I do not know all of the restrictions to the application of the fluid
   coupling, but if you are looking for something that will absorb
  "chatter"
   and does not generate a lot of heat, have you considered the Dodge
  coupling
   that Molt Taylor used in the IMP and mini-IMP?


http://www.dodge-pt.com/products/pt_components/flexidyne/flexidyne.html

   I had heard at one time the company was not "aviation" friendly due to
   liability issues.

   Just a thought.

   K. Carl Milbrodt PE


   As far as I can figure it out they are limited to 1800 RPM
   and they are very heavy. We need something that will survive 7500 RPM


   Paul Lamar
   --

   A Flexadyne is a centrifugal clutch.
   Bud Warren used a centrifugal clutch on his gear drives. A single
plate
  with weights with ramps and rollers to clamp up instead of the springs
  in a
  normal clutch.
    Most centrifugal are drum type rather than disc. Disc is likely
better
  for high rpm.  The SGF coupling is the lightest, simplest, least
  expensive
  and quickest way to deal with the drive line vibration.  Do you think
  that
  Porsche, M-B, BMW, General Motors and the other car companies that use
  them
  are guessing?

  Murry I Rozansky



  The rubber couplings really don't deal with low RPM aircraft gear box
  chatter.
  Their real function is to mitigate the torque pulses effect on the
gears.
  What we need is both but I have not come up with a light weight
  fluid coupling or a centrifugal clutch yet. In the mean time we will
  continue to idle the rotary at 1800 engine RPM or higher. After all the
  prop is only turning 632 RPM.

  Paul Lamar

The Molt Taylor flexidyne is a centrifugal dry fluid clutch by
Dodge-PT.  They use a steel shot sandwiched between wavy housings/plates
to transfer power.
They are not light.
Flexidynes apparently worked well for many folks using 0-200's or less.
One Cirrus VK-30 owner mentioned a MTB Failure of a few hours with an
IO-550?   I believe they are using an off the shelf Lord LCD damper now
with many hundred successful hours.

There are a lot of engineered industrial and marine dampers out there to
choose from...

Here is a viscous torsional damper redrive project I was involved with
years ago.  The prototype was built and flown.
Many additional variations and concepts were discussed.

   http://www.eaa245.org/Presentations/EA81Torsion/Torsion/sld028.htm
   http://www.eaa245.org/Presentations/EA81Torsion/Torsion/sld022.htm

Cheers
Cary



Cary, would this be a dual mass damper? VW has used dual mass
flywheels with
success to remove VNH.
Bill Jepson


Hey Bill;
I don't think this damper would fall into the dual mass flywheel class
of devices.
This design was quite light.
The intent of this damper was to provide damping and several failsafe
components for power transfer -
springs, rubber and silicone viscous damping.
The silicone fluid worked based on viscosity only, no pumping or
calibrated holes or jets  (but were discussed).
trying to avoid cavitation.
You could hear it work at start-up and shutdown.

The damper fluid was changed to a high viscosity silicone after starts
on a cold day
(25-30 degrees F) with oil blew out a PSRU bearing seal on the ground.
We live in the cold northern wastes...
Learned that oil viscosity is ridiculously non-linear near 32F.
If my poor memory serves, it was something like 2+ orders of magnitude,
the silicone was less than 1 order.
Remember this if nothing else ;)

BTW, a lot of the bike dampers in the other threads look like many OTS
marine dampers.

Cheers
Cary