Can we use the RX8 transmission in the FC?

 

Yes!! I have one in an rx3 and there is way less room

 

Is it similar to the FD?

 

Anything is possible with enough money and work. There are reports of some people completing this swap, but the general consensus is it's not much of an upgrade for most applications.

 

General Consensus of who?? I would guess from folks who have never actually done it. I thank that is a perfect upgrade, especially for an NA application. I have no regrets. I run a 4:44 rear gear, same as the rx8, and my power band is pretty much anywhere i want it to be!! keep in mind my car is pretty light and i run a big ported 13b with a Holley and free flowing exhaust.

 

I have seen reports on this forum over the years that the RX8 transmission can't take the abuse the TII tranny can. Obviously this doesn't matter for NA or even some hybrid turbo cars, but making 350+whp I haven't seen a lot of supporting data stating it's up to the task.

 

From what I understand the RX8 uses an Aisin AZ6 which is similar to the Miata 6 speed. People swap out Miata 6 speeds for TII trannies to hold more power; the MiataTurbo community places the AZ6's break point somewhere around 350-400 WHP.

 

Yes but it's not a direct swap. This thread covers the most of it. Biggest hurdle seems to be getting a working speedometer since there is no provision for one on the transmission.

https://www.rx7club.com/2nd-generati...-fc3s-1063279/

 

every part of the Rx8 trans is beefier than the miata. they are both AZ6's, but share almost no parts

 

General consensus based on the math/gear ratios. Don't get me wrong; I've considered this swap for my peripheral port FC, but I don't think the difference in gearing in the Renesis transmission is worth the work. In addition, the only Renesis transmission worth swapping is the second generation with upgraded synchros. These transmissions are much higher in cost than first gen Rx8 transmissions.

The rear gearing makes a world of difference and has the most effect on your power band. Unfortunately, the FC has a stupidly long pinion and there are no easy (read: cost effective) methods to obtain better rear gearing. Your only options are a 1k welded pinion via Mazdatrix (and you need to send a pinion to them, with no ETA on turnaround times), swap in an Rx8 rear diff (will need custom mounts, driveshaft, etc), or to spent 1500-2k on a Ford 9" swap

 

the Rx8 gearing is pretty much the factory race gearing with a granny 1st, if you're revving the engine higher, its way way way way better.

the T2 trans works great with a turbo car, but for some reason the PP engines tear them to shreds

 

Interesting, I thought the Rx8 gear ratios were a negligible upgrade for the FC. I just had my T2 transmission rebuilt and thought about selling it to swap in a second gen Renesis transmission. The T2 trans definitely doesn't thrive at higher RPM's that I'm always in.