failure diagnosis: luk’s guide to troubleshooting clutch-system
TRANSCRIPT
passenger cars
Failure DiagnosisLuK’s guide to troubleshooting clutch-systemfailures and malfunctions
The LuK Clutch Course
31
Dual-mass Flywheels: their design and operation
Dual-Mass Flywheels redistribute the mass moment of inertia and thus shift resonance frequencies to a range well below the normal operating range. The periodically occurringcombustion cycles inevitably cause fluctuations in rotation rates. The spring/dampingsystem of a Dual-Mass Flywheel virtually isolates the rest of the drive train from these fluctuations and provides the smooth running of all components of the secondary mass,(clutch, driven plate, transmission, and drive shafts) that follow in the drive train.
1
2
34567890ß“„”
¿¸qwertzuio0ß
Primary rotating mass and damper housingSecondary rotating mass and friction surfaceCover for primary rotating massHubArced compression springTubular spring guideFlange and diaphragm springGrease reservoirMembrane sealFriction and supporting ringCaged ball bearingsO-ringSealing and insulating capDiaphragm springs providing basic friction controlLoad-transmitting friction washerDiaphragm springSheet-metal cover plateRivetWasherCentering pinStarter ring gearVentilation slotsMounting holePositioning holeLaser weldDiaphragm-spring clutch Rigid driven plate
Transmission Transmission
Dual-mass flywheel
The previous style
Schematic
Resonance at around 1,300 rpm
Driven-Plate Torsional-VibrationDamper
FlywheelClutch
Engine
Transmission
Resonance at around 300 rpm
Engine Primaryrotatingmass
DMFTorsional-VibrationDamper
Secondary rotating massFlywheelClutch
Transmission
How it works(Transmission of torsional vibrations)Conventional flywheel and driven plate with
torsion-vibration damping
Engi
ne s
peed
(rp
m)
Engi
ne s
peed
(rp
m)
Time (s)
Time (s)
EngineTransmission
Dual-mass flywheel
Engine Transmission
400
300
200
100
Engi
ne to
rque
[Nm
]
00 10 20 30 40
ComputedMeasured
Rotation angle [°]
Partial loop in the normaloperating range withlow damping
High dampingduring load changes
32
The LuK Clutch Course
Damped Flywheel Clutch – their design and operation
Primary rotating mass and damper housingSecondary rotating mass and friction surfaceCover for primary rotating massArced compression springMembrane sealTubular spring guideCover retaining ring and flangeVentilation slotsStarter ring gearMembrane sealSheet-metal supportBalance weightVentilation slotsCaged ball bearings with sealing and insulating capAllen-head screwDiaphragm springLoad-transmitting friction washerSheet-metal retainerDiaphragm springDowel pinTensioning pinGrease reservoirLaser weldAperture for accessing retaining bolts Pressure plate with friction surfacesVentilation slotsDiaphragm springTilt ringsRiveted studLeaf springRivetAperture for accessing retaining boltsHubAllen-head screwDiaphragm springSegment rivetSpring segmentLining rivetClutch liningsRivetHubAnnular mass (primary rotational mass)Rivet
1234567890ß“„”¿¸qwertzuiopü»«æˇ3̃23̃33̃43̃53̃63̃73̃83̃94̃04̃14̃24̃3
6
9
4
12
21
1
2
8
13
17
18
19
15
41
40
14
43
16
5
35
22
7
3
11
34
39
12
38
37
30
31
36
27
32
24
33
25
29
28
26
20
10
42
23
8
7
1
2
6
11
10
4
3
5
9
The LuK Clutch Course
33
Self Adjusting Clutches – their design and operation
CoverAdjusting ring (chamfered ring)Compression springDiaphragm springSensor diaphragm springStudStudLeaf springPressure plateStopDriven plate
1234567890ß
Sensor-diaphragm spring
Pivot for the main diaphragm spring
Adjusting wedge
Main diaphragm spring
Sen
sor
pres
sure
Rel
ease
pre
ssur
e
new wornnew
worn
