The XR1200 makes use of
the clutch assembly formerly found on the XB
Buells. It is similar in its external
dimensions to the XL clutch assemblies, and,
with some modification during installation it
is said to be possible to retrofit a XL
clutch into an XR. The XR/XB clutch
design does have some improvements over the
regular Sportster clutch.
Several of the clutch
parts, including the full fiber and steel
plates, are interchangeable with an XL clutch
- but the clutch shell, hub, pressure plate,
bearing, etc. are different.The XR/XB clutch has an
internal compensating mechanism to reduce
drivetrain shock under hard launches and
sudden downshifts. It also incorporates
a "judder" spring to reduce chatter when the
clutch lever is released.
Below is a picture of
the complete clutch assembly, after it
has been removed from the primary case.
It is comprised of two main parts:
- the outer clutch shell
with the starter ring and drive gear for the
primary chain, and
- the inner clutch hub
with the fiber and steel clutch plates,
pressure plate, and diaphragm spring
The below is a side
view of the clutch assembly.
The center clutch
Adjustment Screw and Release Plate must be
removed to unscrew the nut on the main shaft
to remove the clutch assembly from the
primary. But, this shaft needs to be
back in place to disassemble the clutch pack.
The below picture shows
the gap between the outer diaphragm spring and
the back of the pressure plate. (These
are the openings between the eight standoffs
that hold the outer retaining ring that keeps
the clutch pack together.) Nominally,
this gap is about X/Y" wide. This allows
the Ball and Ramp assembly, activated by the
clutch lever and cable, to pull the Pressure
Plate outward about 1/8" and let the
friction and steel plates spin freely to
disengage the engine from the drivetrain.
In my clutch, the seat
ring that helps keep the clutch pack
retaining ring in place had broken, and part
of it had wrapped under the diaphragm spring
restricting the movement of the diaphragm
spring and pressure plate. This
was causing the clutch to constantly drag
when the clutch lever was pressed.
Hence, the eagle-eyed may notice that I had
actually already removed the broken retaining
ring seat in these pictures, and temporarily
re-assembled the clutch pack.
Spring Movement Range
Before the clutch diaphragm spring is removed,
the clutch pack can be lifted out of the outer
clutch shell as a unit to inspect the clutch
shell. (In Big Twin and XL Sportster
clutch assemblies, the center hub is pressed
into the center bearing in the clutch
shell.) The XR/XB design makes it easier
to install slipper clutches and other clutch
Here is a look at the
inside of the front of the clutch shell.
Andbelow is what the
back of the clutch shell looks like.
Notice the six recesses
that house the springs which buffer the
compensating mechanism in the XR's clutch
shell. The clutch housing consists of
two pieces which are riveted together and will
wind up slightly during accel/decel.
They are buffered by the compensating springs
to take some of the shock out of the
The next two pictures
show a couple of the compensating springs in
their housings. These springs have been
known to break under heavy use but, in good
condition some of them will be loose or move
when the clutch is disassembled. They
are different lengths in order to engage at
different points and soften the shock of
sudden engine accel/decel on the drivetrain.
Compensating Spring - Alt
Separately, here is the inner clutch pack
removed from the outer clutch shell, with the
diaphragm sping and its retaining ring still
holding the pack together.
To disassemble the clutch pack, it is placed
back in the outer clutch shell to keep plates
aligned as the spring compressor tool is used
to release the retaining ring on the diaphragm
needs a spring compressor tool to compress
the diaphragm spring and take the pressure
off of the retaining ring, so that the ring
holding the diaphragm sping in place can be
The first step to
installing the tool is to thread its center
shaft on to the clutch Adjustment Screw.
Spring Compressor - Install
With the center threaded part installed, the
outer ring and support bearing are set in
place, and the handle threaded on. Then
the center shaft is held in place with an open
end wrench while the handle is turned -
compressing the diaphragm spring to release
the tension on the retaining ring.
The diaphragm spring
should only be compressed enough to release
the pressure on the retaining ring.
CAUTION: Over-tightening can damage the
diaphragm spring and clutch pack.
With the diaphragm spring pressure removed,
the retaining ring (and the seat which would
be installed under it) can be removed from the
grooves in the fingers of the clutch
hub. A screwdriver may be needed to help
lift the retaining ring out of the grooves in
the clutch hub to remove it.
The below picture shows the diaphragm spring
retaining ring, and its seat ring. The
seat should be a continuous ring - mine had
cracked in one spot, and was no longer staying
properly in place on top of the diaphragm
spring. It was actually restricting
movement of the diaphragm spring and the
pressure plate, and causing my clutch to drag
badly. (I had pulled the seat off
earlier in the day, when I was examining how
it broke, and hence it is not shown in the
With the retaining ring removed, I pulled the
clutch pack back out of the clutch shell and
removed the stack of parts - starting with the
This is the 400 lb
Barnett MT-77 diaphragm spring. A better
choice for most XR1200 builds would be the 360
lb Barnett MT-81 spring or the 350 lb spring
in the SE Performance Clutch Kit. The
MT-77 is a very stiff spring at the clutch
Next off is the clutch pressure plate.
With it lifted off, the stack of fiber
friction and smooth steel clutch plates
There are seven full sized friction plates
(37911-90) in theXR1200 plate stack.
These are alternately interlaced with the
smooth steel plates. The friction plates
are notched on their outer edge and engage the
clutch shell. The XR parts manual
describes the friction material as "paper."
This friction plate has about 20,000 miles on
it. The friction material may look thin,
but if you take a look at a new plate (click here to see a new SE
friction plate), it
actually has a good amount of material
The stock plates have friction material placed
on it in individual tabs. The SE plates
have a continuous ring of friction material
with a waffle print pressed into them.
There are also seven steel plates
(37913-90) in the clutch pack.
These are notched on their inner side to
engage the clutch hub. With the
diaphragm spring released exerting force
on the pressure plate, the stack is clamped
together and the engine can drive the
The eighth, and bottom, friction plate in the
XR1200 clutch pack is a narrow plate.
This plate has a concave judder spring
installed in its center and is supposed to
help reduce chatter when the clutch is
released. This narrow friction plate is
not found in the SE Performance Clutch Kit,
and would need to be separately purchased if
the SE kit is used for the full plates.
Below is a picture of
the concave judder spring.
And the judder spring
in the center of the narrow fiber plate, where
it would be when installed on the clutch
Spring with narrow Plate
The last part in the clutch plate stack is the
seat for the damper, or "judder" spring, that
goes against the clutch hub. The judder
spring will spin on this seat as the clutch
initially engages to help reduce vibration as
the clutch lever is released.