mirabile

Same as my radiator thread. I searched and found a lot of people claiming a lot of different transmissions were the best for the 20B.
What do people think...Clutchless?

felix_is_alive

this of course my good man depends on what youre going to use the car for , is it going to be drag,track or street i think most people doing this are using the stock turboII or stock 3rd gen gearbox , seems to hold fine to a certain power level
some guys where talking about a ford transmision not shure though

Rocking Rotary

iTrader: (14)

Felix has got that right. It all depends on the power and use for it. I am on my stock FD gearbox and have not had any bad luck with it.

Turbo 3

iTrader: (3)

stock FC TII trans is fine for up to 500 HP or thereabouts for street/track. Drag racing is another animal is you are essentially trying to break everything so the requirements are a bit...more.

rarson

Yeah, obviously it'll also matter how you drive the car. If you go easy on it, the stock stuff will be okay no matter how much power you're making, but if you throw on slicks and try to launch the car hard with gobs of power, then obviously you'll break things rather quickly.

I always used to laugh when John Shepherd would talk about how he "babied" his tranny on his AWD Talon. It's the fastest DSM out there, running crazy times, and he's talking about how he babies it because he runs a modified stock tranny. Sure doesn't look like he's babying it!

mirabile

My plan right now is the drive the car, with occassional trips to Atco, and at some point do a little auto x. So basically I need something that is all around multi purpose. Right now its probably just another stock tranny because I am starting to grind going into 5th. However I really like what I have read about the Greddy trans, but I think it was discontinued and cant find the link I had it on.....Anyone ever seen/driven one....nice prce tag on it too.

Bitchn7

I ran a S6 RX7 box in my 20B JC Cosmo, previous to me obtaining it the box had been behind a 600+HP supercharged 20B in a 2nd Gen running slicks at the drag strip for quite some time, box was fine.

wptrx7

If you are looking at spending Greddy money, why not go with a T56?

Rhode_Dog

Doesn't the T56 take higher RPM's unkindly?

mirabile

I heard the same about the T56. Can anyone confirm or deny this?

Rhode_Dog

I read somewhere on the forums about it being unfriendly to higher revs because of its synchro design, but I am no expert on the T56.

If I were in a situation to ditch the stock gearbox, I would go with a V161 (the MKIV supra transmission with shorter ratios). Guess the big drag is the custom bellhousing.

patman

iTrader: (3)

I think some versions of the t56 are high rpm friendly and some are not. Unfortunately I dont know which are which...

wptrx7

I think the viper ones are, but I don't think they are Rotary high, lol.

patman

iTrader: (3)

ona turbo 20B, what are you really gonna run tho? not more than 8k i wouldnt think... what does a viper redline at?

Turbo 3

iTrader: (3)

I've driven a T-56 on a '96 camaro that was rebuilt with stock ratios but hardened gears and it handles a 10K redline no problem making 900 HP AND 900 torque to the wheels! Don't know how a stock box would hold up but why wouldn't you rebuild it anyhow for this application???

rarson

What was the engine attached that was making 900 whp and spinning to 10k??

FDNewbie

iTrader: (10)

You guys need to check out this thread: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/t56-tranny-fd-609461/ If you go the T-56 route, you need to use the double/triple synchro setup, steel fork, and upgraded input shaft. It's all discussed in the thread. Long read, but worthwhile. And yes, the built T-56s can handle very high rpms and very high torque levels.

Re: the Greddy (and other dogboxes), I'd read these first...
- https://www.rx7club.com/forum/showpo...&postcount=165
- https://www.rx7club.com/20b-forum-95/jerico-5-speed-20b-155219/

As you can see, there's no dogbox you can get that will do the trick w/o an ENORMOUS amount of custom work to fit it into the FD, plus a $10,000+ tab for the tranny itself (ie Holinger). Reason being, all the ones that fit in the FD case a) can't handle the torque, and b) will fail due to the casing flex at higher torque levels.

Basically, the answer is there currently is no REAL answer for serious hp levels. Having said that, however, mirabile my honest advice for you is to keep your power levels LOW, being that it's an early series block. In fact, the top 20B builders in the country (professional racers and consultants for Mazda) testify the block is only good for about 600 - 700 hp at short spurts - and that's assuming it's built and *clearanced* properly, rotating assembly is balanced, the correct seals and rotors are used, and the boost level isn't too high. And even then, you're looking at e-shaft and HOUSING flex past 8K rpm. So honestly, I'd stick w/ a stock tranny if I were you, keep the power level around the 450 mark, and you'll pretty much be fine.

That's my $0.02. But I mean hey, what would I know. It's not like I did any reseach or anything

~Ramy

Turbo 3

iTrader: (3)

It is a '96 LT1 bored and stroked to 402 cu in., supercharged (6 psi) and no IC. It had a little bit of work done to it Needless to say, when I drive it, it doesn't go past 7K as I don't want to overrev it and it is so fast that you don't need to rev it that high anyhow... scary as hell!

mirabile

If only I would be happy with 450. haha. Anyhow, I appreciate the advice, and will most likely break some stock ones. Thing is, if the engine breaks, I will rebuild it.

FDNewbie

iTrader: (10)

Well breaking stock ones isn't a prob, cuz they're cheap to rebuild, and easy to source. But replacing gears from a custom tranny (HKS, Greddy etc), good luck. Pretty much everyone is slowly getting out of the FD scene, simply due to age...

