Gear ratios?
 

All,

I'm doing a bit of research for my FC road racing friends from the ITS series...can we swap in ratios from the 79-85 series cars into NA 2nd gens bc all I find is a 4.30 rear and some of these tracks could use shorter gearing since the NA motors are so low on torque. The 79-85 boys can swap in anywhere from 3.90 - 5.12 gears, now THATS adjustability...are the NA FC's at all interchangeable with the FB tranny/rear? BTW, we run a 325I at Z-1 Performance and the FC's regularly SPANK us even though we outpower them severely...they just maintain speed and balance so well, our head driver wants me to strip my street NA FC and toss in a cage and slicks (all my other mods are legal for the series, even my type coilovers and camber plates - but I'm goin the TII swap route thanks to Kevin Landers...the motor he built for me is just sitting in our shop for the past few months waiting for me to get the time to swap it in hehe). The 4.30 rear from the GTUs won't do it for these boys, they need more hehe

Thanks!!
Jon

You have a couple of options. Ill start with the weaker ones. You can use a miata pumpkin mated to the FC rear housing, using a n/a LSD. That opens up the full range of miata/FB gears(theyre the same). You will need a custom diff mount, and a custom driveshaft because the diff is shorter. Second option is use the miata/FB ring gear, and cut the end off the miata pinion, and weld it onto the longer n/a pinion shaft. But if youre putting down good power, this may not be strong enough for you.

Next set of options is to mate up an FD diff. There is a 4.77 ratio available, as well as a 4.3. But I dont know if it would be worth the fabrication. A better bet may be a ford 8.8" IRS diff. They were in the mid 90's thunderbirds, and in the IRS Mustang Cobras. That has a wide range of cheap gearsets available(~$200 each, vs $500 for RX7 gearsets).

Either way, you want to check your rules, and see exactly what is legal.

Regearing Transmissions
 

Here is my page on regearing mazda type 2 transmissions:

http://www.angelfire.com/darkside/de...nsmission.html

I have an 83 GSL 5th gear in my truck and am getting ready to put a S5 tranny in from a 7 conv.

You could put a B2200 tranny in, all you would have to do is put your bell and tail housings on the 2200 tranny then bolt back up in your car. All type 2 transmissions are made the same so the only difference would be the ratios. This is only for modifying factory transmissions though, I don't know if you guys are running aftermarket performance ones or not.

Tell your friends to contact SpeedSource
http://www.speedsourceinc.com/conten...mplate=history
I think they have 5.12 gears