1234567
8910111213
1415161718
1920
21
22
2324
25
34
The LuK Clutch Course
Driven Plates – design and operation
Predamper friction washerPredamper diaphragm spring (1st stage)Predamper hub flangePredamper compression springsPredamper compression springsPredamper cageMain-damper diaphragm spring (1st stage)Centering conePredamper diaphragm spring (2nd stage)Predamper load-transmitting washerPredamper cageMain-damper diaphragm spring (2nd stage)Main-damper friction washerLining rivetFriction liningsSpring segmentSegment rivetCounter plateMain-damper compressionspringsMain-damper compressionspringsDriven plateHubMain-damper friction washerMain-damper auxiliary flangeSheet-metal spacer
12
34567
89
0
ß“
„”¿¸qwe
r
tzuio
2000
1000
0
-1000
0 0,1 0,2Time [s]
No torsional-vibration damper
Vibrations at idle speed
0 0,1 0,2Time [s]
With torsional-vibration damper
EngineTransmission
Ang
ular
acc
eler
atio
n [r
pm/s
2 ]
D
The LuK way to...
35
...cost-effective, efficient clutch replacements
/ Clutch pressure plate: Clutch driven plate’ Release bearingM Flywheel? Transmission input
shaft! Crankshaft
First things first:• Are the correct parts available?• It is crucial to check before installation, compare
with dismantled parts.
In particular, the following should be noted:Check wear of the pilot bearing; renew if necessary.Check shaft sealing rings on engine and transmissionside for leakages and replace if necessary.Flywheel: Check friction surface for scoring andcracks. Note the prescribed tolerances for reworking!Caution! Rework the screw fixing surface for theclutch to the same extent as the treated friction surface.DMF: The friction surface may not be reworked!Check the clutch disc for lateral runout prior to assembly (max. 0.5 mm).Check the clutch shaft for damage, lubricate splineprofile or shaft. Remove excess grease.Manufacturer's recommendation: LuK high-performance grease (LuK-AS item no. 414 0014 10). Grease containing suspended solids isnot suitable.Note! Chemical nickel-plated splines are not to belubricated!Note the correct installation position of the clutchdisc! Use centering pins for assembly.Check the guiding sleeve of the release bearing for wear and replace if necessary; use suitable lubrication.
Tighten the clutch assembly crosswise with the prescribed torque. Always remove and install the SAC clutch with the special tool approved by LuK-AS(LuK-AS item no. 400 0072 10).Take into account the centering of the clutch assemblyon the flywheel! With external centering, take intoaccount the condition of the pilot diameter of theclutch assembly and the flywheel.Inconsistencies in diaphragm spring tabs or releaselevers, caused by thick ness tolerances in the frictionlining, regulate themselves after a short run-in time.If the fixed setting carried out by LuK in the factoryis readjusted, the warranty is void!Check clutch operation for function and wear! Replacethe clutch cable - check the bearings.Check clutch operation for function and wear! Replacethe clutch cable - check the bearings. Check thehydraulic system for leaks and vent if necessary.Check the release stroke of the slave cylinder’s pistonrod. Check whether the initial position is reached.When changing the clutch, also replace the hydraulicconcentric slave cylinder (CSC).Check the alignment of the engine to the gearbox.Replace dislodged gearbox dowels!Set release bearing clearance at 2-3 mm. Constantrunning bearings are o perated with a pre-load of 80–100 N. Only combine bearings which have plasticsleeves with metal guiding sleeves.
1
2
3
4
5
6
8
9
10
11
12
7
13
14
Right Wrong!
