Car Mechanics - February 2016

100 Pages·2016·16.02 MB·English

25 of your toughest car problems solved by our experts
Beginners’ guide to Timing
Multimeters
belt
change
Volvo
2.4D
Air filtration
upgrades
Increase your engine’s performance
SAVING YOU MONEY SINCE 1958
Twin-clutch 10
DIY
Service PAGE
SPECIAL
GEARBOXES
Citroën DS3
e-HDi full check
How they work
What goes wrong
DIY repairs
Power
Dismantling a
steering
wet clutch system
pipe swap

Mechatronics
MINI
BMW 1.6
actuator stripdown
WIN
PARTS GUIDE DIAGNOSTICS BUYING USED
Renault VW Golf
2
prizes
Z4 Clio MkII MkV
Trolley jack,
axle stands
Findlow-costdeals 1.216vinvestigated 2004-2008 models
& foot
pump set February
CM Visit: Philips Automotive Lighting
£346 2016
Worthmorethan
£4.00
U C T S
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Editorial
Martyn Knowles, Editor
Email: [email protected]
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XArethedaysofbuying vehicles–I’msureyou’ll
XToguaranteereceivingacopyof
atraditionalautomatic finditafascinatingread.
yourfavouritemagazineeachmonth,
gearboxwithatorque Idoubtyou’llfindanyother
whynottakeoutasubscription
converterfinished?Isthe publicationofferingsuch
–turntopage96formoredetails.
manualgearboxonthe in-depthknowledgeon
Ifyouprefertoreadthemagazine
vergeofbeingconsigned thissubject.
digitallyonyourmobileorcomputer,
tothehistorybooks? HavingdriventheDSG
wecannowoffereveryissueonthe
Afewyearsago, twin-clutchtransmission
followingplatforms:iPad,iPhone,
Ipredictedcar-makerswill inVAGcars,Icansayitisa Win8,PC/MAC,AndroidandZR4.
stopfittingtheconventional wonderfulinvention,giving TosubscribetoanAndroidversion
manualgearboxby2020. sharpgearchangesand ofCarMechanics,you’llneedtovisit
That’sjustfouryearsaway kickdown.Iplantedthe thiswebsite:http://bit.ly/1N1v0bU
anditmaytakeabitlonger throttleofaVWGolfGTIat
thanIinitiallysuggested. 50mphwhileitwascruising manual ’box, but with broadly similar
ButIstillthinkthedays in6thanditswiftlystepped fuel consumption figures.
oftheself-shiftmanual downtwogears,making One proviso: twin-clutch gearboxes
gearboxarenumbered. overtakingeffortless. have strict recommended service
That’swhyourlead Thebenefitofthese schedules and it’s essential to meet oil
articleinthisissueisa gearboxesisthelackofa and filter change intervals. So, if you’re
special10-pagefeatureonthesubject torqueconverter(whichmakesthe looking to purchase a used vehicle,
oftwin-clutchgearboxes.Evenifyou’ve autoboxslowerandheavierthanan make sure you check any service
neverdrivenone–althoughtheyare equivalent-enginedmanual).Youshould history for maintenance mileages and
nowfittedtoasurprisingvarietyof getstronger,fasteraccelerationthana invoices to indicate appropriate care.
Man to Man
XOverthefestiveperiod,IstayedwithfamilyontheIsleof
Man(IOM).Ifyou’venotbeenbefore,it’sworthavisittothis
islandlocatedintheIrishSea,measuringjust14mileswide
by33mileslong.SomeIOMmotoringlawsdifferfromthe
UK:therearenoannualroadworthinessexaminationsfor
vehiclesoverthreeyearsoldandthemaximumspeedisn’t
60mph,it’swhateveryouconsidersafe!Butwhatmakes
theIOMabitspecialforanypetrolheadisitspassionfor
motorsport,classiccarsand,ofcourse,itslegendaryTT
The Isle of Man
circuit,whichannuallyhostsrapid-actionmotorcycleracing. Motor Museum.
