEDDRONING,OWSPEED

DRONINGHASARANGEOFUPTOMPHKPH

ANDHASAFREQUENCYOFTO(Z-IDDLE

SPEEDDRONINGHASARANGEOFTOMPH

TOKPHWITHAFREQUENCYOFTO(Z

5NPLEASANTDRONINGATHIGHSPEEDDRIVINGISA

LONGDURATIONNONDIRECTIONALHUMMINGNOISE

THATISUNCOMFORTABLETOTHEEARS(IGHSPEED

DRONINGHASARANGEOFMPHKPHANDUP

WITHAFREQUENCYOFTO(Z

4HETHREECLASSIlCATIONSOFDRONINGARESPEED

ANDFREQUENCYRELATED!LOWSPEEDDRONING

SOUNDHASALOWERPITCHTHANAHIGHSPEED

DRONINGSOUND

4HETABLESUMMARIZESTHESPEEDANDFREQUENCY

RANGESFORTHETHREETYPESOFDRONING

3PEEDAND&REQUENCY2ANGESOF$RONING

30%%$2!.'%&2%15%.#9

2!.'%

,OW3PEED

$RONING

5PTOMPH

KPHTO(Z

-IDDLE3PEED

$RONING

TOMPHTOKPH

TO(Z

(IGH3PEED

$RONING

MPH

KPHANDUPTO(Z


13/70

4HEORY

$RONINGCANOCCURWHENACCELERATING

DECELERATINGORDRIVINGATACONSTANTSPEEDBUT

MOSTOFTENOCCURSWHENACCELERATING$RONINGUSUALLYISAPPARENTATASPECIlCENGINERPMOR

VEHICLESPEED&OREXAMPLETHElGUREILLUSTRATES

HOWTHENOISELEVELOFAVEHICLEINCREASES

WITHVEHICLESPEED!SVEHICLESPEEDREACHES

ACERTAINRANGETHESOLIDCOLOREDAREASOFTHE

lGUREALARGEINCREASEINTHENOISELEVELOCCURS

4HESPEEDORRPMRANGEATWHICHUNPLEASANT

DRONINGOCCURSISRELATIVELYNARROW7HEN

DRONINGOCCURSATASPECIlCVEHICLESPEEDTHERANGEISGENERALLYWITHINMPHKPHOFTHAT

SPEED7HENDRONINGOCCURSATASPECIlCENGINE

RPMTHETECHNICIANSHOULDCHANGEVEHICLESPEED

VERYSLOWLY#HANGINGVEHICLESPEEDQUICKLYWILL

MAKEITDIFlCULTTOCHECKTHEDRONINGBECAUSE

RPMWILLPASSTHROUGHTHESPECIlCRANGETOO

QUICKLY

$RONINGISUSUALLYGENERATEDBYMORETHANONE

COMPONENT)NMOSTCASESITISNECESSARYTO

ELIMINATEALLTHECAUSESINORDERTOREMOVETHEDRONINGNOISE&OREXAMPLEUNPLEASANTDRONING

CANOCCURWHENENGINEANDDRIVELINEVIBRATIONS

ARETRANSMITTEDTOTHEBODYPANELSCAUSINGTHEM

TORESONATE!IRCLEANERAIRINTAKEANDEXHAUST

NOISESCANCOMBINEANDCAUSEDRONINGINTHE

PASSENGERCOMPARTMENT

/THERITEMSTHATARESOMETIMESRESPONSIBLEFOR

UNPLEASANTDRONINGINCLUDE

s "ENDINGRESONANCEOFEXHAUSTPIPESs 2ESONANCEOFAUXILIARYEQUIPMENT

s "ENDINGRESONANCEOFPROPELLERSHAFT

s 2ESONANCEOFSUSPENSIONLINKS

s 4RANSMISSIONOFENGINEVIBRATION

s 4RANSMISSIONOFEXHAUSTNOISE

s 4RANSMISSIONOFINTAKEAIRNOISE

4HEBENDINGRESONANCEISANORMALOCCURRENCE

FORSTRAIGHTTUBESANDPIPESANDEXHAUST

ANDDRIVESHAFTS4HESECOMPONENTSDEFORM

RESONATEATKNOWNFREQUENCIES%NGINEERS

DESIGNCOMPONENTSSOTHATTHEBENDING

RESONANCEWILLNOTOCCURDURINGTHENORMAL

OPERATIONOFTHEVEHICLE


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4HEORY

"EAT

&ORBEATSOUNDSTODEVELOPTHEREMUSTBE

TWOSOUNDSOURCES&OREXAMPLESTRIKINGA

TUNINGFORKPRODUCESAPURETONEOFACERTAINFREQUENCYPITCH)FASECONDTUNINGFORKWITH

AVERYDIFFERENTPITCHISSTRUCKEACHTONEIS

DISTINGUISHABLEFROMONEANOTHER(OWEVERIF

THEPITCHESOFTHETUNINGFORKSARESIMILARTHE

TWOTONESPRODUCEABEATSOUNDWITHAPITCH

THATOCCURSINCYCLESATTHEDIFFERENCEOFTHETWO

FREQUENCIES)FTHEPITCHESOFTHETWOSOUNDS

ARETHESAMEORONLYSLIGHTLYDIFFERENTTHEY

AREINDISTINGUISHABLEANDAREPERCEIVEDASONE

SOUND4HElGUREILLUSTRATESTWOTUNINGFORKSPRODUCING

SOUNDWAVESWITHTROUGHSANDPEAKS4HETWO

WAVESHAVESLIGHTLYDIFFERENTFREQUENCIES4HE

SOUNDLEVELBECOMESHIGHERWHENTHEIRPEAKS

OCCURATTHESAMETIME4HESOUNDLEVELDROPS

WHENAPEAKOFONEWAVEOCCURSATTHESAME

TIMEASTHETROUGHOFTHEOTHERWAVE7HENTHE

TWOWAVESCOMBINETHEYPRODUCEABEATSOUND

INWHICHLOUDNESSCHANGESPERIODICALLY

!

