brake kit troubleshooting guide

8/6/2019 Brake Kit Troubleshooting Guide

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Table of Contents

Brake Bleed Guide

BenchBleedingandTestingtheMasterCylinder...............................................Page4

BleedingtheLines..............................................................................................Page6

Brake Troubleshooting

TroubleshootingChart.........................................................................................Page7

TroubleshootingBleedingDifculties.................................................................Page10

TheRightValves.................................................................................................Page10

CheckBoosterPushrodAdjustment...................................................................Page11

CheckFlexibleBrakeHoses...............................................................................Page12

CheckPedalAssembly.......................................................................................Page12

CheckProperAlignment.....................................................................................Page13

MasterCylinderTest...........................................................................................Page13

PowerBrakeBoosterTest..................................................................................Page14

CombinationPropValveTest..............................................................................Page15

StickingProportioningValve...............................................................................Page15

BrakeFade.........................................................................................................Page16

Typical Brake System Congurations

QuickReferenceGuides.....................................................................................Page16

Copyright2006byMBMarketing&Manufacturing,Inc.

No reproduction, digital or otherwise

canbemadeofanypartofthiscatalog

withoutexpresswrittenauthorization.

CautionWeencourageyoutounderstandthattheinstallationofanycomponentor

kitshouldonlybeperformedbyapersonthatisexperiencedintheproper

operationofbrakesystems.Further,theresponsibilityfordeterminingthe

suitabilityofacomponentorkitisyourresponsibility.

Be SafeWestronglyencourageyoutotestyourbrakesunderacontrolledcondition,

beforeoperatingthevehicle.Severalstopsinasafeareaatlowspeeds

shouldbemadeandthengraduallyworkuptonormalspeeds.Obviously,

nooneshoulddrivewithanuntestedbrakesystem.


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Brake Bleed Guide

Read these instructions carefully and completely before installing your Disc Brake Kit. This

guide is set up to be generally followed in order. Here are a few basics to help ensure a safe

brake system:

Followingthestepsinthisguidewillensurethatyouwilleasilypinpointanytroublespotsinyour

brakesystemwhileinstallingandassemblingthesystem,eliminatingmanyheadaches.FollowittotheT,andwearecertainyouwillhaveapleasurableexperiencewithyourupgrade.

Useonlynewbrakeuid.Contaminateduidcancausedamagetothesensitivehydraulicbrake

componentsduringthebleedingprocess,corrodecomponentsandincreasethelikelihoodof

systemfailure.Evenunuseduidthatwasopenedatanearliertimeshouldnotbeused.Brakeuid

ishydroscopicmeaningthatitabsorbsmoisturefromtheair.Thismoisturedegradestheproperties

ofthebrakeuid.

Cleanlinessisveryimportant.Makesureyoucleanthettingsandsurroundingareabefore

openinganypartofthebrakesystemtokeepcontaminantsfromenteringtheuid.

Forpowerbrakeupgrades,besuretocheckforaminimumof18in.ofvacuumpriortoperforming

theupgrade.Vehicleswithtallheadsorsuperchargersmostlikelywillnothavesufcientvacuum.If

youdonothavesufcientvacuum,checkyourintakemanifoldforclogging,vacuumttingsandfor

collapsedvacuumlines.Alsoaskusaboutour12voltvacuumpump.

Nevereliminateloopsfromvacuumlinesastheseactasmoistureandvaportraps.Checkthe

vacuumlinesforgasodororthepresenceofmoisture.Gasfumescandeterioratetheinternal

rubbercomponentsofthebooster.

Donotusepetroleum-basedsolventstocleanbrakecomponents.Useonlycleaninguids

specicallydesignedforbrakessincetheyleavenoresiduewhentheydry.

Donotusecompressedairtodrybrakecomponents,evenlteredairmaycontainmoistureor

tracesofoil.

Checkbrakelinesforcracked,leakingorswollenlines.Thesemustbereplaced.

Donotmoveordrivethevehicleuntilarmpedalisestablished.

Bench Bleeding and Testing the Master Cylinder

ManypeopleskipthisVITALLYimportantstepinbleedingtheirbrakesystem.Benchbleedingthe

mastercylinderMUSTbeperformedanytimeamastercylinderisinstalled.Ifthemastercylinderisnotbled,itwilltakeyouatleasttwiceaslongtobleedthesystemandthenthereisnoguaranteethatyou

haveremovedalltheairfromthesystem.Themastercylindertestisapreliminaryprecautionandmay

needtobeperformedatalatertimeshouldtherebeaneedforfurthertroubleshooting.

DO NOT SKIP THIS STEP!Failure to follow these procedures is unsafe and may void your warranty!1. AllnewmastercylindersfromMBMincludeabenchbleedingkitthatincludeseverythingyouneed

toperformthebenchbleedingprocess.

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2. Beforebenchbleedingthemaster,completelyinstallallofyourbrakecomponentsandupgrades

includingthemastercylinderandbrakelines.Thisissothatyoucanhookupthemastercylinder

assoonaspossibleafterithasbeenbenchbledtokeepgravityfromleechinguidfromitduring

theinstallationoftheothercomponents.

3. Afterinstallingthesystem,removethemastercylindercompletelyfromthevehicle.Master

cylindersMUSTbebenchbledoutsidethevehicleandwithoutanyothercomponentsattached.

