STM Slipper Clutch
The slipper clutch that started it all! STM Slipper Clutches are beautifully
fabricated in anodized aluminum alloy and titanium. Selected for use by Ducati's World
Superbike team, still the best choice for higher horsepower machines.
These are the EXACT Same STM Clutches that are used by Ben Bostrom, Noriuki Haga,
Franki Chilli, and
Many other Top Road Racers World Wide.
ALL STM Clutch is made IN HOUSE at the Italy Shop, with the highest tollerance and
quality control. Each part is stamped with a Part number, and Serial number to keep quality control
and records of all part made.This insures what you receive is only the best, everytime.
All STM parts start with an in-depth,
comprehensive design process. Every aspect of the part’s function and life are
scrutinized, with special consideration given to performance. Together with
involvement from our numerous factory race team partners, we strive to produce
the most technologically advanced parts available on the market. Our parts are
not only beautiful to look at, they are the highest quality, most durable, and
peak performing parts money can buy. All STM parts are constructed from the
highest grade of raw materials. They are CNC Machined to the tightest tolerances
and our clutch components are hard coated to ensure longevity. Once completed,
STM parts undergo maximum scrutiny in the toughest torture environment… the
racetrack. Through over a decade of direct race involvement at the world level,
STM parts have been refined and perfected .
What does a
slipper clutch do?
During rapid downshifting, a slipper clutch temporarily
reduces the amount of friction in a clutch, which
disconnects (to a degree) the final drive and transmission
of a motorcycle. The result is a decrease in engine braking
and an increase in rear wheel freewheeling.
What are the benefits of using a slipper clutch?
Performance: Decreasing engine braking leads to increasing
the amount of rear wheel freewheeling. When rear wheel
freewheeling is increased, cornering speed is also greatly
increased. An increase in cornering speed directly leads to
lower lap times! Also, the slipper clutch frees up the
rider’s attention so they can focus it on other aspects of
riding like reference points, body position, lean angel,
braking, etc. Safety: The engine is spinning at one speed,
the rear wheel typically is spinning at a higher rate of
speed. When engine speed is NOT properly matched to rear
wheel speed during rapid downshifting, this results in a
situation called “Rear Wheel Hop”. What this means is that
the rear wheel starts to hop up and down violently until the
two speeds are equalized. Slipper clutches eliminate rear
wheel ‘hop’, which ultimately increases the control of a
motorcycle. Once the rear wheel starts to hop, it has lost
contact with the ground… which means the rider has lost
control of the motorcycle! If the rear wheel is hopping and
loses contact with the surface, a rider may be able to slow
the motorcycle, however the bike can not be turned. This can
lead to an accident. If the rear wheel is allowed to
freewheel, it can remain in contact with the ground and the
bike can be turned. Basically, through use of a slipper
clutch rea wheel hop is eliminated, control is increased
which could be the difference between going through a corner
and leaving the road surface.
Why use a
slipper clutch off road?
Performance: It is a common misconception that a slipper
clutch will have no benefit in off road conditions because
the dirt will give way and the felt engine brake will be
minimized. This is not true, engine braking will always be
felt and more importantly it can upset the handling of the
motorcycle. A slipper clutch allows the rear wheel to
freewheel under rapid downshifting conditions… which leads
to increased corner speed and lower lap times. Stability:
Consider that every time the face of a bump or whoop section
is hit, the rear wheel is torqued and opposing force is
applied to the engine. This typically results in the rear of
the bike being thrusted upward. This throws the front of the
bike down and the result is a ‘sea-saw’ effect, or bucking
back and forth. Usually the only way to combat this is to
get off the gas. However, when using a slipper clutch
through a difficult whoop section, as the rear tire hits the
face of each whoop, the clutch is allowed to open up and
keep the rear wheel spinning… this increases stability and
leads directly to the bike staying level; which allows the
rider to stay on the throttle. The same is true when landing
a jump. As the bike flies through the air, the rear wheel
may slow down. Upon landing, the rear wheel is rapidly
accelerated again and opposing torque is applied to the rear
wheel and subsequently the engine. The result is increased
downward force on the front end. With a slipper clutch, the
rear wheel is permitted to freewheel upon landing. This
leads to increased stability on landing, being able to ride
out of the jump faster, and often in many cases enables the
rider to use softer front suspension settings for increased
feel and control in other parts of the track. In addition to
increasing riding benefits, STM slipper clutch systems
prevent engine over-revving. Reducing engine over-rev
preserves the function of engine components and leads to
increased engine life.