"

#

(Z

(Z

3OUND7AVES#ARETHESUMOF3OUND7AVES!AND"

4HEmUCTUATIONIN-AGNITUDEIS0HASINGOR"EATING

4HESENSATIONOFABEATSOUNDISMOST

NOTICEABLEWHENTHEFREQUENCYDIFFERENCEIS

TO(Z)FTHETWOFREQUENCIESARECLOSERTHEIRTONESAREINDISTINGUISHABLEANDARESENSED

ASTHESAMESOUND)FTHETWOFREQUENCIES

AREGREATERTHAN(ZAPARTEACHTONEIS

DISTINGUISHABLEFROMONEANOTHER

"EATSOUNDSCANRESULTFROMACOMBINATION

OFMANYTYPESOFVIBRATIONS#OMMON

COMBINATIONSTHATRESULTINBEATSOUNDSINCLUDE

s %NGINEANDAIRCONDITIONINGCOMPRESSOR

s %NGINEANDPOWERSTEERINGHYDRAULIC

PUMPOROTHERACCESSORIES

s %NGINEANDVIBRATIONSOFTHEDRIVESHAFT

s 4IRENONUNIFORMITY

s 4IREANDDRIVESHAFTVIBRATIONS


15/70

4HEORY

2OAD.OISE

4HESOUNDSTHATOCCURWHILEDRIVINGONGRAVEL

ORROUGHLYPAVEDROADSISANEXAMPLEOFROAD

NOISE4HISTYPEOFNOISEISCONTINUOUSANDHASACONSTANTCHARACTER2OADNOISECANOCCURATALL

VEHICLESPEEDSORWHENTHEVEHICLEISCOASTING

ANDHASAFREQUENCYRANGEOFTO(Z!