Thismeansthatifthekitisshippedwithabooster,proportioningvalveandplumblinesattachedtothemastercylinder,theymustallberemovedpriortobenchbleeding.

4. Besuretoplacethemastercylinderlevelinavicetosecureitproperly.Ifthemastercylinder

isnotlevel,notalltheairwillbeabletoberemovedfromthemastercylinder.Thisisoneofthe

mainreasonswebenchbleedthemastercylinderoffofthevehicle,togetitperfectlylevelduring

thebleedingprocess.Removethemastercylindertopandllitwithbrandnewbrakeuidtothe

appropriatelevelasindicatedinthemastercylinder.Thisisgenerallyabout1/2-1fromthetopof

thereservoirliptoallowforthermalexpansionofthebrakeuid.

5. Inserttheplasticttingsthattintothetwosideportsofthemastercylinder,(Note:ondualported

mastercylinderswheretherearefourports,chooseonesideandusebothportsonthatoneside

toperformthebleedprocess.)Insertonerubbertubeintoeachoftheplasticttingsandthelooseendsshouldbeinsertedintothemastercylinderreservoir.Theplastictabshouldbeusedtohold

thetubesinplacebyslippingitoverthereservoirseparatorandthehosesthroughtheroundholes.

6. Coverthetopofthemastercylinderwitharagtohelppreventuidfromsplattering,protecting

yourpersonaswellasyourvehicle.Beawarethatbrakeuidismildlycorrosiveandmaydamage

paintedsurfaces.

7. Usingawoodendowelorabluntmetalrod,compressthemastercylinderplungerwithslowdeep

strokes.

8. Oncethelargebubbleshavesubsideditshouldbecomeincreasinglymoredifculttocompressthemastercylinderpiston.Continuetodosowithslowshortstrokesatthebottomofthepistonstroke

untilnomorebubblesappear.

9. Therubberhosesandplasticttingsmaynowberemovedfromthemastercylinder.

10.Securethemastercylindertop.

11.Nowtestthemastercylinderbyblockingoffthemastercylinderportsusingthecorrectsize

invertedareplugsorboltswiththeappropriatethreadsizefortheportsonyourmastercylinder.

Dualportmastercylindersthathaveportsonbothsidesneedtohaveallfourportsplugged.The

protrudingconeoftheinvertedareseatinthemastercylinderportismadeofasoftmaterialthat

caneasilybedeformedifovertightened.Ifusingbolts,besuretojustsnugtheboltssoasnottodamagetheconesealsurface.Thisconemateswiththeinvertedare(expandedmouthopening)

ofthebrakelines.Ifyouhavetheability,youcanalsodrillapointintotheendofthebolttohelp

preventthisfromoccurring.

12.Attempttocompressthemastercylinderpistonforapproximately30seconds.Themastershould

giveasolidandunchangingresistancetotheconstantforce.


6/207

13.Installthemastercylinderandleaveenoughroomonthemountingnutstoallowforsome

movementofthemaster.Thiswillallowyousomebreathingroomwhilescrewinginthehydraulic

linestohelppreventcross-threadingthettings.

Bleeding the Lines

Manyofyouwillbetemptedtoglazeoverthissectionthinkingthatyoualreadyknowthis.Continue

readinganyway,justbearwithus.Youmaypreventsmalloversightsthatwillcausemajorheadaches.Wehavedevisedthistoassistyouintheinstallationofyourkitandtoreducethenumberoftechnical

callsinregardstotheseissues.Manytimeswegetcallsfrompeoplewhoshouldhaveknownbetter.

Soletsworktogethertomakesureyourinstallationwillbeassmoothaspossible.

1. Formastercylinderupgradestoexistingpowerboostersetups,removeanyresidualvacuuminthe

boosterbyapplyingthebrakepedalafewtimeswiththeengineoff.

2. Removethemastercylindercoverandchecktheuidlevel.Makesureitisattheappropriatelevel

foryourmastercylinder,thisistypically1/2to1fromthelip.Besuretochecktheuidleveloften

duringthebleedingprocessandadduidasnecessarytopreventairfromenteringthemaster

cylinder.IfthishappensyouMUSTstartoveratbenchbleedingthemaster!

3. Replacethemastercylindercap.

4. Theuseofourspeedbleederswillallowyoutoperformthisjobbyyourselfbysimplycracking

thespeedbleederenoughtoallowuidtobeforcedthrough.Thespeedbleederhasaninternal

checkvalvethatpreventsuidandairfromreturningintothecaliperoncethepedalisreleased.

Thisremovesthenecessityofclosingthebleederscrewbeforethepedalisreleased,allowingone

persontobleedthebrakes.Otherwiseyouwillneedanassistanttopumpthebrakepedalwhile

youopenandclosethebleederscrewsattheappropriatetimesduringthisprocess.

