Found these rotors in my oem engine. Why is the surfaces TOTALY different? It looks like one is milled and the other one is "grinded". Dont know if that is the english word for it but i think you can guess what i mean.

The smooth rotor also has the greenish color on it, exactly as the side of all the rotors have.

So whats your comment? Is this common?

 

Completely normal.

 

It is very common. We see it a lot in Mazda remans where they only replaced one rotor. Other times we see it in the original engines after cleaning the carbon off. Just make sure that the weight codes are the same or within one letter.

 

ive seen new rotors out of the box like that, either they have 2 machines, or they let the bit get dull before they changed it.

 

Thanks for the answers. I too belive in the "2 machines" theory. The dull bit theory is also good but i dont belive it, the difference is to great. How does 20 year old rotors look like? Maybe they tested a different type of machining when the FD came but kept the old machines. Just theories...