what is the difference between a s4 and s5 rear iron? is there even a difference? i have a s5 and it recently cracked so im looking for another one. someone offered me one off a s4, thats why im asking.

 

im pretty sure there interchangable correct me if im wrong..but the s5 is stronger i believe

 

http://www.rotaryresurrection.com/2n...ron_break.html

 

WOW, that pretty much sums it up, THANKS!!

 

one more question. are s4 tII and s5 tII rear irons interchangeable?

 

I believe they are - but you want the S5 rear with both strengthening mods - probably off a 91 or later car - I broke my rear iron - probably down to twisting forces on a hard launch.

 

Check your e shaft too....I just noticed a small crack in mine lOl.

This was a 3'rd gear down shift and unsprung clutch....I'm not too quick to say it was detonation with those factors unless some thing happened unknowingly after two years of torture .
s6's have it soo easy.....

 

Well....I just cracked mine too! Must be something about Idaho?
Can you use a S6 iron?

 

I took a bunch of measurements when I upgraded to s5 irons: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/just-measured-s5-turbo-rear-iron-factory-bracing-pics-795339/

I measured a 19% thicker dowel pin landing on the s5 I had, which came out of a 91 JDM engine I believe. Also, the secondary port runners are slightly bigger on the s5 irons, you can see it if you compare the s4 and s5 turbo LIM gaskets. I ended up swapping to all s5 irons and then used s5 JDM intake manifolds.

That won't work, there are a bunch of differences

 

I cracked a S5 iron.

 

that really sucks guys

 

what ecu are you running?

 

you can crack FD irons too... it does happen

 

HBP, Haltech E6k, T72 running 23 PSI with meth injection.
Running 11.4 AFR
Pulls like a SOB!
Apex seals are fine. Don't think I detonated. It happened in the middle of 2nd gear and pulled hard all the way thru 3rd. Didn't die when I came to stop like a blown engine does.
I thought my car was on fire! Grabbed the fire extinguisher and opened the hood. Engine was coated with oil!