5. Thewheelfarthestawayfromthemastercylinderisbledrstwhichinmostcasesisinthisorder:

rightrear,leftrear,rightfront,leftfront.Failuretobleedintheproperorderwillcauseairtoremaininthelines.Thisisbecauseifyoubleedashortline,(ex.frontlines)beforebleedingalongline(ex.

rearlines),theuidintheshortlinewillcompressandpreventenoughpressurefrombeingbuiltup

inthelonglinetoexpeltheair.Furthermore,incorrectbleedingorderwillcausepressuretobuild

upononesideoftheproportioningvalve,causingittocloseonthelowpressuresidemakingit

impossibletoforceuidtotherearlines.Ifthishappensyouwillneverbeabletobleedthesystem

untilyoureadjusttheproportioningvalveasdescribedlaterundertheheadingTestCombination/

ProportioningValveandthenstartover.

6. Itmaybenecessarytoremovethe

calipersfromthecaliperbrackets

whileleavingthehosesattached.The

calipersmustbeorientedinsuchawayastoensurethebleederscrews

pointup.(Seegureatright)Ifyou

bleedthelineswiththecalipersonthe

rotor,airmaybecometrappedinside

thecaliperreservoirandthebleeding

willbeunsuccessful.Thecaliper

shouldbeorientedinsuchawayas

toallowairinsidethecaliperinternal

reservoirtoescape.Sometimesthis

Allairwillbebled

fromthiscaliper

AllairwillNOTbebledfrom

thiscaliperasairgetstrapped


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meansthebleederscrewispointingstraightupandsometimesitisatalittlebitofanangle.Itis

recommendedthatyoudonotallowthecalipertohangfromthebrakehose.Insteaduseapiece

ofwireorhangertopositionthecaliperscorrectly.Otherwisedamagetothebrakehosesmay

result.Ifyoudonditnecessarytoremovethecaliperfromtherotor,becertaintoinsertablock

thatisapproximatelythesamethicknessastherotorbetweenthebrakepadstopreventthecaliper

pistonsfrombeingpushedoutofthecaliper.

7. Crackthebleederscrewsattheappropriatewheeljustenoughtomakeiteasytoloosenlater.Attachalengthof3/16clearplastic,vinyltubetotheendofthebleederscrew.Submergethe

otherendofthetubeintoacontainerlledwithbrakeuid.

8. Crackthebleederscrewopenjustenoughtoallowuidtoleavethevalveandhaveanassistant

slowlyandrmlyapplypressuretothepedal.Havetheassistantholdthepressureonthepedal

untilyouseenomoreairbubblescomingoutofthehose.Closethebleederscrew.Thenhavethe

assistantreleasethebrakepedal.

9. Repeatstep8untilnomoreairisseenleavingthetube.

10.Closethebleederscrewtotheappropriatetorqueforyourapplicationandproceedtothenext

wheelinthebleedingorder,repeatingsteps8and9foreach.Besuretochecktheuidlevelinthemastercylinderfrequently.

11.Rellthemastercylindertotheappropriatelevelwhennishedwiththeentirebleedingprocess.

12.Checkthepedal,itshouldfeelsolidwhendepressedwithnosponginessandshouldholdunder

constantpressurewithoutdropping.Ifnecessary,repeattheentireprocess.

13.IfyouareindoubtoftheeffectivenessofthebrakesystemDONOTDRIVETHEVEHICLE!

Brake Troubleshooting

Troubleshooting Chart

Symptom Cause Solution

NotEnoughBrake BrakeFade SeeBrakeFadeonpage16

Vehicleistooheavyfor

brakesystem(drumbrakes,

addedlargerengine,etc.)

Performboostertest,seepage14

Performmastercylindertest,seepage13

Installboosterorincreaseboostersize

Increaserotorsize

BrakeLightonDashison Airinlines BleedBrakeSystem

UseSpeedBleederstofacilitatebleeding

Underbraking-Carpullstoonesideoronewheel

locksup

OiloruidonbrakepadDebrisinbrakelines

Collapsedlines

Cleanorreplacepadsandcheckfordirty,damagedorleakylinesorcalipers

RockHardPedal InsufcientVacuum Checkvacuumpressure,seePowerBrake

BoosterTestonpage14

BlockedVacuumCheck

Valve

Badpowerbooster

FrozenWheelCylinder

BindingPedallinkage

CrackedVacuumHose

SeePowerBrakeBoosterTestonpage14

Replacecaliper

Inspectpedalassembly

Inspectvacuumhosetoboosterforcracks


8/209

Spongy,LoworNoPedal AirinLines Bleedbrakesystem


AeratedBrakeFluid Completelyushandreplacebrakeuid

Checkforoverheatingconditions

Parkingbrakeoutof

adjustment

Checkcablesettingindrums/rearbrakes

Unequalpressurebetweenfrontandrearlines SeeCombination/ProportioningValveTestonpage15

