Has anyone done the Miata tranny swap in a 1st gen, from what i here all you have to do is r and r the bell housing and shifter section with orig rx7 and center section is the same.
this with a 4.88 rear end is supposed to be the **** in road racing.

 

huh?

 

Hmmmm... Sounds interesting... Miata tranny will probably be cheaper than rebuilding my current one... Bearings are a bit noisy.

Can you say 6 speed?

 

oh man, if we can get the 6 speed in... IM DOWN! WOOT!

 

Well, supposedly there's three types of Mazda RWD trannies...

Type 1 is usually called the Rib Case... It's a fairly old design used on the old RX2,3,4,Cosmo and stuff..

Type 2 is the N/A RX-7 tranny. Also used on the RWD 626, GLC, Miata, and B2200 and lower trucks...

Type 3 is a newer incarnation of the old Rib Case... It's used on the RX-7 Turbo, the 929, and the B2600 Truck...

The transmissions are somewhat modular... They seperate into 3 components...

Bell Housing, Center section (Main Gearbox), and tailshaft housing. Tailshaft housing contains the 5th gear as well...

Bell housing is simple enough... Bolts the front of the gearbox to the engine... Swap engines, keep the bell housing with the original type of engine... (Guess it wouldn't be too hard to put a Miata 4 banger in an RX-7... Or a rotary in a Miata. It's also how you get a rotary in a Mazda pickup truck )

Center gearbox contains most of teh gearing for the tranny... Leave it alone...

Tailshaft housing contians the 5th gear... You can swap out one part of the 5th gear this way to get either a taller or lower 5th gear... Common mod on the B2200 and 2000 pickup trucks is to swap out an RX-7 5th gear for better highway milage... You will have to recalculate your ratio since you're swapping only one gear in the set...

I'll post a link later on that details this ****... It's pretty cool.

 

yes, i have switched over the miata tranny guts to the rx7 tranny case..... the input shaft is the same spline as the rx7 tranny, you just have to trim the splines down 1" to fit the back of the rotaty motor...the output shaft is also the same as the rx so the driveshaft fits too,, without any mods.....
the gear ratio is much closer with the miata tranny wich helps acceleration alot.....

 

I'm still thinkin' about a SIX SPEED!!! How badass would that be?!?!

Dan

 

the 6 speed wont work. the housings are only swapable for 5-speed rwd trannys. Also.. if you could find one, it would be around $6k. at least thats what they go for on ebay.

Rob, good to know that you can keep the transmission intact. i knew that the gears where interchangable, but wasnt sure about the transfer case (right word, middle section?) itself fitting.

 

I really, really wish we could have a 6 speed, 60 mph is 3000 rpm, kinda high

 

6K for a tranny, sounds a little high.....

 

The smooth case transmissions have integrated bell housings, so the tranny guts are swapable but the tranny housings are not.

 

The miata 6 speeds go for $2500-3000 if you can find them. rare.

do a search in the race section on 626. I did a writeup on this. I have a 81 626 RWD box in my 1st gen. has even better ratio's than miata but the gears are physically 1mm thinner so it cannot handle gobs of torque or more than 250 hp and slicks. BUT those trans are typically in very good shape when you get them because they were driven slow and easy typically. Mine only needed two shift forks and seals.

i only needed to trim the input shaft splines back 0.50 inch.

BITCHIN gear ratio's. much less rpm drop between shifts.

 

I was looking up miata tranny info because i have a good miata trany (good internals) gearbox is a bit messed up (locked up out of the car so the gears are 100% well working condition)
im selling it for 150.oo HOPE SOMEONE IS INTRESTED

 

Verrrrrry Nice Info there PELE.
Do you know which Tranny (besides the GSL-SE) has the best 5th gear for cruising?

I wonder which 5th gear I could swap onto my TII/FB tranny for a better 5th gear. I was thinking of going with a 3.55 rear end to cruise better as well.

But If I could change "just" 5th gear, this help with highway cruising, and would not hurt my acceleration like lowering my rear end gearing would.

 

i dont know what they retail for.. but the only new one i ever saw on ebay was $6000. so whatever tahts worth....

 

good site for tranny info or mazda info
www.solomiata.com
randy stockers' site... good guy no doubt

 

Six gears is two too many.

- Pete (I start in 2nd and don't go past 4th...)

 

I am trying to put a miata tranny into my SE, but I gave up on tearing it down myself. Its just too confusing. I am going to take it into a tranny shop next week and have them finish it up and machine it down.