Clutch System Diagnostic Guide
LuK’s Complete Guide to Clutch Operation and Failure Diagnosis
The LuK RepSet® Clutch Line
The Brand Professionals Trust
When it comes to a job as complex and labor intensive as a clutch replacement, you can’t afford a
comeback. Cheap, inferior parts can cost you hundreds of dollars in unreimbursed labor. For over
thirty years, smart technicians have staked their reputation – and their customers’ satisfaction –
on genuine LuK RepSet® clutch and clutch system components.
Trust Genuine Original-Equipment Quality
“Cheaper” Isn’t Less Expensive
• Every LuK RepSet® is 100% functionally tested and
guaranteed to meet OEM performance specifications.
• Each LuK RepSet® contains everything you need to • The replacement clutch market is full of mix-andmatch parts from various sources, a practice that
creates quality and installation problems.
get the job done right: new clutch, disc, release
bearing, pilot bearing, spline tool and lubricant.
• LuK offers a complete line of clutch system
components, including flywheels, hydraulic release system components and cables.
• LuK offers the industry’s best technical support: online, on-call and in print.
• Value-priced brands from offshore manufacturers
achieve savings with inferior raw materials, thirdworld labor and no quality control.
• Quality flaws are not always visibly obvious.
Parts might bolt-up, but will fail prematurely –
often shortly after installation.
Current OE LuK-Equipped North American Vehicles
LuK premium clutch sets offer
the highest in-house manufactured
content in the industry —
when you control
the content, you control
the quality.
•
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Audi
BMW
Cadillac
Chevrolet
Dodge
Ford
General Motors
Honda
Hyundai
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Jaguar
Jeep
Lincoln
Mazda
Pontiac
Saab
Saturn
Toyota
Volkswagen
For more information about the LuK RepSet®
clutch line, genuine LuK flywheels and
hydraulic release system components, visit
www.Schaeffler-Aftermarket.us.
Table of Contents
Clutch System Diagnostic Guide
LuK’s Complete Guide to Clutch Operation and Failure Diagnosis
This guide was prepared as a
reference for all automotive
professionals who distribute and
install the LuK RepSet® products.
We hope you find it useful and
informative.
The photographs of damaged
clutch
system
components
represent common system failures.
Compare them to the products
you remove to assist in your
diagnosis. Keep in mind that the
damage you see may be more
pronounced or more subtle than
these examples.
For additional technical information
and support, call the LuK Technical
Hotline
at
1-800-274-5001,
8:00 a.m. to 5:00 p.m. ET
Monday
through
Friday
or
check our on-line support at
www.Schaeffler-Aftermarket.US.
Table of Contents
Clutch Function and Components
Clutch Function
Disc
Clutch
Self Adjusting Clutch
Flywheel
Release Bearing
Pilot Bearing / Bushing
Before and During Teardown
Driving Habits and Clutch Wear
Before You Start
Complete Repair
Inspection of External Components
Teardown
Removing the Transmission
Clutch Diagnosis
Diagnostics
Release Problems
Noise
Chatter
Slipping
Hard / Soft pedal
Installation Tips
10 Things You Should Know to do the Job Right
Release Systems and Other Parts
Resurfacing the Flywheel
Inside the Bell Housing
Free Play Adjustment
Reinstallation of Components and Transmission
Finishing the Repair
Technical Tips
No Release
Release Bearing Installation
Slave Cylinder Bleeding Procedures
Internal Slave Cylinders
Sometimes Different is Okay
GM Release Bearing
Adjustable Clutch Master Cylinders
Nissan & Infiniti DMF Installation Procedures
GM Concentric Slave Bleeding Procedures
Most Common Reasons Why They Come Back
Just Looking at the Parts
Self Adjusting Release Bearing
Active Radius
New Style BMW Release Bearing
2
2
3
4
5
5
6
7
7
8
8
9
10
10
10
12
12
14
16
18
20
VARIOUS
8
9
10
11
20
30
30
VARIOUS
12
14
16
18
22
24
26
28
30
31
22
22
23
23
Illustrations
24
Patented Designs
32
Engine Displacement Conversions
© 2013 Schaeffler Group USA Inc.
Printed in U.S.A.
2
Inside Back Cover
Clutch Function and Component Parts
Clutch Function
Vehicles equipped with manual
transmissions contain clutch
systems that connect and disconnect
the engine and transmission. The
clutch system enables the driver to
shift gears.
Clutch System
When the clutch is disengaged, the
release mechanism actuates the
fork. The fork contacts the release
bearing, moving it against the
clutch diaphragm spring fingers.
This action allows the clutch
pressure plate to lift away from
the flywheel, opening a very small
space between the disc, flywheel
and pressure plate. When the disc
moves away from the flywheel,
power flow from the engine to the
transmission is interrupted. The
engine crankshaft and flywheel are
rotating at a higher speed than the
disc and transmission input shaft
that are coasting.
When the clutch is engaged, the
disc slips briefly to provide smooth
engagement and, once again, the
clutch clamps the disc against the
flywheel. This causes the input
shaft to turn, transmitting engine
power to the transmission.
Disc
Disc
The disc is a critical component in
providing long service life for the
clutch system. It provides smooth
engagement and dampens engine
vibrations.
It is mounted to the input shaft
between the flywheel and the
clutch. It can slide forward and
backward on the shaft, but cannot
rotate without rotating the shaft.
Important component parts include
the hub-flange and the torsion
springs. The hub-flange is located
between a cover plate and a retainer
plate. The hub is splined to fit the
input shaft.
2
Technical Hotline 1.800.274.5001
Clutch Function and Component Parts
Torsion springs in the damper
assembly smooth engagement and
dampen vibrations. Some discs
include idle-stage dampers, either
small springs around the hub, or
friction washers inside the disc. As
pulsations from the engine reach
the disc, the springs compress
and expand to cushion or dampen
vibrations and eliminate gear rattle.
Clutch
Friction material is riveted to
numerous metal components
called marcels, or cushion
segments. Waves in marcels soften
engagement. Some heavy-duty
discs do not contain marcels. They
are made with cerametallic friction
material, characterized by abrupt
engagement and some chatter.
Clutch
The clutch clamps the disc against
the flywheel during engagement.
During disengagement it releases
pressure on the disc, creating a gap
large enough for the disc to move
away from the flywheel and enable
the driver to shift gears.
A typical diaphragm spring clutch
consists of a pressure plate, a
diaphragm spring, a pivot ring,
drive straps and a cover. When
the release bearing contacts the
tips of the diaphragm spring
fingers, it moves them toward the
flywheel. The outside diameter of
the diaphragm spring pivots on
the pivot ring inside the cover.
This action lifts the pressure plate
off the flywheel through the drive
straps that connect the cover to the
pressure plate.
Lever style clutches produce clamp
load by pressure from coil springs.
As the friction material of the disc
wears, the springs expand, reducing
their clamping force. At the same
time, pedal effort remains high. As
Disc Torsion Damper
7
2
8
5
a result of these disadvantages,
passenger cars and light trucks are
now almost exclusively equipped
with diaphragm spring clutches.
Diaphragm
spring
clutches
maintain higher clamp load than
lever style clutches throughout
the service life of the clutch. As
disc friction material wears, clamp
load increases during the first half
of clutch life before decreasing
gradually to its original level.
Diaphragm spring clutches require
less pedal effort the further the
pedal is actuated, reducing stress
on release system components.
When replacing a coil spring clutch
with a diaphragm spring, always
remove over-center or releaseassist springs. Designed to reduce
the higher pedal effort associated
with coil spring clutches, overcenter springs may overcompensate
when a diaphragm spring clutch is
installed. This can result in a very
soft pedal and, in some cases, a
pedal that will go to the floor and
stay there.
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3
Clutch Function and Component Parts
Load sensor
On clutches with wear adjustment,
the load sensor detects the
increase in release load caused by
wear and correctly compensates for
the reduction in facing thickness.
Unlike a conventional clutch,
the (main) diaphragm spring is
supported by the sensor diaphragm
spring instead of being riveted
to the cover. In contrast to the
strongly regressive main diaphragm
spring, the sensor diaphragm
spring provides a sufficiently wide
range of almost constant load. The
constant load range of the sensor
diaphragm spring is designed to
be slightly higher than the desired
release load. As long as the release
load is smaller than the load of the
sensor spring when dis-engaging
the clutch, the pivot point of the
main diaphragm spring remains
stationary. As facing wear increases,
the release load increases, the
counterforce of the sensor spring
is overcome and the pivot point
4
Engine side
1
2
3
4
5
6/7
8
9
10
Engine side
Gearbox side
Gearbox side
Clutch cover
Adjusting ring
Pressure spring
Diaphragm spring
Sensor diaphragm spring
Rivet
Tangential leaf spring
Pressure plate
Cover limit stop
9
8
moves towards the flywheel to a
position where the release load
again falls below the sensor load.
When the sensor spring deflects,
a gap develops between the pivot
point and the cover, which can be
compensated for by introducing a
wedge-shaped component.
Design of a Self-Adjusting Clutch
with load sensor
The load sensor with thickness
adjustment wedge can be released
in a simple and effective manner.
In comparison to the conventional
clutch, the only additional parts
required by this design are a sensor
diaphragm spring and a ramp ring.
The sensor diaphragm spring is
suspended in the cover and its inside
fingers support the main diaphragm
spring. Because of centrifugal forces
the wedges which provide the
actual adjustment are positioned
in circumferential direction. A steel
adjusting ring with ramps moves on
opposing ramps in the cover. The
steel adjusting ring is preloaded
in circumferential direction with
pressure springs which force the
ring to close the gap between the
diaphragm spring and the cover
when the sensor spring deflects.
Graph 1 shows the release load
curves for a conventional clutch with
new and worn facings. In contrast,
compare the significantly lower
release load of the SAC® as shown in
graph 2, which has a characteristic
curve that remains virtually
unchanged over its service life.
5
6
4
2
1
3
10
7
An additional advantage is the
higher reserve for wear, which no
longer depends on the length of
the diaphragm spring curve (as in
conventional clutches), but rather
on the ramp height, which can easily
be increased to 3 mm for small and
10 mm for very large clutches. This
represents a decisive step towards
the development of highly durable
clutches.
Sensor diaphragm spring
Clutch cover
Adjusting ring
Pressure spring
Diaphragm spring
1
Release load
In recent years Self-Adjusting
Clutches have become the standard
equipment in applications with high
engine torque or with increased
requirements for wear reserve.
The essential advantages of the
SAC® over conventional designs
are:
• Low release loads which remain
constant throughout the entire
service life
• Excellent driving comfort
throughout the entire service
life
• Increased reserve for wear and
consequently longer service
life thanks to automatic wear
adjustment.
