Quick questions, are front and rear rotors of the same year and make swappable. Can a front rotor from one engine become a rear rotor for another engine. I cant think onf any reason and I am pretty sure they are identical, just wondering if there is some reason that they can not be switch.

 

yes, they are swappable

 

Thanks, I was pretty positive that they were, I just wanted to make sure.

 

If you are using a rotor from another engine in your car, it is not front/rear that you should be concerned about, it is their balance.

Rotors should have their balance codes within one letter of each other: EI: A C rotor can be matched with a B, C, or D rotor, but not with an A or an E rotor.

(The rotor codes are stamped into the rotor side faces).

Ideally, you want your codes to match.

I do not know the consequences of mismatching codes (such as A rotor with D rotor), as I have never built or dissassembled an engine as such.

 

Yeah, I know if you go to Mazda they have the same part number.

Very good point scathcart!

If you are using a rotor from a diff. motor I would use the whole rotating assembly ecc. shaft and both rotors that way they should be balanced together.

 

Very interesting, I never heard of that.

 

Rotor Codes?
Ok My son and I are rebuilding a motor for a 90 GXL.
The original rotor for the front is trashed.
The two rotors we plan on using are from two
different years. Not sure what year the other rotor is.
But it has a overall machined look to it. The original one has a machined dish only and the rest of it is smooth. Can these two rotors be use in the motor we are assembling?

 

Ooooo... may not be such a good idea.
Sounds like you MIGHT have an S4 and S5 rotor there.
You can't mix them... the s5 rotor is lighter, and has higher compression.
You can't use S5 rotors (even if you have both of them) in an S4 engine (or vice versa) without using the coresponding year front counterweight.
Wiegh the rotors, if they are within a few dozen grams of each other they are fine.
The other thing- S4 rotors have a raw cast surface in the depression on each rotor face (rough). The S5 rotors have that surface machined clean.

 

The dish of both rotors are machined. Except the one has an overall machine look to it?

I can email high resolution pics if you like.

 

Just weigh them, compare the depth of the dish, and compare the profile/curvature of the each rotor to make sure they are identical.