Bit of a background...
I'm going to be starting building a kit car soon, currently do all the research and sourcing parts etc.
While i'm going to be using an Rx8 as a donor as they pretty much 10 a penny, i've got my hands on a 13b REW as the power plant.
It is literally just the bare engine so i'm looking into what gearbox would be best suited for it.
The plan is to street port and supercharge it and hopefully get about 450bhp.
I was hoping to use the gearbox from the donor Rx8, but after reading up the 6 speed won't be able to handle the power very well.
I know an FD gearbox would be ideal and can take it no probs, but i've also been told the 5 speed from a 192 is the same box, but i cant find anything to confirm this online?

If this is the case it would be ideal and save me some money, does anyone here know if they are indeed the same, or just if it could take the load?


Cheers all
Jon

 

welcome to the board.

is "192" just a typo for '92? i think there was a '92 FD in some countries, i don't know if yours is one of them. if it is, then clearly it will be the same.

since this will be a kit car - and assuming you have the liberty to do about anything you want with it - you have options. the T2 tranny can handle 450. no problem. so that's one option. simple, bolt-on and likely to be less or equal to the FD tranny in terms of costs.

another option is trying the Rx-8 tranny. 95% of people that post say they are weak and i don't doubt it, but a LONG time ago i saw an Rx-8 20B build and the person decided to modify an Rx-8 tranny. i don't know if he was successful or not (he had gotten as far as using a custom input shaft when i last saw it) and if so, i don't know the outcome. i just figured i'd mention it in case you'd be interested since you said your donor car is an Rx-8. custom works usually means BIG money though.

there are other options, but i figured those are the two that don't require swapping bell housings, so i'll leave it at that for now.

 

Thank you

Sorry, i should have been clearer in my post.
By 192 i meant the 192 model Rx8.
In the UK there was really only 2 main models of Rx8, the 192 with a 5 speed box and the 231 which had a 6 speed.
So in terms of a donor i can choose which one i use.

I know the 6 speed cant handle the power, but i've been told the 5 speed from an Rx8 is the same as the box on an Rx7 FD and that can.
What i'm struggling to find out is if this was just hot air or they are in fact the same?

I'm quite lucky to be a CNC machinist so i can do a lot of modifications or make an adaptor myself if need be.
But i'd rather not have to bother to be honest.

 

my friend you have just taught me something and have given me an idea/solution for 2 of my projects in one felled swoop. thank you.

yes. (based on a photo i've actually had for a couple of years now) it appears that the 5-speed Rx-8 was a Type R (ribcase) and therefore is at least related to the FD tranny. my guess is it would have different ratios, but that's simple enough to check.

 

Erm, not entirely sure how i helped, but you are very much welcome! haha

I've only been delving into the world of rotaries and Rx's for a month or 2 so i'm still on the steep part of the leaning curve.
I wasn't originally planning to use an REW engine, was just going to get a good condition Rx8 and use that.
But then the REW came up for sale threw a mate and suddenly the idea off a potential 1000bhp per ton popped into my head!

But back to the point....
Thank you, that is close enough to a confirmation for me.
It would seem logical that they are related, it would be cheeper for Mazda to use essentially the same box than develop a new one.
At the end of the day even if it does go pop it won't be the end of the world, the car will only be used for Sunday fun and maybe some track days.

Ta muchly

 

JonnyH, you're spot-on about Mazda doing some parts-bin engineering whenever possible. Our pilot bearings are the same exact ones put into use in 1967 with the Cosmo 110S!

Actually diabolical1, wouldn't it be closer to the TII transmission? Both the RX8 (in 6-speed form) and the TII FC both use the same N318 Clutch setup. The 5-speed one has a N317 prefix on the clutch (never saw that before!) and a N319 prefox for the bellhousing. N319 is normally a Japan-spec TII Automatic-specific prefix, so this has got me stumped.

Gut feeling says it's closer to a TII at the bellhousing, but with the improvements shared with the FD and RX8's 6-speed

 

Reminds me of my Nova days and being able to drop a Calibra engine in and using a load of different parts from a load of different Vauxhall's

You might be right there though, i loosely recall reading something about having to swap bell housings and an automatic one was involved somewhere.
The details escape me

But still, so long as it can (hopefully) handle the oomph and pretty much bolts strait on it's all good.

 

1. i never knew about the 192 or 231 codes, but given where i live that's not surprising. as far as i know we only got the automatics with our 4 port engines.

2. well, long story, short, i have two projects: one on paper and one that i'm actually currently working on that i was thinking what to do for a transmission. i've had a few photos of the Rx-8 5 speed box (pirated from Higgi's build thread ) for quite some time now and not once did i look closely at the box until yesterday when i did so for the sake of your thread. i think the Rx-8 5 speed will solve the "problem" in both projects, so i will be going on the hunt for one in a few months - after the holidays are over.

that's how you helped me.

nothing new there - for a manufacturer to share parts between models. however, the one piece that seems a bit bass-ackwards to me is why use it with the low-power engines? assuming it is a Type R tranny (my conclusion was based solely on a few photos since it seems to have a separate bell housing and the ribcase), then it would be stronger than the 6 speed used in the high-power cars. would it be for a mileage rating in certain markets like North America? i don't know ....

 

would it be closer to the T2? i have no idea. my comment was off-the-cuff defaulted to the FD simply because JonnyH had referenced it in his original post. i, myself, wasn't making a distinction between the FC and FD. i was just commenting on the Type.

that said, i'm nowhere near as well-versed as you with the tranny/clutch codes. so i simply could not have given it much thought past Type M versus Type R versus whatever type the Rx-8's 6 speed is. as i understand it, the 6 speed has no lineage with the rotaries at all, it is allegedly a Gen 3 Miata transmission (or so i've read) fit to a rotary.

reading what you wrote though, it certainly makes a little sense to me. if N319 relates to automatic T2s, then that falls in line with the 5 speed being available only with the 4 port MSP engines.

based on the light you've shed, i'm thinking they just bolted that bell housing to the old Type R and adjusted gearing and tail housing to suit the Rx-8.

aside from gearing and differences in bell housing and starters, are there many (or any) differences between the Type Rs used in the factory turbocharged cars?

if you get a minute, you should check out Higgi's build thread and tell me what you think. you can post back here or PM me. last time i looked at it, the photos were still there, but if it turns out they're gone, let me know and i can furnish a couple. ahh ... the benefits of internet thievery.

 

RX-8 5 speed is pretty much FC TII/FD gearbox as far as i can tell when i put one next to the other (of course bellhousings are different and tailshaft housings as well)
Gears rations are mostly same too...

 

i would use a s5 turbo tranny for ease of push style throw out bearing

 

I second the recommendation of a TII transmission if only because of the proper push type release bearing. The FD transmission is a pain in the *** to deal with because of the pull clutch and that stupid snap right which holds it in place.

 

RX8 5 speed transmission uses proper push type bearing, and works fine with FC TII flywheel/clutch setup.....