Paul,
I went out to the airport today to see how much I could accomplish on the flexplate
damper project.  I found some .090 silicone sheet and cut enough pieces to do 1/3 of the
damper.  In the process I discovered some things I hadn't anticipated.
First, the 6, 10mm counter-weight bolt heads stick up 3/8".  The three paddles from
the spline plate are short enough to miss the bolts, but that renders the last 3/8" of
depth useless for damping purposes, but you already knew that.
Also, the three paddles on the engine side are shortened, I assume to
  clear
the bolt heads needed to attach the spline plate.  So, another 1/4" of unused space.
That leaves a space of 1" to pack in enough silicone sheet to handle 350 hp.  I'm not sure
silicone is up to the job.
Do you have anything in mind to fill in the gaps caused by the bolt heads?
I was thinking of cutting spacers out of 3/8" phenolic sheet for the engine side, and
1/4" phenolic sheet for the psru side.  This should keep the silicone sheet in place.
Comments?
As for the silicone sheet, I feel that .090 is too thin for this application, but that
is all I had on hand.  A quick ebay search revealed some 1/2" silicone sheet for $81 (1/2"
x 36" x 12").  That should be
  plenty
to do a few dampers.  Or, do you think we could cast some dampers?  (Just
  a
thought.)
Mark


Well if we can come up with a low height spline plate
  bolt head we can lengthen the paddles on the engine side.
I had already thought about the 10 mm bolt heads. I figure we
  could glue silicone sheet in there to act as a spacer. It would
  not be subject to compression. Plywood would also work. So too phenolic as you
suggest or fiberglass.
Lets try the .090 on a ground run to get a feel
  for the situation. Try idling the engine below 1800 RPM
  to see what happens. I'll fly out for the test.
Looks like we can make the paddles on the gearbox side
  wider. See damper10-mod.jpg 1/4 inch is no problem
  if you think that will fit.
Some modeling clay in there without the rubber
  will reveal a lot.
If you want something changed to fit better let me know.
  2 7/8th or 3 inch tube might be better than the 2 3/4
  that is in there now.
Paul Lamar

Paul,

For test purposes, we could weld some .125" or .250" thick strap to the
outer face to see how it works.  We could radius it if too tight.

Mark

I meant 2 3/4 " Inch tube.

I am am not sure I follow you on this. Make sketch on paper
and scan it in. Or use MS Paint. Strap rolled up to
increase the outer diameter of the tube? Hard to do :)

Get back to me after the clay and I will send you a front (gear box
side) with a larger tube. I think I have some 3 inch OD
4130 tube lying around.

BTW glue those silicone parts together with red RTV.


Paul Lamar

Here is what it looks like with a 3 inch inner tube and socket head metric 10 mm bolts. I
think this is an improvement but we can still test what we have. This is a minor change in
the over all scheme of things.

Paul Lamar


 Paul
I was thinking and I know that is dangerous, but is there a type of self curing rubber
that we could inject into the damper after we have it assembled that would hold up? I told
you that I shouldn't think but it's an idea.
Peter

Yes. Silicone is available in pour able liquid form.
The Silicone RTV stuff you get in the hardware store could be used
but it has the consistency of peanut butter.

Paul Lamar