STM Design:
All STM parts start with an in-depth, comprehensive design
process. Every aspect of the part’s function and life are
scrutinized, with special consideration given to
performance. Together with involvement from our numerous
factory race team partners, we strive to produce the most
technologically advanced parts available on the market. Our
parts are not only beautiful to look at, they are the
highest quality, most durable, and peak performing parts
money can buy. All STM parts are constructed from the
highest grade of raw materials. They are CNC Machined to the
tightest tolerances and our clutch components are hard
coated to ensure longevity. Once completed, STM parts
undergo maximum scrutiny in the toughest torture
environment… the racetrack. Through over a decade of direct
race involvement at the world level, STM parts have been
refined and perfected .
What Make STM so Good ?
Ball & Ramp Actuation:
STM was instrumental in developing the Ball & Ramp Actuation
technology. In order for a slipper clutch to work, there
must be a reduction in friction in the clutch pack. This is
typically accomplished by using a drum and hub which are
independent of one another. When these two components rub
together during slipper clutch operation, friction, heat &
wear are greatly increased. STM solves this problem by
placing ball bearings between the hub & drum. The result is
not only much smoother slipper clutch operation… but a
significant reduction in friction and heat. This all leads
to increased clutch durability and component life.
PEP –
Progressive Engagement Plate
The progressive engagement plate is a titanium nitrated
plate that allows the clutch pack to float or shift slightly
when the clutch closes down after the slipper aspect has
been activated. This provides for smoother clutch closure
and decreases the abruptness a rider may feel when the
clutch begins to lock up again.
Diaphragm
Springs
Diaphragm Springs have 3 distinct advantages over the
traditional helicoil springs used in clutches.
#1. Digressive Lever Engagement – helicoil springs are
progressive, meaning the more you compress the spring, the
more difficult it becomes to compress. With diaphragm
springs the opposite is true. A diaphragm spring
progressively becomes harder to compress through 3/4 of the
travel, however the last 1/4 of travel actually becomes
easier. What this means to a rider is that as the clutch
lever travels towards the handlebar, the lever pull gets
easier for the last 1/4 of travel as the lever approaches
the bar. The result is when a bike is on the starting line,
you do not have to give as much throttle to effectively
launch the bike off the line.
#2. Less Drag than Helicoil Springs – when helicoil springs
are installed in a clutch they are slightly compressed…
meaning they are dragging. Diaphragm springs are at rest in
the STM clutch and therefore have no drag on them.
#3. More consistent and even pressure on clutch pack which
eliminates "hot spots" in the pack. This leads to better
clutch lock-up and increased clutch pack life.
STM Clutches
are fully adjustable
An aspect that sets STM slipper clutches apart from all
others is their ability to be adjusted & tuned in both the
primary & secondary. The primary spring controls the
pressure on the clutch pack during lock up. STM diaphragm
primary springs are weighted in Kilograms and offered in
10Kg increments. There are several different weights to
choose from (sold individually). Through the use of varying
weights, the engine builder can adjust the amount of
pressure on the clutch pack to compensate for any engine
modifications and subsequent increases in horsepower. The
secondary spring is what controls the amount of engine
brake. The lighter the secondary spring, the less engine
brake; the heavier the secondary spring, the more engine
brake. The 85mm diaphragm secondary springs are weighted in
Kilograms and offered in 10Kg increments. There are 6
different weights to choose from (sold individually).
Through the use of varying weights, the rider can adjust
the amount of engine brake desired to fit their individual
riding style.
Forced Lubrication System
FLS - Forced
Lubrication System
The ‘FLS’ – Forced Lubrication System is unique to STM
clutches. The system is a complex network of oil passages
that actually increases the amount of engine oil flowing
through the wet clutch. The FLS reduces running
temperatures and increases cleaner conditions inside the
clutch which increases the performance and longevity of the
clutch components and pack.
STM Slipper Clutches kit assembly uses original Friction
Plates, Drive Plates and basket.
STM can be found on AMA Factory
Yamaha's
As well as a majority of World Superbike, and Moto GP Teams
STM STREET Slipper Clutches Price List For "Off
Road" STM Application Please click Here >>
STM OFF ROAD <<
PART #
PRODUCT DESCRIPTION
SALE PRICE
FAP-S040
Aprilia RSV4
'09-'11
$1449.95
$1129
FAP-S030
Aprilia
Dorsoduro 750
'09-'10
$1,449.95
$1129
242-1100
Aprilia
RSV1000 ALL YEARS
$1,259.95
$1059
FBM-S020
BMW
S 1000RR '09-'11
$1,450.95
$1129
FBM-S010
BMW K1200 '05-'06
$1,350.95
$1129
FHD-S020
Buell 1125R '08-'10
$1,449.95
$1129
FDU-S150
DUCATI Hyper Motard SLIPPER CLUTCH KIT
"Evoluzione
Racing SBK" (125mm)