can anyone say whether the s4 or s5 tII tranny fits better into a 12a 1st gen with a stock manual tranny? just seeing which one will require less modifications with the x member.

thanks

 

I have a 87-88 N/T FC S4 trans in my car. The ratios are higher than S4, in fact they're the highest of all RX-7 transmissions. All I had to do was swap the tailshaft..

 

I'm not sure about the 12a, but in my 13b, the cross member just had to be drilled for the S4. I later swapped in an S5 but kept the tail from the S4 as I was already set up for it.

 

sweet thanks!!! do you have an original 13b manual tranny from first gen tho? mine is 12a first gen...

 

No, it's a 87-88 Non-Turbo trans out of an S4 mated to my 76' 12A in my 85' 12A 1st gen.

 

if you are going to run a 12a . you need to find a rx4 bellhousing . because the turbo2 starter will not make contact with the 12a flywheel.

 

what if im getting tII flywheel and clutch/ aslo auto first gen rear counter?

 

So what tail shaft do you have on there then... sorry i wasn't more clear

 

If you are using a NA FC trans (either S4 or S5) you should be able to just swap a FB tail shaft on and be done with it.

If we're talking T2 then the S4 is a bit more straightforward, since the bottom of the S4 tail shaft housing has a flat mounting surface like the FB does. The S5 has angled mounts and are just generally harder to work with (in my opinion anyway) In either case however at least some modification will be needed as the FB mount will not just bolt right up to the S4 tail housing...
Not sure how clear that was, pics would probably help explain it better...

 

I'll try and assist with what 82transam is saying with a picture-here is a 12a mount with the holes elongated to mate up with an S4 box.



As said before the S5 mount is very different so harder to alter.

 

i never try it....i always look for the rx4 b/h. so i no that the engine is balance.

 

What he said.

 

Thanks for the pic captainbizarro! I actually have an S5 box in my T2 Fb right now and the mount is cobbled together at best... Came across a scrap S4 T2 box a few months back and I'm planning to swap its tail shaft housing onto my trans at some point soon so I can neaten the mount up...
If anyone is still confused what we're talking about I can try to get some pics tomorrow...

 

thanks guys!

 

So if i get a rx4 bell then i can use stock flywheel and clutch from 12a trans?
dont know if i would want to do this tho...

 

yes you can... and also on the rx4 b/h you have to make the hole a little bigger to make the starter fit. for a guy like you this is no problem.

 

Here is an S4 mounted in my car:





I used to have some pictures of the S4 and S5 next to each other, but I can't find them right now.

 

nice!! Thanks for the compliment

 

mikeric, that looks pretty nice and straight forward. think ill be looking for an s4

 

So if i get the s4 tII tranny and bolt it up to my 12a can i use the stock 12a flywheel with a tII clutch? Then just use a tII starter and slave? are the diameters different from 12a na clutch to 13b t clutch?