Incorrectpedalratio SeeCheckPedalAssemblyonpage12

Badexiblebrakehoses SeeCheckFlexibleBrakeHosesonpage

12

Boosterpushrodoutof

adjustment

Checkboosterinstallationprocedures

Calipermisalignedtorotor

becauseofbentcaliper

bracketorloosewheel

bearings

Checkcaliperbracketalignment

Replacewheelbearings

Hardlinesbentabovemastercylinderuidlevel

Replumbhardlinetoremainbelowmastercylinderuidleveltoavoidtrappingairin

thelines

Mastercylinderboresize

toosmallforapplication

Smallboremastercylinderrequireslonger

pedaltraveltoapplybrakes

Badpowerbooster SeePowerBrakeBoosterTestonpage14

Airinmastercylinder Benchbleedingthemastercylinder,see

page4

Badmastercylinder SeeMasterCylinderTestonpage13

BadorleakyCaliper Replacecaliper

Mastercylinderlocated

belowcalipersorlinesw/

noresidualcheckvalve

SeeTheRightValvesonpages10

DrumBrakes:Noresidual

checkvalves


DrumBrakes:Upgraded

largerdrums


DrumBrakes:Overarched

shoes

Replacedrum,itmayhavebeenturnedtoo

manytimescausingnotenoughcontact

betweenshoesanddrum

DrumBrakes:Oversized

WheelCylinderformastercylinder

Replacewithlargerboremastercylinder


9/2010

OverheatingorDragging

Brakes

Improperlyadjustedparking

brake

Checkmanufacturersrecommended

settings

Pre-loadedmastercylinder

orpowerbooster

SeeCheckPedalAssemblyonpage12


DrumBrakes:Residual

checkvalves

Removeresidualcheckvalve

Frozenparkingbrakecable Replaceparkingbrakecable

BadCalipersorwheel

cylinders

Replacecaliperorcylinder

Overlledmastercylinder Filltocorrectlevelformastercylinder,

typically1fromlip

DrumBrakes:Drumsoutof

adjustment

Drumsmaybeadjustedtootight,readjust

Pedaltoolowor

excessivepedalfreeplay

Incorrectpedalratio

Toomuchspacebetween

boosterpushrodand

mastercylinderpushrod

SeeCheckPedalAssemblyonpage12

ParkingBrakenotworking ParkingBrakeoutof

adjustment

Checkmanufacturersrecommended

settings

PoorPanicBraking Airinlines Bleedbrakesystem


BrakeFade SeeBrakeFadeonpage16

Vehicletooheavyforbrake

system(drumbrakes,

addedlargerengine,etc.)

Testbooster,seepage14

Testmastercylinder,seepage4


Increaserotorsize

InsufcientVacuum Checkvacuumpressure,seePowerBrake

BoosterTestonpage14

BlockedVacuumCheck

Valve

SeePowerBrakeBoosterTestonpage14


DrumBrakes:Upgraded

largerdrums


DrumBrakes:Noresidual

checkvalves


DrumBrakes:Overarched

shoescausingnotenough

contactbetweenshoesand

drum

Replacedrum,itmayhavebeenturnedtoo

manytimes

DrumBrakes:Oversized

WheelCylinderformaster

cylinder

Replacewithlargerboremastercylinder


10/2011

Troubleshooting Bleeding Difculties

Ifyouarehavingdifcultygettingalltheairoutofthesystemoryouarenotobtainingarmpedal,try

thesestepstoassistinthebleedingprocessandtrackdownproblemareasonthevehicle.Aspongy

pedalisusuallycausedbyairinthesystem.

1. Whilebleeding,raisetheendofthevehiclethatisbeingbled,thismayhelpairtrappedinthesystem

torisetowardsthebleederscrew.

2. Whilebleeding,lightlytapthecaliperwithahammer.Thiscandislodgeairbubblesthatclingtothe

wallsofthecaliperreservoir.

3. Checkfordamagedbrakehosesthatmaybeinternallyexpandingfromthelinepressure.(See

CheckFlexibleBrakeHoses onpage12).

4. Uselinelocks(vice-grips)torestrictuidowintherubberlinesateachwheelbetweentheframe

andtheaxletohelppinpointthetroublespot.Lockallfourwheelsatthesametime.Beawarethat

crushingthebrakelinescandamagethem.Tohelppreventthis,wrapthejawsofthelinelocks

withashoptowelandclosethelinelocksjustenoughtorestricttheowofuid.DONOTOVER

TIGHTEN!

5. Withthelinestoallfourwheelsblockedoff,checkthepedal.Youarelookingforarmhardpedal

thatdoesnotdropunderconstantpressureoverashortperiodoftime.Ifyougetahardpedal,then

theproblemisdenitelyatoneofthewheels.Ifthepedalisstillspongy,rstmakesurethelinesare

effectivelyrestrictedandtrythepedalagain.Ifyoustilldonothavearmpedal,thenremovethe

mastercylindertofollowthebenchbleedandtestprocedure.

6. Ifyoudohaveahardpedal,thenremovethelinelocksfromthefarthestwheelfromthemaster

cylinderandpressthepedal.Ifthepedalisspongyagain,thewheelyoujustreleasedistheproblem

wheelandrequiresfurtherbleeding.(Inreardiscbrakes,theproblemmayalsobethattheparking

brakeneedsadjustment.Checkyourparkingbrakeadjustmentbeforeproceeding.)Makesurethatallthestepsforbleedingarefollowed.Ifyouarestillhavingdifculty,wesuggesttheuseofspeed

bleederstohelpensureairdoesnotreturninthelineswhenthepedalisreleased.Otherwisea

powerbleedingsystemmayneedtobeemployedoraprofessionalbrakespecialistmayneedto

checkthesystem.

7. Ifthepedalisstillrmthencontinueontothenextwheelintheproperbleedingorder,whichisthe

wheelwiththenextlongestlineinthesystem,releasethelinelockatthatwheelandtestthepedal

again.Notethatitisnormaltohaveasmallamountofincreaseintravelasyoureleasethelinelocks

fromeachbrakehose.

