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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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