• Release bearing over-travel is
prevented by the diaphragm
spring end stop
Further advantages:
• Simplified release system
design
• Shorter pedal travel
• New engineering concepts to
reduce the clutch diameter
(torque transfer)
• Shorter release bearing travel
throughout bearing life
Self Adjusting Clutch (SAC®)
Worn
New
2
Sensor load
Self Adjusting Clutch
(SAC®)
New Worn
Technical Hotline 1.800.274.5001
Clutch Function and Component Parts
Flywheel
Dual-Mass Flywheel
Bolted to the end of the crankshaft,
the flywheel provides the mounting
surface for the clutch. During
engagement, the disc is clamped
against the flywheel by the pressure
plate.
In addition to its other functions,
the flywheel acts as a heat sink,
dissipating heat and moving it away
from the clutch pressure plate and
disc friction material. The flywheel
must provide a smooth, flat surface
in order for the clutch to operate
properly.
The dual-mass flywheel is designed
to absorb engine vibrations
before they are transmitted to the
driveline where they can create
gear rattle. This is achieved by
splitting the conventional flywheel
into two sections: a primary section
that bolts to the crankshaft,
and a secondary section, onto
which the clutch is bolted. The
primary section of the flywheel
contains springs to isolate engine
vibrations and a torque limiter to
prevent engine torque spikes from
exceeding engine and transmission
component strength. When torque
spikes occur, the torque limiter
allows the primary section of the
flywheel to turn independently of
the secondary section, saving the
driveline and transmission from
damage.
Diagnosing the cause of a slipping
complaint on vehicles equipped
with a dual-mass flywheel can be
difficult because the flywheel, not
the clutch, may be the cause. Dualmass flywheels are designed to
protect the drivetrain by allowing
a slight amount of slip to dampen
the effects of torque spikes.
Torque limiters on some flywheels
can weaken over time and allow
slipping to occur at lower torque
levels.
Examine clutch system components
to determine the root cause of the
slipping. Neither heat marks on the
pressure plate nor disintegrated
or contaminated friction material
indicate a worn dual-mass flywheel.
If the clutch does not appear to
be the cause, a new flywheel is
required.
Release Bearing
The release bearing is attached to
the fork and slides on a bearing
retainer that is attached to the front
of the transmission. The movement
of the fork causes the release
bearing to slide across the bearing
retainer and press against the tips
of the dia-phragm spring fingers.
Ball bearings in the release bearing
enable it to turn while applying
pressure to the fingers. In order for
the clutch to function properly, the
bearing retainer must be exactly
parallel to the input shaft and
provide a smooth surface for the
release bearing.
Angular-contact bearings, found
in hydraulic release systems and
self-adjusting cable systems,
are in constant contact with the
diaphragm spring fingers. Selfcentering bearings are designed
to
compensate
for
slight
misalignment between the engine
and transmission. It is normal for
these bearings to be “off center”
until they contact the diaphragm
spring fingers.
Off center
Angular-contact bearings may appear
“off-center” until initial contact with
the diaphragm spring fingers.
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5
Clutch Function and Component Parts
Some vehicle designs utilize
a concentric slave cylinder. It
eliminates the need for a number
of release system components,
including the release fork, pivot
ball and bearing retainer. Its
location inside the bell housing
makes it difficult to trouble­shoot.
To avoid added labor costs later,
LuK recommends replacing the
concentric slave cylinder when the
clutch is replaced.
If the LuK RepSet® part number is
the correct one for the application,
you can be sure the components
will fit and function properly,
despite differences in appearance.
In the case of release bearings
that appear dissimilar, you can
measure three dimensions on each
of the bearings and compare the
results. The dimensions should be
identical, indicating they are fully
interchangeable.
Use a caliper to measure the following dimensions on the new bearing
and the one you remove from the vehicle.
Bearing Contact Diameter (DIM #1). The bearing contact surface is the
area that contacts the diaphragm spring fingers. It is also called the face.
Measure from the center of the face on one side to the center directly
across on the other side.
Inside Diameter (DIM #2). This is the measure of the center of the
bearing.
Height. This dimension is not necessarily the overall height of the
bearing. On a bearing assembly, measure from the face of the bearing
to the fork contact point at the collar (DIM #3a). In the case of a bearing
only, measure from the face of the bearing to the bearing collar contact
point (DIM #3b).
Pilot Bearing/Bushing
Most rear wheel drive, and some front wheel drive, vehicles with manual
transmissions use a pilot bearing/bushing. The pilot bearing/bushing
supports and centers the transmission input shaft and clutch disc.
When the clutch is disengaged, the pilot bearing/bushing allows the
flywheel to maintain engine RPM while the input shaft is slowing down and
stopping.
If the vehicle has a high output
engine, the misalignment will cause
the input shaft gear to not mesh
with the counter shaft gear properly
and ultimately will cause the gears
to fail (See figures below).
Types of pilot bearing/bushing
include conventional ball bearings,
needle bearings and sintered
bronze bushings.
When a pilot bearing/bushing fails,
a driver may exhibit: no release;
the transmission may pop out of
gear; noise; vibration; and, if not
fixed, catastrophic failure of the
transmission.
Early signs of the pilot failing may be noise whenever the clutch is
disengaged. The driver may also notice that the transmission is difficult to
shift between gears or hard to put into reverse or first gear when stopped.
When the pilot is failing, or has failed, the input shaft will be allowed to walk
around causing it to go off center. When this happens, the transmission
input shaft will begin moving around inside the transmission causing the
gears and synchronizers to be off center resulting in the transmission
popping out of gear.
When a clutch is replaced the pilot
bearing/bushing should always be
replaced as part of the service.
6
Technical Hotline 1.800.274.5001
Before and During Teardown
Driving Habits
and Clutch Wear
Constant
engagement
and
disengagement of the clutch will
wear away disc friction material.
The rate at which wear occurs,
however, depends largely on the
driving habits of the operator and
vehicle usage.
Clutch System
Driving behaviors and conditions
that decrease clutch service life
include riding the clutch pedal,
high RPM engagement, excessive
slipping, harsh downshifting,
lugging the engine, excessive
vehicle loading, and engine,
transmission and suspension
modifications.
Begin every clutch diagnosis
by discussing the symptoms of
the clutch operation with the
customer. Collect information
about the operating conditions
and working environment of
the clutch. If possible, road test
the vehicle with the customer
driving to duplicate the problem. Establish the vehicle mileage
and clutch history and mileage.
If the old clutch had relatively
low mileage and final diagnosis
shows signs of driver abuse,
take a ride with the customer
to observe their driving habits.
Explain how certain behavior
you observe reduces clutch
service life.
Slipping the clutch during
engagement creates excessive
heat, damages the clutch and
flywheel contact surfaces and
accelerates disc friction material
wear. Riding the clutch reduces
the clamping force of the
disc; power transfer from the
spinning flywheel is not fully
applied to the disc. The result
is premature wear of the disc
friction material. Waiting in traffic
with the vehicle in gear and
the clutch disengaged loads
the release bearing excessively.
Over time, this shortens release
bearing life and can eventually
cause noise.
Lugging the clutch occurs when
the driver selects the wrong gear
for the vehicle speed and
load. Under low speed/high
load conditions, a lower gear
should be used to reduce the
torque applied to the clutch. Selecting a higher gear causes
excessive loading of the disc
that can damage the disc hub
and torsion springs as well
as the clutch drive straps. Over-revving the engine and
high-speed downshifting can burst
the friction material. www.Schaeffler-Aftermarket.us
7
Before and During Teardown
INSTALLATION TIP
10 Things You Should Know
To Do The Job Right
1. The dual mass flywheel is a wear item and should be replaced at EVERY clutch change.
2. Solid flywheels should be replaced or surfaced at EVERY clutch change.
3. Verify all contents and inspect them BEFORE installation.
4. As little as a fingerprint can contaminate a disc.
5. Diaphragm spring clutches are superior to lever style EVERY time.
6. NEVER grease a bronze pilot bushing.
7. Product/compound used to prevent seizing is NOT spline lubricant.
8. Flush hydraulic release systems and replace fluid with fresh new fluid recommended by the manufacturer.
9. Self-Adjusting Clutches (SAC®) are preset by the factory and require no modification.
Before You Start
When a customer brings in his or
her car for a clutch related problem,
it is important to understand
fully what their concern is. It
is possible that the perceived
problem is a normal characteristic
of the vehicle.
Talk with your customer to
understand their concern and
determine when the problem first
started. You may have to take a
test drive with the customer to
verify the problem.
It is important to verify the cause of the failure. Once the problem has
been identified, talk with the customer about the repair procedure and
how the system operates.
Make sure the customer understands and feels comfortable with the
repair being performed on his or her vehicle.
Complete Repair
Complete clutch repair is diagnosing the cause of the damage, fixing the
problem and examining and replacing all worn and damaged components.
Component parts incur wear. Some adjust their operating points
to compensate for normal wear in disc friction material. The
service life of clutch components is not infinite. “As-new”
performance cannot be expected in all cases when only
LuK RepSet® components are installed.
Examination and replacement of all worn clutch system components
is critical to ensure the full service life of the clutch and disc. And it is
inexpensive insurance against comebacks.
When the vehicle is pulled into the shop for repair, the first thing that
should be done is to check for Technical Service Bulletins (TSBs). Many
times the manufacturer is aware of common problems with the clutch
system and may have updated information and parts to fix the problem. If no TSB’s are found, start by checking all the external parts related to
the clutch system.
10. Crankshaft end play will cause release problems. Always inspect and diagnose adjacent systems for possible problems.
LuK prototype installations tune clutch
products for future production vehicles.
8
Technical Hotline 1.800.274.5001
Before and During Teardown
Inspection of External Components
INSTALLATION TIP
Clutch Pedal
•
When checking over the external parts, examine the clutch pedal
linkage under the dash. Additionally, check all bushings and
connections related to the clutch pedal. Insure all linkages move
freely and do not have excess play in them. Clutch Release Cable
•
If the vehicle has a clutch release cable, verify that the cable is
routed in the correct location. Verify the clutch cable is free from
binding. Check to make sure the cable has not stretched. Hydraulic Release System
•
If the vehicle is equipped with a hydraulic release system, verify
the fluid is clean and filled to the proper level. Next, check for any
signs of fluid leakage from the clutch master cylinder, clutch fluid
line, and clutch slave cylinder. Hydraulic cylinders are subject to wear
from heat and vibration. Replacement
may be necessary to ensure complete
clutch repair.
Bell Housing
•
Some vehicles use a concentric slave cylinder (internal slave
cylinder), which is located inside the bell housing. Look for any
signs of leakage coming from inside the bell housing.
