Carthik

I have done a search, and from what I know (correct me if im wrong), s4 and s5 NA transmissions can bolt right up to a gsl-se with a minor exchange of parts between the transmissions. Is it the same with 12A? Also, why would one go about doing this? (are they stronger? different gear ratios?

thanks,

Carthik

Naegleria_Fowleri

I am going to say that the S4 and S5 NA transmissions are stronger. I'm not sure on the different gear ratios.

Why are you wanting to swap transmissions?

blazer1313

what year 12A? for all 1st gens the hole where the shifter sits is farther back than the stock tranny so some cutting and new shift boot may be in order. Gear ratio's are really the only thing different. IMO I would just find a GSLSE tranny...no fabricating and 5 is a higher ratio..i think i said that right...60 mph is ~2700 RPM instead of 3000 RPM. Capable of handling up to ~200 HP depending on how many miles are on it.

Hyper4mance2k

iTrader: (40)

To swap in a na S4 or S5 tranny all you have to do is swap in a FB tail shaft and it's bolt in. The benifits are they are a tiny bit stronger. Better turbo gear ratios, and a huge 5th gear for cruizeing down the freeway at 2ooo rpms. if your going to build a na engine I'd recomend a 626 or miata tranny.

Rx-7Doctor

iTrader: (13)

Correction time. Applying to manual transmissions.

The Sa model transmissions have shifters that are closer to the dash area than the FB's. Which means when putting a 1st gen transmission from a 81-85, (engine size makes no difference) the transmissions have the same bolt pattern and lenght.
You have to cut the tunnel back approx 2.5 inches to install the above transmissions in the Sa. There is also an exception on the later model Sa transmission where the actual tail shaft housing and internals of the shift forks can be transfeered to the Fb transmission and the modifying of the tunnel is not needed.
The transmission from the 13B Gsl-Se is the same bolt pattern and lenght as all 1st gens are. The only difference is in the final gear ratio.
The 2nd gen N/A transmissions from 86-88 are also the same lenght and have the same bolt pattern as all 1st gen transmissions. The only mod needed to install the later 86-88 N/A transmission is to swap out the tail shaft housing when installing these transmissions in a 81-85 model. Again with the 79-80 models you still have the tunnel issue to deal with.

Thanks to Wackyracer for the input on the 89-91 N/A transmissions.

Using the Fb transmission in the Sa also requires more than just a shifter boot modification if you have the early years and have to cut the tunnel. The shifter now sits too close to the shifter console trim. Therfore modification of the console, shifter trim, and shifter boot are needed.
The easiest solution I can see for the above modification is to have the Fb shifter modified to duplicate the original configuration of the Sa shifter. Then you can use the original Sa shifter trim and boot.

Siraniko

iTrader: (13)

With the S5 tranny, you cant swap 1st gen tailshaft housing due to large rear counterweight.

Rx-7Doctor

iTrader: (13)

I'm confused Wacky. What does the rear counterweight have to do with the tailshaft housing?

Siraniko

iTrader: (13)

Typically, you can swap tailshaft housing so you dont have to cut the floor board. However, that is not the case on a S5 tranny. If you look at the S5, the back end has an oval shape as there is a large counterweight in the back.

Rx-7Doctor

iTrader: (13)

Thanks Wacky for the corrected info. I will edit my post to reflect the correct info.