Apartfromthevarietyofvehiclesyouseeontheopen
road–theislandersseemtodrivealotofJapaneseimports Theownersalsogavemeanexclusivetourofthe
–there’sacoupleofmotor-relatedmuseumstovisit,both museum’srestorationarea,whichisnotonpublicdisplay,
locatedinJurbyatthenorthoftheisland. wherethevariousexhibitsarepreparedfordisplay.
TheTransportMuseumatJurbyairfieldhousesavast TheCunninghamsarealsointerestedinalternative
displayofpredominantlyoldManx-relatedbusesandlorries, power.DenisistryingtorunaToyotaPriusMkIIintothe
aswellasafewclassiccars.Youcanclamberaboardanold ground–andfailing,asitkeepsondelivering!He’salsojust
Routemasterbusandenjoyitsuniqueambience.Admission takendeliveryofafully-electricTeslaModelSwithaP90D
tothemuseumisfree,andit’sopenfrom10am-4pmevery badgeontherear.Incaseyoudon’tknow,thismeansithas
SundayfromNovembertoEaster,thenonSaturday,Sunday a90kWhbatteryfora6%increaseinrangeoverthetop
andTuedayfromEasteruntilOctober. 85kWhmodel.Italsomeansthere’sa‘Ludicrous’button on
WithinviewingdistancefromtheTransportMuseumis thedash,which,whenactivated,canblasttheTeslafrom
theimpressive,newly-built(well,fromMay2015)Isleof 0-60mphin2.8seconds!Sadly,Ididn’tgettotestthis!
ManMotorMuseum.Thisisafascinatingprivatecollection TheCunninghams’latestadventure,though,istotry
ofvehiclesandmotorcyclesthathasbeenassembledby tobreakthelandspeedrecordforasteam-powered
father-and-sonDenisandDarrenCunninghamover40 motorcycle.They’vebuiltabespokebike–whichwe
years.TheCunningham’sportfolioisimpressiveandvaried. witnessedwarmingupandridingawayforatestrunonopen
Over100vehiclesareondisplay,includingsomemodelsI’d road–tocompetelaterthisyearatBonneville,USA.
neverseenbefore,likethe1954Greyhoundbus.Thereare AdmissionpricetotheIsleofManMotorMuseumis£9.50
cars,buses,trucks,transporters,fireengines,ambulances, peradult,andit’sopenfrom10am-5pmeveryWednesday to
includingone-offsandprototypes.Manyoftheexhibitswere Sunday.Youcanwatchaninterestingvideoofthemuseum
acquiredfortheiruniquenessandrarity. here:http://bit.ly/1K8sbBF
p
www.greatmagazines.co.uk/carmechanics February2016 CarMechanics 3
Contents
66 Citroën DS3 e-HDi
FEATURES
62
Full step-by-step service guide.
6 Dual-Clutch 72 Help!
Transmissions Eight pages of your toughest
Everything you need to know motoring problems solved.
about automated manual ’boxes.
80 Diagnostics Doctor
32 Multimeter Masterclass Your diagnostics queries sorted.
A beginners’ guide to the
essential workshop tool. CM visits Philips 83 Renault Clio 1.2 16v
Automotive Lighting Probing the Siemens SIM32
inGermany.
62 CM Visit: Philips management system.
Automotive Lighting
We tour the German plant. BUYING
REGULARS
90 Mechanex 50 VW Golf MkV
Report from the 2015 trade show. Find the finest example of the 20 C M Insider
perennial German best-seller. The latest tools and accessories.
93 2015 Index
54 BMW Z4 60 D ealer’s Diary
Sourcing new and used parts. Steven Ward inadvertently
PROJECTS washes some soundproofing.
36 Volvo S60 2.4D WORKSHOP 64 Your Letters
Part Three: A new cambelt, water
pump and tensionsers are fitted. 24 Tales from 88 Our Cars
the Workshop Rob Bradshaw’s Peugeot 205s.
