transmission gear selection questions

[Whizbang]

since i am going to have to drop the fuel tank here soon and see why the pump is getting no fuel, lets talk about a future upgrade i am planning!

The transmission replacement!

The stock rx7 transmission has some piss poor gear selection. The stock 12a gearbox is shown below.

3.674 (1st) 2.217 (2nd) 1.432 (3rd) 1.00 (4th) 0.825 (5th)

The spread does not take advantage of what the engine can really do. For the sake of my build, the Mazda Comp Manual PDF (see the FAQ) has some good information on the Mazda Competition Transmission. If you want one...well that sucks because your looking for a surviving used one.

BUT the information i did get from the PDF is the gear selection of the comp. transmission.

2.350 (1st) 1.608 (2nd) 1.240 (3rd) 1.00 (4th) 0.881 or 0.839 (5th)

This information is priceless for the sack of want to do. As a bonus, that setup was used with the 4.88 final drive and a 12 PP. Ill be running a 4.78 with a 13b Bridgeport. So i am close to that the "perfect" setup would be.

So why does it matter that i know the ratios of a transmission i cant buy anymore? Well thanks to people with more time and money than i have, there are bell housings and other adapters to run other transmissions on the Mazda Rotary.

The transmission i want to use, if i can find an adapter for the GM 1-1/8" 26 spline, is the Richmond Gear Super T10 with the 2.43 (1st) 1.61 (2nd) 1.23 (3rd) 1.00 (4th) non overdrive and is only about 1500 dollars.

The ratios are very very close to the Mazda Comp.

But i dont know of a GM adapter, ill have to look, but if i cant find one, the option for the Ford T5 adapter exists.

The ratios for the Richmond Gear Super Street 5spd are:
2.89 (1st) 1.85 (2nd) 1.31 (3rd) 1.00 (4th) 0.77 (5th)

OR there is also the Richmond Gear 4+1 5pd with

3.27, 4.06, or 4.41 (1st) 2.13 (2nd) 1.57 (3rd) 1.23 (4th) 1.1 (5th)

I do not like that setup for one reason, first gear is useless with a 4.78.

I think i need to call Summit and see what other options not listed in the catalog are....