i heard from a couple old timers that you can put a miata transmission in an fb... anybody know about this? if so, how?

 

Yes, search.

I will start you off with this, you need to shorten the input shaft.

 

It is possible, but the gains are not very much to justify the work IMO

 

This is the next upgrade for my FB, I like the ratios in the MIA TIA trans than the stock FB trans I am using right now.

 

Change bell housings, input shaft, and tailshaft and it ought to slide right in.

I think you'd see more advantage in ratios by swapping the rear ends, to tell you the truth. Also a little easier I would guess.

Note that I haven't done either of the above, but I sell lots and lots and lots of used parts for both cars, so I know what the parts look like.

 

cool thanks for the input...now it's time to save some money

 

Would a 6 speed Miata trans work with the same modifications?

 

I thought you took the guts from the Miata trans and put them in the FB case with a reformed input shaft?

 

You could do that, but from the looks of it the center section is the same.

You might have to take the whole damn thing apart to swap bellhousings, so the point may be moot, but I'd rather just bolt on the front and rear (and input shaft) and be done with it.

on edit:
You know, I've never taken a first gen tranny apart (aside from the tailshaft off to replace bent shift forks in customer transmissions), but I do have some parts I've been left or acquired various places. In effect we're both saying the same thing -- you probably have to take the thing so far apart that in effect you're just replacing the guts.

 

When I read Kims thread like 2 yrs ago I think they took the guts from the Miata trans and put them in the FB box like everything just bolted up but the input was like an inch or so bigger and had a different chamfer on it than the FB unit

 

Ding! We have a winner.... See here for more: http://mazdatrix.com/faq/miatainputshaft.htm

 

ive done it, lots of work and its a weaker gearset. end result, i broke the tranny with a stock 12a(with mods), not banging the gears.

 

No you cannot bolt the tranny in. It is not a bolt on affair, the bellhousing is connected to the caseing, so you just can't swap it. You need to take the guts of the miata tranny and swap it into the FB case. Then you need to modify the imput shaft. SEARCH This has been covered and there are even walk throughs. It's good for roadrace cars that rarely see high power or hard gear changes or launches. The gear set is weaker and will fail as Robert said.

 

It really is a nice gearset and the rpms don't drop as much when shifting gears. It keeps you in the powerband = better acceleration. If you need a tranny rebuild then now's the time to do it.

79-82 rear wheel drive mazda 626 trannies have better ratios than the 5 speed miata. It's the same swap but better ratios.

And I have an 81 RWD 626 box behind my 12aJBridgeport and it's taken a lot of shifts on the road race track just fine. The REPU has an 80 RWD 626 box and I've launched hard at autocross and it's just dandy. I LOVE these ratios.

Just don't use a 1st gen rx7, Miata or 626 box on a turbo motor or for drag racing. They're not built for that and can't take the torque nor shockloading. But on the street or road race track they are great if you don't abuse them.

I'd guess Rob's Miata box was in need of TLC.

 

LOL! In reality the FB box isn't suited to NA applications for dragracing. I've broken two on my street ported 13b. One snapped the imput shaft on a gear change the other snapped the output shaft clean in half from a 3500rpm launch.

 

Putting a Miata tranny in an FB. Heres my How-To:

Step 1. Open hatch.

Step 2. Insert transmission.

Done!

~T.J.

 

Lots of roadracers are using the Miata gearset in the FB case with no issues. So for street applications it will work great.

I just built a transmission with a Miata 1-4 and truck 5th gear. My other roadrace transmission has 626 gears. So +1 on Brads post. Those gears work really well.

I looking forward to using the new transmission with the truck 5th. Should work well on the TMS (texas motor speedway) roval.

Here is the Mazdatrix how to on the input shaft mod. http://www.mazdatrix.com/faq/miatainputshaft.htm

 

You used a truck 5th? What's the ratio on that?

What donor vehicle? REPU or B2000 or B2200?

I thought the 5th/Rvs gearset was in the tailshaft housing and that you use the RX-7's tailshaft housing.

I just picked up my 1999 Miata tranny today.

 

Nuff said for me!

 

If i was you id just go with a turbo 2 tran's, that's my opinion..

 

I have a miata tranny in my 73 RX-3. much better than any RX-7 trannies I've used. TII tranny is an overkill for a N/A and much heavier than a N/A tranny.

 

no, its a different design.

if you want a 6 speed, remember its a closer box, so it'll rev HIGHER on the freeway, the RX-8 trans bolts up like t2, except the shifter is further forward, instead of further back.

 

Has anyone done the RX-8 trans yet?

 

If some body did a rx8 6speed are the flywheel and cluch the same.I did a turbo2 s4 swap in my 87 base model, i think it's a good idea to put a rx8 trans in a turbo car.