And I hope the block doesn't break/blow. Rebuilds on 20Bs are rediculously expensive, and some parts are EXTREMELY rare (irons, e-shaft).

patman

iTrader: (3)

Ramy,

What is this based on? I was under the impression that the only difference between the early and late 20Bs was the thicker castings on the irons, is there something else I didnt know about? I was planning to pin mine and hoping to make around 750whp, i hope this is still going to be possible...

Thanks
Pat

FDNewbie

iTrader: (10)

Pat, to put it delicately, it's based on talking to the handful (literally) of ppl who are adept 20B engine builders. Manderville, Drummond, etc. Ppl who Mazda consults for data on the 3 and 4 rotor motors. These are the professionals in the game.

Yes. The E-shafts were prone to the "snap torque" phenomenon, allowing them to do just that - snap in half. They were thus upgraded for the B series and up, yet only the C & D series had upgraded backing plates The prior series had less "meat" on the side plates.

A) Depends entirely on who builds your motor. A 3-rotor is NOTHING like a 2-rotor; the building skills aren't equivalent. Moreover, the *most critical* part of building a 3-rotor is the clearancing -- something that you can ONLY know via tons and tons of experience. Furthermore, unless you get fancy w/ the rotors and seals, the block is only good for 600 or so hp. It can handle 700 hp in short spurts, but not for any sustained time period. Ditto with redline; you're realistically looking at an 8,500 rpm redline (8,000 would be even better). Beyond that, not only are you prone to e-shaft flex, but also housing flex, despite dowel pinning the motor.

Of course, you *can* make more power on the block, and it *has* been done. But I remind you of 2 things: 1) Just because you can doesn't mean you should. There's no telling of how long it'll last, and rebuilding a 3-rotor is not just cost-prohibitive, but many of the parts are very difficult to get ahold of. So even if you have the money, you may not even be able to find the parts. 2) Some of the people well known for making tons of power on 3-rotors are also hardcore racers, which tear down their motors quite often. I have yet to meet someone on the forum who's interested in maintaining that kind of maintenance schedule

Just something to think about...
~Ramy

patman

iTrader: (3)

well...i think i will continue as planned then...if i do break it, hopefully it will be after i graduate, and i can afford to just get a kiwi kit or something. I wasnt planning on running 750 hp all the time, just at max boost for race days or dyno pulls. 500 or so will be street trim. I never planned on revving over 8k anyway, so thats no problem. The motor will be built by me, so forget about the experience thing. You might think thats dumb, but I've built every single part of my car, and the experience is half the fun for me.

mirabile

ooooohhhh Ramy. Dont worry so much.

As always your insight is appreciated. It would be too bad to have to rebuild it, but though parts are expensive, I have not found them all to hard to find. Just need to have the time to look.

Getting out of the FD scene? If the scene has been "shrinking" thats news to me. I guess you would know better, since your business is based around it.

Anywho, this thread was based around the best possible choice for transmissions, and what people had done with their 20Bs. The feedback has actually been pretty good before the digression.

Final answer Ramy, what Tranny would you use on your 20B?

FDNewbie

iTrader: (10)

Sounds like a wise plan My worry is what may happen when she's on the dyno, trying to make the 750. My honest advice would be tune for the power levels you're positive your build can handle, and leave it at that. If I'm being overly cautious, worst case is you have a 500hp 20B If I'm right though, you can easily be one of the tons of guys who end up selling their entire project when they realize a proper 20B rebuild is $8,000+...

Oh I'm with you. I like to learn and experiment as well. But (this is just me), there are some things where the ability to gain experience comes at to high a cost - the expense of dealing w/ a blown 20B and byebye to a very nice turbo as well.

That's one way to approach it. If I were in your shoes, I would rather approach it by saying I'll do the swap all by myself, and make sure I buy an already running motor, and leave it stock. I personally don't think it's a good idea to try and mess w/ the internals yourself. I've seen one to many of those trials go sour...

My simple answer to that is, the more you know, the more you'll worry. And the few that have done the research feel exactly the same.

I personally think it's very unfortunate that one too many a people take 20B building too lightly, only to realize how serious they *should* have taken it the first time around. I don't want to belong to that camp. The guys down under have TONS of experience w/ 20Bs (as well as rotaries in general), and are simply *years* ahead of us when it comes to these things. So when they speak, I really do listen - esp. when they're professional racers who have been in the game for *years* and are sharing with me their invaluable experience on what went wrong and what NOT to do, and how to do it right.

Well expensive and hard to find are often used interchangeably. I don't know how long you've been in the 20B game, but I can tell you that only a year or two ago, the number of motors and spare parts was *easily* 2 - 3 times more scarce now. So a lot of it has to do w/ perspective.

Yes it's most definitely shrinking unfortunately. If you don't see it yet, give it a bit more, and you'll notice it. That doesn't mean the FD isn't still well respected and adored by many; it just means that the market for it deminishing - and even if it isn't deminishing considerably (which I think it is), it's new competitors' markets are growing exponentially - enough to make it hard to impossible to justify maintaining production for FD parts. Look at the 350Z, WRX, and STi crowds. They make the FD market look non-existant, and to companies, it's *always* about a cost-benifit ration. We simply aren't worth the expense more and more everyday.

The best answer for that would be to hold off on your tranny until this issue is solved. It's kinda late in the game, but I think we're about to have a breakthrough in the next few months

Who said anything about me having a 20B? lol. But if I had a 20B FD, based on my research, the T56 is the hands-down winner, no questions asked. Again, HOW this is done hasn't been finalized 100%, but as I mentioned above, sit tight, cuz the solution is about to become clear shortly.

~Ramy