36
LuK Clutch-Service-Tips
The following easy to use charts are provided to enable clutch problems to be easily identified and make diagnosis simpler
Tangential straps damaged
Damaged levers/spring fingers
Cover assembly distorted
Driven plate distorted
Corrosion on friction material
Driven plate seized or sticking on gearbox input shaft
Facing too thick
Facing material sticking
Torsion damper broken
Gearbox snout damaged
Damaged spigot (pilot) bearing
Insufficient release travel
Excessive release travel
Driven plate seized to flywheel or to pressure plate
Renew the clutch pressure plateCheck straps before fitting
Renew clutch pressure plate
Renew clutch pressure plate
Straighten driven plate
Clean the facing, remove all signs of corrosion
Remove burrs or renew plateRemove all corrosionUse correct grade of greaseCheck parts are correct to application
Check parts is correct to application
Renew driven plate
Check driven plate for correct installation
Renew bearingCheck suitabilityLubricate snout
Renew bearing
Replace clutch cableBleed the systemRenew the release system
Check release system operation
Clean rust and corrosion from facing material
The clutch was droppedDamaged on replacement
Incorrect assembly
Cover assembly not bolted down evenly and sequentially
Check driven plate lateral runout (max 0.5 mm)
Vehicle not run for a long period
Damaged spline profileRust on input shaftIncorrect grease usedIncorrect spline profile
Incorrect driven plate
Grease or oil contaminated
Driven plate incorrectly installed
Damaged release bearingIncorrectly matched partsNo grease used
Worn
Incorrect clutch cable or adjustment incorrect.Air in the hydraulic systemRelease system damaged
AClutch fails to disengage
Problem Cause Remedy
Pressure plate overheating
Clutch housing, levers or diaphragm spring broken
Diaphragm fingers worn
Clutch facing worn out
Clutch facing contaminated
Uneven wear pattern on flywheel side of facing material
Flywheel thickness incorrect
Gearbox snout damaged
Clutch cable heavy in operation
Release system heavy in operation
Renew clutch assembly
Renew oil seal
Follow correct installation procedures
Adjust pre-loadRenew clutch assemblyAdjust free play
Renew clutch assembly
Renew oil sealsRenew clutch assembly
Re-machine flywheel
Machine bolting surfaceRenew flywheel
Renew gearbox snoutUse correct lubricantCheck parts for suitability
Renew clutch cableCheck for correct cable assy
Renew bushesLubricate bearings or bushes
Thermal overloadIncorrect partsBroken diaphragm springOil contaminated
Incorrect installation
Excessive release bearing pre-load
No free play
Normal wear and tearIncorrect pressure plate
Oil seals leakingGearbox splines overgreasedRelease bearing overlubricated
Badly worn flywheel
Incorrect machining of flywheel bolting surfacenot machined to same dimension as runningsurface
Non/incorrect lubricantDamaged release bearingIncorrect combination of bearing and snout
Clutch cable damaged Incorrect cable
Damaged bushes on release arm or shaftBushes or bearing not lubricated
BClutch slip
Problem Cause Remedy
LuK Clutch-Service-Tips
37
Pressure plate uneven
Facing contaminated with oil
Facings contaminated with grease
Incorrect facing material
Facing damp
Difficult or hard operation
Air in the hydraulic system
Damaged gearbox snout
Engine/gearbox mountings
Engine not tuned/misfiring
Replace clutch cover Install correctly
Renew oil sealsReplace driven plate
Renew driven plateRenew release bearing
Check plate is suitable for application
Operate clutch to remove moisture
Fully inspect the release systemCheck bearing/snout combinationRenew all suspect parts
Renew any suspect or damaged parts
Renew the snout and use correct grade of lubricant
Replace mountings
Check engine for correct running
Broken or bent tangential strapsDistorted cover
Oil seals defective
Excessive grease on splinesand release bearing
Incorrect plate fitted
Moisture penetrated facing