VERYlNEVIBRATIONALSOMAYBENOTICEABLE

2OADROUGHNESSANDTIRESAREMAJORSOURCESOF

NOISEANDVIBRATIONTHATOCCURDURINGDRIVING

3INCETHESOURCEOFROADNOISEISIRREGULARROAD

SURFACESDIFFERENTTYPESOFTIRESCANINmUENCE

THEAMOUNTOFROADNOISE4HEIMPACTFORCEFROM

ROADSURFACESTRANSMITSTOTHETIRESCAUSINGTHEMTOVIBRATE4HISVIBRATIONINTURNTRANSMITS

TOTHESUSPENSIONANDBODY4HERESONANCE

CHARACTERISTICOFTHEPASSENGERCOMPARTMENT

AMPLIlESTHEVIBRATIONANDGENERATESANNOYING

ROADNOISE


16/70

4HEORY

"RAKE3QUEAL

4HEMOSTCOMMONBRAKESYSTEM.6(CONCERN

ISBRAKESQUEAL"RAKESQUEALISAHIGHPITCHED

NOISE)FBRAKESQUEALONLYAPPEARSWHENTHEVEHICLEISlRSTPUTINTOOPERATIONITMAYBEDUE

TOMOISTUREONTHEBRAKELININGS

"RAKESQUEALALSOCANOCCURWHENFRICTIONIS

CREATEDBETWEENBRAKECOMPONENTSDURING

BRAKING7ORNORDAMAGEDBRAKECOMPONENTS

CANPRODUCEAVIBRATIONRESULTINGINBRAKESQUEAL

4HISHIGHFREQUENCYNOISECANOCCURUNDER

DIFFERENTBRAKEPEDALPRESSURESVEHICLESPEEDS

ANDBRAKETEMPERATURES

$RUMBRAKESUSUALLYEMITALOWERPITCHNOISE

THATGETSLOUDERWITHINCREASEDBRAKEPEDAL

PRESSURE$ISCBRAKENOISEISGENERALLYAHIGH

PITCHEDSQUEALTHATOCCURSUNDERLIGHTPEDAL

PRESSURE

4HEMAJORVIBRATIONSOURCESOFBRAKESQUEALARE

s 7ORNBRAKESHOES

s .ONUNIFORMTHICKNESSOFBRAKEDISCOR

DRUMSs %XCESSIVERUNOUT

s $AMAGEORCONTAMINATIONOFFRICTION

SURFACES

"ECAUSEOFTHECOMPLEXNATUREOFBRAKESAND

THEMANYDIFFERENTPARTSFOUNDINTHEMTHE

BESTWAYTOCORRECTBRAKESQUEALISTOFOLLOW

SERVICEPROCEDURES$URINGBRAKESERVICE

ALWAYSTHOROUGHLYCLEANANYFRICTIONSURFACEBEFOREREASSEMBLINGTHEBRAKE!WIDEVARIETY

OFCOATINGMATERIALSUSEDONBRAKEBACKING

SURFACESANDTHEINSTALLATIONOFSHIMSANDCLIPS

CANHELPELIMINATEBRAKESQUEAL.6(CONCERNS


17/70

4HEORY

#OMPELLING&ORCEAND6IBRATING"ODY

6IBRATIONSOCCURWHENTHEREISACOMPELLING

FORCEOREXCITINGFORCEACTINGUPONANOBJECTTHATCAUSESTHEBODYTOVIBRATE,OCATINGTHE

COMPELLINGFORCETHESOURCEOFTHEVIBRATION

CANASSISTINELIMINATINGAN.6(CONCERN

4HEMAJORCOMPONENTGROUPSTHATPRODUCE

COMPELLINGFORCESARE

s 4IREANDWHEEL

s $RIVELINE

s %NGINEANDTORQUECONVERTER

6IBRATION4RANSFER0ATH

6IBRATIONSTRAVELTHROUGHAVEHICLESSTRUCTURE

SIMILARTOTHEWAYRADIOWAVESTRAVELTHROUGH

AIR6IBRATIONSAREOFTENNOTICEDINACOMPONENT

FARREMOVEDFROMWHERETHEYAREGENERATED

4RANSMISSIONOFAVIBRATIONTOOTHERCOMPONENTS

ISCALLEDhTELEGRAPHINGv&OREXAMPLEANOUTOFBALANCEFRONTTIREANDWHEELASSEMBLYMAY

RESULTINANOTICEABLESTEERINGWHEELSHAKE)N

THISCASETHEWHEELANDTIREASSEMBLYISTHE

ORIGINATOROFTHEVIBRATIONTHESUSPENSIONISTHE

CONDUCTORANDTHESTEERINGWHEELISTHEREACTOR

6IBRATION

6IBRATIONISTHEREPETITIVEMOTIONOFANOBJECT

BACKANDFORTHORUPANDDOWN4HISMOTION

ISAFUNCTIONOFTIMEANDISMEASURABLEIN(Z

6IBRATIONCANBEDESCRIBEDINMANYWAYSWHICH

INCLUDE

s 3HAKE

s 3HIMMY

s 3HUDDER

6IBRATIONSCANBECONSTANTORVARIABLEAND

OCCURDURINGAPORTIONOFTHETOTALOPERATING

SPEEDRANGE6IBRATIONSUSUALLYARECAUSEDBY

SOMEROTATINGCOMPONENTORCOMPONENTSOR

SOMETIMESBYTHECOMBUSTIONOFTHEAIRFUEL

MIXTUREINTHEINDIVIDUALENGINECYLINDERS

5NDERNORMALCIRCUMSTANCESAROTATING

COMPONENTDOESNOTPRODUCEANOTICEABLEVIBRATION(OWEVERIFTHECOMPONENTHAS

IMPROPERWEIGHTDISTRIBUTIONIMBALANCEORIS

ROTATINGINANECCENTRICPATTERNOUTOFROUND

ORBENTTHENANOTICEABLEVIBRATIONMAYBE

PRODUCED)FTHECHARACTERISTICSOFTHEVIBRATION

CANBEMEASUREDTHEINFORMATIONABOUT

THEVIBRATIONCANBEUSEDTOMATCHITWITH

COMPONENTSTHATARETHELIKELYCAUSE

4HEREAREMANYTYPESOFVIBRATIONPROBLEMSON

AVEHICLE4HECLASSIlCATIONOFVIBRATIONSASSISTS

THETECHNICIANINTROUBLESHOOTINGANDREPAIRING

THECUSTOMERCONCERN


18/70

4HEORY

6IBRATION/RDER

/RDERISTHENUMBEROFDISTURBANCESCREATED

INONEREVOLUTIONOFACOMPONENT!SINGLEHIGHSPOTONATIRECAUSESONEDISTURBANCEPER

REVOLUTIONANDISCALLEDAlRSTORDERDISTURBANCE

