Doug,
All the lightened flywheels have their sizes tare taken off the manual
flywheel. I assume because the lightened flywheels are used in performance
vehicles with manual gearboxes. Remembering lightened flywheels are NOT
turned down cast manual flwheels but turned steel flywheels to preset
weights. Many can be purchased off the shelf ( or ordered) for many
different model engines.
All manual flywheels are smaller than the Auto flex-plates.
I believe all manual flywheels are the same diameter 298mm OD and all
flex-plates are the same diameter 320mm OD.
I can't for the life of me wonder why the RX8 would be different - but I
haven't checked. Perhaps someone is confusing the manual and flex-plate
OD.
I believe the Ross PSRU's used the manual diameter for their lightened
flywheels. This also tends to provide more room in an auto bellhousing.
Their wouldn't be a problem making a lightened flywheel in either
aluminium
or steel in either diameter - as Richard Sohn has done with the single. It
would require the engine to be balanced OR make it the same weight as the
combined flex-plate and counter weight. Understanding the weight must be
in
the correct place. Richard achieved this with lightening holes, however
this
is an assumption on my part. As flex-plates become more scarce, perhaps
this
will be only course available to new builders.
I think a flat plate would be easier to mount Tracy's type dampers but
would
recess the starter ring more toward the engine, requiring a starter with a
longer snout- probably not too big a deal as their are other ways around
this as well.
Hope that helps !
George ( down under)
Doug,
I checked the difference between depth of the flex-plate at the rear face
(that Tracy recommends), it's only 5mm - that's 5mm difference because of
the recessed centre.
If using aluminium for a flat plate, that 5mm would be the back side of the
turned recess, as in the manual flywheel which holds the ring gear- problem
of the depth of the starter solved!!
The builder that has a RX8 flex-plate, could he quote the OD please!
George ( down under)
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