•
Check the bell housing for any signs of fluid contamination due to
a leaking engine or transmission. Leaking fluid can be the cause
of the clutch issue the customer is experiencing. Fluid leaking into
the bell housing can contaminate the clutch disc. Engine and Transmission Mounts
Loose engine and transmission mounts can simulate a clutch problem. •
Check u-joints / half-shafts and drive line angle. Verify that u-joints
/ half-shafts are not binding or loose. •
Check carrier bearings and mounts. Verify the carrier bearing and
mounts are tight and not walking around inside the mount. •
Look for any aftermarket parts that may change drive line angle. Attention to detail, thorough
examination and replacement of
all worn clutch system components
can eliminate immediate offthe-lift problems and prevent
premature
clutch
failure.
Always follow manufacturers’
guidelines for clutch removal and
replacement.
Release System and
Other Parts
Inspect all release system
components and replace any that
are worn. This includes the clutch
cable, pivot bushings, fork, fork
pivot ball, and hydraulic slave and
master cylinders. This inspection is
especially important if the vehicle
has high mileage and the owner
experienced release problems.
Always check the condition of
halfshaft, carrier bearings, universal
joints, driveshaft components and
powertrain mounts. Examine other
vehicle components that have worn
during the service life of the clutch.
Drive line components and engine
and transmission seals that were
new when the original clutch was
installed have been subjected to
heat and vibration. Worn drive line
components are a common cause
of vibration. They must be replaced
to prevent problems with the new
clutch.
Even if inspection does not indicate
leaks, replace rear main bearing
and transmission input shaft seals
on high mileage vehicles. It is not
realistic to expect high mileage
seals to continue sealing through
the service life of several clutches.
After all external components have been checked, remove the
transmission.
www.Schaeffler-Aftermarket.us
9
Before and During Teardown
INSTALLATION TIP
Resurfacing the Flywheel:
Increasingly original equipment
clutch systems are designed without
allowance for flywheel resurfacing.
If manufacturers’ specifications
indicate this, the flywheel cannot
be resurfaced and must be replaced
during clutch installation to avoid
contact between the disc and
flywheel, and catastrophic failure.
Proper resurfacing of the flywheel
is critical to clutch operation. When
resurfacing a stepped or cupped
flywheel, be sure to machine the
contact surfaces by equal amounts
to maintain specified tolerances. Do
not assume the existing dimensions
are correct, particularly if there were
release or engagement problems. If
the flywheel shows signs of extreme
overheating and deep scoring, it
must be replaced.
Clean the mating surface between
the crankshaft flange and
flywheel mounting surface. In
some applications, flywheel bolts
require the use of a special thread
sealer to prevent oil leaks. Refer
to manufacturers’ specifications
for thread sealer and torque
specifications. If the flywheel has
been handled by grease- or oilcovered hands, clean it with an
alcohol-based cleaner.
Due to their design, LuK does not
recommend resurfacing dual-mass
flywheels. For some applications LuK
offers solid flywheel replacements
for dual-mass designs. Engineered
as bolt-in replacements, LuK RepSet
and solid flywheel replacement
options provide increased torque
capacity. Many include larger
diameter clutches than the original
equipment. 10
Teardown
Organize teardown procedures to keep track of parts and speed
installation. Many of the procedures you use during removal of the old
clutch can prevent errors. As you remove the old clutch, note all bolt
locations. Bell housing bolts may have different lengths, diameters and
thread pitches. If any of the bell housing bolts are used to attach a
ground cable to the transmission, mark the bolt and its location. Clean
and check all bolts for thread damage.
If the crankshaft flange bolt pattern is symmetrical, mark the relationship
of the flywheel to the crankshaft mounting flange to eliminate a
balance problem. If the pattern is asymmetrical, the flywheel will only
go on one way.
Removing the Transmission
During transmission removal pay careful attention to detail. When the transmission is being removed verify the dowel pins between
the engine and transmission are not missing and are in good condition. Inside the Bell Housing
•
Check for leaks and fluid contamination
•
Examine the input shaft for wear and free play
•
Verify the condition of the following components:
- Throw-out bearing
- Bearing retainer
- Release fork and pivot ball
•
Inspect the concentric slave cylinder for leaks.
After all of this has been thoroughly examined, it is time to
diagnose the clutch. Clutch Diagnosis
Clutch Fingers
•
Look for signs of heavy wear, melted fingers, uneven fingers, and
contamination. •
Next, look for signs of over heating. Pressure Plate
•
Determine if the pressure plate has hot spots or bluing on the outside. •
Unbolt the clutch pressure plate evenly and in a star pattern. Unbolting the clutch pressure plate incorrectly may cause damage
and warp the pressure plate.
While removing the pressure plate be careful the clutch disc does
not fall out.
•
When removing the pressure plate, remove the disc at the same time. •
Place both clutch and disc on a work bench. •
Carefully examine the pressure plate and disc. •
Inspect the pressure plate for bluing and hot spots on the friction
surface. •
Check the pivot ring to insure it is not broken or missing. Make sure
the drive straps are not bent or broken. Technical Hotline 1.800.274.5001
Before and During Teardown
Disc
•
Check for stop pins that have been hit. •
While looking at the stop pins also examine the damper springs to
verify they are not loose or missing. •
Examine the disc center hub for splines that are worn or stripped out. •
Look for excessive grease. •
Check the friction surface of the disc for contamination. •
Measure the disc thickness per manufacturer specs.
•
Determine whether the friction surface is burnt or missing. •
Look for evidence of the damper package interfering with the clutch
pressure plate or flywheel. Flywheel
•
With the flywheel still bolted
to the crankshaft, examine the
friction surface.
•
Determine if the flywheel shows
signs of over heating, hot spots,
or cracks.
•
If the flywheel is stepped,
measure the step and compare
it to OE specs.
It is recommended to replace the
flywheel anytime the clutch is
changed. LuK solid flywheel replacements are
a cost-effective option to the dualmass flywheel.
Many of today’s vehicles do not have adjustable clutch release systems. Machining as little as .010 of and inch can cause release issues.
•
Remove the flywheel. •
This is a good time to examine and replace the engine rear main seal. Pilot Bearing/ Bushing
If the vehicle is equipped with a pilot bearing/bushing inspect the
condition of the bearing/bushing. Many times this step is overlooked or
the pilot is not replaced. The pilot bearing is the cause of many clutch
related problems. Most pilot bearings fit in the end of the crankshaft,
some fit into the flywheel. INSTALLATION TIP
Inside the Bell Housing:
Clutches create abrasive debris as
they wear. This powdery abrasive
penetrates all the components
inside the bell housing. If these
components are not properly
cleaned and lubricated, they can
cause release or engagement
problems. Look for signs of oil
contamination inside the bell
housing. If found, locate and repair
the source. Examine the input shaft splines
and bearing retainer for wear
and damage that will limit
disc travel and cause release
and engagement problems. If the
bearing retainer is damaged or
distorted, replace it. Repair sleeves
are available for some designs in
which the bearing retainer is a part
of the transmission housing. The
repair sleeves enlarge the diameter
of the bearing retainer and must be
used with a release bearing with a
larger inside diameter.
Inspect and clean the bell housing
and engine block mating surfaces.
Make sure the locator dowels and
dowel holes are clean to eliminate
installation problems and prevent
misalignment.
ONE-PIECE HOUSING
.
If the pilot fits in the end of the crankshaft, use the special tool designed
to remove these bearings. INPUT
SHAFT
.
.
Bell Housing
Now is a good time to clean inside the bell housing! •
STEEL
REPLACEMENT
SLEEVE
.
Remove as much grease, oil, and clutch material as possible. The
cleaner the job the better the clutch will work. ORIGINAL BEARING
CONTACT SURFACE
Repair sleeves eliminate the need to
replace the entire transmission housing
for applications in which the bearing
retainer is part of the housing.
www.Schaeffler-Aftermarket.us
11
Diagnostics: Release Problems
RELEASE PROBLEMS
TECH TIP
No Release
Air in the Hydraulic Release System
Although they offer many more benefits than drawbacks, hydraulic release
systems are vulnerable to drawing in air,
because the fluid reservoir is typically
vented to the atmosphere. This design
is necessary to allow air to escape. But
what goes out can also come in, and
therein lies the problem. The fluid itself makes its own contribution. Hydraulic
fluid is hygroscopic, meaning it attracts
moisture or water. Remember your
chemistry? Water is one-part oxygen –
that’s air!
So, you have a vented system filled with
fluid that attracts moist air. Chances are,
if the clutch is not releasing properly, air
is your culprit, especially if the vehicle
sits for long periods of time. To correct
the condition, begin by bleeding the
clutch system. The technique will vary
depending on the system design, so
consult the vehicle manufacturer’s
recommendations for your specific
application.
Metal: Not Enough of it on the Flywheel
Another increasingly common condition
that causes clutch release problems is an
over-machined or “thin” flywheel. Newer
vehicles provide minimal clearance
between the flywheel crankshaft bolts
and the disc damper. An interference
condition can result from removing as
little as .025” from the flywheel friction
surface. Some applications require the
flywheel to be replaced along with the clutch, because there is no allowance for
flywheel resurfacing.
An improperly machined flywheel
can also cause release problems. Specifically, step and cup dimensions,
which
are
critical
to
clutch
function. If these dimensions
are off by as little as .010” – less
than 1/64 of an inch – the clutch may
not release properly.
Other Causes of No Release
If you’ve ruled out air in the system or an
improperly machined flywheel, you may
need to dig a little deeper to find the
root cause of the release problem. Other
potential factors include firewall flex, a
pilot bearing hung-up on the input shaft, release fork flex, an incorrectly adjusted
master cylinder, or a worn release cable. 12
No release is probably the most common of all clutch problems.
The purpose of the clutch is to couple and decouple the engine and
transmission. The clutch allows for a smooth take off and stop as well as
the smooth changing of gears to meet different driving demands. Poor
clutch release makes it difficult to impossible to start and stop the vehicle
or change gears.
Common release problems are: •
Air in a hydraulic release system
•
A flywheel that has been machined too thin, or
•
A flywheel where the step or cup dimension is out of specification.
Hydraulic fluid used in clutch release systems is hydroscopic (it attracts
moisture). Through this moisture in the air is also introduced into the
release system potentially causing release problems. As stated above, a
flywheel that has been machined too thin can cause the release system
to run out of travel creating a no-release situation.
Yet, another condition may be that the disc damper can interfere with
flywheel crank bolts resulting in no release as well.
Flywheel step and cup dimensions are critical to proper clutch operation.
Too tall of a step or too shallow of a cup can create a “thick disc condition.”
A thick disc condition will reduce or eliminate clearance between the
disc, flywheel and clutch friction surfaces and cause release problems.
Flywheel run out should also be inspected.
The conditions listed above account for the majority of “No Release”
problems however, other, less common conditions do contribute to no
release as well. Bent drive straps on the clutch, worn pilot bearings, a
bent release fork, or a worn or binding release cable can all contribute to
release problems. Any component in the release system that flexes, like
a fork or fire wall, can “ absorb travel” and cause no release.
