S4 and S5 NA clutch differences?
 

Looking for a stock clutch disc 225mm and I need to know why Mazdatrix has two part numbers. http://www.mazdatrix.com/f86-92nt.htm

The S4 version fits '83 to '88. The S5 version is $38 cheaper. What gives?

Also notice the S/S Heavy Duty disc directly below? It just lists one part number for '83 to '92.

Has anyone used the S5 disc with a Racing Beat light steel flywheel and a street strip pressure plate? How did it drive?

I have mixed and matched various series' clutch discs with no issues. There are basically only 2 versions of clutch disc, the smaller NA diameter and the larger turbo diameter. I think the reason some application charts list different PN's for s4/s5/coupe/vert/whatever, is a slight change in the thickness of the disc...i.e., how long it will last, how much wear material is present. Aftermarket stock-type clutch discs are manufactured with varying thicknesses anyway...I have measured new clutch discs anywhere from 0.340" to 0.325".

Bottom line, as far as I can tell (I have done tons of parts comparisons and swapping over the years, while working on hundreds of cars) you can use whichever variant you want. I've even used a t2 clutch disc in an FD before. I think I once looked up the ACT disc-only part numbers (they are stock, oem diakin discs for the SS kits) and found that all 87-95 turbo disc applications used the same part number.

It looks like I'm going with the S5 disc, street strip pressure plate, and light steel flywheel. Thanks!

Do not use the S5 flywheel on the on an S4 motor if you are talking about one with a built in counterweight.

The S5 counterweight is different then the S4 counterweight because the S5 rotors are lighter.

As long as you use the right flywheel to the engine you should be fine.