2gslse

instead of getting diff. rotors why don't you buy 3mm seals and use the ones you have?If you do get the rotors make sure that you have the counter weight off the front of the engine and either a rear counter weight or flywheel so that it will still be balanced correctly.

boost_creep

Scary, Scary this is scary stuff. Chino hold up a sec......Are there any rotary techs close to where you live, if not you need to go buy a haynes or a shop manual and read some. Do this before you undertake any form of dismantling or rebuilding. To work with rotary motors you need to be part mechanic, part engineer and a full time lover.

chino

thank you guys.i have the hayes manual but i did'nt pay attention to the rotors groove and i bought 2mm apex seals,2mm corner plugs,93 corner springs,j-tech intake,racing beat exhaust,holley 650,the side housings and the center housing are street ported conservative.i have worked on some other areas with rx-7 but never internally,but when i inserted the apex seals in the rotors groove something was telling me that something was wrong here that why i asked you guys because i know you guys know and you have comfirm what i thought and i thank all of you for responding so fast.i can do the engine i know how put the o-rings and springs,water o-rings,and i follow the hayes manual i believe i be ok now i know that i have to be more careful next time.thank you again to all of you.

RONIN FC

Hey, listen to 2gslse, get the counterweights to match the rotors or the engine will be a disaster.

BDC

Really?



Why then did my S4/S5 combination motor work? I swapped a Series 5 short block into my FC yet I kept my series 4 front counterweight (yep, I changed the front covers and had that all apart) and series 4 aftermarket lightened-steel flywheel and it worked fine. The flywheel c/w and front c/w are a matched pair; the rotors are a weighed and matched pair; the two together are not.



B

RONIN FC

Well, then enlighten us. What is the purpose for the counterweights. Why would Mazda make specific ones for different rotors?

BDC

Good question. I don't readily have the answer as I'm not as learned on some of that area of physics but I do know that, pragmatically speaking as much as I hate it, you can swap the counterweight and flywheels as a pair, and the rotors as a pair, and not disturb the 'balance' as it were.



It worked for me and I marched into it unknowingly at the time I did it.



B

RONIN FC

Your e-shaft bearings must have taken serious abuse. The difference in weight may not be enough to grenade the engine first start up. But something I wouldnt venture into.

BDC

Could you please explain to me why from a physics standpoint how changing the outer rotational balancers, as a pair, will make the entire shaft assembly wobble?



I've been running this same combination for almost 20,000 miles now, with many revs, without any hitch.



I don't understand where you're coming from here from a technical standpoint ..



B

IGY

BDC is exactly correct. As long as you keep the counter balances in pairs, and the rotors in pairs it will work fine. If you use a S4 front and a S5 rear you would swear you are sitting on top of jackhammer(seen it). Don't know why it works, but it does. Just like S4 rotors in an FD motor with FD counter balances.