44 MINI One 1.6
56 Modifications: Filtration 98 Ted Connolly
Part Six: Sorting the suspension,
power steering and droplinks. Fitting performance air filters. Ted tries out the Jaguar XF.
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Instant expert
Twin-clutch
transmissions
This automated manual
Volkswagen Group’s
gearbox is referred to as
six-speed wet
clutch DSG is the
a twin-, double- or dual-
most common twin-
clutch transmission. clutch transmission
encountered on the
Rob Marshall looks at used car market.
how they evolved, how
they work and how the
technology is faring in
the real-world.
Co-developed by BorgWarner
and the Volkswagen Group,
for the car-maker’s transverse
front- and four-wheel drive
applications, the compact Direct
Shift Gearbox or Direktschaltgetriebe
(DSG) was released in 2003 and was
the first mainstream twin-clutch
transmission. At its introduction, themarket,and
twin-clutch units could swap ratios isapproximately
more directly and more efficiently thesamesizeas
than conventional epicyclic-geared adual-clutchgearbox.
automatic transmissions. They were also afterheleftemploymentwithAndré
more efficient, due to their direct drive Citroën.Kégresse’smainprioritywas
A shaky start
and lack of a torque converter. While notefficiency,buttorelievethetediumof
revolutionary at the time, traditional Althoughmanypeopleassociatethe changinggear,inthedayswhenmanual
automatics have since caught up. For twin-clutchtransmissionwithGerman transmissionsynchromeshwasinits
example, ZF’s nine-speed transverse manufacturers,itsworkingprinciples infancy.Thisnecessitatedthedriverto
autobox is said to be more efficient than werepatentedbyaFrenchmilitary double-declutchandmatchtheengine
any other twin-clutch transmission on engineer,AdolpheKégresse,in1935, speedwiththatofthetransmission,
W Twin-clutch units
tend to possess internal
wet clutches on more
powerful cars, such as
this Mitsubishi SST,
fitted to the Evolution X
as an optional extra.
X Historically, dry
twin-clutches tend
to be used on less
powerful cars and
replacement dictates
careful shimming prior
to fitting. While more
efficient, they tend not
to last as long as the
wet types.
p
6 CarMechanics February2016 www.greatmagazines.co.uk/carmechanics
Twin-Clutch Transmissions
How they work CLUTCH1
CLUTCH2
OUTPUT TO FRONT
XWhilecross-sectionsmakethem INPUT SHAFT2 INPUT SHAFT 1 AXLEDIFFERENTIAL
OUTPUT TO
appeartobeincrediblycomplex,
REAR AXLE
twin-clutchtransmissionsarefairly DIFFERENTIAL
straightforward.Althoughoften
describedastwogearboxesinone,in
facttheycombinetwoinputshafts,
withoneshaftfittinginsidetheother,
eachofwhichpossessesaclutch.
4th GEAR 5th GEAR
InputShaft1hoststheodd-numbered
gears(1st,3rd,5thandreverse)and 6thGEAR 1stGEAR 7th GEAR CENTRE
DIFFERENTIAL
InputShaft2theeven-numbered
gears(2nd,4thand6th).Whenone 2ndGEAR REVERSE 3rdGEAR
GEAR
shaftisbeingdriven,thesecond
This is afour-wheeldriveAudiS-tronicdual-clutchunit,usedontheQ7model,whichshares
shaftispreparedwiththenextratio.
VolkswagenGroup’sDSGlayout.NotehowInputShaft1issituatedwithinInputShaft2.
Whenachangeoccurs,InputShaft
1’sclutch,K1,disengagesasInputShaft2’sclutch,K2, valves,throughwhichpressurisedfluidispumped,to
engagestodeliveraseamless,smoothandswiftshift. operateboththeclutchesandgearshiftselectors.
