hey has anyone done this, i went to a shop in my city today and stumbled upon a guy who used to race spec7...i think, now he's into miata's, anyway i was talking to him bout the fb and he suggestes the miata gears in an fb case, anyway i was wondering what everyones thought on this was

 

Why? are they stronger? better ratios? make a neater noise?

 

I'm curious as to why you would do this as well.

 

"Sport compact car" made mention once that miata's tend to do really slick burnouts... this would be related to the gearing (1st and rear) in a tiny engine like that.

here's the ratios FROM THE ARTICLE:
1st gen, six speed.
--------1
3.76
--------2
2.269
--------3
1.645
--------4
1.257
--------5
1
--------6
0.843

-------rear (if you care)
4.3

 

I don't know what the advantage is, but i'd like to point out that mazdacomp lists these as their race tranny (and you pay $$$$ for it to).

Alvin

 

Simple - the Miata gears aer much closer together - "Close Ratio". I race an EP SA and the gear ratios are just too far apart, the motor falls right off the good powerband on upshifts. The Miata box has much closer ratios, so it drops less RPM between each gear.

I believe that the Miata gearset fits in the Rx-7 box, with the main modification being the pilot shaft has to be shortened.

 

yep, thats it

 

Damn that sound nice!. Would that benifit a stock 12a FB?

 

yeah the closer ratio is the only real benefit, the only thing is i think they might be weaker dont quote me on that, but for an na fb with less then 200hp and low torque numbers it word be fine, at least so i was told, i read a post on here somewhere about a fc doing this and the chick that had done it said she loved it much zippier, no more tree pulling in 1st, and no huge gap between 2nd and 3rd....anyway im just speaking thru hearsay so please dont quote me, i posted this here to see if anyone had done it to the first gen and what they thought of it, especially in the daily driver....thanks

 

later model miata boxes have dual helical gears too.

miata boxes are not weaker than FB.

You can do the same with 79-83 626 RWD boxes, I have one of those in my rx7 and REPU. closer gears than miata. Really zips along, much less rpm drop between shifts. But the gears are 1mm thinner = weaker. But my 12a j bridge and 13b SP has not broken it yet. I talked to a guy who had one behind his SCCA GT-3 car for 5 years with slicks, 626 internals never broke but the belhousing did. Eventually. Simple fix.

Do a search in the race section on 626 RWD for how to do it.

6 speed miata box does not fit into FB case.

 

u got it. pix in my bro's RX-2 with FB tranny/miata 5 speed internals.

 

how does the miata compare with the TII (strength wise)?

 

there are now 5 mazda rwd transmissions.

split case: this is used in the early 1200/r100's, case is split vertically. only bolts to the 10a/1200engines

R box: there are 2 variations on this. theres the early (71-78) and late (87-now), the early has the non turbo style clutch, and input output shaft diameters. the late transmissions, are the turbo boxes.

M box: introduced for the 78 rx7/b2000, its used in every non turbo 2wd, non turbo car (miata, fb, non turbo fc, b2000/b2200).

Y box: this is the asin made 6 speed used in the miata and rx8.

P box: this is the transmission built by mazda for ford, its used in the rangers and 94+ b trucks, its also grown a 6th gear for the 06 miata's

so the miata trans isnt much stronger than the stock fb transmission because its almost the same thing.

 

T2 box is definately stronger than Miata box. Bigger input & output shafts plus other strong items including the rib case. You only need a turbo box if you....well..... have a turbo. It's torque + sticky tires (or abuse) that kill trannies. n/a <peripheral port does not have torque, turbo does.

You don't need to shorten the input shaft like the pic above. It's only 1/16" longer than FB and there's room in the e-shaft for that. Cutting off the input shaft tip like above is not needed and what about pilot bearing? I never shortened the input shaft, just had to grind the splines down about 1/2" so it'll maintain the same shape as FB input shaft.

 

I'm about 99% sure that the 626 gear box will bolt right to a fb bell housing and tail end shifter housing thing. then go right in. I've beenina car with one big 1st gear, but close gears it was fun!

So what exactly is needed to put a t2 box in a fb. just a trannie mount and custom drive shaft? or is there a mix and match of parts aproach that will make it bolt in?

 

dbl pst

 

the 626 case will take an FB bellhousing. The shifter location on the 626 tailhousing is 4.5" forward of FB, and very close to SA. Uses a long shift lever. It's easy to get one into an SA due to shifter location being very close.

 

that's the word tailhousing. If what I was told was correct, then you could use fb bell and tail housings and the 626 case would work, correct?

 

I believe that may work. But the deal is, if you're taking the bell and tail housings off, might as well remove the case and replace the shift forks which are usually bent or worn, and the synchros too.