Causes of Release Problems
External
Internal
• Contaminated hydraulic fluid
• Incorrect release system
adjustment
• Air in the hydraulic release
system
• Defective or worn release
system components
• Defective or worn pedal
bushings or brackets
• Flexing of the firewall or
any release component
attachment point
• Misalignment of clutch
components
• Corroded, damaged or
improperly lubricated input
shaft splines
• Worn pilot bearing/bushing
• Worn bearing retainer
• Bent or worn release fork or
pivot ball
• Worn linkage components
• Stretched release cable
• Excessive or incorrect flywheel machining
• Bent clutch drive straps
• Bent or distorted disc
• Improper transmission
lubricant
• Improper bolting of the clutch
Technical Hotline 1.800.274.5001
Diagnostics: Release Problems
Post Teardown Diagnostics
Bent Drive Straps
Broken Drive Straps
Disc-to-Flywheel Interference
Change in drive strap profile
Possible causes:
• Lugging the engine
• Improper handling
• Engine miss
Straps that have completely
broken apart
Contact between damper spring
housing and flywheel or flywheel
mounting bolts
Possible causes:
• Disc installed backwards
• Flywheel too thin/overmachined
• Incorrect parts
Possible causes:
• Lugging the engine
• High-speed downshifting
• Driver abuse
Note: This kind of damage is most
likely caused by lugging the engine,
which focuses heavy shock loads on
the clutch package.
Disc Damaged on Outer
Circumference
Friction material edges broken or
cracked
Possible causes:
• Incorrect parts
• Mounting washers too large
Note: If incorrect washers are used
under the clutch mounting bolts,
they can damage the disc and may
pinch the disc against the flywheel,
preventing disc movement and release.
Excessive Finger Wear
Damaged Disc Splines
Excessive wear on diaphragm fingers
Broken or worn splines
Possible causes:
• Improper installation/
misaligned
• Worn input shaft
• Incorrect parts
Possible causes:
• Defective release bearing
• Malfunctioning self-adjuster
mechanism
• Incorrect clutch adjustment
(mechanical systems)
Note: Excessive free-play on a
manually-adjusted system can cause a
release problem.
Rusted Disc Splines
Bent Cover Housing
Splines that show evidence of corrosion
Possible causes:
• Incorrect/inadequate lubrication
• Bellhousing not sealed properly
Note: Excessive moisture in the bellhousing,
combined with inadequate or incorrect lubrication of
the input shaft, can cause the disc splines and the
input shaft to rust. This restricts the disc from sliding
freely on the shaft when the clutch is disengaged.
Failure Analysis Flow Chart
Inside Bell
Housing
Outside
Bell Housing
Bent Drive
Straps
lugging engine
high-speed
downshifting
Note: A worn transmission input shaft
allows excessive movement between
the shaft and the disc spline. When
movement occurs, high shock loads
are concentrated on the spline and
shaft. Failure to align the disc prior to
installing the transmission can result in
spline damage.
Cover does not sit flat on a flat surface
Possible causes:
• Improper handling
• Not aligned over dowel pin
• Not bolted down evenly
Note: Carefully inspect all components before
installing; return any damaged components. When
installing the pressure plate cover assembly, carefully
align the pilot holes with the flywheel dowel pins.
Bolt the cover down evenly in a “star pattern”.
Restricted Disc
Movement
Transmission
seized pilot bearing
incorrect
transmission fluid viscosity
misalignment
damaged spline
no lubrication
dirty/rusty disc
spline or input shaft
bent disc
mounting washers
too large
Misalignment
distorted bellhousing
missing dowel pins
Hydraulics
Mechanical
Cable
improper bleeding
obstruction (reduced
pedal travel)
firewall flex
firewall flex
worn bushings
worn fork or pivot ball
defective self-adjuster
stretched cable
firewall flex
www.Schaeffler-Aftermarket.us
13
Diagnostics: Noise
NOISE
TECH TIP
Release Bearing Installation
The release bearing/design fork on
many General Motors applications
makes it very easy to install the parts
incorrectly with the leaf spring clip
of the fork above the bearing collar.
Improper installation will cause
slipping, hard pedal and release
problems. Ensure the leaf spring is
installed under the bearing collar.
CORRECT
leaf spring clip
release bearing collar
INCORRECT
There are several types of noises associated with the clutch assembly. Most of these noises are caused either by various bearings or by a low
preload on the release bearing.
Listed below are diagnoses of some different noise conditions: • With the engine running, transmission in neutral and clutch pedal
up, a grinding or grating noise would indicate a bad transmission
input shaft bearing.
This is identifiable because the input shaft bearing is the only bearing
with a load on it during this test.
• With engine running, a noise that is present throughout the clutch
pedal travel would indicate a bad release bearing.
This is identifiable because the release bearing load is increasing as
the clutch pedal is pushed further downward.
• A noise that is only present when the clutch pedal is fully depressed
(clutch disengaged) would indicate a bad input shaft pilot bearing.
This is identifiable because the pilot bearing only has a load on
it in the disengaged condition as it rotates around a stationary
input shaft.
• With the engine running a noise that goes away when slight clutch
pedal pressure is applied would indicate a low release system
preload.
This eliminates the release bearing as the possible cause of the
noise, because a bad release bearing would make more noise with
a higher load. A low preload will allow release system components
such as a release fork to move around on pivot points and create
noise. Most modern release systems require a preload on the release
bearing that cause it to run whenever the engine is running.
• Interference can also create noise. A flywheel machined too thin will allow the disc hub to contact the
crank bolts and produce a scraping noise upon take off ( launch ). This noise will go away as the vehicle gets under way because the
disc and flywheel will begin turning at the same speed.
Causes of Noise
14
External
Internal
• Incorrect release system
adjustment
• Worn driveshaft or halfshaft components
• Worn engine or transmission mounts
• Broken cable self-adjuster
• Worn or improperly
lubricated pedal components
• Worn or defective input shaft
bearing
• Defective or misaligned release
bearing
• Worn, misaligned or improperly
lubricated pilot bearing/bushing
• Worn, bent or improperly
lubricated fork
• Worn input shaft
• Improper disc installation
• Misalignment
• Damaged bearing retainer
• Loose flywheel bolts
• Damaged disc splines, worn
stop pins or broken damper
Technical Hotline 1.800.274.5001
Diagnostics: Noise
Post-Teardown Diagnostics
Damaged Disc Splines
Broken or worn splines
Possible causes:
• Improper installation /
misaligned
• Worn input shaft
• Wrong parts
• Defective pilot bearing
Note: A worn transmission input shaft
allows excessive movement between
the shaft and the disc splines. When
movement occurs, high shock loads
are concentrated on the splines and
shaft. Failure to align the disc prior to
installing the transmission can result
in spline damage.
Noise
Source
Growling or grinding when the clutch is engaged
Transmission
input shaft
bearing
Squealing when the pedal is actuated and held
Pilot bearing or
pilot bushing
Chirping that intensifies
when the pedal is
slowly actuated
Release
bearing
Chirping while idling in neutral that
disappears when the
pedal is slowly actuated
Fork/pivot ball
contact point
Damaged
Release Bearing
Damaged Disc Hub
Possible causes:
• Worn stop pins
• Driver abuse
• Incorrect parts
• Improper installation
Possible causes:
• Misalignment
• Manufacturing defect
Failure Analysis Flow Chart
Clutch
Related
Damaged Quill
Galled or worn bearing
contact surface
Possible causes:
• Improper installation
• Misalignment
• Worn fork or pivot ball
• No free-play
• Insufficient lubrication
Damaged Disc
Spline
Damaged Quill
Damaged
Disc Hub
improper installation
misalignment
worn stop pins
worn input shaft
insufficient or
incorrect lubrication
incorrect parts
misalignment
driver abuse
improper installation
overstrocking
Actuator
Related
Fork
Pivot
Pedal
Self-Adjuster
worn or broken
worn or broken
worn bushings
broken
insufficient
lubrication
insufficient
lubrication
insufficient
lubrication
vibration
misalignment
Bearing
Related
Transmissions
Input Bearing
Pilot Bearing
worn or defective
incorrect lubrication
defective
misalignment
misalignment
Release Bearing
www.Schaeffler-Aftermarket.us
15
Diagnostics: Chatter
Chatter
TECH TIP
One of the most bothersome clutch related problems is chatter.
How To Bleed Slave Cylinders
Without Bleed Screws
If the slave cylinder has a gold allen
screw, do not remove or loosen it. This
set screw is not intended to be used for
bleeding purposes.
1. Push the slave cylinder pushrod
inward and disconnect both bands
of the retaining strap to enable the
pushrod to fully extend. Do not cut
or discard the retaining strap.
2. Tilt the slave cylinder at a 45-degree
angle. The master cylinder line port
should be facing upward with the
port at the high end of the slave. Fill
the slave cylinder with fresh, clean
brake fluid.
3. Insert the master cylinder line into
the slave cylinder port. Lubricate
the o-ring with brake fluid and
insert the retaining pin.
4. Hold the slave cylinder vertically
with the pushrod facing the
ground. If this is not possible due
to the master cylinder line, position
the slave as far vertically as
possible without putting excessive
load on the master cylinder line. The slave cylinder must be lower
than the master cylinder.
5. Remove the master cylinder
reservoir cap. 6. Slowly push the slave cylinder
pushrod
into
the
slave
approximately one inch, watching
for air bubbles in the master
cylinder reservoir. Air in the release
system should be purged after 10
to 15 strokes of the slave cylinder
pushrod.
7. After all air is purged from the
system, slowly push the slave
cylinder pushrod back into the
slave and reconnect the two bands
of the retaining strap.
8. Install the slave cylinder with
the retaining strap in place. The
retaining strap will break free with
the first stroke of the pedal. Note: The plastic cover over the end of
the pushrod must be retained; it
acts as a lubricant between the
pushrod and the fork. Removing
the cover can cause a no-release
condition.
16
Chatter can be detected as a pulsing or a grabbing sensation originating
from the driveline or chassis / suspension and resonating into the vehicle
cabin.
Chatter is sometimes difficult to diagnose because it has many root
causes, and some of them may not seem related at first. Chatter that originates from the bell housing can be caused by
contaminated friction material. Contamination may be from grease or oil
during installation, or by excessive application of lube on the input shaft
splines. Leaking rear engine main seals or transmission input shaft seals
can also be a source of contamination. Contamination by any lubricant
will cause the disc friction material to have an uneven coefficient of friction
that can cause grabbing and lead to a chatter condition. Another cause
of chatter in the bell housing is created by any condition that causes the
disc to be clamped unevenly between the clutch and flywheel. Some of these conditions may be: • Damaged drive straps on the clutch (using the clutch as a brake);
• An improperly machined flywheel (too much lateral run out); • A warped disc (transmission not properly supported during
installation); • Or, a warped clutch cover (tightened using impact wrench vs. evenly
hand tightened using a torque wrench).