Additionally,twooutputshaftsareinconstantmeshwith Thetransmissionoilactsnotonlyasahydraulicmedium
thedifferential.Asinglereverseshaftisfitted,too. butalsocoolsthewetclutches.Consequently,theoilreturned
Insidethesix-speedDSG,theclutchesareactuated fromtheclutchpackscanreach100°Cinnormaluse.Cooling
hydraulicallybytheMechatronicsunit,acombinedECUand isachievedbypumpingtheoilintoaheatexchangerontop
agloriously-simplehydraulicvalvecircuitthat’sactivated ofthegearbox,throughwhichenginecoolantflows.Apair
bysolenoids;Mechatronicsisderivedfromcombiningthe offilterskeepstheoilfreeofcontaminants–oneofthem
terms‘mechanics’and‘electronics’.Inessence,itsECU islocatedinthebaseofthetransmission;theotherisa
(sealedtotheMechatronicsbody)receivesinformation renewablefilterthatissituatedwithinadedicatedhousing
relatingtonotonlyinternalspeed,gearpositionand inthecoolingcircuit,ontopofthecasing.Volkswagen
temperaturebutalsoparametersthataretakenfrom stipulatesanoilchangeinterval(typically,every40,000
thecar’sothersensors,includingthoserelatingwith miles,butcheckyourhandbooktobesure),atwhichpoint
theengineECU,ABS,shiftlevermoduleandinstrument theremovablefiltermustbereplaced.Anywarrantyclaim,
cluster.ThisinformationispassedtotheMechatronic’s incidentally,isvoidunlessthisworkhasbeencarriedout
ECU,whichcontrolsthesolenoidsthatactivatehydraulic withthecorrectlubricantandanOE-specificationfilter.
toavoidtheembarrassingcrunchof How motorsport for its rally Quattros, possibly thanks to its
spinninggears.HisAutoServegearbox R&D director at the time, Dr Ferdinand
improved the breed
placed two manual gearboxes within a Piech, being a grandson of Ferdinand
single casing, along with a pair of clutches; Porsche expressedastronginterest Porsche. Recalling the experiences of
one engaged the odd-numbered ratios, in the technologyandtransferredits the 530bhp Group B Audi Quattro being
the other one managed the even gears. development toStuttgart.Notonlywas fitted with the PDK transmission in his
The now defunct Automotive the transmission’slowweight,super-fast book, Walter Röhrl Diary: Memories of a
Products of Leamington Spa, gear-changes andhighefficiencyideally World Champion, the rally ace reminisced
Warwickshire, revisited the concept suited to economy-mindedconsumers, about the difference the transmission
40 years later, when it fitted various but the eliminationofacceleration made: “The PDK made the acceleration
production cars (including the original lapse and the reductionindrivetrain even crazier… I could change gear at full
Ford Fiesta) with its experimental power losses madethematantalising throttle, without any decrease in pulling
Hot-Shift gearbox in the 1980s. The proposition for motorsport.Aftertwo power, or any falling-off of turbo boost.”
work was overseen by Harry Webster, years’ intense refinementforracing Despite this, when Audi withdrew
former technical director of British purposes, the PorscheDoppelkupplung from Group B rallying a year
Leyland, just prior to his retirement. (PDK or ‘doubleclutchdevice’)wasborn. later, it also abandoned any
The Hot-Shift project intended to not At around thesametime,the further PDK development
only address the inefficiencies of the technology was alsobeingutilisedbyAudi programmes.
conventional automatic gearbox’s torque ROB’S
converters, especially when coupled to TOP TIP
low-powered, smaller capacity engines,
but also to create an automatic-type Nevertrytocure
anoilleakbyusing a transmission
transmission using manual gearbox
stop-leakadditive. The types
components, which would simplify
containingglycol will swell all
mass production, because of increased rubber seals within the unit.
economies of scale. A main priority
was to ensure a seamless gear-change, Gettingtheoillevelright
without disconnecting drive from the isessential.Followany
instructionscarefullyif
engine, so, like the pre-WW2 AutoServe,
doingtheworkathome.
the heart of the Hot-Shift system was
Pictured is a cross-section of
two manual transmissions and a pair of the combined oil drain/level
clutches, housed within a single case. plug on the six-speed DSG.
p
www.greatmagazines.co.uk/carmechanics February2016 CarMechanics 7
Twin-Clutch Transmissions
clutch DSG is the most likely unit to both fuel economy and driving pleasure.
