Redliner223

iTrader: (6)

I know there is a 2 to 3 inch difference in the sa and fb transmissions but my question is can you make a hybrid between the two?
Is it possible to take the shifter piece of a sa transmission and put it on a fb transmission to keep from cutting up the center console of you car?
Or can you swap gear boxes between the two?
The fb's have a remote shifter so I just don't know how that effects everything.

Siraniko

iTrader: (13)

Yes you can shorten it as most of us over at the old school section have done to 81+ trannies on a pre-81 chassis. If i were to do it again, i will use a S5 or another FB with miata internals (i currently have it in one of my RX-3).

Redliner223

iTrader: (6)

Sweet!!! Good to hear.
Did you shorten it using the method I mentioned or did you do something else?

t_g_farrell

iTrader: (1)

Like this maybe:

https://www.rx7club.com/old-school-o...ny-rx3-479612/

j9fd3s

iTrader: (3)

the late SA and FB gearboxes use the same shift fingers, so you can swap tailshaft housings between the two.

t_g_farrell

iTrader: (1)

I was going to mention that but wasn't really sure of it and couldn't find a good write
up that talked about it.

Redliner223

iTrader: (6)

Yeah, I read up on that. So a transmission from a '80 would work with a '81+ transmission but not a '79.
We're looking into a 2nd gen trans swap right now.
Thanks guys.

j9fd3s

iTrader: (3)

actually we don't know that, Peejay asked, and i looked up parts, and Mazda changed all the forks and shift rod ends from bolts to roll pins sometime in 1980, and then kept these same parts until some time later enough that we didn't care.

so basically the guts of a later 1980 transmission are the same as the guts of an 81+ trans, so swapping the tail housing was easy. it may be that the 79 stuff works too, and actually since the only difference on the tailshaft housing is the shift rod, this would be easy to change over

Sgt.Stinkfist

iTrader: (6)

If we can get some definitive info on the early SA trans, I would heavily consider swapping a FB tail shaft housing onto my 79 4-speed

bumpstart

all the rear sections swap.. even those from piston variants

( the forward most piston engine "M" gearbox position is desirable for those with r100 )

there is a couple of minor pitfalls

often you have to swap over the appropriate fingers
( ie.. if using a s1 rear section on a later box,, you need to grab the claws / fingers )

and as noted ,, very early version had grub screws,, later ones have dowel pins
and some later ones have a detent piston on one of the claws to stop it jumping out of gear

its a swap i have done many times ( and ive also modified dozens of boxes for revised shifter position using the old 103mm measure and cut shut for extension housing )


pins



different tail housing shift position types
half on floor is s1 position .. next to it is the shifter position from an 85 courier , next to that is the s2 box ( sans shifter turret ), with a 103mm cut shut to approximate the s1 position

and foreground in a 12aT gearbox.. with rear section removed

..i had just put together a s1 box.. with the 12at fingers .. and the 12at shifter extension housing ,, back into the HB cosmo it came out from
( this 12at box is buggered and will typically overselect at the hubs, leaving two gear engages and the box locked up , and needs the hub selection forks bronzed up )




the 103 mm cut shut to a s4T "R" box extension housing .. "M" box principle is identical ( indeed the shift extensions are derived from each other )

Redliner223

iTrader: (6)

So making a hybrid is possible?
If we had both transmission lying side-by-side a direct swap is a possibility?
You will need to grab the claws and fingers from the s1 transmission?
Is this something that can be done in a garage or parking lot or is a professional required?

bumpstart

you can do it at home.. all you need is the pin punch, a couple of sockets/ spanners and some RTV silicone

there is several methods to get the rear section back on , some move all the fingers to the neutral position and drop the rear section on with a slight twist to get the oil feed rail in

others select reverse in both fingers and in the shifter tower .. still a bit of a knack to it

others drop the roll pin out of the shifter cup inside the shift tower, and remove the selector rod entirely,, fitting this into the fingers,, then sliding the rear section back over the lot

Redliner223

iTrader: (6)

Doesn't sound too terribly complicated.
Should we use the dowel pins or the grub screws when putting it back together?

bumpstart

go with what fits,, you have two lots of everything.. i expect both will be roll pin anyhow
.. at worst you may need a tap and drill bit but dont think it will go that far
( and if fitting s1 rear housing then disregard the last suggestion on how to fit the rear housing as it will not apply to the "internal" type select rod )

Redliner223

iTrader: (6)

Yeah, we're just putting a s1 tail housing on a s2 transmission.
So it'll be pretty much straight forward once we get everything laid out.
Any warnings?

bumpstart

nope , stick everything to neutral and drop the rear on with some angle , then a twist to both clear the drip rail , and engage the selector rod into the claws