I ask cause the time has come to change out the gearing for my '87 n/a sport streetport to eek out more power to the wheels. I've heard about the miata and six-speed swaps - what about from mazda trucks? how bout ford trannies?

I considered a 6-speed, but nixed the idea in favor of the more streetable 5-speed. I'd prolly ditch the 5-speed for a 4-speed overdrive if avail. I'm definitely NOT interested in swapping in a big V-8 tranny like the T-5 as I consider it overkill / too heavy for a n/a rx7.

post what you know and what you're currently using. Feel free to include your diff ratios and where they're from too. If you've got turbo please state that too.

thanks ~rich

 

you'd be better off getting some lightweight 15's and tuning tire hieght to get more torque, keep in mind you will lose top end speed and be shifting slightly quicker.


for every pro there is a con, you don't just get more power from changing gears.

 

I'm witcha on that already - been scoping out some lightweight staggered 16x6 + 16x7's - if I were hardcore motor I'd stay 15's but my vanity screams "fill those wheel wells!" lol plus, the larger diameter will give me a lil more grip since I'm sticking with 7's on the rear.

I'm hoping to match gearing for a powerband that's 4.5k+

whatchu running Karack?

~rich

 

well...with a streetport you are probably seeing a nice sweet spot in your revs at ~ 5,000-6,500??

why not go with an RX-8 6speed, with the slightly closer ratios you will be in that sweet spot more so than now...plus it will bolt to the motor no sweat - just need a custom driveshaft...also you WILL hear of guys burning those trannies out but thats with a TII, ith you /A stretport you are probably only near or MAYBE at the level of a stock renesis so you'll be fine durability wise...

I am running a stock TII trans in my TII...

 

more gearing = more shifting = less power to the wheels while streeting. the fewer gears you have to shift the better. but if I were autocrossing I'd agree with you 100%.

~rich

 

the R type tranny (as found in the manual tranny 929, V6 manual tranny RWD MPV, Turbo RX-7s and Trucks) was also used in Ford F 150s and rangers.

So, why don't you look at the standard R type tranny???

 

good points!

 

miata tranny goes in without too much difficulty, see my thread for details. it does not give more power, as Karack said, but there is a noticable difference in acceleration and gearing.

 

I am not 100% on this but I have heard of Starion guys using TII trannys...so I think the Starion bellhousing is the same...but dont hold me to that.

-Matt

 

run a powerglide and 5000 stall

 

hehe...good ol' two speed....

 

a mazda miata uses the same transmission thats in the rx7. it will bolt up fine. early to mid 90's model year

 

IIRC the input shaft has to be modifed on the miata tranny, ask rxgirl7 she knows all about that

 

just found something about a borg-warner super t-10...lightweight aluminum 4 speed with nickel gears that came in a variety of gear ratios used during the 70's. anyone have any knowledge of these being used on a rotary? ~rich

 

Get a custom rear end made, I saw a 5.2 diff on ebay for its racing the otherday, now that would put some power at the wheels.

 

its not the same transmission, the ratios are different, and it doesnt bolt up...you put the miata gears in the fc case, and modify the imput shaft. makes quite a difference