hello, i've been rebuilding engines for a while, but i've always been using sets of rotors and counterweights that came together from a specific engine. Just recently i got the chance to take apart two S4 Turbo II engines and take whatever was good still. Of course only one rotor was good in each engine, and my question is, can i use these two rotors to build another engine? i already called mazdatrix and they told me since the engine won't be a race engine, just for regular everyday driving, that i could mix these two rotors and as long as i have the front and read S4 counterweights(which i do). However i'm still sort of iffy about doing this since i heard a while back from a friend that there are different rotor balance classes, so i couldn't mix rotor weights, unless i identifyed the rotor balance class. so to the engine builders, what do you think? or what do you know? and if you do know anything about the balance classes, let me know how to identify markings on the rotors.

 

Im in no way an expert or a builder, but here is an exerpt taken from mazdatrix website:

Balancing of the rotating engine assembly parts is usually only necessary for high RPM race engines, or when mixing rotors, counterweights, flywheel, or using lightened rotors. Please call for specifics before sending in your engine parts.

 

the balance class thing doesn't really apply, because the rotors are graded PER BATCH, and a rotor from say 1986 and a rotor from 2010 will not weigh the same even though they will have the same grade stamp.

and well hey if its really a big deal, balancing isn't expensive.

 

pineappleracing.com has a video on their site about balance and rotor weights they also have alot of good other info on there too.

 

For general street driving, as long as the balance is the same within two letters, you should be fine.