Saw a few threads about this. It pointed me to mazdatrix webpage about flywheels.
http://www.mazdatrix.com/b5.htm

I figure they arent interchangable because of the difference in weight of the rotors, and counterweights as well. But I figured I'd ask. Thanks

 

You're right, they're not interchangeable. If you use an aftermarket flywheel with the right counterweight for the engine, then yes.

 

You are correct.

However aftermarket flywheels will list as fitting both S4 and S5 engines.
To use an aftermarket, you need to get a counterweight off of a car that used to have an automatic transmission. (You need to match the proper series.)

After that, the only difference is the clutch size, turbo or N/A.

 

sooo.... what if i take a 89 NA mated to an auto, take the thrust plate off, and put a S4 TII flywheel on it. will that be balanced, or not. because S4 and S5's use diff counterweights due to diff rotor sizes and weights built into the flywheels. so if i wanted to do that, i'd need to use a S5 NA flywheel, correct?

my problem is that i have a S4 TII engine and trans. engine is currently being rebuilt, but i have a S5 NA engine i'd like to use.... but even if i put the S5 NA flywheel onto the S5 engine, i cant use it cause NA's use a 225mm disk at 32 splines vs the TII's 240mm at 33 splines....

so for me to get my S5 engine into an RX, i'd need a NA trans, because i cant use the TII i have unless i have something to go with my S4TII flywheel or buy an aftermarket flywheel and use my existing rear weight from the thrust plate...

is my thought process right, or did i get something wrong?

 

i thought the t2s and na trans would swap over... aslong as you had the right counter weight fly wheel and clutch kit...
the splines on the transmission spline to the clutch not the actual motor. so in essence all you need is the above mentioned stuff ...

 

if i have a s4 na with a stage 1 centerforce clutch.

j/w if you can swap a s4 tii flywheel in?
need counterweight?