I respect to a stock FC engine, I know there is the flywheel, crank and counterweight. The question is....is the flywheel itself zero balance, or is it offset weighted? I know on a V8 that if you have a crank counterweight that it's because the crank is offset weight and the flywheel is zero, but I have no idea about the rotary setup.

 

S4,for instance has a S4 Front counterweight and a Rear S4 Flywheel(manual).
The counterweight is part of the Manual 5 speed flywheel.
If you go to s5 internals then you use s5 front CW and rear flywheel.
If you go to aftermarket light flywheel then the Counterweight is Separate and corresponds to the Engine.You can use a Rear Auto counterweight for a S4 Auto as a CW for the Rear CW with the aftermarket flywheel.That is IF you are putting it on a S4..s5 uses S5..
The aftermarket flywheel is not weighted,but rather attaches TO the counterweight.
Counterweight must match engine internals,and series.

 

Ok, so if I need a zero balance flywheel, I can go aftermarket or have a stock S4 flywheel modified for zero balance?

 

Toss all that V8 thinking out the window..
We are talking Rotary engine here!
The counterweights are to offset the spinning of the Internals.(rotors).
Front CW..2 rotors..Rear CW..
You can't put on an Aftermarket flywheel and have NO counterweight.The engine will get damaged.
BUT you can get the Stock flywheel machined to take a bit of weight off,as long as you keep the Counterweight's weight the same.
(Euro-drive in Burlington Ontario did this.)

 

Hehe...you need to throw out the rotary thinking too.... I'm doing an all electric powered car. That's why I need a zero balance flywheel.

 

ah..Ok..gotcha.
just use an Aftermarket Manual flywheel then,as it has NO counterweight!
..By the way,I Forgot about that Electric Car thing that you had going,so it may be good to include that info later on down the line..
...down the line..oh..groan...!
Oh,auto flywheel would have no counterweight too.

 

I'm retaining the clutch and 5 speed, so just need a stock setup, just no counterbalance. I'll look into the aftermarket one.

Oh, and it says electric powered RX7 in my signature

 

You'll still have to make a custom adapter to mate the electric motor's output shaft to the flywheel. The stock configuration uses a keyway cut in the stock counterweight/flywheel. Neither of which you can use due to the imbalance they would cause. But then again, you aren't limited to the keyway system since you're not using a stock e-shaft either. So really any coupling mechanism can work.

Why are you trying to use a transmission instead of running the electric motor straight to the driveshaft?

 

The adapter kit for the RX7 comes with the motor plate and the adapter to bolt the flywheel to the motor. The research I've done tonight, shows it is designed to use the Turbo style flywheel with the bolt on pattern (adapter takes the place of the counterweight). So I guess I'll be buying an aftermarket light flywheel.

As for the transmission, I plan to use the car on the highway, and more than one gear is best for this application. Plus it's free reverse. Most EV conversions use a stock manual trans. The direct drive guys don't generally see highway driving.

 

Thanks for the info. I guess I'm just more familiar with the Tesla drivetrain that utilizes a single gear transmission. But I'm sure the motor and control setups are very different. Interested to see how this project turns out.