Ok I'm rebuilding another engine. This time I want to use a 26# flywheel and corresponding counterweight.

I have a nice pressure plate and clutch for the 83-85 flywheel 26# and I want to be this my starting point...should I use the corresponding factory rotors (light) or can I use the heavy ones? I want to use the heavy old rotors... (these are in perfect shape, busted a main bearing in the light ones) ...on either rotors I will use the proper counterweight that matches the flywheel.

 

Don't forget that the flywheel also needs to match the rotors, not just the front counterwight. Are you trying to use '79-'82 rotors with an '83-'85 flywheel? That's a no-no.

 

ok so basically all the rotating parts have to be matched exactly as they left factory. So rotors and flywheels/counterweights are NOT intercheangable? I noticed after doing a nice long search that MANY engines have only the correct frnt counterweight and flywheels but most people ignore the correct rotor application...I just wanted to be sure.

No problem I got the whole setup as it left factory. Just need to resurface the flywheel and get a new clutch I just wanted to use my existing new clutch.

thanks jeff

 

is there an advantage on using the older setup, older-82 light flywheel/heavy rotors vs. the newer 83-85 heavy flywheel/lighter rotors? has anybody ever thought of checking to see any differences in output?


BTW I'm talking about 12a

 

I've thought about the differences between '82 and '83 like you have. The lighter rotors are better at high RPM. I'm not sure if that means they accelerate faster (they probably do), or if they just handle the higher speeds better, but your flywheel also plays a significant part in accelerating the whole assembly. The lightest you could do would be '83-'85 rotors with an aluminum flywheel, unless you wanted to get crazy and start removing material from the rotors and counterweights.

I guess the cool 2nd and 3rd gear chirps of the '79-'80 cars were reduced in '81-'82 cars with their lightest flywheels, even though the rotors were still the same weight as '79-'80. Then, the '83-'85 cars got a slightly heavier flywheel, but the rotors got lighter. I think the 2ns gear chirping ability might have improved, along with better performance at higher RPM. 3rd gear chirps are probably still possible with '83-'85 cars, but not as easy as '79-'80. Or is the performance of '81 through '85 cars similar even though Mazda played around with the weights of everything? Anyone know?

 

wheel chirping ability???

hehe nice way to put it. I doubt there is a very noticeable difference...what really puzzles me is that u mentioned the fact that the lightest one could do would be 83-85 with an AL FW.

Why can one install an aluminum flywheel and get away with no vibration and yet not be able to use the lightweight stock flywheel? see my point? kind of doesn't make sense since an AL flywheel is lighter than any of the stock FWs and thus would also not balance correctly with the rotors.


sorry if I'm getting too picky

 

I think it has to do with the counterweight

 

Yes. You're forgetting about the rear counterweight. The rear counterweight is actually built into all stock flywheels, but aftemarket flywheels actually bolt to an automatic rear counterweight, from an automatic transmition car. I think that's the critical info you were not sure of. This rear counterweight needs to match the rotors and front counterweight. Then you could use a light steel flywheel or aluminum. Personally, I like the light steel, but that's just me.