The Right Valves

Usingthecorrectvalvingforyourapplicationiscriticaltotheproperoperationofyourbrakesystem.

Therearefourtypesofvalvesthatperformdifferentfunctionstothebrakesystem.

Metering Valves-ThesevalvesareusedtoequalizebrakingactionofaDisc/Drumbrakesystem

bypreventingthediscbrakesfromapplyinguntilabout75-135psihasbuiltupinthe

lines.Thisdelaysthediscbrakesandallowsthedrumstocatchup.Thisprovides

rearstabilityonwetsurfacesandreducesfrontpadwear.Meteringvalvesare

generallylocatedinthelinestothediscbrakes.Inmostofourkits,themetering

valveisapartofthecombination/propvalve.


11/2012

Proportioning Valves-Thefunctionoftheproportioningvalveistolimitpressuretotherear

brakesrelativetopedalforce,especiallywhenhighpressureisrequiredtoapplythefrontdisc.This

preventstherearwheelsfromlockingupasweightisshiftedforwardduringbraking.Proportioning

Valvesaregenerallylocatedinthebrakelinetotherearbrakesandsometimes

areincorporatedintothemastercylinder.Theyareavailableaseither

presetoradjustablevalves. Note that adjustable proportioning valves

are not DOT approved for street driving and should only be used for

racing applications!

Residual Check Valves-Thesevalvesareusedtoholdacertainamountofpressureinthelines

evenwhenthepedalisnotpressed.Thisisasortofpreloadedlinepressuretoactivatethe

brakesmorequickly.Theywillgiveahigher,harderandmoreresponsivepedal.Residual

checkvalvesshouldnotbeusedasasubstituteforaproperlyfunctioningsystem.

Forinstance,donotuseresidualcheckvalvesinplaceofcompleteandproper

bleedingproceduresaspresentedinthisguideandourBrakeBleedingGuide.

Checkvalveswillmostlikelybenecessarywhenthemastercylinderislower

thanthecalipersorhardlinesrunhigherthanthemastercylinderuidlevel.

Indiscbrakesa2lb.residualcheckvalvepreventsuidfromowingback

withoutcausingthebrakestodrag.Withdrumbrakes,a10lb.valveisusedto

compensateforreturnspringtensioninthedrums.Residualcheckvalvesaregenerallycolorcodedbluefor2lb.andredfor10lb.foreasyidentication.

Combination Valves-Thesevalvesoffermultiplefunctionalityinasingleunit.Theycombinethe

functionsofbothameteringvalveandaproportioningvalvewiththeaddition

ofabrakelightwarningswitch.Thebrakelightwarningswitchsignalswhen

thereisanimbalanceofpressureinthesystemcausedbyaprobleminthe

frontorrearbrakes.Theyarebyfarthebestvalvetouseforalldiscbrake

conversions.AllourkitsuseDOTapprovedCombinationValvesdesigned

specicallyforeitherDisc/DiscorDisc/Drumapplications.

Check Booster Pushrod Adjustment

Thepushrodthatactuatesthemastercylindermustbeproperlyadjusted.Ideallythereshouldbe

onlyslightclearancebetweentheboosterpushrodandthemastercylinderpushrod.Interferencewill

preloadthemastercylinder.Whenthesystemispreloaded,itbuildspressureeachtimethepedalis

pressed.Sincethemastercylinderisnotallowedtofullyreleasethepressurefromthepreviousstroke,

thesystemwilleventuallylockthewheels.Toomuchclearancewillcauseexcessivefreeplayinthe

pedal.

TherearebasicallytwodifferentmastercylindersthatweuseforourChevyandFordkits,thedeep

boremastercylinderandtheshallowboremastercylinder.Todetermine

whichmastercylinderyourboosterissetuptomatewith,youcandothefollowingsimplecheck.Forshallowboremastercylinders,thepushrod

shouldbeapproximatelyushwithorbelowtheboosterface.Deepbore

mastercylinderswillprotrudepastthefaceoftheboosterbodybyabout

1to1-1/2.Notethatdeepboremastercylindersarerequiredformanual

brakesandshallowboremastercylindersaregenerallyusedforpower

brakesystems.Wenowsupplyamastercylinderpistonadapter(pictured)to

accommodatebothmastercylinders.Youwillonlyusethisadapterwhenyou

haveadeepboremastercylinderwithashortboosterpushrod.

Pistonadapter


12/2013

Check Flexible Brake Hoses

Inspecttheexiblebrakehosesfortypicalsignsoffatigue.Hosesshouldbecheckedfor:

Damage:Checkforlargesurfacecracks,scufngorwornspots.Iftheoutercasinghassevere

cracksorabrasions,thehoseneedtobereplaced.Thecasingistheprotectionforthehose,ifitis

damaged,thedeteriorationofthehosecantakeplacewithpossibleburstfailure.Linesshouldbe

exibleandrmratherthanhardandstiff.

FaultyInstallation:Twistingthehoseorrubbingagainstwheels,tiresorchassiswillcause

prematurelinedeterioration.

