There's something not right about that chart. The gear drops are *way* off: according to it, the Miata has the tightest 1-2 shift. In reality, the Miata 1-2 is the same as the 1st-gen RX-7 1-2 shift: RPM drops to 60.2% for the Miata, 60.3% for the 1st-gen. (The 626 transmission drops to 56.5%, the FC units to 57.6%.)

It looks like the "spacing" is just calculated by subtracting one from the other instead of dividing. By that method, a 1.5:1-to-1:1 shift would be the same spacing as a 3:1-to-2.5:1 shift... clearly not the case.

 

peejay is right, you cannot compare ratio differences by subtracting numbers; ratios do not work that way.

 

just too round out the tread the 06 miata 5 speeds are the same internally as the earlier miata's.

the 06 miata 6 speed however is unique, its based on the ford/mazda truck transmission

 

Hey, just to dig this up, out of curiousity, how durable can the RWD 626 boxes be made? We have a Prather built unit in an FC case, and I'm just curious how long it's going to last in the (12A powered 1st gen) EProd car.

 

Anyone have another info about this input shaft? I've found it via Mazda Comp, but I can't seem to find anyone who has used it or who knows anything about it. Is it larger diameter, or just made from a different grade of steel? Anyone?

/Bumping an old thread, so sue me.

 

If I recall correctly, that input shaft is to go with the Emco built close-ratio gearset. To simplify things, the gearset was/is made for any of the smoothcase transmissions, with the input shaft bought seperately so that the gearset can be used in either Miata or RX-7 boxes. Not going to be compatible with the normal gearsets.