Entering the real world
be encountered in the used car market Cramming more gears within the
Porsche appeared to lose interest, too, today, this article focuses on that variant. compact casing is also a possibility;
but the company’s road versions of the The ‘twin-clutch’ moniker references Volkswagen was developing a 10-speed
PDK were co-developed later with ZF a pair of wet clutches but, to make the DSG unit, which was shelved at the end of
Friedrichshafen AG. The production gearbox more efficient for engines last year, possibly due to other unexpected
reality debuted in 2008, over five years with lower outputs (initially less than factors that are making demands on the
after BorgWarner/Volkswagen Group 250Nm), dry clutch packs have been company’s cash resources.
introduced their six-speed DSG to the used. Most notably, Volkswagen Group Other car-makers also sell models
world, beneath the bonnet of the Audi introduced the twin dry clutch seven- with twin-clutch transmissions, but
TT 3.2-litre V6. While Audi had called speed DSG for its 1.4- and 1.6-litre the majority of them were developed in
its system S-tronic since 2006, it was petrol models. The reasoning behind collaboration with major transmission
basically the same as Volkswagen’s DSG, subsequent developments, which suppliers, such as ZF, LUK and Getrag.
although a seven-speed longitudinal include the use of less oil, electric (not Such units share the same operating
version was developed for some four- mechanical) oil pumps and clutch principles as DSG. The second most
wheel drive applications and varies only friction materials with improved heat popular version tends to be the six-speed
in internal details, the main difference transfer properties, has been to increase PowerShift unit, which can be fitted with
being two internal oil circuits. As efficiency even further, while driving either wet or dry twin-clutch packs, and
Volkswagen Group’s six-speed, wet down tailpipe emissions and enhancing is fitted to a variety of Volvos and Fords.
DSG: What goes wrong?
XDespitebeingaremarkableengineeringfeatthat
hasbeenmass-producedinmillionsofvehicles,many
unhappycustomershaveventedtheirireatVolkswagen
forprematureDSGfailure.However,oneissuemightbe
relatedtocarsalespersonsfailingtocommunicatethe
subtledifferencesbetweenautomatICandautomatED
manualtransmissionsandthatcertaintraditional
‘slush-box’drivinghabitscandamageaDSG.
Insidethewet-clutchDSG,thefrictionmaterial,usedon
theclutches’multipleplates,isimmenselyresilienttowear.
Strangely,thesteelplatesonwhichtheybeartendtosuffer
more,suchasdevelopinghigh-spotsandscoresor‘blueing’
withoverheating.Therefore,manyclutchproblemscan
beblamedoneitherexcessiveheat,aninternalhydraulic
pressureproblem(usuallycausedbytheMechatronics)
orpoordriving,suchasholdingthecaronahillwithjust Thelatestdrytwin-clutcheshandlemoretorque.Launchedinlate
2015,Suzuki’ssix-speed,twindryclutchTCSScanhandleupto
thethrottle.Intheabsenceoflubricant,thedryclutches
320Nm,insteadofthe250Nmofearlyunitsfromothercar-makers.