• Glazed friction material (slipping or excess heat).
Chatter can also begin in the vehicles suspension or driveline. All of
the following areas need to be inspected to determine the root cause of
chatter and eliminate it: •
•
•
•
•
•
•
•
Universal and CV joints (for wear and damage); Engine / transmission mounts (for wear or breakage); Cross member (for looseness); Suspension grommets (for excessive wear); Springs (for wear or breakage); Torque damper on transverse mounted engines( for wear); Improper driveline angle; Suspension modifications and lift kits.
Causes of Chatter
External
Internal
• Loose or broken engine or
transmission mounts
• Misalignment of chassis and
drive line components
• Worn or damaged universal
or constant velocity joints
• Missing bell housing dowel pins
• Loose transmission cross member
• Loose rear leaf spring bushings or spring u-bolt nuts
• Worn or bent fork
• Bent or broken drive straps
• Warped or grooved flywheel
• Missing flywheel dowel pins
• Wear or excessive lubrication
of input shaft splines
• Worn pilot bearing/bushing
• Worn bearing retainer
• Worn or damaged disc splines
• Clutch distortion or bent drive
straps
• Oil- or grease-contaminated
friction material
• Improper bolting of the clutch
Technical Hotline 1.800.274.5001
Diagnostics: Chatter
Post-Teardown Diagnostics
Bent Drive Straps
Bent/Broken Disc
Change in drive strap profile
Possible causes:
• Lugging the engine
• Improper handling
• Engine miss
Note: This kind of damage is most
likely caused by lugging the engine,
which focuses heavy shock loads
on the clutch package.
Excessive run out
Possible causes:
• Shipping damage
• Improper installation
Note: Carefully inspect each disc
before installing; return any that
are bent, distorted or damaged.
To prevent disc damage and
distortion:
Damaged Disc Splines
Broken or worn splines
1. Use an aligment tool,
2. Support the housing with a
transmission jack.
3. Rotate the input shaft to align it
with the disc spline.
Possible causes:
• Improper installation /
misaligned
• Worn input shaft
• Incorrect parts
Note: A worn transmission input
shaft allows excessive movement
between the shaft and the disc
spline. When movement occurs,
high shock loads are concentrated
on the spline and shaft. Failure to
align the disc prior to installing the
transmission can result in spline
damage.
Uneven or Broken Fingers
Contaminated Friction Surface
Damaged clutch diaphragm fingers
Possible causes:
• Improper installation
• Bent cover housing
• Manufacturing defect
Any foreign substance on friction material, pressure
plate or flywheel
Possible causes:
• Leaking rear main engine
• Leaking front transmission
• Excessive lubricant input shaft splines
• Leaking slave cylinder
Note: Any foreign substance allowed to contaminate
the friction material can cause problems. If oil,
grease, or hydraulic fluid get on the friction
material, chatter can result.
Note: Carefully inspect all components before
installing; return any that were damaged during
shipping. A deformed or improperly installed cover
affects diaphragm finger parallelism, resulting in
uneven pressure plate clamping.
Failure Analysis Flow Chart
Clutch
Component
Related
Driveline &
Chassis
Related
Installation
Related
Drive Strap
Distortion
Cover
Distortion
Finger Height
Variation
Friction
Material
high-speed
downshifting
lugging the engine
improper handling
improper installation
improper installation
defective part
cracked diahragm spring
cerametallic
contaminated
cracked facing
Engine
Chassis
Driveline
Transmission
worn pilot bearing
engine misfire
broken motor mounts
worn thrust bearing
spring shackles or bushings
transmission mount
U-joints
C-V joints
carrier bearings
worn input shaft
worn input bearing
Procedure
Component
excessive
lubrication on
input shaft
missing
bellhousing dowel pins
Flywheel
Related
www.Schaeffler-Aftermarket.us
Friction
Surface
uneven
heat damaged
Instllation
loose flywheel
missing dowel pins
17
Diagnostics: Slipping
TECH TIP
Internal (Concentric) Slave Cylinders
Slave cylinders located inside the bell housing
require special handling to guarantee proper
operation.
1. o not cut the plastic straps. They are
D
designed to hold the hydraulic piston in
place during installation. They will break
free the first time the clutch pedal is
actuated.
.
.
PLASTIC STRAPS
To avoid added labor costs later, LuK
recommends replacing internal slave
cylinders when the clutch is replaced.
2. Do not change the position of the release
bearing. Moving the bearing from its
position may result in damage to the seal
and void the warranty.
3. Be careful not to drop the slave unit or
bend the hydraulic lines. Inspect new slave
cylinders for damage prior to installation.
Inspect all protective grommets to make
sure they are not damaged and they
are properly installed. These grommets
prevent damage from vibration.
4. I nstall the slave without grease. To prevent
damage and leaks, do not clean the slave
with solvents.
5. Use the new pin and retaining nut included
in the LuK RepSet®. Do not reuse fasteners,
and avoid over-tightening the flare nut to
prevent cracking of the housing.
6. U
se only the manufacturers’ recommended
brake fluid. Make sure the fluid is fresh.
7. F or some Jeep applications, it is necessary
to remove the “quick disconnect” fittings
from the hydraulic lines.
18
SLIPPING
Slipping is one of the most common clutch problems. Slipping can occur right after installation or after years
of service. A slipping clutch can be subtle, appearing in
high gear during acceleration, or more noticeable, not
allowing the vehicle to get up to speed.
The main causes of slipping are high release bearing
preload, improperly machined flywheel, and friction
material contamination.
High release bearing preload can be caused by many
factors. Common causes include:
•
•
•
•
•
•
•
•
•
Improperly adjusted master cylinder push rod
Binding slave cylinder
Binding release cable
Worn or damaged over center spring on clutch pedal
Worn or damaged release bearing and retainer
Worn release fork and pivot ball
A blocked compensation port in the master cylinder
Worn clutch pedal bushings
Or any other condition that would cause the release
system to “ride the clutch pedal.”
A improperly machined flywheel that would cause
slipping would mimic a “ thick disc condition.” A thick
disc condition is a flywheel step that is too tall, or a
flywheel cup that is too shallow. In these situations the
clutch diaphragm fingers will pull down past flat, or go
over center. Due to the characteristics of the diaphragm
spring the clamp load will be diminished, leading to a
slipping condition. A thick disc condition can also lead
to clutch release problems, caused by less clearance
between the disc, pressure plate and flywheel.
Contaminated, friction material can also contribute to
a slipping condition caused by a loss of the material’s
coefficient of friction, due to the contamination. Common causes of contamination include: over
lubricated input shaft splines, leaking engine rear main
seals, and transmission input shaft seals.
Causes of Slipping
External
Internal
• Incorrect release
system adjustment
• Defective, worn or
binding release
system components
• Blocked master
cylinder port
• Binding slave
cylinder
• Defective cable self-adjuster
• Worn disc
• Oil leaks or excessive lubrication
• Improper flywheel
machining
• Misalignment of the release bearing
• Defective dual-mass flywheel
Technical Hotline 1.800.274.5001
Diagnostics: Slipping
Post-Teardown Diagnostics
Disintegrated Friction Material
Cracked or Broken
Friction Material
Friction material is broken down,
fibrous and/or powdery
Large chunks of broken friction
material - No evidence of excessive heat
Overheating
(damaged by excessive heat)
Heat discoloration, usually tan,
brown or black
Possible causes:
• Inadequate free play
• Defective self-adjuster
• Defective hydraulic
components
• Incorrect parts
• Binding linkage or release
bearing
• Driver abuse
Possible causes:
• Inadequate free play
• Defective self-adjuster
• Defective hydraulic
components
• Incorrect parts
• Binding linkage or release
bearing
• Driver abuse
Note: If the cover and/or disc
show exposure to extreme
heat, it is likely that the root
cause of the problem likes
with the actuator mechanism:
linkage rods, cable or hydraulic
components.
Possible causes:
• Improper handling
• Manufacturing defect
Note: If a clutch is operated
partially relesaed for a prolonged
period (or under heavy loads),
the amount of heat generated will
exceed the engineered limits of
the friction material. Generally,
an overheated pressure plate and
disintegrated friction material are
seen together.
Failure Analysis Flow Chart
Immediately
After
Installation
Hydraulics
stuck slave cylinder piston
blocked
compensation port
Bearing Travel
Restricted
Incorrect
Parts
worn quill (hub)
bearing too long
misaligned bearing
insufficient torque
capacity
Mis-Machined
Flywheel
After
Limited Use
Insufficient
Free Play
Binding
Linkage
Linkage or
Cable Binding
Contaminated
Friction
Material
Overheated
Components
worn bushing
hydraulic leaks
seized bearing
worn fingers
worn housing
worn plate or disc
worn cross shaft
engine/trans. oil leaks
defective release system
excessive lubrication
improper adjustment
Driver Abuse
blown friction
material
defective self adjuster
www.Schaeffler-Aftermarket.us
19
Diagnostics: Hard / Soft Pedal
INSTALLATION TIP
Free Play Adjustment:
Replace the clutch cable with every clutch
installation. In systems with self-adjusting
cables, always check for correct operation of the
self-adjusting mechanism. Adjust the cable or
mechanical linkage free play to the manufacturer’s
specifications. Then operate the clutch several
times to make sure that the cable housing is firmly
seated in its mounts. Test drive the vehicle and
make any final free play adjustments.
Examine the master and slave cylinders for leaks.
On vehicles equipped with hydraulic release
systems, replace the hydraulic fluid with fresh
fluid from a sealed container to avoid damage to
the seals. Follow manufacturers’ recommendations
for fluid type.
The degree of difficulty in bleeding a system often
depends on the angle at which the hydraulic
components are mounted. LuK offers a line of
reverse fluid injection bleeder tools. With one tool,
one technician can bleed the hydraulic system
quickly and efficiently.
Hard / Soft Pedal
HARD PEDAL
Hard pedal is a common complaint in vehicles
equipped with manual transmissions.
This condition can be caused by many factors. Most
newer and some older vehicles use clutch release
systems that are hydraulic. Hydraulic release systems
also incorporate mechanical components to engage
and disengage the clutch. Wear, binding, or lack of
lubrication in these mechanical components can lead
to a hard clutch pedal condition.
Starting with the clutch pedal, pedal bushings that are
worn should be replaced. If the vehicle is equipped
with an over center assist spring on the clutch pedal
it should be inspected, cleaned and lubricated. The
pedal stand off brackets should be inspected for
cracks and flexing. The release fork and pivot ball
should be inspected for wear, flat spots, and proper
lubrication. The bearing retainer and release bearing
inside the bell housing should also be inspected for
wear and proper lubrication.