)FTHEWHEELROTATESTIMESPERSECONDTHERE

AREDISTURBANCESPERSECOND4HISCREATESA

lRSTORDERDISTURBANCEOF(Z

)FTHETIREDEVELOPEDASECONDHIGHSPOTA

SECONDORDERDISTURBANCEWOULDRESULT4HE

WHEELROTATINGTIMESPERSECONDPRODUCES

DISTURBANCESPERSECOND4HISCREATESASECOND

ORDERDISTURBANCEOF(Z4HREEHIGHSPOTS

CREATEATHIRDORDERDISTURBANCEANDFOURHIGH

SPOTSCREATEAFOURTHORDERDISTURBANCE(IGHER

ORDERDISTURBANCESCONTINUETOPROGRESSINTHIS

WAY

4HEVIBRATIONORDERCANAIDTHETECHNICIANWHILE

TROUBLESHOOTING&OREXAMPLEAVEHICLEHASAN.6(CONCERNTHATISPRODUCINGAVIBRATIONAT

(Z!FTERCALCULATINGDRIVESHAFTFREQUENCYITIS

DETERMINEDTHEDRIVESHAFTHASAFREQUENCYOF

(Z4HESECONDORDERFREQUENCYOFTHEDRIVE

SHAFTIS(Z4HISMATCHESTHEFREQUENCYOF

THE.6(CONCERN

"YDETERMININGTHATTHE.6(CONCERNISA

POSSIBLESECONDORDERVIBRATIONYOUWOULDLOOK

ATCOMPONENTSTHATCOULDCAUSEAVIBRATION

OFTHISTYPE5NIVERSALJOINTSWOULDBEAGOODCOMPONENTTOCHECKBECAUSEITISPOSSIBLE

THEYCOULDPRODUCETWODISTURBANCESWITHEACH

REVOLUTIONOFTHEDRIVESHAFT!MISSINGDRIVE

SHAFTWEIGHTCOULDBEELIMINATEDFROMTHELIST

OFPOSSIBILITIESBECAUSETHISSITUATIONWOULD

PRODUCEAVIBRATIONOFTHElRSTORDER

&IRSTORDER6IBRATION

3ECONDORDER6IBRATION


19/70

4HEORY

6IBRATION/RDER%XAMPLES

(ALFORDERVIBRATION

(ALFORDERVIBRATIONISCREATEDWHENANY

COMPONENTTHATROTATESATHALFTHECRANKSHAFT

SPEEDISOUTOFBALANCEORHASEXCESSIVERUNOUT

!NEXAMPLEOFTHISISCAMSHAFTIMBALANCE

"ALANCINGTHECOMPONENTORCORRECTINGTHE

RUNOUTMAYBRINGTHEVIBRATIONTOANACCEPTABLE

LEVEL

&IRSTORDERVIBRATION

&IRSTORDERVIBRATIONISCREATEDWHENANY

COMPONENTTHATROTATESATCRANKSHAFTSPEED

ISOUTOFBALANCEORHASEXCESSIVERUNOUT

%XAMPLESAREmYWHEELORTORQUECONVERTER

IMBALANCEANDCYLINDERTOCYLINDERMASS

DIFFERENCES)NRARECASESTHECRANKSHAFTITSELF

MAYBEIMBALANCED"ALANCINGTHECOMPONENT

ORCORRECTINGTHERUNOUTMAYBRINGTHEVIBRATION

TOANACCEPTABLELEVEL

3ECONDORDERVIBRATION

3ECONDORDERVIBRATIONISCAUSEDBYTHEUPAND

DOWNMOTIONOFTHEPISTONS4HISREVERSALOF

MASSANDMOTIONCREATESANATURALVIBRATION

3YMPTOMSOFENGINEIMBALANCEINCLUDE

s !LOWSPEEDSHAKEFELTBETWEENAND

2EVOLUTIONS0ER-INUTERPMTHAT

HASAFREQUENCYOFTO(Z

s !ROUGHNESSSOMETIMESFELTANDHEARD

BETWEENTORPMATAFREQUENCYOFTO(Z

&IRSTANDSECONDORDERENGINEVIBRATIONSUSUALLY

AREDETECTEDDURINGTHENEUTRALRUNUPTEST

4HIRDORDERVIBRATION

!THIRDORDERVIBRATIONISCAUSEDBYANY

COMPONENTTHATHASTHREEHEAVYSPOTS


20/70

4HEORY

3HAKE

6IBRATIONSATTHESTEERINGWHEELORSEATORANANNOYINGVIBRATIONATTHEmOORAREINDICATORSOF

hSHAKEv3HAKEGENERALLYHASAFREQUENCYOF

TO(Z4HEREARETWOTYPESOFSHAKE

s 6ERTICALUPANDDOWN

s ,ATERALSIDETOSIDE

6ERTICALSHAKEISSEVEREVERTICALVIBRATIONOFTHE

BODYSEATSANDSTEERINGWHEEL!TREMBLINGENGINEHOODORREARVIEWMIRRORALSOCANBEA

VERTICALSHAKESYMPTOM

,ATERALSHAKEISSIDETOSIDEVIBRATIONOFTHE

BODYSEATSANDSTEERINGWHEEL!TREMBLING

VIBRATIONINTHEDRIVERSWAISTORHIPSMAYBEA

SYMPTOMOFALATERALSHAKE

4HEMAJORVIBRATIONSOURCESOFVERTICALAND

LATERALSHAKEARE

s 2OUGHNESSOFROADs 4IREIMBALANCE

s .ONUNIFORMTIRES

s "ENTOROUTOFROUNDWHEELS

s $RIVELINE

s %NGINE

4YPESOF6IBRATION

6IBRATIONSINAVEHICLECANBEANYONEOFTHE

FOLLOWINGTYPESs 3HAKE

s 3HIMMY

s "RAKE6IBRATION3HUDDER


21/70

4HEORY

3HIMMY

6IBRATIONTHATCAUSESTHESTEERINGWHEELTO

OSCILLATEISKNOWNAShSHIMMYv4HEBODYOF

THEVEHICLEALSOMAYVIBRATELATERALLY3HIMMYGENERALLYHASAFREQUENCYOFTO(Z4HERE

ARETWOTYPESOFSHIMMY

s (IGHSPEEDSHIMMY

s ,OWSPEEDSHIMMY

(IGHSPEEDSHIMMYOCCURSWHENDRIVINGON

SMOOTHROADSATHIGHSPEEDS(IGHSPEED

SHIMMYTYPICALLYHASALIMITEDSPEEDRANGEINWHICHSYMPTOMSARENOTICEABLE

,OWSPEEDSHIMMYOCCURSWHENTHESTEERING

WHEELBEGINSTOVIBRATEASTHEVEHICLEISDRIVEN

ACROSSABUMPATLOWSPEEDS

4HEMAJORVIBRATIONSOURCESOFHIGHSPEEDAND

LOWSPEEDSHIMMYARE

s 2OUGHNESSOFROAD

