is this possible?? if so how do u need to change the flywheel, and if so do u then need to change the counter weight

 

I think you mean "12a to T2 tranny" because mounting a 12a tranny on a T2 would make absolutely no sense at all, and would be something that you'd probably have to talk to the second gen section about

Can you mount a T2 tranny in your FB? Yes. Have you searched on this? There are many, many threads that deal with this, so if you search and still have questions, post them. And when you do, be specific.

Jon

 

I think all you have to do is take the back plate off of the 12a and place it on the back of the 13b and use the flywheel and counterweight off of the 12a in place of the 13b TII. Don't quote me on that, but I believe that is how it works.

 

Yes,itll work and its a great way to kill a 12A trans really quick.

Youll need...
Rear counterweight for the type of TII engine you have (S4 or S5)
12A aftermarket light flywheel,steel or alum. (225MM clutch is best)
12A clutch (225MM for more strength)
12A starter and trans

 

could u not just use the flywheel and counter weight from the 12a on the 13b and change the back and plate and go from there??

 

you're also going to have to factor in gear ratios here. far as i know the T2 + 12a and your GSL rear is going be pretty badly matched.

is your trans busted or something?

 

I've heard a lot of people saying that they put TII trannies on FBs.... They're stronger and from what I hear a pretty easy swap.

IIRC it's only bellhousing, shifter... but I could be wrong

Here's some useful transmission information:
http://members.ij.net/mrmazda/interc...html#TBPATTERN


Info on Gear Ratios:

Mine's an '84-'85 non GSL-SE so it has ratios of

RX-7 85 3.622 2.186 1.419 1.000 0.807

RX-7 Turbo 87-91 3.483 2.015 1.391 1.000 0.719


So only your fourth gear would be the same. This could cause problems with your spedometer's accuracy and will definitely give you a different effect when it comes to acceleration. Since the Turbo one is built with turbo hp in mind, you'll probably have slower take-off, though I can't be sure since I can't remember exactly how the transmission gear ratio relates to accel/top-end right now (it's very late).

According to the site above:

"Group 4
RX-7 FC/Series 4 & 5 Turbo

Simple functional equivalent bolt-in

1987-91 5-speed
Comments:

1. These boxes are derived from the much stronger pre-RX-7 rotary boxes. Synchronizer design was significantly improved, and the output shaft size was increased, requiring a larger driveshaft yoke.

2. Turbo models use larger clutches and flywheels and a different starter than NA models.

3. Bellhousings from the pre-1979 boxes can be substituted for use with NA starters, flywheels and clutches, partially easing their use in 1st gen cars. Sales volume from 1974-78 was sufficient that finding a used such transmission to cannibalize should not require heroic talent. The other obstacle to their use in 1st gen cars is the shifter location much farther rearward. Solving this latter problem requires some clever shifter reengineering (possibly using a portion of the original transmission's shift mechanism) or a hatchet job on the console.

4. Ford used a variant of this transmission in some of its products in the 1980s. "

Jon

 

What the hell does changing the end plate have to do with anything? That's impossible and would serve no purpose even if it were.

The correct way to do it is in the post above yours.

 

Try not to give advice based on the fact you *think* you *might* know how something works when it's actually complete crap. That's how most of the misinformation is spread on this forum.

 

the gear ratio's will give you quicker acceleration than a normal TII with TII trans(provided you have enough rear end traction). the trade off, you will be shifting much more frequently up to 4 gear, and 5th gear will give you less fuel economy for highway driving and will also reduce your maximum speed in top gear. I'm interested in the performance advantage/dissadvantage this will create. Let us have some 0-60 times once you get-er-done

 

Gear ratios do differ between the two,but its minimal and on such a light car,your unlikely to suffer any consequences.I ran my TII trans for a while before going to the TII engine and it worked just fine.

Jason,you cant swap flywheels from one engine to the next,unless they are the same series.Rotor weights changed many times over the years and the flywheel/counterweights changed with them to maintain balance.The rear weight is integral to the flywheel on manual trans engines.Its seperate on automatic cars.
The only way to hook up a 12A trans to a 13BT is to install a flywheel/clutch combo thats compatible with the 12A trans,but will also keep the 13BT properly balanced.
Thats why you need the 13B automatic rear counterweight(S4 or S5),then bolt on an AFTERMARKET 12A flywheel to the counterweight,then the clutch,trans,starter,ect...

 

thanks guys yah this all makes sense now i dont really know what i was thinking last night when i made a few of those posts oh well looks like i might just turbo the 12a will see i have a few different idea but n/a is getting boring

 

just out of curiosity, what rear end ratio is the TII? that was more my concern, since i know even using the GSL-SE trans with a GS rear-end make 5th pretty much pointless unless you tend to drive at 160kph for extended time periods.

 

Its close to the SE,4.10 I believe.
But with factory 16" wheels and 55 series tires,its about the same overall ratio as the factory 4.07 SE with 14" wheels and 65-70 series tires.

 

I run 13b-t with a n/a transmission. Used a lightweight flywheel, and auto counterweight.
Its way cheaper than the T-2 trans conversion. I get Na trans at the local salvage yard for 50bucks. They last atleast 3-4months, if you know how to shift.Oh and i drift the hell out them too

 

Who wants to change the trans 3-4 times a year when the TII trans will laugh at 300HP and last 15 years!?Its not that hard,and youll save yourself LOTS of greif and bucks just doing it right the first time.

TII trans=typically not more than a N/A trans,$40-$80 from a U-Pull-It.
Mods to fit TII trans into car=damn near free.
Custom big driveline that can take the power and abuse =$175.
Machined TII flange to fit FB rearend and a new size seal=$45.