If the vehicle has a mechanical release system all
linkage and bell cranks need to be inspected for wear,
bending and proper lubrication.
Hydraulic components can contribute to a hard pedal
if their cup seals become swollen due to the use of
incorrect hydraulic fluid. A binding or worn cable as well as an improperly
routed cable can create a hard pedal as well.
SOFT PEDAL
Late model hydraulic systems are
difficult to bleed properly through
conventional
methods.
Reverse
bleeding is usually required.
The opposite of hard pedal would be a soft pedal
condition. A soft pedal condition can appear after
the install of a new clutch kit due to a redesign. Additionally, a clutch that was replaced at mid-life,
could exhibit soft pedal. This would be due to the
characteristic of a diaphragm clutch increasing clamp
and release load up to mid-life of the friction material. An over center spring on the clutch spring will some
times lead to a soft pedal complaint as well.
Figure 2
Figure 3
20
Technical Hotline 1.800.274.5001
Diagnostics: Hard / Soft Pedal
Causes of Hard / Soft Pedal
External
• Binding or improperly routed cable
• Binding cross shaft due to worn bushings or incorrect lubrication
• Bent fork
• Worn pedal bushings
• Blockage or worn seals in the hydraulic system
• Worn pivot ball
Internal
• Worn, damaged or improperly lubricated bearing retainer
• Worn or damaged fork
Post-Teardown Diagnostics
Note: There is nothing in the design of the pressure plate that would cause
the pedal load to increase significantly.
Bent Fork
Worn or Binding Cable
Worn Quill
Possible causes:
• Bearing installed
improperly on fork
Possible causes:
• Binding in casing
improperly routed
Galling on quill shaft
Possible causes:
• Insufficient or incorrect
lubrication
• Misalignment
Failure Analysis Flow Chart
Worn Quill
Inside
Bellhousing
insufficient or incorrect lubrication
improper release
bearing installation
Binding
Cross Shaft
worn shaft
worn bushings
insufficient or incorrect lubrication
Outside
Bellhousing
Cable
Hydraulic
Mechanical
binding in casing
system blockage
improperly routed
swollen seals
worn or binding linkage
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21
JLaTP - Just Looking at The Parts : Why Does It Look Different?
Why Does The Part Look Different?
Finger Height
• Unmounted clutches may have significantly
different appearances.
• Different manufacturers’ parts for the same
application may have different appearances.
When automotive technicians order parts for a repair
job they know they need the right part, and a quality
part as well. So it is just a common procedure of any
repair job that technicians will inspect the new part
to make sure it is a correct as well as a quality part
without any visual or functional flaws that would lead
to a poor repair job and a customer come back.
Self-Aligning Release Bearings
Many of today’s release bearings may not look like the
original bearing coming out of the vehicle.
A large number of release
bearings are now of the “selfcentering” type. At first it may
appear that the bearing race
and bore are not concentric
(having the same axis).
Self
Adjusting
Also, some of the newer
release bearings can also
adjust to different “angular”
positions. Which gives the
appearance that the bearing
race is loose and wobbly.
Lever vs. Diaphragm
• In EVERY case - diaphragm is an upgrade
form lever style clutches.
• Diaphragm can be used in EVERY instance
to replace a lever style clutch.
Diaphragm Benefits:
• Easier pedal effort
• Higher clamp load
Diaphragm
Lever
22
These types of release bearings adjust to any slight
misalignment between the engine and transmission.
This helps them run cooler and reduces axial and
radial bearing wear. And that is an important asset
of these types of bearings because with modern
hydraulic clutch release systems the release bearing
runs constantly whenever the engine is running.
This is an example of a self
aligning bearing that looks to
be off center (non concentric).
The tech will actually be able
to physically push the race
back and forth by hand.
This shows the type of self
aligning bearing that can
adjust to angular differences
between the bearing retainer
on the transmission and the
diaphragm fingers of the
clutch .
(Note the large amount of
movement of the bearing
race.)
Technical Hotline 1.800.274.5001
JLaTP - Just Looking at The Parts : Why Does It Look Different?
Active Radius
Many newer design clutch friction discs are designed with a thinner
band of friction material than the original disc that came in the vehicle.
The thinner band of material on the newer design may seem like a bad
thing to some technicians as they compare the new and original parts
that came out of the vehicle. Conventional thinking would be that more
is better; more friction material will mean a stronger clutch.
Sometimes Less is More
The active radius of a friction disc is defined as the distance from the
center of the disc’s splined hub to the center of the friction material. So by using a thinner band of friction material on the disc, the active
radius will be increased. The active radius can be thought of as a lever.
The longer the lever the easier it is to move a given load.
4.704”
The pictures illustrate how a thinner band of friction material will
increase active radius and therefore the torque capacity of a clutch.
The disc on the top has a thinner band of friction material than the disc
on the bottom. This will increase the active radius and torque capacity
of a clutch.
4.367”
New Style BMW Release Bearing
New BMW applications with manual transmissions will use a new style release bearing. This new release bearing,
manufactured by INA bearing, will incorporate two different mounting positions. The different positions will change what
is known as the fork- to- face dimension. The fork- to- face dimension is simply the distance from where the release fork pushes on the bearing to the face of the
bearing that contacts the diaphragm fingers on the clutch. With this new innovative design, one release bearing with
both a short and long mounting position, will be able to adapt to many more vehicle applications than a conventional
style release bearing.
33.5 mm
Long mounting position
All North American BMWs will use the short
(28.5mm) mounting position.
All European BMWs will use the long
( 33.5mm ) mounting position.
28.5 mm
Short mounting position
Using the incorrect long mounting position (33.5mm) on North American
BMWs may result in a clutch slipping condition and damage the clutch
and disc friction material. There may also be drivability concerns such as
undesirable clutch pedal feel and operating point, such as a high pedal.
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23
Illustrations
INSTALLATION TIP
GM Release Bearing Installation
The design of the release fork on many GM
applications can contribute to a very common
installation error.
The GM release fork
has two spring steel
fingers attached to
the back side of the
release fork. These
Correct Installation
fingers have a radius
on the tips at the
end of the fingers. When installed onto the
release bearing correctly the radius or rounded
tips of the fingers allow the release bearing
to “rock” or pivot.
Bent Clutch Cover
Related Symptom:
Release problems.
Cause:
Hydraulic seal damaged
from incorrect installation
Bearing damaged from
incorrect Installation
24
Uneven finger wear from
incorrect installation
Related Symptom:
Chatter, no release.
Damage prior to installation,
misaligned flywheel dowel
pins, improper installation
of the clutch.
Cause:
Broken Torsion
Damper
Burnt Friction
Material
Related Symptoms:
Harsh engagement, no
release.
Related Symptoms:
Cause:
High RPM engagement
abusing the torsion damper
and causing the springs to
fracture and dislodge from
the retainer plate.
Riding the clutch, defective
release system, improper
release system adjustment,
clutch components unsuited
for the torque of a modified
engine, friction material
contamination during
installation.
When the release fork is installed incorrectly onto
the release bearing, it will not allow it to pivot and
will cause the release
bearing to bind on
the release fork. This
binding will damage
the back flange of the
Incorrect Installation
release bearing.
Other symptoms of improper installation can include
a binding or hard pedal at mid stroke of the clutch
pedal as the release bearing will bind or dig into the
release bearing retainer on the transmission. Also
hard shifting or no release can also occur because
the release bearing will not contact the clutch
diaphragm fingers evenly. This can cause uneven
wear on the release
bearing and clutch
diaphragm
fingers.
In extreme cases the
hydraulic
release
system components can
be damaged.
Bent Clutch
Drive Strap
A no-release condition will
result if the springs lodge
in other clutch system
components.
Damage prior to installation,
misaligned flywheel dowel
pins, improper installation
of the clutch, using an air
tool to install clutch, and not
torquing the clutch in a star
pattern.
Chatter, release problems.
Cause:
Technical Hotline 1.800.274.5001
Illustrations
Bent Disc
Broken Hub
Related Symptom:
Related Symptoms:
Chatter.
Cause:
Improperly supported
transmission during
installation, disc installed
backwards.
Incorrect installation
of the disc will result in
interference between the
disc and flywheel, causing
clutch malfunction.
Broken
Damper Plate
Broken Segments
Noise, engagement
problems.
Related Symptom:
Noise.
Cause:
Cause:
Disc was not properly
aligned and the
transmission input shaft
was forced into the hub,
shoving the center of the
hub out.
No release.
Driver abuse over-torquing
the disc, lugging the engine,
high RPM engagement,
harsh downshifting, vehicle
suspension or engine
modifications.
The abrasion marks on
the leading edge of the
disc splines indicate the
input shaft was forced
onto the hub. Never force
the transmission into
the disc or use the bell
housing bolts to pull a
transmission into place.
Related Symptom:
Cause:
High RPM engagement,
worn pilot bearing, worn
transmission input shaft
bearing, misalignment
between the engine and
transmission, improperly
supported transmission
during installation.
If the transmission jack
is removed before the
transmission is properly
bolted to the engine, the
weight will bend the input
shaft, causing uneven
engagement and partial
release.
Burst Friction
Material
Chatter Marks
Contact Marks
Contaminated Clutch
Related Symptoms:
Chatter, release problems.
Related Symptoms:
Related Symptoms:
Related Symptoms:
Hard pedal, chatter, no release.
Causex:
Harsh downshifting, high
RPM engagement, engine
over-revving caused by
missing a gear, coasting
vehicle at a high speed with
transmission in gear and
clutch disengaged.
The clutch may have friction
material embedded between
the diaphragm spring and
the cover.
Cause:
Incorrect installation of
the clutch. The clutch was
distorted when it was bolted to the flywheel
incorrectly.
Chatter marks were caused
by the uneven actuation
of the diaphragm spring
fingers. Heavy finger wear
would be evident on the
diaphragm spring fingers
opposite the chatter marks.
Hard pedal, no release,
excessive pedal free play,
noise.
Cause:
Incorrect release bearing
installation.
The fork was installed with
the leaf-spring clip over the
top of the release bearing
collar, causing uneven force
to be applied to the bearing.
Chatter, slipping.
Causes:
Leaking transmission or
engine seal.
On high mileage vehicles,
always replace the rear
main bearing and the
transmission input shaft
seals.
The fork must be installed
with the clip under the
collar.
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25
Illustrations
INSTALLATION TIP
Adjustable Clutch Master Cylinders
Following a new clutch installation there is nothing worse than experiencing
slipping or release problems. Many times installers even begin to believe
that the new clutch kit is defective. This is not correct, in most cases! The majority of the time a simple, quick adjustment will alleviate any
problems. Most Japanese/Korean imports utilize an adjustable Clutch
master cylinder. When a new clutch kit is installed, the master cylinder
needs to be re-adjusted to work properly with this new kit and avoid
release and slipping problems. Following the steps listed below demonstrate the proper way to adjust the
master cylinder and avoid potential release problems with the new clutch:
Preventing No Release:
1. Verify that hydraulic fluid is clean and that correct fluid was used. This
can be done using a brake fluid tester. If one is not available and your
unsure always change the fluid with manufacturer recommended fluid.