s 4IREIMBALANCE

s .ONUNIFORMTIRES

s "ENTOROUTOFROUNDWHEELS

&OREXAMPLEATIREWITHEXCESSIVERUNOUTOUT

OFBALANCEOROUTOFROUNDMAYCAUSEHIGHOR

LOWSPEEDSHIMMY4HISISBECAUSETHETIREFAULT

GENERATESAVIBRATIONATAPARTICULARFREQUENCY

7HENTHEVIBRATIONOFTHETIREREACHESTHE

NATURALFREQUENCYOFTHEVEHICLESFRONTUNSPRUNG

COMPONENTSSUCHASTHEFRONTAXLETIRES

ANDWHEELSTHEYSTARTTOVIBRATE7HENTHE

FREQUENCYOFTHEFRONTUNSPRUNGCOMPONENTS

MATCHESTHENATURALFREQUENCYOFTHESTEERING

SYSTEMRESONANCEOCCURS4HISRESONANCE

CAUSESTHESTEERINGWHEELTOVIBRATEHEAVILYIN

THETURNINGDIRECTION


22/70

4HEORY

"RAKE6IBRATION3HUDDER

"RAKEVIBRATIONSHUDDERISTRANSMITTEDTHROUGH

THEBRAKEHYDRAULICLINESTOTHESUSPENSION

SYSTEMSTEERINGSYSTEMANDTHEBRAKEPEDAL"RAKEPEDALPULSATIONISGENERATEDWHEN

APPLYINGABRAKEWITHANONUNIFORMDIAMETER

DRUMORADISCBRAKEWITHNONUNIFORMBRAKE

DISCTHICKNESS

"RAKESHUDDERCAUSESTHEINSTRUMENTPANEL

STEERINGWHEELANDSOMETIMESTHEENTIRE

BODYTOVIBRATEVERTICALLYANDBACKANDFORTH

DURINGBRAKING)TALSOMAYRESULTINBRAKEPEDAL

PULSATIONRELATEDTOWHEELROTATIONANDCAN

OCCURDURINGANYBRAKINGCONDITIONORVEHICLESPEED.ORMALLYBRAKESHUDDERHASAPEAKAT

TOMPHTOKPHANDHASAFREQUENCYOF

TO(Z

#ERTAINOPERATINGCONDITIONSCANAFFECTTHE

CAUSEOFTHESEVIBRATIONS4HESEINCLUDE

s %XTENDEDPERIODSWHERETHEVEHICLEIS

NOTINOPERATION

s "RAKEDISCSURFACEIRREGULARITIESDUETO

FOREIGNAGENTSOILORGREASEANTIFREEZEETC

s $EFORMATIONOFBRAKEDRUMDUETOPOOR

INSTALLATION

)FTHEDISCROTORHASEXCESSIVETHICKNESS

VARIATIONFRICTIONFORCEONTHEBRAKINGSURFACE

VARIESDURINGBRAKEAPPLICATION4HECHANGEINTHEBRAKINGFORCEGENERATESAVIBRATIONATA

CERTAINFREQUENCY4HISVIBRATIONISTRANSMITTEDTO

THESUSPENSIONSTEERINGANDBRAKEPEDAL4HE

VIBRATIONCANALSOTRANSMITTOTHEBODYCAUSING

ITTORESONATE

4HEROOTCAUSEOFDISCBRAKEVIBRATIONSHUDDER

CONCERNSISTHICKNESSVARIATION4HICKNESS

VARIATIONCANBECAUSEDBYAROTORTHATHAS

LATERALRUNOUT,ATERALRUNOUTCANBECAUSED

BYIMPROPERWHEELTIGHTENINGPROCEDURESANDTORQUEVALUESASWELLASHUBRUNOUT!STHEROTOR

WOBBLESLATERALRUNOUTCONTACTISMADEWITH

THEBRAKEPADS!SSECTIONSOFTHEROTORMAKE

CONTACTWITHTHEPADSSMALLAMOUNTSOFMETAL

WEARFROMTHEROTORSURFACE4HISCONTINUES

UNTILENOUGHMETALISWORNINSECTIONSTOCAUSE

THICKNESSVARIATION4HISISWHYIMPROPERWHEEL

TIGHTENINGPROCEDURESOFTENTAKEWEEKSOR

MONTHSTOPRODUCEBRAKEVIBRATIONS

4HESAMEISTRUEFORHUBRUNOUT2ESURFACINGORREPLACINGROTORSWHENTHEHUBHASLATERALRUNOUT

ISUSUALLYASHORTTERMREPAIR!LWAYSFOLLOW

SERVICEINFORMATIONFORPROPERWHEELTIGHTENING

PROCEDURESANDTORQUEVALUES#HECKTHEHUB

FORLATERALRUNOUTWHENRESURFACINGORREPLACING

ROTORSFORABRAKEVIBRATION

)FTHEVIBRATIONORNOISEISCAUSEDBYTHEBRAKE

SYSTEMREFERTOSERVICEMANUALINFORMATION

FORTHEVEHICLE0ROCEDURESTOCHECKDRUMS

ANDROTORSFOROUTOFROUNDTHICKNESSVARIATIONANDLATERALRUNOUTARECOVEREDINTHESERVICE

INFORMATION

/VERTIGHTENINGWHEELBOLTSSUCHAS

WITHANIMPACTWRENCHOFTENCAUSES

ROTORWARPAGE

"ESUREWHEELNUTSARECORRECTLY

TORQUED


23/70

4HEORY

2IDE#OMFORT

2IDECOMFORTPLAYSALARGEPARTINACUSTOMERS

SATISFACTIONWITHTHEIRVEHICLE!VOIDINGABNORMALVIBRATIONSENSURESAQUALITYRIDECOMFORTLEVEL

.ORMALVEHICLEVIBRATIONSAREARESULTOFROAD

ROUGHNESS$URINGNORMALOPERATIONTHE

VEHICLEEXPERIENCESVIBRATIONBETWEENTHE

SPRUNGCOMPONENTSBODYANDSUSPENSIONAND

THEUNSPRUNGCOMPONENTSAXLESTIRESAND

WHEELS4HISISANACCEPTABLECONDITIONUNLESS

THESPRUNGORUNSPRUNGCOMPONENTSBECOME

DEFECTIVEWORNORDAMAGED

7HENUNSPRUNGCOMPONENTSRESONATEWITHTHESPRUNGCOMPONENTSTHERESULTISPOORRIDE

COMFORT2IDECOMFORTVIBRATIONSMAYCAUSETHE

VEHICLETOROLLPITCHANDBOUNCEWHICHMAY

CAUSEACUSTOMERCONCERN0OORRIDECOMFORT

CANBEMINIMIZEDBYENSURINGSUSPENSIONAND

STEERINGCOMPONENTSARENOTDAMAGEDORWORN


24/70

4HEORY

(ARSHNESS

