J-spec and non J-spec transmission difference?
 

Is there an actual difference between a J-spec and a North American transmission?

Are they not the exact same transmission?

I would also like to know.
bump.

Good Question. Anybody know?

From 91-95 yes, probably. After that, who knows. I've never seen any listed changes.

However, I have seen quite a few japanese FD 'troubleshooting' lists, and while many of the problems are the same (hoses, solenoids, etc), the 5th gear synchro issue has never been mentioned.

bottom line: I don't know either

same tranny till '95 for sure.

The explanation for the 5th gear synchro has an easier answer: After 1995, Mazda created an upgraded/improved 5th gear synchro. I just replaced my old one with the improved one.

I have a J-spec tranny but have no idea what year it's from...the only difference I noticed is that my 5th gear ratio is higher...

Not sure if this is common knowledge but i've read that the LSD has a different ratio in Japan. Is this right?

Don't know about the tranny.

most of the FC trannys that came from Japan have shorter gears compared to us ones

Actually, I thought there was a TSB issued in 93 with the 5th gear synchro being strengthened, along with the "shift select spindle" being changed with a higher spring rate to help with missed shifts.

So then there should be no conflicts with putting a J-spec transmission into a North American FD. It should be a direct bolt in. The reason I ask is that I have an auto and would like to do a transmission swap in the future and thought that if I could get a hold of a 96 plus transmission I could avoid the 5th gear synchro problem.

http://www.scuderiaciriani.com/rx7/s...t_spindle.html

You may have already seen this site, but just in case, this is what I'm going off of. Notice that the TSB mentioned is dated 1-94. From this, I think that anything 94 or newer would already have the 5th gear synchro issues addressed. Also, I think there is some discussion of switching from Auto to Manual on this same site.
Do a search on this forum as well, I think the topic of JDM vs US Domestic transmissions have come up before. ;)

What about the "spirit r" 6 spd tranny? I've been wondering if it would be possible to put it in our cars. I have a 93 touring, just a thought.

There is seriously more to life and RX-7's than J-Spec and non-j-spec nonsense.

http://www.rotorsportsracing.com/per...drivetrain.htm

the spirit-r has the exact same 5 speed as the rest of the newer FD's

i just bought a used JDM tranny and will be installing it tomorrow. i'll let everyone know what i think of it after it's in and running

Was wondering how the install went and how the jdm tranny feels.

i have jdm tranny and can't feel a difference but doesn't mean there might not be one. i though the only difference between a us and jdm was just the turbos, at least when it comes to the trans and engine

....

right on, thanks for the input.

I personally was thinking about getting the GURU racing Dog Box setup. Anyone have this setup?

i've only gottem about 2 hours of seat time with the new tranny, but it feels a lot smoother than my old one. no big difference though

i have a 97 but have no idea how it runs. havent put it in yet....

I've done it. There is no issue.

Haha.

Do you have any idea what you'll be getting into?

Enlighten me. . .

gear whine, and no synchros, not exactly your street friendly modification.