Hi all, this is likely an easy question to most of you, I just want to be sure before comitting to/messing up something. To be more specific, I have an NA S4, I pulled and disassembled my motor. My front rotor is an "E" and my rear, which is damaged and needs to be replaced, is a "D". I'm aware the rule-of-thumb is staying within a letter difference when changing rotors. However, I'm also aware there are front and rear counterweights for the rotors. Am I limited to buying another "D" rotor? Can I drop in another E rotor? Can I just drop in two completely different rotors without rebalancing? What are my options? Thanks in advance

 

I’m not an expert by any means, but rebalancing your parts would be the most surefire way to guarantee everything plays nicely together, regardless of the rotor casting letters.

 

you might weigh the new rotor and see how far away it is from the old one.

 

You shouldn't need to with the proper factory counterweights, I always have my assemblies balanced even with the same letter designation.