2. Locate the master cylinder push rod that attaches to the clutch pedal.
3. Using the picture (Fig. 2) as reference, extend the push rod to allow for
more throw. 3 to 5 mm is the recommended free play, if unsure always
refer to the vehicle service manual. After the rod has been extended,
tighten the locking nut.
Contaminated
Friction Material
Related Symptoms:
Chatter, slipping.
Causes:
Leaking transmission or
engine seal, excessive
lubrication.
Lubricate input shaft splines
with a very small amount of
high-temperature grease.
Slide the disc on the splines
to distribute a thin film.
Remove the disc and wipe
away any excess.
Caution: DO NOT extend the rod out too far. Extending too far out can
block the compensating port in the master cylinder. When the rod is
extended out too far the clutch pedal will have zero free play and the
compensation port will be blocked. 3 to 5 mm is the recommend free
play. If unsure always consult with the Vehicle service manual.
Preventing Slipping:
1. Verify that hydraulic fluid is clean and that correct fluid was used. This
can be done using a brake fluid tester. If one is not available and your
unsure always change the fluid with manufacturer recommended fluid.
2. Locate the master cylinder push rod that attaches to the clutch pedal.
3. Using the picture (Fig. 3) as reference, shorten the push rod to allow
for less throw. 3 to 5 mm is the recommended free play, if unsure
always refer to the vehicle service manual. After the rod has been
shortened, tighten the locking nut.
Note: In a slipping
situation the rod is
too long, causing
the compensating
port to be blocked
off not allowing fluid
to return to the fluid
reservoir.
Figure 1
Flywheel
Interference
Related Symptoms:
Noise, problems with
disengagement.
Causes:
Excessive flywheel
machining causing the disc
to contact the flywheel
mounting bolts, installing
the disc backwards, failure
to maintain proper flywheel
step dimensions.
If the flywheel shows signs
of extreme overheating and
deep scoring, replace it.
Figure 2
26
Figure 3
Technical Hotline 1.800.274.5001
Illustrations
Cracked Cable
Housing
Embedded
Friction Material
Excessive Finger
Wear
Excessive
Lubrication
Related Symptoms:
Related Symptoms:
Related Symptoms:
Slipping, noise.
Related Symptoms:
No release or engagement.
Causes:
Causes:
Causes:
Hard pedal, chatter.
Causes:
Incorrectly routed or pinched
cable.
A number of problems
can occur inside the cable
housing, causing the cable
to stick or bind. Always
replace the cable on vehicles
equipped with cable release
systems.
Harsh downshifting, high
RPM engagement, engine
over-revving caused by
missing a gear.
The disc friction material
burst when the clutch was
disengaged, lodging friction
material between clutch
system component parts.
Excessive bearing preload
caused by riding the clutch,
incorrect release bearing
installation, defective
hydraulic release system
or cable self-adjuster,
insufficient free play
causing the bearing to
ride constantly on the
diaphragm spring fingers.
Slipping, release problems.
Excessive lubrication of the
input shaft splines.
On startup, the excess
lubrication spun off the
input shaft onto the
pressure plate.
The release bearing may
seize or make noise before
slipping is noticed.
Friction
Material Contact
Friction Material
Contamination
Grooves and
Heat Marks
Related Symptoms:
Related Symptoms:
Related Symptoms:
Causes:
Causes:
Causes:
Chatter, slipping.
Flywheel not resurfaced or
resurfaced improperly.
The flywheel must have a
smooth, flat surface in order
for the clutch to actuate
properly.
Chatter, slipping.
Leaking transmission or
engine seal, contamination
of the friction material
during installation.
Release problems.
Riding the clutch, defective
release system, improper
release system adjustment,
clutch components
unsuited for the torque of a
modified engine, improper
resurfacing of a step/cup
flywheel.
www.Schaeffler-Aftermarket.us
Melted Fingers
Related Symptoms:
No release, extreme noise,
slipping.
Causes:
Worn bearing retainer,
incorrect release bearing
installation, worn or bent
fork.
The release bearing seized
and stopped rotating.
The contact marks on
the diaphragm fingers
were caused by abrasion
and heat from constant
contact with the bearing.
The release bearing would
be melted, blue and/or
destroyed.
27
Illustrations
INSTALLATION TIP
Nissan & Infiniti DMF Installation
Today’s vehicles are becoming more and more complex to service. Proper procedures
are very important to follow when making repairs to today’s vehicles. This is
especially true when working on Infiniti and Nissan dual mass flywheels.
2008-2012 2003-2007 2002-2006 2005-2012 2003-2007 2008-2012 Nissan 370Z 3.7L Nissan 350Z 3.5L
Nissan Altima Nissan Maxima 3.5L
Nissan Xterra, Nissan Frontier 4.0L
Infiniti G35 3.5L Infiniti G37 3.7L
Overheated
Pressure Plate
Related Symptoms:
Release problems.
The vehicles listed above have a crankshaft tone ring built into the flywheel. The dual
mass flywheel is not indexed on the crankshaft and can be installed different ways.
When installed incorrectly, the vehicle may not start, have a check engine light, and
the engine will not rev past 2,000 RPM.
When removing a dual mass flywheel from the vehicles listed above, it is recommended
to make your own indexing marks on the flywheel and crankshaft. When installing
the new flywheel transfer your marks from the old flywheel to the new flywheel to
ease installation and assure proper indexing.
Causes:
Riding the clutch, defective
release system, improper
release system adjustment,
clutch components
unsuited for the torque of a
modified engine.
The disc would have burnt
friction material.
If you have already removed the flywheel and did not make any indexing marks,
follow this procedure for proper installation:
1.
With
the
flywheel
removed, look for the
alignment dowel pin
hole on the end of the
crankshaft.
2. On the new flywheel
find the same alignment
dowel pin hole. This can
be done by finding the
locating hole and notch
on the front side of the
flywheel.(see Figure 2)
3. When you have located
the notch and hole on
the front side, flip the
flywheel over and find
the same hole that goes
all the way through the
back side. Then look at
Figures 1-3 and find the
dowel pin hole.
4. When both have been
located align the two
holes and torque the
flywheel to the proper
specifications.
5.
28
See Figures 1-3 to aid
in locating the correct
dowel pin holes. Dowel hole
Flywheel
Dowel
Crankshaft
Engine
Figure 1
Alignment hole
Notch
Figure 2
DMF
Front Side
Worn Friction
Material
Causes:
Alignment hole
Dowel hole
Figure 3
DMF
Rear Side
If the clutch has high
mileage, this wear is
normal; however, if mileage
is low, possible causes
include riding the clutch,
excessive vehicle loading,
defective release system,
improper release system
adjustment, improperly
machined flywheel, clutch
components unsuited for
the torque of a modified
engine.
Technical Hotline 1.800.274.5001
Illustrations
Pressure Plate
Heat Rings
Uneven Finger Wear
Related Symptoms:
Incomplete release, noise.
Chatter, slipping.
Causes:
Oil contamination, flywheel
not resurfaced or resurfaced
improperly, failure to
maintain flywheel step/cup
dimensions.
When resurfacing a stepped
or cupped flywheel, be sure
to machine the contact
surfaces by equal amounts
to maintain specified
tolerances.
Related Symptoms:
Causes:
Incorrect installation of
the clutch. The clutch was
distorted when it was bolted
to the flywheel incorrectly.
Uneven Friction
Material Wear
Worn Bearing
Retainer
Causes:
Related Symptoms:
Riding the clutch, defective
release system, improper
release system adjustment,
use of clutch components
unsuited for the torque of a
modified engine. The pressure plate side
would have chatter marks on
the side opposite the lighter
finger wear.
Worn Splines
Worn Stop Pins
Related Symptoms:
Related Symptoms:
Related Symptoms:
Causes:
Excessive bearing preload
caused by riding the clutch,
incorrect release system
adjustment, defective
hydraulic release system.
Causes:
Incorrect release system
adjustment, worn fork or
fork pivot points, insufficient
lubrication of the bearing
retainer, worn ball stud
causing the fork to apply
uneven pressure to the
release bearing.
For the clutch to function
properly, the bearing
retainer must have a smooth
surface and be exactly
parallel to the input shaft.
Worn Grooves
Slipping, chatter.
Hard pedal, incomplete
release.
Harsh engagement, chatter,
no release.
Causes:
Missing engine alignment
dowel pins, worn pilot
bearing, worn input shaft,
misalignment between the
engine and transmission.
Chatter.
Causes:
Driving in high gear at low
RPMs, causing the disc
torsion damper to contact
the stop pins, high RPM
engagement, excessive
vehicle loading.
Check for misalignment on
high-mileage vehicles and
those in which the engine or
transmission was replaced.
www.Schaeffler-Aftermarket.us
29
Installation Tips
TECH TIP
GM Concentric Slave Cylinder
Bleed Procedure
Reinstallation of Components
and Transmission
•
Install the new pilot bearing/bushing if installed in
the end of the crankshaft.
•
Install the flywheel following the manufacturers
torque specs. It is critical to follow the proper
torque specs! Most General Motors vehicle designs do not provide
access to the slave cylinder without removing the
transmission from the engine. Additionally, some
models do not have bleed ports. To assist with bleeding these problematic slaves,
the steps outlined below detail the proper procedure
to correctly bleed the system while the transmission
is off the vehicle.***.
1. Verify that the clutch master cylinder has a full
fluid fill. If not, add additional fluid until full.
2. Insure that the clutch master cylinder is
mounted level on the firewall. Some vehicles
may require the master cylinder to be unbolted,
leveled and re-mounted to the firewall.
If the flywheel is torqued incorrectly the end of
the crankshaft can be distorted and cause the rear
main seal to leak.
•
Once the flywheel is properly installed use a good
cleaner and thoroughly clean the friction surface
of the flywheel. •
Once complete, insert the clutch alignment tool
into the clutch disc and connect to flywheel. •
Attach the clutch pressure plate onto the flywheel. •
Torque the bolts down following a star pattern, to
manufacturer’s specs.
Failing to follow proper torque specs will result
is a warped pressure plate and will cause clutch
related problems. 3. Install the concentric slave cylinder on the
transmission. Note: Some slave cylinders have
the input shaft seal built in. (Fig. 1) This seal
MUST be lubricated! Failure to lubricate will
result in seal damage and leakage.
4. Lift the transmission up into the vehicle but do
not mount the transmission to the engine. With
the transmission lifted, reach up and connect
the hydraulic line to the slave cylinder.