Makesurethatthetubeandhosematingsurfacesarecleanandfreefromnicksandburrs.Newseal

washer(s)shouldbeused.Doublewallsteeltubingshouldalwaysbeusedtoreplacehardlines.Care

shouldbetakenwhenreplacingbraketubing,tousetheproperbendingandaringtoolsandtoavoid

kinking,routingthetubesagainstsharpedges,movingcomponents,inhotareasorabovethemaster

cylinderuidlevel.Alltubesshouldbeproperlyattachedwithappropriateretainingclipsandtabs.

Check Pedal Assembly

Somethingthatmanypeoplearenotawareofwhenupgradingtheirsystemisthebrakepedal

adjustment.Improperpedaladjustmentcandothefollowing:

Preloadtheboostercausingbrakestodragandeventuallylockup.

Damagetheboostersinternalcomponentsbyactuatingatanimproperangle.

Allowslopinthepedalifadjustedtoolow.

Manyvehicleshaveasecondholeonthepedalassemblythatwasoriginallyintendedforpowerbrake

applications.Therequiredholeisgenerally1to1-1/2lowerthantheoriginalmanualbrakehole.Ifthereisnosecondhole,youmayneedtodrilltheholeinthepedalarmtoproperlyalignthepushrod.

Theeasiestwaytodeterminetheperfectlocationforthisholeistondthecenterofthepushrods

verticaltraveltoensurethatitsactuationisasinlinewiththeboosteraspossible.

1. Gentlylifttheendofthepushroduntilitstopsandnotethelocationwheretheclevisonthepushrod

locatesonthepedalarm.Markthislocation.

2. Thengentlypushthepushroddownuntilitstops.Markthislocationaswell.

3. Theproper hole locationisinthemiddlebetweenthetwomarksonthepedalarm.Markanddrill

thenewholeinthecenterofthepedalarm.Attachthepushrodtothepedalarm.

4. Checkfreeplayinthepedalbyapplyingpressuretothepedalwithyourhandandnotinghowfar

thepedaltravelsbeforeresistanceisfelt.Itshouldbeapproximately1/4.Thisfreeplayallowsthe

mastercylinderpistontoreturntotheat-restpositionandpreventspreloadingthesystem.Too

muchfreeplaywilldropthepedaltoofarbeforeapplyingbrakepressureandmayevenhitthe

oorbeforeapplyingfullbrakingforcetothesystem.Notefreeplayisalsodependentuponproper

adjustmentoftheboosterpushrod.


13/2014

Check Proper Caliper Alignment

Theproperalignmentofthecalipersiscriticaltoasafebrakesystemandinpreventingprematurewear

oftherotorsandpads.Itmaybenecessarytogrindsmallprotrusionsonthecalipertoensureaproper

tandalignmentofthecalipersonthecaliperbrackets.DONOTgrindonthecaliperbrackets,thiswill

weakenthedesignofthebracketsandmayleadtobrakefailure.Beawarethatgrindingcanproduce

atremendousamountofheat.Becauseoftherelativelythinamountofmaterialoftheplate,subjecting

thebracketstothisheatmaycausingthemtobecomebrittleandbreakunderstress.

Ifthewheelangeiswarpedcausingthecaliperandbrackettonotalignproperlywiththerotor,insert

oneortwowashersbetweenthewheelangeandthecaliperbracket.Usethewasherstoshimthe

assemblyandalignwiththerotorasnecessary.

Master Cylinder Test

Notethatthistestofthemastercylinderrequiresacompletere-bleedingofthesystemsincethebrake

linesareremovedfromthemastertoperformthistest.Thisiswhyweincludethistestduringthe

benchbleedingprocess.However,justbecauseyouhaveperformedthetestduringbenchbleeding

doesnotmeanthatairhasnotenteredthe

mastercylindersincethen.Shouldairenter

themastercylinderatanytimeafterbench

bleeding,themastercylinderMUSTbe

removedfromthevehicleandbenchbled

again.Anumberofthingscancauseairto

enterthemastercylinder:

Iftheuidlevelsdroptoolowduringthe

bleedingprocess.

Ifthemastercylinderwasleftsittingfor

toolongafterthebenchbleedingbeforehavingthelinesinstalled.

Mishandlingofthemastercylindersuchasifitweredroppedorjarredexcessively.

Totestthemastercylinder:

1. Removethebrakelinesfromthemastercylinderports.

2. Blockoffthemastercylinderbrakelineportsusingthecorrectsizeinvertedareplugsorboltswith

theappropriatethreadsizefortheportsonyourmastercylinder.Dualportmastercylindersthat

haveportsonbothsidesneedtohaveallfourportsplugged.Theprotrudingconeoftheinverted

areseatinthemastercylinderportismadeofasoftmaterialthatcaneasilybedeformedifover

tightened.Ifusingbolts,besuretojustsnugtheboltssoasnottodamagetheconesealsurface.

Thisconemateswiththeinvertedare(expandedmouthopening)ofthebrakelines.Ifyouhave

theability,youcanalsodrillapointintotheendofthebolttohelppreventthisfromoccurring.Most

GMmastercylindersuse9/16-18threadsforthefrontportsand1/2-20threadsfortherearports.

MostFordmastercylindersuse3/8-24threadsforthefrontportsand7/16-24threadsfortherear

ports.

