Courtesy of Mike Cecchini
This procedure is for standard 851, 888, 996
models and can be used for overall guidance for the S, SP and SPS variants.
The term "stacking" is actually "thickness", but thickness in a special way.
For this article it means an arrangement of plates in a particular way to a
specific depth or thickness. For clarity, the term "outboard" means farthest
away from the engine and "inboard" meaning closest to the engine.
Ducati Clutches are to be stacked to 38mm plus (+) or minus (-) 2mm. This is
all the plain steel plates (9 for the 851/888) and all the friction plates (7
fiber coated plates for 851/888)........but NOT the outboard end pressure
plate. The pressure plate is the one with the deep holes that the clutch
springs reside. I know.........I didn't mention the 916/996. Not to worry.
Note: There is one 1.5mm thick steel plate amongst your nine (9) 1.5mm & 2.0mm
flat steel plates that is slightly arched (curved). This curved plate is
barely discernable to the naked eye and is marked with a single "dot" (aka
punch mark) near one of it's inner circumference serrations. This "dot"
indicates 2 things. #1. You have found the curved plate and #2 "this" is the
concave side of this curved plate.
You can confirm this by placing the plate on a
flat piece of glass and pressing your finger tip on the outer circumference of
the plate and pressing down. The opposite side (180 degrees) will rise off the
surface of the glass.
Friction plates (usually 7) are the ones with the "tangs" on the outer
circumference, these tangs fit into the outer clutch basket. The 9 steel plates
have inner circumference serrations that fit into the inner clutch hub.
Ok...........now that you have the basics, here's the stacking order of the
clutch, starting with the first plate that you should put into the clutch basket
(inboard).
1.5 mm steel plate with "dot" facing outboard
2.0 mm steel plate
3.0 mm friction plate
2.0 mm steel plate
3.0 mm friction plate
2.0 mm steel plate
3.0 mm friction plate
2.0 mm steel plate
3.0 mm friction plate
2.0 mm steel plate
3.0 mm friction plate
2.0 mm steel plate
3.0 mm friction plate
2.0 mm steel plate
3.0 mm friction plate
2.0 mm steel plate
Overall guidance:
You will need 9 steel plates with a combined thickness of 16mm to 18mm.
You will need 7 friction plates with a combined thickness of 18mm to 20mm
Bruce Myers (BCM Motorsports) note:
This last 2.0mm steel plate can be interchanged with a 1.5mm "dot" (curved)
plate facing INBOARD (not outboard like the first 1.5 mm plate) ----IF :
1. You need to adjust the stack to get your 38mm stack height (thickness)
--OR--
2. If you want a very progressive (soft) clutch engagement as opposed to a
clutch that can/will engage at a definite "now" feel. Your choice.
Also..........any of the steel 2.0mm plates can be exchanged with 1.5mm steel
plates along the procedure to reduce stack thickness or increase stack
thickness as needed to achieve your 38mm stack. You will see the need for this
as friction plates wear.
New 3.0mm friction plate service limit (minimum) is 2.5mm. 2.0mm and 1.5mm
steel plates only need replacing if scored or warped.
I realize that many of you will not have spare plates of any kind, but when/if
you change out your clutch (now that you know the stacking procedure) you will
have spare (used good) plates left over from previous clutch change-outs. Not
to mention that you can buy individual plates from people like Barnett and
others so that you can adjust your clutch stack.
Final footnote: the bolts that hold the caps on the clutch springs. 5 ft lbs.
(60 inch lbs) is the proper torque. The metal the screws are threading into is
cast aluminum and extremely soft material. These bolts (10mm hex heads) are
extremely easy to strip. We Americans have a tendency to use large wrenches
and large 1/2 inch drive ratchets that have long handles. This scenario
encourages excessive tightening of bolts and screws (over torqueing). If there
is a single bolt on the whole motorcycle that you need to be very careful
with.........this is the one. Do not use locktite on these bolts as it can
easily remove the threads the next time the bolt is removed. Soft aluminum and
steel is not a good combination for locktite. Easy way......or hard
way..........your call.
Mike Cecchini