I have a highly modified RX-7 13B engine and the tranny blew after it was autocrossed hard about 50 times by the prior owner. I was going to put another M box tranny in there from a low mileage donor. I have no plans to race. My car puts out about 240 hp. Do I really need to convert to a twin turbo type R tranny if I don't plan to race much? Maybe I'll do a couple of laps but not in a race. Thoughts?

 

not sure what type the M transmission you are referring to is but i assume it is the non turbo split case. the turbo II transmission will hold up to just about whatever an n/a can throw at it, up to around 450RWHP, you will need the TII clutch and modified driveshaft from madatrix or have one custom made to adapt to the n/a differential. i have used all the stock hydraulics without an ill effects on some cars, although they are different as well.

 

The TurboII being the r-type if I remember correctly.

 

well at any rate, there is no need to swap to a 3rd gen transmission. they are virtually almost identical to the TII tranmission aside from the BS they call a powerplant frame and crappy pull type clutch, but slightly better syncros and shifter mechanism.

 

mazda refers to the NA style transmission as the M type, and the turbo as the R type.

i'd just stick with the M type, the turbo trans doesn't last very long behind an uncorked NA motor, and doesn't like high rpm shifting either.

the turbo gearing is pretty lousy for an NA too.

best cheapest option is the miata gears in FC case..

 

he already stated he doesn't plan to race it so the R type will outlast the engine so long as he doesn't do a ton of 9k+ RPM speed shifting.