nah whens its made a write up then i second a sticky

 

ok, for comparisson purposes, here are the charts showing the ratios and difference between the two gearboxes. these charts are specific to my car

stock


miatabox

 

wow.....congrats......It's about damn time......Is the fender still in need of repair or did you put that other one on yet???

 

Pretty much just an RX-8 transmission

 

I'd be up for a T56?

 

interesting. good work! never seen it done before.

 

i havent really had time to put the fender on yet. next time your in the area, you have to test drive my new setup

 

thats funny i heard the miata box was different than the 8

 

Yea, I want to know more about the 6spd miata box in the fc...

 

Heres the specs for the 8:

Gear Type 6 Speed Manual
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

and for various models of the miata:

94-97 5-speed 12.86:1 7.74:1 5.45:1 4.10:1 3.34:1
99+ 5-speed 13.5:1 8.12:1 5.72:1 4.30:1 3.50:1
6-speed* 14.7:1 8.87:1 6.43:1 4.91:1 3.91:1 3.30:1
Mazdaspeed 15.4:1 9.30:1 6.75:1 5.15:1 4.10:1 3.46:1

as you can see, the ratios are fairly different. im not sure how much power the mazdaspeed box can handle

 

so what exactly did u do to the miata input shaft to make this work?.....im interested in this...but need more info....

 

Nice work =)

 

I've been doing homework on this same swap for my 1st gen (That may soon be a 1.5 gen.)

First, some links for anyone else interested:
All the gear ratios ANYONE would ever need: http://members.ij.net/mrmazda/tranchrt.txt
5th gear interchange chart: http://members.aol.com/solomiata/Mia...terchange.html
SoloMiata drivetrain interchange guide: http://members.aol.com/solomiata/Drivetrain.html
Regearing Mazda transmissions: http://www.angelfire.com/darkside/de...nsmission.html
Miata VS RX-7 input shaft comparison: http://myweb.cableone.net/currie/tom/RX7/trans.html

I was wondering how the new 1st gear felt on launch.

My stock 1st is 3.6:1 (Though I'm upgrading the rear end from 3.9:1 to 4.3:1)
FC stock 1st is 3.4:1

Miata is 3.1:1... Seems like you'd lose a bit of torque there... Something the rotary has not much of.

I want to get the 5th gear out of an S5 N/A for the highway.

 

archive

 

wow, thanks for the info i havent tried launching the car yet, when i took it to willow, we started from a parade lap. ill try to get a feel for that in the next few days. for street driving, its a lot less difficult than we thought it would be.

 

Here's some information I got from some rough calculations. It's shift points, and mph for (your car with) 4.3 gears. I threw your data into excel (I plan on a high revving motor and a miatabox with 4.3 would be great) and got this.

7000 | 37.2 | 63.4 | 89.3 | 116.1 | 138.3
7500 | 39.9 | 68.0 | 95.7 | 124.4 | 148.2
8000 | 42.6 | 72.5 | 102.1| 132.7 | 158.1
9000 | 47.9 | 81.6 | 114.9| 149.2 | 177.8
10000| 53.3 | 90.6 | 127.8| 165.8 | 197.6

If anyone else wants any numbers (shift points to-from, other RPMs, other rear ends) just PM me.

 

the charts i provided are calculated with a shift point of 7500rpm, for track use. it would be interesting to see one calculated for street use lol.
one thing i would like to point out is the change in the upshift from 2nd to 3rd. with the stock box, i would shift into 3rd at 7500rpm, and it would barely be inside my powerband, at times it would even be boggy. with the miatabox, im well inside my power band when i shift to 3rd. for me, that is a big advantage.

 

The mx5 trany is not very strong. It will snap at 250hp and 235ftlbs or so. If you are under that and playing sounds like its a sweet swap. I wish I had a first gear that long its about useless in a T FC.

 

It's only as good as any other N/A tranny.

I figure so long as you're not doing drag launches on 8 inch wide slicks, with a turbo or v6 or better you should be okay.

 

on friday, james was kind enough to let me drive his '89 GTU with stock motor and trans, for comparrisson purposes. even in a straight line i could feel a big difference. the gears in my FC feel substantially shorter in comparrisson to the stock setup. id like to have more time to compare the two setups, ideally on a track, but that probably wont happen.
car feels great!

 

ok i need a bit of clarification...the miata box has longer gears..meaning its more geared toward a higher top speed... wouldnt this make u slightly slower in acceleration but have a higher top speed?? when u say shorter u make me think it would accelerate faster, but the gear ratios are saying you would accelerate slower...hmm am i missing somehting?

 

the miata transmission has shorter gear ratios, therefore it increases acceleration, and lowers the top speed slightly. the first gear is taller, and the rest, including 5th, are shorter.

 

1st = long
4th - 5th = short
for autoX purposes. good ****, Claire.

 

2, 3, 4, and 5th shorter

y'all are welcome to putter around the block at the saturday meet.

 

can I drive your car if you goto the meet?