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)
George,
Thanks for your input. The challenge is fitting the CVT into a robust
Bell
housing with sufficient depth and width. My old RX-4 semi automatic
bell
housing is a little too old to be trusted and is not as robust as the
RX-8.
Also the starter motor comes from the front and interferes with the PSRU
housing. Worst of all it looks clunky. The automatic bell housing
looks
good and if I can find some dimensions for it I'll pick one up.
Cheers mate
Doug
Here are some pictures of Doug's old RX-4 semi automatic bell housing.
Don't chop it up Doug. It is probably a collectors item.
Paul Lamar
Doug,
What a coincidence, I just had a Cosmo Auto BH in my hands on the
weekend. I
needed to check the extra bolt hole placement and the young chap up the
road
( neighbour) has two of them.
I know Don Dunbar in Western Australia is using one for his development
and
wondered if it was up to the task. Well I can honestly say this is a well
made BH and appears very strong indeed. The reversed starter would suite
your purpose as well.
What dimensions would you need - I noted the front face bolt pattern,
which
is 214mm (8 3/8") Dia and depth of 168mm (6 3/8"). Just from looking at
the
RX8, I would say it was equally well made with the extra bolt hole in the
same place as the Cosmo ( perhaps) at 101.25 degrees, just left of the
top
centre. However I would say it's much longer, by just looking at the
Photo
Paul has shown.
I guess it boils down to, if you need more than 6 3/8" of depth!?
George (down under)
Gidday George,
Thanks for your fast response. I think the Cosmo is out because the Bell
47
diameter is definitily over 214mm. It is excellent for use with Tracy's
unit
though. I'm heading to the office now to check. I would be interested to
know the dimension of the front face and depth of the RX-8 housing if you
come across one. I am busy putting ALL parts into Rhino now as Paul has
repeately stated, it does make it a lot easier to design the total engine
layout. I know this but it doesn't make it less painful:)
Doug
Doug,
I would like to know as well - perhaps this could be accepted as a plea for
information from those who have access to one. However I will look around
and report anything I find.
The answer to your problem might be, a straight tube section ( thick Al
tube) with through bolts to the rear (or front) housing with an aluminium
face plate to pick up the Bell planetary housing - much like Tracy's
planetary housing.
Or a thinner steel tube to steel flange front and back - should be much the
same weight and very strong. Your bolt circle diameter is 360mm ( one bolt) to
364mm for the remainder.
If you give me the ID of the Bell planetary housing you need, perhaps we can
brainstorm something up.
Also if there was a 'Drag type' steel bellhousing available for the Mazda
engine - this could be more easily modified.
George ( down under)
George,
The Bell 47 outer extreme OD is 300mm. At the eight mounting holes pitch
diameter it is approx. 280mm. The old RX-4 semi auto intermediate housing
is fairly straight so there is enough room on the face if I could shave 5mm
off of the diameter of the starter motor. The old starter motor were big and
clunky so a new one may be possible.
Still no response on the snowmobile starter motor diameter from Steve but I
can search that information somewhere else as I also need to check out
snowmobile CVT sizes. Scooter CVT belts are WAY to long.
As an alternative to this housing the RX-8 auto housing may work.
Scaling from this picture I am guessing the front face diameter is about 288
mm. But the length appears to be about 250 mm. which means mounting the
engine farther back reducing heat exchanger space, and new motor mount.
Nope. I have about 130 mm to shoe horn in a flywheel and CVT. Interesting
challenge. I may have to go with your tube or space design yet. Let me get
the components or drawings in hand before we go down that path.
Doug
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