My car is a 1987 RX-7 FC S4.
Yesterday, I was going to change the gearbox fluid when I looked under my car, and I saw this:



I found it to be weird, because the S4 FSM shows a picture of the gearbox, and it looks like this:


While the S5 FSM "says" the gearbox looks like this:


Does this mean that my car as a S5 gearbox although my car is a S4? Or is it something I'm missing?

 

The first picture from the FSM is a TII tranny and the second is a N/A

You can tell by the diff mount (unless they swapped the shifter housing like i did)

 

Yes, I forgot to mention that my car is a N/A

So that means I have to look on the diff mount to find out if they changed it?

 

Yes, but i think you are just confused by the pictures in the FSM

The S4 tranny pictured is from a Turbo, not N/A.
Ribbed tranny cases are turbo, non-ribbed is non-turbo (both S4 and S5)

S4 and S5 gearboxes are the same, apart from the diff mount and maybe some gear ratios. The plugs are in the same locations

 

Yes, I was quite confused about this because the S4 FSM only shows one picture about the S4 N/A gearbox, and show lots of them about the Turbo S4. And even that one picture is not very good...

So what differences should I spot on the diff mount so I can confirm if my car's gearbox is from a S4 or a S5?

 

S4 single rubber diff mount in the center
S5 dual rubber diff mount at an angle on both sides

 

So I believe this a single mount?


...and that means it's a S4 gearbox. Am I correct?
Or am I looking at the wrong place?

 

Yes

 

Thank you for your help, Furb.

By the way: Do you know what tool I should use to unscrew the fill plug? I've been trying with a 14mm wrench, but was not successful with it. Also the plug head looks like it's square, unlike any other screw I've come across so far...

 

There are special tools for that, but a wrench would have to do the trick
You just need the correct one that fits right, or use an adjustable wrench

There may be loctite on the threads so it takes some effort

 

Ok, thank you.

 

^^^^^^^^^^^^^^^^^^^^^^^^
**WARNING! Misinformation!**

All FC transmissions use 3 rubber pieces: two rubber blocks at angles and the one in the center.

The S4 T bracket attaches vertically [it's a T shape] and has the rubber blocks further outside. The S5 Y bracket is a Y shape, attaches diagonally and has the blocks closer to the center. Both sets of blocks are at an angle
Both of those brackets extend vertically into the crossmember [they go through the center of that third rubber bushing.]

 

Allright Derekcat, thank you for the heads up.
I'll check that out.

 

thats good information to know

 

Haha the way this response is worded made me chuckle.

Good job D-cat, that is a very good way of wording that!

 

hehe thank you ^_^

It was very confusing when I was trying to figure all this out for my manual swap, so I try to make it as clear as possible for people.

One little clarification though: the S4 T bracket does have the ends of the top of the T bent upward, this is where the blocks attach to it.

 

I've recently done a S4 to S5 transmission swap and noticed the difference in the bracket connecting the transmission to the cross-mount just as D-cat pointed out. From the looks of it you have a S4 transmission as the passenger side of the cross-member has a small hole to access the lower nut of the transmission mount.