3. Applyconstantpressuretothepedal,thepedalshouldberm,hardandshouldnotdropovertime.

RearDrumReservoir FrontDisc

FluidReservoir

Secondary

PistonSecondary

PistonSeal

Primary

PistonSeal

PrimaryPiston


14/2015

4. Ifthepedalissquishytheremaybeairinthemastercylinder.Benchbleedthemasteraccordingto

theinstructionsaboveandtestagain.

5. Ifthepedalisrmandthendropsovertimeunderconstantpressure,themastercylindershouldbe

replaced.

Power Brake Booster Test

Ifthepedalfeelshardwhiletheengineisrunning,theboosterisntoperatingcorrectly.Ifyoususpect

theboosterisdefective,donotattempttodisassembleorrepairthepowerbooster.Doingsoisunsafe

andwillvoidyourwarranty.

Test 1

1. Withtheengineoff,pumpthebrake

pedaltoremoveanyresidualvacuumin

thebooster.

2. Holdpressureonthepedalwhileyou

starttheengine.Whentheengine

starts,thepedalshoulddropabouta

1/4,thisindicatesthattheboosteris

workingproperly.

Test 2

1. Runtheengineacoupleofminutes.

2. Turntheengineoffandpressthepedalseveraltimesslowly.Therstpumpshouldbefairlylow.

Thesecondandthirdshouldbecomeslightlyrmer.Thisindicatesanairtightbooster.

Test 3

1. Starttheengineandpressthebrakepedal,thenstoptheenginewiththepedalstillpressed.Ifthe

pedaldoesnotdropafterholdingthepressureonthepedalfor30seconds,theboosterisairtight.

Test 4 - Inspect the Check Valve

1. Disconnectthevacuumhosewhereitconnectstotheintakemanifold.Donotdisconnectthe

vacuumlinefromthebooster.Airshouldnotowwhenpressureisapplied,butshouldowwhen

suctionisapplied.Ifairowsinbothdirectionsorthereisnoairow,thevalveneedstobe

replaced.

Test 5 - Verify Enough Vacuum

1. Checktheoperatingvacuumpressurewhentheengineisatnormaloperatingtemperature.There

shouldbeaminimumof18in.ofvacuum.Vacuummaybeincreasedbyproperlytuningtheengine,

checkingforvacuumleaksandblockagesinvacuumlines.

Vacuumcheckvalve

receivesvacuum

fromtheengine

Hubthat

transfersforce

toMaster

Cylinder

Rubber

diaphragm

Rodfrom

pedal

Poppit

valve


15/2016

Combination Prop Valve Test

1. Useatestlightbyattachingacliptoapositivecontactonthevehicleandtouchthepointofthe

testertotheelectricalconnectionofthecombinationvalve.Ifthelightdoesnotcomeon,thevalve

systemisoperationcorrectlyandnofurthertestingisrequired.

2. Ifthelightdoescomeon,thisindicates

thatthepressuredifferentialvalveisstuckinthefrontorrearposition.

3. Bleedthebrakesystemtodetermineif

thefrontorrearlinesareblockedoff.Set

uponefrontwheelandonerearwheel

forbleedingatthesametime.Crack

bothbleederscrewsandgentlypump

thepedalafewtimes.Theblockedside

willtrickleuidoutwhenthebleeder

screwiscrackedandthepedalpressed.

Anunblockedlinewillsquirtuidoutthe

bleeder.

4. Thelinesthatareclearmustbeleftopenandtheblockedlinesshouldhavethebleederscrews

tighttocausepressuretobuilduponthatside.Besuretousethestandardbleedingproceduresto

preventairfromenteringthesystem.

5. Slowlypressthepedalwithsteadypressureanumberoftimesuntilthelightgoesout;thiswill

centerthedifferentialvalve.Youmayalsohearapopcomefromtheproportioningvalve.Thisisthe

meteringvalvereturningtoitsequalizedposition.Whenthelightgoesout,closethebleederscrew.

Sticking Proportioning Valve

1. Bleedthebrakesystemtodetermineifthefrontorrearlinesareblockedoff.Setuponefrontwheel

andonerearwheelforbleedingatthesametime.Crackbothbleederscrewsandgentlypumpthe

pedalafewtimes.

2. Theblockedsidewilltrickleuidoutwhenthebleederscrewiscrackedandthepedalpressed.An

unblockedlinewillsquirtuidoutthebleeder.

3. Thelinesthatareclearmustbeleftopenandtheblockedlinesshouldhavethebleederscrew

tighttocausepressuretobuilduponthatside.Besuretousethestandardbleedingproceduresto

preventairfromenteringthesystem.

4. Slowlypressthepedalwithsteadypressureanumberoftimesuntilthelightgoesout.Thiswill

centerthedifferentialvalve.Youmayalsohearapopcomefromtheproportioningvalve.Thisisthe

meteringvalvereturningtoitsequalizedposition.Whenthelightgoesout,closethebleederscrew.

