Subject: RX8 Flywheel
From: Rotary Engine
Date: 10/31/2006, 2:55 PM
To: AA-me




    >
    > Does anybody have a line on RX8 automatic flywheels and
   counterweights?
    > Mazdatrix quotes $380. or so and Ithought that was a bit much. I have
    > one on a 13B and wonder if they are the same. Karibian
    >

    > Bruce Turrentine put a 13B flex plate on my Renesis engine to fit
    > Tracy's redrive.
    >
    > Scott Gettings

   Scott/ Karibian,
   The counter weights would be the most expensive parts - getting the
   right
   weight is the most important part. The flex-plate is balanced to
   itself, I
   don't believe the 13B counter weights are the same as the RX8 counter
   weights - although I have never weighed them, perhaps Tracy has!?
   George ( down under)


   I have an rx-8 flywheel.... no counterweights. It is different than
   the flywheel required by tracy Crook for his PSRU.

   Paul Kvernplassen

   -----------------------------------------------

   What you have is a flywheel Paul. What people need is a flex
   plate with balance weight for an RX8. The only thing they have
   in common is the ring gear and I am not sure about that.

   Jim Mederer, how much money would it take for you to make
   a batch of 25 sets of RX8 flex plates and counter weights?
   The flex plate does not have to be identical. Just the ring
   gear and flat surface near the ring gear must be in the
   same longitudinal position. No clutch wear surface required.
   It will be bolted to this device.

   Could it be done for less than what Mazda charges for flex
   plate and counter weight?

   This appears to be a recurring problem for us as many
   six port RX8 manual tx engines are being converted to use auto
   tx flex plates and counter weights. The two parts could
   also be combined in theory to cut the cost. Something
   like the PS flywheel without the large gear.

   Paul Lamar ...No rotor no motor.


Hi Paul,

   Our cost for the RX8 rear counterweight, N3Z2-11-52X, Our part #
11458 is $109.70.

   It would certainly be possible to machine a "drive disc" with a ring
gear mounted.  In modest quantities, it might come out a bit cheaper
than $380.00 with the counterweight and ring gear, but with what bolt
circle?  What disc stiffness is necessary?

Jim Mederer

Not much disc stiffness. No real loads on it other than
the starter and the torsional. Can  get you get ring gears?
Seems like 3/16th mild steel would work. Perhaps you can find
some one to stamp press it out of 3/16th mild steel or even
normalized 4130. It needs that recessed center.
AC Spruce sells 18" by 18" .190 thick 4130 for
$90. If you buy 18" by 36" .190 4130 that will make three for $120
total or $40 material cost each and have a lot of 6 by 12 pieces
left over.

The stamp press tooling would be easy to machine on a large lathe. It does
not need all the holes the stock one has. Just the four 3/8th to
mount Tracy's torque isolator. The customer can drill those. Weight
is not an over riding concern.  The stock counter weight is cheap
enough. The kit will sell for the next five or ten years.

Paul Lamar ...No rotor no motor.

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