Clutch cableRelease lever bearingsGearbox snoutMaster or slave cylinder
Leaking or damaged master/slave cylinders or pipes
Incorrect lubricant used
Incorrect or damaged mountings
Carburettor, fuel injection ignition timing
CClutch judder
Problem Cause Remedy
Bearing running eccentricallyto diaphragm fingers
No drive
Incorrect driven plate
Torsion damper broken
Release bearing defective
Spigot (pilot) bearing defective
Damaged damper spring breakout
Renew bearing
Renew pressure plate or driven plate
Fit correct driven plate
Fit correct driven plate
Renew bearing
Renew bearing
Renew driven plate
Bearing not centreing
Torsion damper incorrect for vehicles application
Incorrect damper
Not rotating smoothly
Bearing seized
Incorrect driving habitsWrong gear selection
Clutch makes a noise
Problem Cause Remedy
Incorrect pressure plate
Damaged gearbox snout
Release system bearings or bushes worn
Clutch cable damaged
Fit correct pressure plate
Renew release bearingCheck combinationGrease bearing and snoutUse correct grade of grease
Renew bearings and bushesLubricate where required
Renew cableCheck for suitability
Release load too great
Release bearing damagedIncorrect combinationNo grease usedIncorrect grease used
Bushes worn or not lubricated
Normal wear and tearIncorrect cable fitted
EClutch pedal is heavy in operation
Problem Cause Remedy
D
38
LuK Troubleshooting and Service-Tips for Passenger Cars
Start off by asking the customer these questions:
Regarding malfunctions:What is malfunctioning?How was the problem noticed? How long has itexisted?
Regarding wear:Clutch mileage? Is it the originalclutch? Has the clutchbeen abused?
Regarding usage:Is the vehicle new? Who drives it?
Regarding past repairs:Have the clutch and/or transmission been repaired?
The engine revs at startup/acceleration – but the speed increasesonly slowly or not at all.
Friction values of the mating friction surfaces too low, dimensions of the mating friction surfaces not OK, contact force of the clutchassembly too low.
QUICK TEST – Put on the hand-brake, start the engine, engage3rd gear, press down on theaccelerator and slowly engagethe clutch ➝ engine does notcut out ➝ clutch defective.
TEST RUN – Upon Accelerationat maximum engine torque ➝the engine suddenly revs fasterbut the speed does not increasefurther ➝ clutch defective.
ACTUATION – Pedal mechanism,clutch play, clutch cable, mas-ter/slave cylinder and hoselines.
SPECIAL CASE (BMW / MERCEDES-BENZ) –Lining thickness may also bechecked with a special tool prior to removal!
CLUTCH DISC – Lining oily,lining greasy, lining carbonised,reduced lining thickness.
CLUTCH ASSEMBLY – Over-heating of the driven plate,heavy scoring on the contactplate, diaphragm springs broken.
FLYWHEEL – Scoring/cracks inthe friction surface, flywheeldepth.
RELEASE SYSTEM – Releasebearing/guiding sleeve sluggish
The vehicle moves despite a depressed clutch, crashing noises whenchanging gear.
QUICK TEST – Start engine, select reverse gear, shiftthrough all gears ➝ gear noises when changing gear ➝clutch defective.
ACTUATION – Pedal mechanism,clutch play, clutch cable, releaselever, release shaft, travel frommaster/slave cylinder, master/slave cylinder and hose lines,fluid levels, air in clutch system.
Clutch fails to disengage Clutch slip1. What are the particular symptoms? 1. What are the particular symptoms?
2. Which components might be defective? 2. Which components might be defective?
Contact force is no longer relieved, clutch disc is not released due totoo little or no lift-off of the clutch assembly.
3. What should be checked before clutch removal? 3. What should be checked before clutch removal?
4. What can be determined after removal? 4. What can be determined after removal?
CLUTCH DISC – Spline profilerusted in, lining on companionfriction surfaces seized up,lining broken/loose, lining retainer plate shaped, liningretainer broken, clutch discincorrectly mounted, lateral runout of the clutch disc, tor-sion damper spring broken.
