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Thanks for the info. I think the AL
version is about 8 or 9 lbs (without the steel clutch surface). I
had thought that the steel racing version was closer to 10-12 lbs;
good to know the actual weight.
If memory serves, the gen2 turbo manual trans has the same dia as
the flex plate & the non-turbos are smaller dia; the used one
I bought certainly is smaller. Again if memory serves, Tracy is
using an aluminum turbo version in the RV4 that has the 'direct'
(no dampers) connection to the sun gear.
I agree that the extra flywheel weight reduces torsional resonance
issues. If my flexplate gives me trouble, I may try to adapt the
damper's hub/spline to the aluminum as 'direct drive'.
Charlie
On 10/20/2021 3:14 PM, David Leonard wdleonard@gmail.com wrote:
Hi Charlie,
The one I got was chromoly and weighed 22#, I am sure an
aluminum one would work as well. The diameter of the ring and
the number of teeth matched the flexplate, but it was closer
to the engine by about a half inch. I had to mill off just
enough of the mating surface so that Tracy's damper
plate& spline socket could fit without hitting the back of
the gearbox mounting plate. The CNC shop also reamed the
bolt holes in the right place. The last job was to mill a
depression in the RD-1B mounting plate so that the starter
would reach the new location of the starter teeth. I figured
a few extra pounds in the flywheel could only help smooth out
the engine.
There is one nice thing about Tracys approach to
vibrational harmonics. He designed it with ample gear lash so
it seems to me that increasing the weight of the flywheel
would be unlikely to worsen harmonics. Otherwise, with a
tight system I would not be as confident. Didn't we all
decide that the issue with many other PSRU's was vibrational
harmonics. Didnt the Ross, Powersport, and Eigenfelner have
this problem? I have had many problems with my early design
RD-1B, but never a problem with the planetary gears
themselves.
Anyway, I do recall there is a difference between some of
the different flywheels between RX-7 generations but I
can't recall which years the ring size matches the flexplate
we use.
Dave Leonard
Do you remember what that flywheel weighs? Was it the
same diameter as the flex plate, or was it smaller, like
the non-turbo manual trans flywheels? Did you remove all
the disk mating surface to reduce weight, or just enough
to mount the damper plate?
I've got an aluminum manual trans flywheel on the shelf,
but it's slightly smaller in dia than the flexplate.
Wondering about weight comparisons, mounting, etc.
In more general terms, the flexplates seem to have a
rather checkered past even in the car. I've got one that
came off the car cracked.
Charlie
On 10/19/2021 11:15 AM, David Leonard wdleonard@gmail.com
wrote:
I used one of these:
I mounted the RWS damper plate. I had to take it
to a CNC shop to take down the face and locate the
mounting holes. I also had to modify the mounting
of the starter, but it was a pretty easy job.
Neil, great job on getting your gear-box into
production. We sure need it.
Dave Leonard
Hello
James,
I
have a stock 13b ( estimated 150 hp) with
RWS equipment. I used a racing aluminum
flywheel and removed the steel clutch
facing. Then I resized the RWS splined hub
to fit. Basically I copied RWS by making a
new plate and riveting on the RWS splined
hub to my new plate. Because the new plate
is a smaller OD I used 6 bolts instead of 4.
I used the same durometer rubber cushions.
Thanks,
Dave
Williams
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net]
Sent: Friday, October 15, 2021 6:27
PM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: flex plate
Dave, do you have a
recommendation for a lightweight flywheel
and flexplate/ damper (brand or type) for a
250hp 13b? Thanks, James Whitehurst
But you should know
that those are prone to cracking, and I
had a catastrophic failure of one. They
were never designed to carry the output
load of the engine, just as a way to
engage the starter. Tracey published a
revision in the archives, or you can
convert a manual fly wheel to work. I
suggest lightweight aftermarket
versions.
Thought so, thanks
Can anyone
confirm which flex plate
fits the RWS redrive? I
believe it comes from a
92 model RX7. But is it
from an automatic,
manual or turbo model?
All are different
apparently.
Thanks
Neil.
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