Just got a new ACT Flywheel and the middle hole is WAY bigger
 

This is a flywheel for 86-92 and when the stock was taken off it was just the one HUGE bolt reverse threaded i believe. this one has a larger hole in the middle with 6 bolt holes around it. Will this fit. I can't get to my RX7 atm.

You need a counterweight from an automatic transmission equipped RX7 of the same series. The counterweight mounts the same way as the stock flywheel (with the huge nut), the flywheel then bolts onto the counterweight.

The counterweight looks like this:
https://img388.imageshack.us/img388/...7109kj4xt4.jpg

^^ yep yep

wow I never knew that... is that for all second gens that are standard?

If you have a series 4, you need a series 4 automatic counterweight.

Series 5, same game.

It is true for ALL 12A/13B/20B. The front counterweight, rotors, and rear counterweight should match the model/year of the car (in a nutshell)

on the stock flywheel the couterweight is built in. That is also why companies can say the flywheel is xx amount of lbs, add the counterweight then it goes up a bit as well. :D

the stock flywheel has the counterweight incorporated into the Flywheel.
The Counterweight that you need are used for Automatics.(from the Flexplate)
when you go to a lighter manual flywheel,that counterweight is needed,as the aftermarket flywheel is sold as just a flywheel.This flywheel is not series specific,so you can put the s4 or s5 counerwieght on,.BUT you need the Correct series counterweight.(so an s4 counterweight for s4..s5 for s5....the N/A and TII counterweights can be used for any application,either N/a or TII..it doesn't have to be a Counterweight Specifucaly for a TII to run the flywheel.it can be from an N/A.
Hope you can decipher that!

just to clarify u have to use a rear counter weight from a car that was auto from the same series

If you need a S4 auto counterweight i have one i can sell you. PM me if interested. - Nick

I can't believe people don't know anything about the counterweight and they want to replace their flywheel ...

+1

+1000

It just proofs that people want to be the next "2f2f" star without knowing a R26B inside a Mustang means a failed ...

cut him some slack, not everyone who sells the ACT flywheels put a footnote that the counterweight is also necessary. on most other vehicles they bolt right up to the CS. it's an easy oversight.