CLUTCH ASSEMBLY – Contactplate, leaf spring compressed,leaf spring broken, diaphragmspring tabs heavily worn, coverbent.
RELEASE SYSTEM – Releasebearing sluggish, release shaftbearing fixed, guiding sleevecorroded.
SPECIAL CASE – Clutch shaft is seized in the pilot bearing ➝Torque is transferred.
5. What might be causing the problem(s)? 5. What might be causing the problem(s)?
Clutch disc is ‘dented’, angular displacement. Normal wear, frequent driving with slipping clutch, shaft sealing ringof the crankshaft or the gearbox leaking, engine tuning.
Noises when clutch actuated, noises whenchanging gear, noises during the journey.
Insufficient or no lubrication of moving parts,friction of rotating parts, loose parts.
QUICK TEST – Engage/disengage clutch,noise from the clutch area?
TEST RUN – Slipping noise? Clutch defective.
ACTUATION – Pedal mechanism, clutch cable,release shaft, master/slave cylinder and hoselines.
CLUTCH DISC – Scoring on the spline, scoringon the torsion damper, grease hole cap of thetorsion damper, torsion spring broken, splineprofile knocked out.
CLUTCH ASSEMBLY – Diaphragm spring tabsworn.
RELEASE SYSTEM – Ball bearing of the release bearing defective, release shaft bearing defective.
Clutch makes a noise
TECHNICAL CAUSES – Defective parts: Clutch cable, release leaver, release bearingsluggish.
EXTERNAL CAUSES – Normal wear, torsiondamper defective, assembly errors.
LuK Troubleshooting and Service-Tips for Passenger Cars
39
Clutch judder
1. What are the particular symptoms? 1. What are the particular symptoms? 1. What are the particular symptoms?
The engine shakes on take up of drive.
Uneven rotary motion of the crankshaft or the clutch shaft, friction values of the matingfriction surfaces uneven, driven plate misalig-ned, contact force increases unevenly.
TEST RUN – Judders in certain driving situa-tions, e.g. also reverse start-up on a hill.
ACTUATION – Pedal mechanism, clutch cable,release shaft, master/slave cylinder and hoselines.
DRIVE TRAIN – ENGINE – Engine manage-ment, engine suspension/engine mount.
GEARBOX – Gearbox suspension/gearboxmount.
DRIVE – Drive shafts, Hardy disc.
CLUTCH DISC – Lining oily, lining vitrified,wear pattern not OK.
CLUTCH ASSEMBLY – Leaf spring compres-sed, diaphragm spring tabs bent, cover shifted.
FLYWHEEL – friction surface not OK.
RELEASE SYSTEM – release bearing/releaseshaft bearing damaged, guiding sleeve corroded.
2. Which components might be defective? 2. Which components might be defective?2. Which components might be defective?
3. What should be checked before clutch removal?
3. What should be checked before clutch removal?
3. What should be checked before clutch removal?
4. What can be determined after removal? 4. What can be determined after removal? 4. What can be determined after removal?
5. What might be causing the problem(s)? 5. What might be causing the problem(s)? 5. What might be causing the problem(s)?
• Clutch shaft over lubricated
• Incorrect lubricant used
• Guiding sleeve corroded
• Assembly error
Clutch pedal can only be depressed by exerting increased force.
Friction in area of actuation, friction in area of the release system.
ACTUATION – Pedal mechanism, clutch cable,release shaft, master/slave cylinder and hoselines.
RELEASE SYSTEM – Release bearing, releaseshaft, release shaft bearing knocked out.
Clutch pedal isheavy in operation
TECHNICAL CAUSES – Defective parts: Clutch cable, release leaver, release bearingsluggish.
EXTERNAL CAUSES – Normal wear, assemblyerrors
Telefon: +49 (0)1 801-753-333Telefax: +49 (0) 61 03-753-297
999
6001
540
21
98/1
.0/0
9.20
08/O
D-G
B