(ARSHNESSRESULTSWHENTHEVEHICLEISUNABLETO

ABSORBVIBRATIONSPRODUCEDBYROADCONDITIONS

4HECAUSESMAYBEDUETODETERIORATIONOFVEHICLECOMPONENTSDAMAGEORMODIlCATION

OFTHEORIGINALEQUIPMENT)NMOSTCASES

HARSHNESSISRELATEDTOCHASSISCOMPONENTS

7HENDIAGNOSINGAHARSHNESSCONCERNPAY

CLOSEATTENTIONTOINTERIORNOISELEVELSINTHE

VEHICLE-ANYHARSHNESSCONDITIONSAREDUE

TOACOMPONENTTHATISNOTALLOWEDTOMOVE

WITHINITSNORMALTRAVELORONETHATHASLOSTITS

ISOLATINGGROMMETSORBUSHINGS4HISMAKES

ENGINEMOUNTSSUBFRAMEMOUNTSBUSHINGSANDSUSPENSIONCOMPONENTSPRIMESUSPECTSINTHE

DIAGNOSTICPROCEDURE

/VERSIZEDTIRESHEAVYDUTYSPRINGSANDSHOCKS

OROTHERVEHICLEMODIlCATIONSALSOMUSTBE

CONSIDERED3OMEAFTERMARKETTIRESEVENWHEN

THEYARETHECORRECTSIZEMAYPRODUCECHANGES

INTHEVEHICLETHATWILLGENERATEOWNERCONCERNS

-ANYCUSTOMERSUSETHEWORDhHARSHNESSvTO

DESCRIBERIDECOMFORTCONCERNS(ARSHNESSHAS

BECOMEAUNIVERSALTERMWHENDEALINGWITH.6(CONCERNSONAVEHICLE&ORTHEPURPOSE

OFTHISCOURSEHARSHNESSISANAGGRESSIVE

SUSPENSIONFEELORLACKOFhGIVEvINRESPONSE

TOASINGLEINPUT)TCANBEASSOCIATEDWITHAN

ABRUPTTHUMPINGNOISEASWELLASANAGGRESSIVE

FEEL

(ARSHNESSOCCURSWHENAVEHICLEVIBRATESFROM

MOVINGACROSSROADJOINTSPROJECTIONSSTEPPED

DIFFERENCESORDEPRESSIONSONPAVEDROADS

$RIVINGONTHEEXPRESSWAYINCREASESTHEPITCH

OFTHETHUMPINGSOUND4HEIMPACTFORCEFROMTHEROADSURFACECAUSESTHETIRESTOVIBRATE

4HETIRESTRANSMITTHEVIBRATIONTHROUGHTHE

SUSPENSIONSYSTEMTOTHECARBODY(ARSHNESS

HASAFREQUENCYOFTO(Z


25/70

4HEORY

6IBRATIONS

6IBRATIONSARENOTICEABLEATTHESTEERINGWHEEL

SEATSANDmOOR4HELEVELANDINTENSITYOFTHE

VIBRATIONCHANGESWITHTHESUSPENSIONTYPEANDTHEBUSHINGSUSED

,ONGITUDINALIMPACTFORCESARETRANSMITTEDTOTHE

LOWERARMSWHERESUSPENSIONBUSHINGSDAMPEN

THEVIBRATION4HEDAMPENEDVIBRATIONTHEN

TRANSMITSTHROUGHTHESUSPENSIONCROSSMEMBER

ANDSTRUTINSULATORSTOTHEBODY

4HERIGIDITYOFTHEBUSHINGSANDINSULATORSIN

THEVIBRATIONTRANSMISSIONPATHHASALARGE

INmUENCEONHARSHNESS4HEUSEOFLOWRIGIDITY

BUSHINGSANDINSULATORSTOPROVIDEGREATERFORE

AFTSUSPENSIONCOMPLIANCESOFTENSTHEIMPACT

FORCEEFFECTIVELYBUTRESULTSINLESSRESPONSIVE

STEERING

!LONGWITHSUSPENSIONSYSTEMDESIGNS

TIRECHARACTERISTICSINmUENCETHEAMOUNTOF

HARSHNESS7HENTIRESEXPERIENCEANIMPACT

FORCEFROMAPAVEMENTJOINTTHEYDEFORMTO

CUSHIONTHERESTOFTHEVEHICLE4HETIRESABSORB

THEFORCETOSOMEEXTENTANDAREANIMPORTANT

FACTORWHENDEALINGWITHHARSHNESS!TTHESAMETIMETHEDEFORMATIONTRANSMITSVIBRATION

TOOTHERPORTIONSOFTHETIRES4HISCAUSESTHE

TIRESTOUNDERGOCOMPLICATEDRESILIENTVIBRATIONS

!TIRETHATCANABSORBVIBRATIONSFROMIMPACTIS

EFlCIENTINCONTROLLINGTHEPROBLEMOFHARSHNESS

)TISEXTREMELYDIFlCULTFORATIRETOABSORB

HARSHNESSVIBRATIONSCOMPLETELY4HESE

VIBRATIONSINVOLVENOTONLYTIRETYPEBUTALSO

INmATIONPRESSURE4HETECHNICIANSHOULDALWAYS

ENSUREPROPERTIREINmATIONPRESSUREWHENTROUBLESHOOTINGAHARSHNESSCONCERN

'ENERALLYASOFTTIREWITHENVELOPING

CHARACTERISTICSPERFORMSWELLINPREVENTING

HARSHNESS2ADIALTIRESHAVERIGIDTREADSANDARE

LOWINENVELOPINGCHARACTERISTICS4HEYTENDTO

CAUSEHARSHNESSPARTICULARLYATTOMPH

TOKPH


26/70

$IAGNOSIS

'ETTING'OOD)NFORMATIONFROM3ERVICE!DVISORS

4OPROPERLYDIAGNOSEANDREPAIRAN.6(CONCERNTHECONCERNWILLNEEDTOBEDUPLICATED

DURINGAROADTEST4HESERVICEADVISORSARE

AGOODSOURCEFORTHESYMPTOMSANDFACTS

SURROUNDINGTHECONCERN0ROPERQUESTIONING

OFTHECUSTOMERWILLUSUALLYPROVIDETHE

INFORMATIONNECESSARYTODUPLICATETHECONCERN

)FTHECUSTOMERISLEAVINGTHEVEHICLEANDWILL

BEUNAVAILABLEFORAROADTESTLATERINTHEDAY

THENITISADVISABLETHATTHESERVICEADVISOR

ORTECHNICIANROADTESTWITHTHECUSTOMERBEFOREHANDTOEXPERIENCETHESYMPTOMSAND

FACTSOFTHE.6(CONCERN

4HE&OUR3TEPS

&OCUSTHEDISCUSSIONWITHTHECUSTOMERON

THESYMPTOMDESCRIPTION

!SKQUESTIONSTHATCLARIFYWHATWHEN

