It's great at 235whp. You have options on gears and the car clearly has a gearing advantage.

 

I need to get my trans put back together so I can have my set up going.

Jkav- I think so. I know for a fact that the rx8 and miata mid sections are the same. I am using parts of an rx8 trans to fix a miata one. I could score a bell housing, If someone could find me s15 guts or s2k guts i could confirm, or ship the parts to someone else to confirm. It would be nice to have different gearsets to play with. I would guesstimate that the s15/ s2k and whatever else uses this trans is the same deal as the miata and rx8 ones. The same midsection and innards, and different bell and tail housing.

Edit, that being said, they probably have some trick-assed parts for the nissan trans.

 

Here's a crapton of S15 6spd info.

The pics/diagrams below are the S15 trans and came from the above link. Looking promising, or no?

 

Very promising.

Looks damn like an rx8.

Cool. I am not sure about the s2k though. It looks much different. Haven't seen an ap2 trans yet.

Also, any pictures of the RX8 transmission you are using to repair the miata Yspeed? Any more details/ have you been using the like gears or are you trying new gear sizes? Sounds like a big step in the right direction. What year iis the trans from? I assume before 08?

Sounds cool. The S2000 is the big question. I am curious about the syncros in that trans possibly working.

 

AP1 and AP2 are 95% interchangeable. I am can't remember the specifics, but I think the drive shaft spline/size is different. We swapped an AP1 trans into a AP2 with just one hiccup.

 

Yeah, they are largly the same.

The driveshaft bolts are different on both ends (tranny and diff). I believe the AP1 has brass syncros and the AP2 has carbon fiber. The gear ratios are slightly different as well, I know 5-6 are longer, and I believe 1-2 are shorter (but that may just be a result of the lower redline).

 

I would be interested in figuring this out. How much do s15 trans go for?

 

S15 trans and 205/50/15 tires @7200 RPM.
Final Drive______3.636 3.90 4.10
1st: 3.626______39 --36 ---35
2nd: 2.200______64 --60---57
3rd: 1.541______92 --86---81
4th: 1.213______117-109--103
5th: 1.000______141-132--125
6th: 0.767______184-172--163

This damn thing has a monster 6th gear. I think the 3.9 would be good if you leave it. I think the 3.636 would be good if you took the 6 speed out of the miata trans. The 4.10 looks great for maybe a NA motor, maybe even a high rev one. Tight first 5 gears, then a nice cruising gear to shut the bumble bees up.

 

That's really good news.

By far, then, the best thing you could do is get the AP2 internals into a Miata box somehow. The Carbon syncros where what I mainly was attracted to when reading through the specs on the box. That would help out shifts a lot I feel, at least it should as it appears to have worked in the new RX-8 box.

Those of you who've hands on dealt with the Ap2 box, it doesn't have a center section like the other AZ-6's does it? It seems to be quite a bit different, where as the RX-8 and S-15 transmissions look quite alike, as with the MX-5 trans.

Keep in mind the Ap2 has a .763 6th gear. basically same as the .767 in the S15 box.

I wonder how hard it is to find a fudged AP2 box.

here's a few ebay auctions. Little on the high side though.
linky ap2
AP2 again
silvia 6 speed
ebay s2000 6 speed

 

I just did the s2000 gears, and it looks like a 4.1 or a 3.9 would be fantastic with that gear set. It is basically like a miata trans with higher overall gears, I think 4th and 5th are closer. You end up with gearing like the mx5 6spd/3.636 with the s2k trans on a 4.10. What final drive do the s2k's run? It seems super high for a car that revs like that.

 

They come with 4.11's stock. A lot of those guys run 4.44's or 4.77'ish gears for some reason. A little crazy. But the Kia Sportage and RX-8 rear end is a common swap, especially with ap1's it seems. I don't know why but like a lot of honda guys maybe they are allergic to boost.

So, now someone really needs to do this. I haven't got the time this month, so don't count on a quick answer from me..

 

Why a S15 gearbox? They are known to be weak and could not handle anything about 400bhp. In fact, the S15 guys making big bhp are swapping their 6spd box for the 5 spd S14 box.

 

Which is probably as much as our box could handle. S15's 14's and 13's are also heavier cars, which would put more wear on the trans. How many 400hp miatas do you know of? Our 5 speed, which is what most of us are upgrading from is lucky to hold 250. I broke one on stockish power and a 6 puck. I would wager to say that most of the other transmissions used are of the same torque rating.

 

This thread has me looking up S2K transmissions. About 430$ shipped on ebay.

At that price, why replace a six speed with anything else?

You can't get decent syncros for a Miata six speed, so they're just thrown away... This would be a great solution. You could actually have a useful first gear on the street!

 

I've been looking for s2k transmissions as well, but I'm planning to see how difficult it is to just put one in a miata. My rough plan it chop two bellhousings in half and make one that bolts the s2k trans to the BP. I have yet to take any measurements, but we'll see. I do have access to a crunchy s2k trans if anyone has a crunched up 6 speed, we could do some fitting and see what works.

 

Why not just put s2k stuff in the miata trans. The bell and tail housings will just bolt up no fabrication required

 

Have you verified this yet? From all ive looked at so far I feel the tail section won't bolt up between s2000 and the other three az6's. Not sure though but I get that feeling from what I've seen and read.

Bell housings I think yes.

Where is this 430 s2000 trans? Ill buy it right now. Link?

 

Are you sure they will bolt up? From the pictures I've looked at the bolt pattern at the bell housing doesn't look the same. I haven't studied the tail section in detail but they look different too. I will know for sure if I can get my hands on a dirt cheap broken 6 speed though.

Another reason is that if I do ever toast a transmission, I don't have to tear it apart and reset gears etc. All I have to do is pull the bell housing off, swap it to a new s2k trans and bolt it back in.

 

Uh, you just go to ebay and do a search for "S2000 transmission."

http://cgi.ebay.com/ebaymotors/2003-...#ht_4454wt_940

That one has a crunchy second, but this is cheap as well, and you don't need the tail housing:

http://cgi.ebay.com/ebaymotors/2000-...#ht_2442wt_940

 

I think the rear gear swap is simpler. I've taken apart a 6 spd. If you are not very skilled, then this project is ripe for disaster. (two non working six speeds)

If you have the skills, then I guess it would be great. I don't think this will end up being a cheap solution. I'm not trying to be a downer. I just don't want someone new to the hobby reading this, deciding it is the latest and greatest, and then getting in over their head.

I am back on board the 3.636 gear swap band wagon.