5. Once the slave and hydraulic line are connected,
reach into the bell housing and push the slave
cylinder back in its bore (Fig. 2), then release
and let it return to its original position. (Fig.
3) Repeat this process 12–15 times. Following
this procedure will force any air trapped in
the hydraulic line back up through the master
cylinder, through its vent cap and out of the
system. Bleed complete.
*** This procedure will work
on ANY concentric slave
cylinder application.
It is the ONLY way to
bleed many newer
applications that do not
have bleeder valves.
Most clutch kits come with spline grease. It’s very
important to put a very light coat on the input
shaft. Remember less is more when it comes to
grease on the input shaft. If too much is applied
it will sling grease all over the new clutch disc
and cause problems.
•
Install the throw out bearing or concentric slave
cylinder. If the vehicle has a concentric slave
follow proper torque procedures. •
Lift the transmission into place using proper
equipment. •
If the vehicle has a concentric slave cylinder follow
the procedure outlined on this page for proper
bleeding.
•
Always use the proper fluid specified in the
owners manual.
Failure to flush the fluid will result in release
problems and leaks in the hydraulic system.
•
Figure 1
Attach the transmission and engine together. Do not force the transmission into the clutch.
Forcing the transmission into the clutch will
damage the clutch disc hub. Do not allow the transmission to hang from the
input shaft.
Finishing the Repair
Once the transmission is reinstalled in the vehicle, test
drive the vehicle to let the clutch break in. Do not drive
the vehicle aggressively.
Talk with the customer and explain not to not drive the
vehicle aggressively for about 250 miles.
30
Technical Hotline 1.800.274.5001
Installation Tips
Most Common Reasons Why They Come Back:
Bent Clutch Cover
Bent Drive Strap
Broken Hub
Related Symptoms:
• Chatter, No Release
Possible Cause:
• Improper mounting
Prevention:
• Follow manufacturer’s
specifications for proper
installation and torque
procedure.
• Do not use power tools to
mount clutch.
• Dropping can cause damage.
Handle with care.
• Inspect your parts.
Related Symptom:
• No Release
Possible Causes:
• Margin of error is zero: this
damage can occur even if
dropped from low heights.
Prevention:
• LuK has industry leading
packaging that prevents most
of these occurences, however,
inspect all components before
installation.
• Mishandled parts - if you install
this, you will do it again.
Related Symptom
• Catastrophic failure
Possible Causes:
• Engine/transmission
misalignment
Prevention:
• Make sure input shaft is
aligned properly with disc
splines.
• Verify dowel pins are installed
correctly in bell housing.
• Inspect input shaft for wear.
• Power tools should not be
used. Tighten bolts by hand.
Contaminated Fluid
Excessive Lubrication
Excessive Finger Wear
Related Symptoms:
• Hard pedal - ports blocked
causing slipping.
• Rust and wear of components.
• Release problems and
eventually premature failure.
Prevention:
• Use only manufacturer specified
fluid.
• Completely flush hydraulic
system.
• When in doubt - replace
components.
Related Symptoms:
• Chatter, Slipping
Prevention:
• Schaeffler Group provides a
grease packet in every LuK
RepSet®.
• Do not apply more grease than
included in kit.
• Remove excess grease from
input shaft.
Related Symptoms:
• Slipping, Noise
• Accelerated disc wear
• Premature failure
Possible Causes:
• Defective release system.
• Driver error - riding the clutch.
Prevention:
• Inspect all components and
consider replacing during
clutch replacement.
This is all you need
AND it’s in the box!
www.Schaeffler-Aftermarket.us
31
Patented Designs
Automakers around the world know they can rely on LuK for clutches, discs and flywheels that are engineered
with the perfect fit and function for each of their new vehicles. Our engineers have created a variety of component
designs to meet the unique performance specifications for original equipment vehicles produced today.
Aftermarket technicians know that our LuK patented-design replacement components will fit right and perform as
expected. For innovative drivetrain solutions the world turns to LuK.
Dual-Mass Flywheel
Self-Adjusting Clutch
The dual-mass flywheel is
designed to absorb engine
vibrations before they are
transmitted to the driveline
where they can create gear
rattle. This is achieved by
splitting the conventional
flywheel into two sections:
a primary section, that
bolts to the crankshaft, and a secondary section, onto
which the clutch is bolted. The primary section of the
flywheel contains springs to isolate engine vibrations
and a torque limiter to prevent engine torque spikes
from exceeding engine and transmission component
strength. When torque spikes occur, the torque-limiting
package allows the primary section of the flywheel to
turn independently from the secondary section, saving
the driveline and transmission from damage.
In conventional clutch
designs, pedal effort
increases as the disc
wears. The self-adjusting
clutch was designed to
keep pedal effort low and
constant over the life of
the clutch. This clutch
design contains a springloaded, self-adjusting wedged ring. As the disc friction
material wears, the wedged ring in the clutch adjusts
for the wear. A special disc design contains a double
layer of marcels. These act as a spring to help lift the
pressure plate off the disc. In addition to increased
driver comfort, another benefit of the self-adjusting
clutch is that it eliminates the need for periodic release
system adjustments.
Keyhole Clutch
Series Damper
The keyhole clutch design
features a spring-loaded
tab cut into the clutch
cover. Tension on the tabs
automatically compensates
for slack in the clutch,
occurring over its life
due to wear between the
diaphragm spring and wire
ring. By automatically compensating for wear, the
keyhole design reduces the chance of clutch failure
due to no release.
Recognizing the dual-mass
flywheel was a complex and
rather expensive solution
to the elimination of gear
rattle, LuK engineers
designed
the
series
damper disc. This design
moves the dampening
function out of the flywheel
and back into the disc. The series damper contains two
rows of coil springs that compress in series; first
the outer springs then the inner springs. The series
damper eliminates transmission noise and gear rattle.
Extruded Hub Disc
Modular Clutch
Two of the most critical
components of the disc for
durability and performance
are the flange and the
hub. These are the disc
components that transmit
the engine torque, the parts
that get the most load. In
conventional discs, the
flange is manufactured by machining a casting. In
the extruded hub disc, the flange is produced with a
stamping that extrudes the center hub by forcing it
through a die. This process produces a disc that is
stronger than conventional discs. The extruded hub
disc offers increased durability and is designed for
heavy-duty, high stress applications.
32
The modular assembly
consists of a clutch, disc
and flywheel riveted
together to create a single,
balanced unit. LuK’s
modular design reduces
installation time and
eliminates the possibility
of contamination and
misalignment
during
installation.
Technical Hotline 1.800.274.5001
Engine Displacement Conversions • Model Years
To Convert
To
Inches
Millimeters
Multiply Inches by 25.4
Millimeters
Inches
Divide Millimeters by 25.4
Cubic Inches
Liters
Multiply Inches by .01639
Liters
Cubic Inches
Divide Liters by .01639
The model year of vehicles
sold in the United States since
1980 can be identified by the
tenth digit of the VIN code
according to the following:
Digit
Cubic CubicCubicCubic
LitersInches
Liters Inches
LitersInches
LitersInches
1.0
1.0
1.1
1.2
1.3
1.4
1.4
1.5
1.5
1.5
1.6
1.6
1.6
1.6
1.7
1.7
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.9
1.9
1.9
2.0
2.0
2.0
2.0
2.1
2.1
2.2
2.2
60
61
67
73
79
85
86
90
91
92
96
97
97.6
98
104
105
107
107.7
109.5
109.8
110
111
112
113
116
118
119
120
121
122
126
128
132
133
2.2
2.2
2.2
2.3
2.3
2.3
2.3
2.4
2.4
2.4
2.5
2.5
2.5
2.5
2.6
2.6
2.6
2.7
2.8
2.8
2.8
2.9
3.0
3.0
3.0
3.0
3.0
3.1
3.1
3.2
3.2
3.3
3.3
3.3
134
135
136
138
139
140
140.5
143
146
149
150
151
152
153
155
156
159
164
169
171
173
177
180
181
182
183
184
189
191
196
198
200
201
204
3.4
3.5
3.5
3.5
3.5
3.6
3.7
3.8
3.8
3.8
3.8
3.9
4.0
4.0
4.0
4.1
4.1
4.2
4.2
4.3
4.3
4.3
4.3
4.4
4.5
4.5
4.5
4.8
4.9
4.9
5.0
5.0
5.0
5.0
209
209.3
210.7
211
214
220
225
229
230
231
232
238
242
243
244
250
252
255
258
260
262
263
265
267
274
275
276
292
300
301
302
304.4
305
307
5.2
5.3
5.4
5.6
5.7
5.7
5.8
5.9
5.9
6.0
6.0
6.1
6.2
6.2
6.4
6.6
6.6
6.6
6.9
6.9
7.0
7.0
7.0
7.2
7.3
7.3
7.3
7.4
7.5
7.5
7.8
8.2
8.8
318
323
330
342
345
350
351
359
360
366
368
370
379
381
390
400
401
403
420
421
425
427
429
440
444
445
446
454
455
460
488
500
534
www.Schaeffler-Aftermarket.us
Model Year
A . . . . . . . . . . . 1980
B . . . . . . . . . . . 1981
C . . . . . . . . . . . 1982
D . . . . . . . . . . . 1983
E. . . . . . . . . . . . 1984
F. . . . . . . . . . . . 1985
G . . . . . . . . . . . 1986
H . . . . . . . . . . . 1987
J . . . . . . . . . . . . 1988
K . . . . . . . . . . . . 1989
L. . . . . . . . . . . . 1990
M . . . . . . . . . . . 1991
N . . . . . . . . . . . 1992
P . . . . . . . . . . . .1993
R . . . . . . . . . . . 1994
S . . . . . . . . . . . 1995
T. . . . . . . . . . . . 1996
V . . . . . . . . . . . 1997
W . . . . . . . . . . . 1998
X . . . . . . . . . . . . 1999
Y . . . . . . . . . . . . 2000
1 . . . . . . . . . . . . 2001
2. . . . . . . . . . . . 2002
3. . . . . . . . . . . . 2003
4. . . . . . . . . . . . 2004
5. . . . . . . . . . . . 2005
6. . . . . . . . . . . . 2006
7. . . . . . . . . . . . 2007
8. . . . . . . . . . . . 2008
9. . . . . . . . . . . . 2009
A. . . . . . . . . . . . 2010
B. . . . . . . . . . . . 2011
C. . . . . . . . . . . . 2012
D. . . . . . . . . . . . 2013
E. . . . . . . . . . . . 2014
LIT086E / 922 321 0260
©2013 Schaeffler Group USA Inc.
5370 Wegman Drive
Valley City, OH 44280
Phone 800 274 5001
Fax 330 273 3522
www.Schaeffler-Aftermarket.us
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