thatarefittedtolower-poweredmodelstendnottolastas
long.Replacementpartsappeartoberestrictedtotrained isimpossible.TheMechatronic’s11solenoidscanfailbut
specialists,becauseunlesstheinitialadjustmentismade asimplediagnostictestusually(butnotalways)pinpoints
correctly,whichrequiresshimmingtoobtaintheoptimum theproblem.Cleverfailsafemodesarealsoincorporated
clearancebetweenthereleasebearingandpressureplate, withintheMechatronics.Shouldaproblembedetected
itcandestroythetwin-clutchunitveryquickly. onInputShaft1,forexample,thehydraulicpressureis
Withwet-clutchtypes,increasingenginetorquetends isolatedfromthefaultygearsets/clutchandthegears
todictatethattheinternalhydraulicpressureissimilarly onInputShaft2willbeusedasaback-up.Theopposite
increased,toreducethechanceofwetclutchesslipping situationwouldoccurifInputShaft2developedanissue.
andoverheating.Anyweaknessinthehydraulicsystem Thetransmissionmightstillfunctionintheeventofan
reducestheclampingforceoftheclutches,causingthem internalsensorfailureandtheresultantloggingofafault
towearoutprematurely.Ifanengineistuned(orthecar code.However,thetransmissionmightselectasinglegear
isusedfrequentlyfortowing),specialistsrecommendthat onlyasanemergencymeasure.Yet,youcanstillidentify
thetransmission’scoolingsystembeupgraded,ifpossible. minorfaults,whichcoulddevelopintomoreseriousissues.
Ifoiltemperaturesexceed145°C,theDSGwillshutdown Judderisacommoncomplaint,noticeablewhenmoving off.
andwillnotselectanyratiountilithascooled. Ifitoccursinnormaloperatingtemperatures,suspectan
Theentiretransmissioncanberuinedifacorrodedheat internalpressureissuewiththeMechatronicsorthetwin-
exchangerpermitsengineantifreeze/glycoltocontaminate clutchpack,orelseapressurelosswithinthetransmission
thehydraulicoil.Apartfromdestroyingthelubricant’s case.Mechanically,theinputshafts(oneofwhichishollow,
viscosity,italsostripsthefrictionmaterialfromtheclutches allowingtheotheronetopassthroughit)arereliable,other
andswellsthemanyrubbercomponents,includingtheseals thantherearendbearingthatcandeteriorateonthesix-
onthepistonsthatactivatethepairofclutchesandthose speedDSG.Thetwooutputshaftstendtobetrouble-free.
withinthehydraulicsideoftheMechatronics.Evenwithout However,duetothehigherrotationalspeedsinvolved,1st,
theingressofantifreeze,theelectricandhydraulicparts 2ndand3rdgearsarefittedwiththree-piecesynchromesh;
oftheMechatronicsunitarealsopronetofailing.Voltage theotherforwardgearsutiliseasimplerconesystem.
spikes,causedbyeitheradyingbatteryorcarelessjump- Crunchingonthedown-changeisawell-knownproblem
starting,candamagethesealedECU,DIYrepairofwhich thatafflictsthelowerratios.
p
8 CarMechanics February2016 www.greatmagazines.co.uk/carmechanics
Twin-Clutch Transmissions
DIY repair propositions Wet clutch or
dry clutch?
XSurprisingly,theDIYmechaniccan over-complex, but that the non-availability XWhilebothwetand
undertakecertainrepairtasks,including of certain components can restrict repair drytypesoftwin-clutch
oilandfilterchangesandremovalofthe options. The following procedure details the transmissionsareoperated
Mechatronics unit. To guide us through a dismantling exercise that is specific to thesix- hydraulically,thefriction
full strip-down of a Volkswagen Group six- speed wet clutch DSG, provides an overview surfacesofwetclutches are
splashedwithtransmission
speed DSG unit, we enlisted the services of of how the unit works and which components
oil,whiledryclutchesare not
VMTP Midlands Limited of Staffordshire. The are known weak-spots. As the gear sets are
lubricatedbygearoil,as with
company’s twin-clutch specialist explained similar to those fitted to conventional manual
conventionalclutchplates.
that the main issue is not due to the unit being transmissions, they will not be stripped.
DSG WET CLUTCH DISMANTLE
1 Unbolt and remove the aluminium heat exchanger from the 2 The Mechatronic’s electrical connector is delicate – even static
transmission, noting any oil seepage and inspecting the electricity can damage the ECU – so wear gloves when
condition of the two rubber seals within the casting’s inlet and outlet. handling the unit and do not touch the electrical pins.
