I have 2 s4 TII rotors I would like to use in my next build, only thing is they are not the same stamped weight or the next step up or down from each other. One is a C the other is an E. Are these OK to use together, or do I need to get a Rotor that is within 1 letter of either of these?

I will probably be lightening the rotors and balancing them anyway, but if I don't and just use them as is will they be ok? I've read stories about people opening mazda remans that had much larger differences in rotors, such as a B and an E, and they didn't have any issues with it running that way.

 

Some how I don't see this being a good idea. but then again, i suppose it depends on how much the wieght difference is and how high you'd like your redline to be.

 

The letters are not always absolute, but you really need a scale to find out how close they are. A is the heaviest and E is the lightest of each type rotor. For an s4, an A rotor might weigh 10.24, a C might weigh 10.16, and an E rotor might weigh 10.08.

But, as I weigh all my rotors, I have seen variances. I have weighed a bunch of C's back to back and had them weigh 10.14-10.18, and then weighed a D that weighed 10.20.

As long as you weigh them and they are within about 0.10lb of each other they should be fine. OF course, the closer you can match them, the more of a "static" balance you have...which doesnt take into account side-to-side and tip-to-tip "dynamic" balances where the shaft, rotors, and counterweights all get done as a unit (more like blueprinting a piston rotating assy).