WHEREANDHOWOFTEN

3UMMARIZEYOURUNDERSTANDINGANDGET

AGREEMENTFROMTHECUSTOMER5SEOPEN

ENDEDQUESTIONSTOPROMPTFORSPECIlCS

%XPLAINWHATYOUWILLDOTOPROCEEDANDGET

ACKNOWLEDGEMENTFROMTHECUSTOMER

$IAGNOSINGAND3OLVING#USTOMER#ONCERNS

$ESCRIBETHECONCERN

s ,ISTKNOWNSYMPTOMS

s !VOIDOPINIONSORDISGUISEDSOLUTIONS

6ERIFYANDANALYZE

s 4RYTODUPLICATETHECONCERN

s ,ISTPOSSIBLECAUSES

,OCATETHECONCERN

s 3ELECTTHEPROBABLECAUSES

s 0RIORITIZETASKS

s )DENTIFYTHECONCERN

2EPAIRTHECONCERN

s $ETERMINETHESPECIlCCAUSE

s 0ERFORMTHEREPAIR

#ONDUCTAQUALITYCHECK

s 2ECHECKFORPROPEROPERATIONAND

REASSEMBLY

s #HECKFORCLEANLINESSANDAPPEARANCE

/THER)NFORMATION3OURCES

s !UDI%LECTRONIC3ERVICE)NFORMATION

3YSTEM!%3)3

n 4ECHNICAL"ULLETINSs /THERTECHNICIANS

s (ELPLINE

s +NOWNGOODVEHICLE

s 4HISTRAININGMANUAL

s 4HE'306IBRATION#ONTROL3YSTEM

/PERATION)NSTRUCTIONS


27/70

$IAGNOSIS

0RE2OAD4EST)NSPECTION

"EGINCHECKINGTHEVEHICLEWITHAVISUAL

INSPECTION"ESURETOCAREFULLYINSPECTTHETIRESUNLESSTHE.6(CONCERNONLYOCCURSAT

ASTANDSTILL0RIORTOTHEROADTESTINSPECTTHE

FOLLOWING

s 4IRES

0RESSUREn)NmATEDTOSPECIlCATION

7EARn#UPPINGmATSPOTSFEATHERING

ANDSHOULDERWEAR

4READGROOVESn#ORRECTDEPTHOVER

ENTIRESURFACE

4YPEn4HETIREISTHEPROPER

APPLICATION

&OREIGNDEBRISn3TONESMUDETC

s 7HEELS

.OTDEFORMEDORBENT

7EIGHTSn0ROPERLYINSTALLEDCORRECT

SIZE 7HEELBOLTSn4ORQUEDTOSPECIlCATION

4IREBEADn5NIFORM

s $RIVELINE

.OTDAMAGEDORBENT

0ROPERLYMOUNTEDANDSUPPORTED

0ROPERLYALIGNED

s %NGINE

"ELTSANDACCESSORIESFORDAMAGE

0ROPERLYALIGNED

-OUNTS

s %XHAUST

.OTDAMAGEDORBENT

0ROPERLYALIGNED

0ROPERLYMOUNTEDANDSUPPORTED

2OAD4EST4IPS

/BSERVETHEFOLLOWINGGUIDELINESWHEN

PREPARINGFORTHEROADTEST

s #HECKTHECUSTOMERREPAIRORDERBEFORE

BEGINNINGTHEROADTEST)TISIMPORTANT

TOKNOWWHICHSPECIlCCONCERNTHE

CUSTOMERHASWITHHISHERVEHICLE4HIS

PREVENTSCORRECTINGTHEWRONGCONCERN

ANDINCREASINGTHECOSTOFTHEREPAIR)F

POSSIBLEROADTESTWITHTHECUSTOMER

s $ONTBEMISLEDBYTHEREPORTEDLOCATION

OFTHENOISEORVIBRATION4HECAUSE

ACTUALLYMAYBESOMEDISTANCEAWAY

s 2EMEMBERTHATTHEVIBRATINGBODYMAY

GENERATEASMALLVIBRATIONONLY4HIS

SMALLVIBRATIONINTURNMAYCAUSEALARGER

VIBRATIONORNOISEDUETOTHEVIBRATING

BODYSCONTACTWITHOTHERCOMPONENTS

s #ONDUCTTHEROADTESTONAQUIETSTREET

WHERESAFELYDUPLICATINGTHENOISEOR

VIBRATIONISPOSSIBLE)TMUSTBEPOSSIBLE

TOOPERATETHEVEHICLEATTHESPEEDINWHICHTHECONDITIONOCCURS)TISBEST

TOCONDUCTTHEROADTESTONAROUTETHAT

HASBEENPREVIOUSLYDRIVENWITHKNOWN

GOODVEHICLES4HISALLOWSFORANYROAD

IMPERFECTIONSIEROADSURFACESANDJOINTS

FROMBEINGTHESOURCEOF.6(CONCERNS

s 4URNOFFTHERADIOANDTHEBLOWERFORTHE

HEATERANDAIRCONDITIONERUNLESSTHE

NOISEORVIBRATIONONLYOCCURSWITHTHEAIR

CONDITIONINGORRADIOON

s $ETERMINEWHICHTESTEQUIPMENTIS

NEEDEDFORTHEROADTEST)FUTILIZINGTEST

EQUIPMENTDURINGAROADTESTITISBEST

PRACTICETOHAVEANASSISTANTDRIVEWHILE

THEEQUIPMENTISBEINGMONITOREDAND

THERESULTSRECORDED

s &ORCOLDWEATHERCLIMATESBEAWARETHAT

SNOWANDICECANBETHECAUSEOF.6(

CONCERNS


28/70

$IAGNOSIS

2OAD4ESTING

4HEFOLLOWINGROADTESTPROCEDUREASSISTSIN

CLASSIFYINGAN.6(CONCERNINTO

s %NGINESPEED

s 6EHICLESPEED

s 7HEELSPEED

%ACHOFTHEFOLLOWINGPROCEDURESHELPSTO

ELIMINATEPOSSIBLECOMPONENTS$EPENDING

UPONTHECAUSEOFTHE.6(CONCERNCERTAIN

PROCEDURESMAYORMAYNOTBENECESSARY

s 3LOW!CCELERATION4EST

s .EUTRAL#OAST$OWN3PEED4EST

s $OWNSHIFT3PEED4EST

s 4ORQUE#ONVERTER4EST

s 3TEERING)NPUT4EST

s 3TEERING)NPUT4EST

s .EUTRAL2UN5P4EST

s %NGINE,OADED4EST

s %NGINE!CCESSORY4EST

3LOW!CCELERATION4EST

4HElRSTVEHICLECHECKTODETERMINEARELATEDSYMPTOMOFAN.6(CONCERNISTHESLOW

ACCELERATIONTEST4HISTESTISUSEDTOIDENTIFY

THENOISEORVIBRATIONIFAROADTESTWITHTHE

