I have a 87 NA that just recieved a mild streetport and a completely new exhaust system and intake. It also has various other upgrades such a sparkplugs/wires, etc. However, my transmission is completely stock, as well as the flywheel. I havn't put the car on a dyno yet but I estimate it to be somewhere around 190-210hp and slightly less torque. Some tuning will undoubtably be neccesary. In any case, I was wondering how much hp/torque the stock NA tranny can take before I start having problems? I know I should have looked into this earlier but in any case I will have enough $$$ to fix it if something is wrong before it comes outa the shop. Any info helps, thanks.

 

You should be OK with the NA tranny around 200 hp if you're gentle with it. Abuse it, it'll likely break.

The magic number seems to be around 200hp to the wheels. More than that, you start breaking the NA trannys by sheering off the teeth of the countershaft input gear.

-=Russ=-

 

Having broke more than one of the NA trannys...

Power isn't your biggest concern. It's how you treat it. Treat it with kid gloves and they'll last. There's many a turbo Miata making over 250whp with a tranny that is for all intents and purposes internally identical to the NA RX-7 box. The alternative is a track car like or ITS prepped RX-7s (making around 175whp) that break boxes on regular occasions because they are abused.

Also I doubt you'll see 200+ crank hp. In the end treat it right and it'll last. Abuse it and it will be short lived no matter the power.

 

what other tansmissions will fit in the FC that are better?

 

Turbo tranny will work with the mazdatrix hybrid drive shaft or the rest of the turbo drivetrain.

 

The Turbo II transmission is MUCH stronger. I know there have been 500WHP FCs running on the stock TII transmission without problems.

-=Russ=-

 

what i meant more is will a T2 tranny last longer than an NA one or is the life about the same?

 

im looking for longevity here. i know my tranny has about 20-25K left on it before i either rebuild it or get another one. i would like to also get a driveshaft with interchangable U joints and a new ACT clutch when i do it.

 

190rwhp w/ those mods? on a s4? If you put 160 to the wheels I'll be surprized. Don't worry about your transmission it will be fine. Just dont beat the hell outa it.

What makes you think your tranny only has 20-25k miles left on it?

 

ive also been through 2 n/a tranny's. I didnt know mazdatrix had a driveshaft to fit the t2 trans, thats definately something to look into. But yeah, the bearings went bad in my first trans, and that was just cuz it had about 130k miles on it. But the second one saw a lot of racing and hard 2nd gear shift locks and lasted maybe 6 months till the little box where the linkage connects to the shift **** broke. But rebuilds are not cheap, the place i went wanted $600.

 

http://mazdatrix.com/getprice.asp?partnum=2691-000

Not a bad price at all, especially with replaceable u-joints. Looks like i'll be lookin for a t2 tranny soon.