I heard it was possible to swap a s4 transmission into an FB with a tiny bit of modification. I would like to know what modification is required. I'm on my second 1st gen trans and im afraid to go into reverse because it is likely to get stuck. The first trans internally crushed itself. I dont even drive hard.
I know that the s4 isnt any more durable, but at least they corrected the depth of the n detent on the 5-r rod.

 

It's trivially easy.

You remove the side cover from the shift tower, unbolt the shifter block from the rod (sometimes this is a roll pin), then remove the eight or ten or twelve case bolts and carefully knock the tailhousing up off of the transmission. Careful that you don't separate any of the other sealing surfaces, that is.

Then, with a pick or circlip pliers, remove the speedo gear (there is a ball under it, don't lose) since you will be using the FB one. Mazda changed the gear mesh between FB and FC, so it's best to not cross-pollinate. On some FC transmissions there is a large mass weight that you need to remove as well.

Put all of the FB parts on the FC trans and bolt it in. If you have a beehive equipped car, you need to remove the breather on the side.

 

for the turbo trans also?

 

Completely different species of transmission, nothing interchanges except that both will bolt up to the same engine. Completely different transmission design, as well as different input (so clutch is different) and output (so driveshaft is different) and the starter doesn't mate to a N/A flywheel, either. Making a new transmission crossmember is trivial compared to the other problems.

Enough has been written on swapping a TII trans into a 1st-gen that, if you're seriously interested, you should be able to find out the particulars. I've never done it myself.

N/A transmissions are cross-swappable mainly because the smoothcase has varied extremely little between March 1980 and, well, today. The main differences are the tailhousing, which determines transmission mount location/style and shifter placement, and the bellhousing section, and also some minor differences with input shaft length (Miata and 626 have a slightly longer input).

 

My race car doesn't use a speedo. So I'm assuming it's not necessary.
-Is the overall length of the trans the same, and
-what is the purpose of the tailshaft swap?
My 12a is in a Corolla, so the shifter position doesn't matter for my specific usage.
-Do they use different driveshaft splines?

 

All - ALL - N/A Mazda rotary transmissions until the RX-8 are the same length, input, and flywheel diameter. The pre-74 stuff might be different.

The reason for swapping the tail housing (not tail shaft) is for shifter placement and trans mount location changes. Really, you could just change the shift tower if you wanted to move the shifter, but since you need to remove the tail housing before you can remove the shift tower...

 

Is the 13B one further forwards, or further back? My corolla has a bit of room for it to move back.

 

The engine makes no difference in shifter placement, just the chassis the trans came from.

2nd-gen have the shifter a little further back. I never bothered to measure.

 

the pre 74 stuff is different, it has a different bellhousing pattern, however the trans mount and shifter location are like the SA. same driveshaft spline too.

the 04-08 Rx8 is the same bellhousing bolt pattern, but it needs a turbo size flywheel/clutch. its got a unique starter. drive shaft is turbo style. the big difference is that the shifter moves forward, so its in the SA spot, however there is some magic shifter tower (the basic trans is used in a few different cars) that moves it back.

the miata version of the Rx8 trans is basically completely different, it uses NA sized clutch/driveshaft, and its not clear if the Rx8 bellhousing would even swap over.

 

Question for you, since you've seen that junk and I haven't.

Does the RX-8 trans have a removable bellhousing like other Aisin transmissions, or is it integrated?

I discovered a while back that the 5-speed Aisins are basically the most cross-swappable transmission pattern ever made. Get, say, a Toyota W58, and there exist OEM bellhousings to bolt it up to an AMC V8 (due to 2.5/4.0 Jeeps) or Mopar 2.2/2.5/2.0/2.4 engines (due to Dakotas and Jeeps) or Chevy front-drive V6s (due to, I think, Isuzus) or Ecotecs (due to Solstices) or Chevy 2.8/3.5/4.2 four/five/six inlines (due to Colorados) and, well, there was a list and it was about 20-25 applications long.

 

its separate. wikipedia says this "December 1997– AZ6 — 6-speed

Honda S2000, Mazda Miata/MX-5/Roadster, Mazda RX-8, Toyota Altezza/Lexus IS200"

i've seen the Mazda boxes, and they look the same but the Rx8 has super beefy shafts (bigger than the FD/turbo), and the miata is M box sized. the S2000 kind of looks related, but where the mazda versions look like mazda transmissions, the S2000 kind of looks like a cross between a BMW trans and the Mazda, so its got no tailshaft, and the drive shaft flange looks like it could hold a guibo (i'm sure it doesn't, honda isn't retarded).

i've never seen the IS trans, but the gearing feels WAY different

the Rx8 people have shift problems, basically instead of the wire spring and detent slider things that Mazda traditionally uses, this thing uses a ball and spring, and if you go too far the ball pops out... makes it a huge PITA to assemble, you have to hold 3 shafts in alignment, without holding them by the shift hubs, so that the damn ***** stay in.

other than that its big enough that it should handle plenty of power, and the gearing is really good

 

Don't knock Guibos, I love 'em. They do a wonderful job of damping out driveline harmonics.

90% of the reason I replace a transmission is because when the bearings get worn, the driveshaft hums in 5th gear. Harmonics suck.

 

hmm, maybe you should put the Rx8 bellhousing on the s2000 trans with a BMW driveshaft.

now that i'm thinking about it the S2000 clutch setup is completely different, the Rx8 actually looks like an M box inside the bellhousing, its got a similar front cover.

 

How do I seperate the tail shaft housing from the gear box? I unbolted all the bolts and Im still not able to knock it up off the transmission, the seal doesnt seem to wanna break.

 

They are stuck together with adhesive. As long as you have all the bolts removed just pull or tap with a deadblow hammer if its stuck. Once the seal pops you have to rotate the tail to make the shift linkages disengage.

 

Ok thanks for the reply. Where is the best place to tap with the hammer? At the seam of the tail shaft housing and gear box?

 

When I took mine apart it just popped apart. I had it standing up on the bellhousing braced with my feet and pulled the tail off with some wiggling. If you need to hit it just use your best judgment. All you're trying you do is make the sealant pop apart.

 

Ok I finally got it off, thanks alot for the help.

 

Is the roll pin in the bottom/bigger whole of the shift block on the s4 trans? If so how do I get it out ?

 

Hi, so I'm a little stuck with putting the tail shaft housing back on. I'm a little confused on how the shiftter linkage is supposed to sit in the gear selector forks/shiftrod forks. Right now I have it only sitting in one of the gear selector forks, that was the only way the tail shaft housing would go on. Did I do this right or is the shifter linkage suppose to go in all 3 of the gear selector forks? I tried to put it in all 3 but it would not work. Red arrow with a ring around are the 3 gear selector forks, pic is not mine and from another thread but should give you guys an idea. If someone could help me out that would be much appreciated. Thank you.