ToFrontInfromMC InfromMC

To

Rear

Metering

Valve

ToFront

Combination Valve


16/2017

Brake Fade

Brakefadeisagraduallossofbrakingpowerthatcanbecausedbyoldbrakeuidoroverheated

brakes.Overheatedbrakesisaverydangeroussituationwhichcancauseoldorcontaminated

brakeuidtoboil.Thegasesreleasedfromboilingbrakeuidwillcauseasquishypedalevenafter

thebrakeshavecooledandcancausebrakefailureifnotimmediatelytakencareof.Thisisallthe

morereasontoONLYusebrakeuidthatisfromanewlyopenedsealedcontainer.Drumbrakescan

compoundtheproblemofoverheatedbrakes.Sincethedrumitselfexpandswhenheated,itincreasestheamountoftravelrequiredbytheshoestoeffectivelystopthevehicle.Brakefadecanalsooccurin

drumbrakesbytheaccumulationofwaterinsidethedrumsinceittrapswaterinside.Thewaterthen

actsasalubricantbetweentheshoesandthedrum,causingineffectivebraking.

Typical Brake System Congurations

Figuringouthowtoplumbyourbrakesystemisquitesimple.Thetwoqualifyingquestionsare:

1. Isyourbrakesystem:Disc/Disc,Disc/Drum,orDrum/Drum?Because...

Drumbrakesrequirea10lb.residualpressure(RPV10)tocounteractthespringtensioninthedrumsystemwhichtendstopulltheshoesawayfromthedrums.

DiscBrakesrequireacombinationvalve(oftencalledaproportioningvalve)andsometimesa

2lb.residualvalve-dependingonwhereyourmastercylinderisrelativetoyourcalipers(seenext

bullet).

2. Fordiscapplications;IsyourMasterCylindermountedaboveorbelowyourcalipers?because...

Ifyourmastercylinderisbelowyourcalipersthena2lb.residualvalve(RPV2)isneededto

preventuidfromowingbackfromthecalipersintothemastercylinder.

Quick Reference Guides

1. Drum Brakes Front and Rear with Master on Firewall or Under Floor-Drumbrakesrequirea

10lb.residualpressure(RPV10)tocounteractthespringtensioninthedrumsystemwhichtends

topulltheshoesaway

fromthedrums.Thiswill

giveyoualongerpedal

travelandspongy

brakes.Theresidual

valveholdsapressure

keepingtheshoes

nearthedrumsgiving

ahigherrmerpedal.

Alsorequiredameteringvalve(PVM)tothefront

(themeteringvalve

preventsnosedive).

10lbResidual(RPV10)

Metering

Valve

(PVM)ToRear

10lbResidual(RPV10)

10lbResidual(RPV10)


17/2018

2. Disc Brakes Front and Drums Rear with Master on Firewall-Adisc/drumcombinationvalve

(PV2)istheeasiestwayto

properlybalanceyourbraking

system.Thecombination

valveistwovalvesinone.It

providesmeteringtothefront

whichpreventsnosediveand

proportioningtotherearwhichpreventsrearwheellockup.We

alsorecommendtheadditionof

a10lbresidualvalve(RPV10)to

thereardrumbrakes.

3. Disc Brakes Front and Drums Rear with Master Under Floor-Thebestwaytoplumbadisc/

drumsystemwhenthemasterisundertheooriswithacombinationvalve(PV2)andthena2

poundresidualvalve(RPV2)tothefront

whichisneededto

preventuidfrom

owingbackfrom

thecalipersinto

themaster.We

alsorecommend

theadditionofa10

lbresidualvalve

(RPV10)totherear

drumbrakes.

How to Plumb Your Rod For Disc/Drum System and Master Under Floor

2lbResidual

CombinationValve

10lbResidualMC

RearAxleHoseKit

* With a remote

fll master cylinder

the 2 lb valve to

the front will not be

needed.

10lbResidual(RPV10)

ToRear

ToFront

CombinationValve(PV2)

ToFront 10lbResidual(RPV10)

2lbResidual(RPV2)

ToRearCombinationValve(PV2)


18/2019

4. Four Wheel Disc with Master on Firewall-Thebestwaytoplumbadisc/discsystemwhenthe

masterisontherewalliswithafourwheeldisc

brakecombinationvalve(PV4).

5. Four Wheel Disc with Master Under Floor-Thebestwaytoplumbadisc/discsystemwhen

themasterisundertherewalliswithafourwheeldiscbrakecombinationvalve(PV4)andatwo

poundresidualvalve

(RPV2)tothefrontandatwopound

residualvalve(RPV2)

totherear.

How to Plumb Your Rod For Disc/Disc System and Master Under Floor

2lbResidual

CombinationValve

2lbResidualMC

RearAxleHoseKit

* With a remote

fll master cylinder

the 2 lb valve to

the front will not be

needed.

ToFront

ToRearCombinationValve(PV4)

ToFront 2lbResidual(RPV2)

2lbResidual(RPV2)

ToRear

CombinationValve(PV4)


19/2020

Let us fill all your Brake, Steering and Suspension Needs

Disc Brake KitsRotorsCalipers

Power Brake UnitsPedals

Booster Conversion KitsPower Brake BoostersMaster Cylinders

Proportioning ValvesProportioning Valve Kits

Proportioning Valve LinesSpindles and SteeringWater Pumps and Alterators

Hydro-Boost Rebuild KitsBrackets & More

Contact us at 800-231-4125 and Discover the MBM Advantage!


20/20

brake kit troubleshooting guide

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