CUSTOMERWASNOTPOSSIBLE4HESTEPSOFTHE

SLOWACCELERATIONTESTARE

3LOWLYACCELERATETHEVEHICLETOTHESPEEDIN

WHICHTHEPROBLEMOCCURS

.OTETHEVEHICLESPEEDANDTHEENGINERPM

)FPOSSIBLEDETERMINETHEFREQUENCYOFTHENOISEORVIBRATION

#LASSIFYTHENOISEORVIBRATION


29/70

$IAGNOSIS

.EUTRAL#OAST$OWN3PEED4EST

4HENEXTVEHICLECHECKWHENPERFORMINGTHE

ROADTESTISTHENEUTRALCOASTDOWNSPEEDTEST

4HISTESTDIVIDESTHEPOSSIBLECAUSESOFTHENOISEORVIBRATIONINTOTWOCATEGORIES

s 6EHICLESPEEDRELATED

s %NGINESPEEDRELATED

s 7HEELSPEEDRELATED

4HESTEPSOFTHENEUTRALCOASTDOWNSPEEDTEST

ARE

$RIVETHEVEHICLEATASPEEDHIGHERTHANTHE

SPEEDINWHICHTHENOISEORVIBRATIONWAS

OBVIOUSINTHESLOWACCELERATIONTEST

0LACETHEVEHICLEIN.EUTRALANDCOASTDOWN

THROUGHTHESPEEDWHERETHECONCERN

OCCURS

#LASSIFYTHE.6(CONCERNASEITHERVEHICLE

SPEEDRELATEDORENGINESPEEDRELATED

s )FTHENOISEORVIBRATIONEXISTSTHENTHECONCERNISVEHICLEORWHEELSPEED

RELATED4HISELIMINATESTHEENGINEAND

TORQUECONVERTERASPOSSIBLECAUSES

s )FTHE.6(CONCERNDIDNOTOCCURDURING

THENEUTRALCOASTDOWNSPEEDTEST

PERFORMADOWNSHIFTSPEEDTESTTO

CONlRMTHECONCERNASENGINESPEED

RELATED

$OWNSHIFT3PEED4EST

4HISVEHICLECHECKHELPSTOCONlRMTHE.6(

CONCERNASENGINESPEEDRELATED4HESTEPSOF

THEDOWNSHIFTSPEEDTESTARE

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ARE

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#HECKFORNOISEWHENTHETORQUECONVERTERIS

NOTLOCKEDUP


30/70

$IAGNOSIS

3TEERING)NPUT4EST

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CONSTANTVELOCITYJOINTSAND5JOINTSCONTAINEDINTHEAXLESOFQUATTRO

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MISSINGLUGNUTS

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31/70

$IAGNOSIS

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32/70

$IAGNOSIS

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n %NGINESCANOVERHEAT


33/70

.OTES


34/70

%NGINE6IBRATIONS

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s %NGINEMOUNTS

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&IRSTANDSECONDORDERENGINEIMBALANCESARE

USUALLYDETECTEDDURINGTHE.EUTRAL2UN5P4EST


35/70

%NGINE6IBRATIONS

4ORQUE#ONVERTER

(ALF/RDER%NGINE6IBRATION

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36/70

%NGINE6IBRATIONS

%NGINE-OUNTS

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37/70

%NGINE6IBRATIONS

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38/70

%NGINE6IBRATIONS

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39/70

%NGINE6IBRATIONS

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40/70

%NGINE6IBRATIONS

4YPESOF%NGINE.OISES

7HENENGINECOMPONENTSDEVIATEFROMTHE

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s 3PARKKNOCKPINGING

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#AUSESOFENGINESPARKKNOCKPINGINGINCLUDE

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s )NADEQUATEFUEL

s )NCORRECTTIMING

s #ARBONDEPOSITSINTHECOMBUSTION

CHAMBER


41/70

%NGINE6IBRATIONS

%XHAUST.OISE

4HEEXHAUSTSYSTEMCANBEASOURCEOFNOISE

%XHAUSTNOISESINCLUDE

s %XHAUSTGASSOUNDS

s -UFmERANDPIPE

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PRODUCEDINEXHAUSTPIPESANDMUFmERS0IPE

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OFTHISISTURBULENCECAUSEDBYAIRGOINGTHROUGH

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s 2ICHFUELMIXTURE

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s &AULTYIGNITIONCOMPONENTS


42/70

%NGINE6IBRATIONS

#OMPELLING&ORCEOF%XHAUST

4HECOMPELLINGFORCEOFEXHAUSTEXITINGEACH

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SSP Audi Noise Vibration Harshness

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