R.P.M.

iTrader: (3)

I know, I know....search...blah blah blah.

I've searched and everyone seems to hate it.

So heres my question:

Would the closer gear ratios of the 6spd be any advantage for a track car? Like I'm not talking 1/4 mile drag racing, but Shanonnville or Mosport or Dunnville.

Would it not be better to have shorter gears to rip through, when entering or exiting corners? I'm not a racer myslef so I dont know. That's why I'm asking

Please dont tell me that the RX-8 tranny is just a weak Miata gearbox and that it will never hold up to a tubo'ed 13B.
I know of a 600whp 20B that is putting power to the ground through an RX-8 tranny. He also ran a 10.4 in the 1/4 mile with it.
Yes it has been modified internally. It doesn't take much to make the RX-8 tranny capable of taking that kind of power.



Anyways it just kinda got me thinkin.......

rotary downshift

lool as far as gear ratio .. it all depoends on driver preferance ... and track ... if ur on atrack with tight windy curves yes the shorter gears will help .. but if your on a track with stairhgts thats essentialy where u will have your *** handed to you ... it just depends on what kind of driver your are .. finess or brute force?

misterstyx69

iTrader: (142)

hey Joe..read RX7GIRL'S thread on her set-up ..Miata gears in a rx7 tranny housing..goes into a lot of detail..It was good info ...Dave/misterstyx69

coldfire

iTrader: (1)

gear ratios are a function of the powerband of the engine, and are quite easy to determine once a power measurement (i.e. dyno graph) is obtained.
theoretically stock ratios are supposed to be calibrated perfectly towards the car, however sometimes a few liberties are taken to get a more "driveable" ratio, and things like 5th gear also. there is also some balancing to be had between the final drive and transmission ratios...
in real motorsports of course, the powerband of the engine is only a base for gear ratios. each track will present it's own uniqueness in choosing gear ratios...

so, really, it depends on the engine you are pairing it up with. ideally, you want to dyno the engine, calculate average shift time, and from the final drive ratio you can calculate the optimum transmission ratios.

one thing to consider is that a 6spd gives you closer speed-points so it can provide better accuracy to keep you in the powerband through various situations.

some stock gear ratios:


Mazda RX-8
Final Drive 4.44:1
1st Gear Ratio 3.76:1
2nd Gear Ratio 2.27:1
3rd Gear Ratio 1.65:1
4th Gear Ratio 1.19:1
5th Gear Ratio 1.00:1
6th Gear Ratio 0.84:1

rx7racerca

iTrader: (1)

I agree with the previous posters that the answer to your question will depend on the track as well as driving style. I would think that in principle, a 6 spd should potentially be better, as it gives you one more gear, suited to your engine's powerband and a range of road speeds. In reality, it's not always that simple; because 1-5 gears become shorter, you may find yourself topping out a particular gear all the time, and yet not spending much time in the next gear before having to downshift again.
Autocrossing provides a good example of this - in my 91 NA, 2nd gear is useful from 50 -~110km/h (yes, I do ignore the redline warning buzzer), meaning that for a typical course, I use first gear for launch, and that's about it. Cars with six speeds, and for that matter most piston engine cars other than v-8s, won't have high enough speed in 2nd, and therefore end up rowing between 2nd and 3rd a lot, or just bounce off the rev limiter in 2nd, because they don't want to upset the car and lose time doing up and down shifts at inopportune moments. If I were to go to a six speed, I would be like many of my fellow competitors, finding 2nd gear just a little to short, but not spending enough time in 3rd to make up and downshifting again worthwhile.
On full course roadracing, the same will apply, but it might be 2-3, 3-4 or 4-5 shifts that become an issue - a given track may find you topping out in a given gear, just before you'd really like it to, such that it's not worth upshifting just to have to downshift again 2 seconds later. On the other hand, a course may work out just nice, where you pull all the way thru a gear just in time for your next braking point and/or downshift. This is the situation you want to have as much as possible on a track - and is the reason the pro racers will vary either the final drive and/or the internal ratios of the gearbox to suit the course.

$_RXHEAVEN_$

well if u do this post ur results cause i want a 6 speed too. there badass

Alak

iTrader: (9)

Keep in mind also that the differential ratio on an RX-8 is 4.44. Thats where the ferocious acceleration comes from. If you want more gear, lower your ratio. I heard going from a 4.10 (or 4.30 in some cases) to the 3.90 (from the automatics) makes a significant difference.

silverrotor

iTrader: (1)

Simularily, Miata gears Into a NA differential.

https://www.rx7club.com/forum/showthread.php?t=229115

01Racing

Im going to share the speed secret Mazdacomp gave me. 1986-1991 na tranmission, 1987-1992 B2200 pickup's 5th gear. When road racing at mosport we NEVER use 1st or 2nd gear, the problem is the na's 5th gear .691:1. The trucks 5th gear is .858:1, which makes 5th gear usable, so you dont need the expense of a 6spd!

Alak

iTrader: (9)

I just learned 01-05 Miata's and RX-8's Share the SAME 6-Speed Transmission. ALSO, the Differential is compatable with RX-7's. Im not sure if its the N/A Housing or TII housing it works with.

coldfire

iTrader: (1)

it's essentially the same transmission but the gear ratios are slightly different.

R.P.M.

iTrader: (3)

Great info people....Thanks!!

The RX-8 uses the same bellhousing as a T2 tranny. Any 13B or 20B can be attached to the RX-8 tranny using a T2 flywheel.

coldfire

iTrader: (1)

i've never gotten a straight answer on a Miata 6-speed onto a 13b (i.e. into an FC).
i don't think it can be straight bolted on, either the bell housing or something else is different. anyone know?

now

iTrader: (1)

so you find a wreck that you can get the trani out for a fair price?
they seem to go for stupid $$$
let me know where so i can grab the motor
matt

Alak

iTrader: (9)

I had a good look at the 6-Speed Miata bell housing the other day. Might small. All things considered, I think they vary compared to the TII.


I would assume that the TII bell housing would essentially bolt on.