ROB’S
TOP TIP
Ifyoususpect
inputshaftbearing noise
onasix-speedDSG, be
waryastheresultant
excessive end-float can
damage the clutch drum
assembly, if ignored.
3 Usea6mm Allen key to remove the flange. The bronze cone 4 The aforementioned cones bear against the differential centre
shouldbe inspected, once withdrawn from the casing. The as a very simple limited slip differential of restricted capacity.
sameprocessis repeated on the other flange. If a broken cone is discovered, check that the area is undamaged.
5 Ifyouintendtoseparatethetwocasing 6 RemovetheMechatronicsunit,by 7 Picturedisthesumpremovedandthe
halves,removethescrews(asshown). unboltingthesumpbolts,priorto oildrained,withthevalvebodyhalf
Theyretainaplasticoilpipewithinthe prisingthesumpfromthetransmission. oftheMechatronicsunitexposed.Whenit
transmission,whichwillotherwisebebroken, Takegreatcarenottodamagetheplastic fails,thediagnosticfaultcoderelatestothe
whenthegearboxcasingisseparated. electricalsocket. pressureadaptationbeingoutoflimit.
p
www.greatmagazines.co.uk/carmechanics February2016 CarMechanics 9
Twin-Clutch Transmissions
ROB’S
TOP TIP
DSG WET CLUTCH DISMANTLE Afterrebuilding,
continued thetransmission must be
calibratedelectronically.
Formoredetails, consult
http://bit.ly/1mBmuY2
8 Disconnect the wire from the Mechatronics unit to the input 9 Remove the bolts that hold the Mechatronics unit to the main
speed sensor, which measures the speed of the clutch drum. transmission case, noting their original locations, because
The drum attaches to the dual-mass flywheel. See Step 16. some of the holes drilled into the casting are unthreaded.
10 TheMechatronicsunitmustbe 11 Ifthereverseshaft’sspeedsensoris 12 Removeitssecuringbolts,liftoffthe
removedsquarely,notatanangle, snappedoff,theMechatronicsunitis endcoveranditsmouldedgasket.
andhandledaspictured.Thisisbecause scrapandnewreplacementcostsstartat Generallyspeaking,thepumpsarevery
thelong,plasticreverseshaftspeedsensor morethan£600.Seetheseparatesection reliable–pressuredropstendtobethe
extensionreachesdeepwithinthecase. onDIYMechatronicsrepairs. faultoftheMechatronicsunit.
13 Beneaththecover,youwillseethe 14 Unscrewitsbolts,removetheoilpump 15 Detachthecirclipandretrievethe
oilpumpandthereverseshaft coverandgasket.Beneathitliesthe shim.Unfortunately,anothercirclip
sensorpick-up,thespeedofwhichis inputshaftbearing,whichisknowntowear holdsthebearinginplacebehindthe
measuredbytheMechatronic’slong andbecomenoisy,audibleasthecarmoves casting,sothegearboxhastobesplit.The
plasticsensorextension. offfromastandstill. splinedoilpumpdriveshaftliftsout.
16 NowthattheMechatronicsunithas 17 Evenifyouareespeciallygentle,the 18 Undotheboltsthatholdthecasing
beenremoved(seeStep10),theinput reversespeedsensorringcandistort. halvestogether.Beingmadeofsteel,
speedsensor’ssecuringboltcanbeundone Fortunately,newreplacementsareboth theycancorrodeintothealloycasing,
Continued
andtheassemblywithdrawnfromthesump availableandinexpensive–notreplacing whichmakesthemtrickytounscrewand on page
casting.Storethesensorinasafeplace. itisafalseeconomy. theirMulti-Splineheadsdamageeasily. 12
p
10 CarMechanics February2016 www.greatmagazines.co.uk/carmechanics