> After some time pondering this flywheel business over the weekend, I'd
> like to challenge the assertion that switching from manual to
> automatic flywheel requires a change to the counterweight on  the
> engine.
>
> The flywheel I have has clearly been balanced independant of the the
> engine.  There are weights welded to the rear face of the flywheel -
> presumably to allow it to spin true.  I assume that an automatic
> flywheel would be no different.  Given this, I cannot see how the
> counterweight -- which is part of the engine assembly -- plays into
> this.
>
> In a similar example, the first step of mounting a redrive is to add
> the dampener plate to the flywheel.  A dampener plate - I might add -
> which greatly changes the inertia of the flywheel & shows itself no
> signs of having been balanced (i.e, no weights added).  I find it
> difficult to believe that this is somehow different, and does not
> require a counterweight change, where the flywheel it is bolted to
> 'does'.
>
> So -- am I missing something here?  Happy to be proven wrong, but this
> is not passing the smell test for me right now.
>
> (Yes, all of this is my desperate attempt to avoid having to fight the
> e-shaft nut off)
>
> Mark
>
> No Mark the counter weight is independant from the weight of the
> flywheel. Once balanced the engine will run fine with no flywheel.
> Only the counter weight is required. However your options are near zero.
> If you have Tracy's dampener plate you must have a disc with a ring gear
> to bolt it too. The ring gear must be in the right place as well
> as the mounting surface for the dampener plate.
>
> You need to start searching for an automatic transmission flywheel
> (flex plate) and a rear counter weight. You should then have the engine
> rebalanced with the new counter weight, the auto tx flex plate and Tracy's
> dampener to be totally correct. Many people don't bother and just get
> the right counter weight. You need to talk to Dave Lemon or John at
Mazdatrix
> about the correct counter weight to be used with the high compression
rotors
> they put in your engine.
>
> There are some light weight flywheels out that that might work however.
>
> Paul Lamar

Mark,
It's like this - you have two counter weights, one at the front and one at
the back.
They work together to balance the engine.

The back one in a manual is the big fat flywheel.

The back one in the Auto, is the second counterweight BUT as Paul says is
bolted to the flexplate ( for proper mounting purposes).
The flexplate is balanced within itself, you might notice a small tab
somewhere.
Therefore the only remaining balancing variable in a particular engine is
the rear counterweight, which is different ( I would suggest) for each
model.

The design of the flex-plate is to accommodate the Auto fluid dampener ( too
heavy for aircraft use), so Tracy has designed his rubber donut designed
damper to fit within the constraints of the availability of light weight and
readily available parts.

Remember that the flexplate is also different for many different models.The
reason for selecting a certain flexplate and starter motor is to give
guidance to the new builder so that he doesn't have to reinvent the wheel.

As Paul says you could use any number of combinations of lightened
flywheels - this is true of starters as well. Including Subaru starters
which match the ring-gear tooth profile. The Mazda specialist shops would
guide you on the selection of counter weight for your particular engine and
fly-wheel or flex-plate selection.

OR you can follow Tracy Crooks guide to set-up for his PSRU.
OR you could totally redevelop the whole thing - however I would advise
against that!

I saw my first Renesis Flexplate yesterday - seems different again!
Hope that helps.
George ( down under)

Folks I would like to offer this info because it is important. The flexplate
necessary comes out of an 86-88 13B NA. It has the wings on it as discribed on
the previous email pictures.
The counter wieght can be interchangeable with other engine types of older
models or turbo versions of the motor ie. 13B Turbo. but you must heed the
differnet weights in the rotors. In order to facilitate Tracy's redrive you will
need to first identify what motor you have with the compression ratio. That will
tell you approx. weight of rotors. Then you will need to order a counterweight
for your engine not for the flexplate. This will keep your balance. If you find
a counterweight at the junk yard you will need to take the whole assembly and
have it balanced. The parts needed to balance will be the e-shaft,rotors,and fwd
and rear counterweights. For an even better balance job you will send in the
front hub and the flexplate to. Pineapple racing will balance it all for you as
well as Hayes Rotary. The job costs about $450 to do it but it is worth it. I
would recommend anyplace else over Hayes as I had great difficulty with turn
around time with them.
Intersting note is that even two identical engines will have different weight
counterweight weights. Mazda Fasctory racing balances to within a gram but they
have told me that several grams difference between rotors and counterweights are
common.

I hope this helps. This is an old topic that was discussed about 3 years ago in
the archives. If you want more info on it. I did  a lot of research on this.
Respectfully,
Doug Mueller
RX-6 13BT
N900DM
Boulder City, Nevada