Here's two picture. First picture has both rotors, second picture I'm pointing to the machined circle by the tip of the rotor.

If you notice that rotor one has 3 circles and one of them is machined, the second rotor only has 2 machined circles. Both are on the gear side. Also the one without the machined grove has the bad bearing.

It's all came from a S4 TII motor. I don't wanna press in new bearings if the rotors are not even matched within series. But I don't know the history of the motor, as I bought it off locally and it had busted coolant seals.

So I need your 2nd opinions, you think these 2 rotors will be fine? I used my weight scale and it said 9.8lbs for both rotors.

Bud

 

I know that there is a .3 cr difference in s4 rotors. So it could be + or - 8.2 or 8.8. But that would be on the indent part of the rotor. Not the face correct?

 

those holes you point to are where mazda removed weight to balance the rotor. since its behind the side seals its not in the combustion chamber.

also the FACE of the rotor generally is the combustion side, where the combustion recess is. where you are pointing is the SIDE or flank of the rotor.

 

If they came from the same motor, then they are matched: they'd better be!

Just make sure the weights are the same, or within a range of 2 letters. Example an A and B or C would work, but not an A and D. Most rotors though are C weight so there shouldn't be too much trouble. To really see if they are fine you have to do your checking according to the FSM.

 

I know 2 letters from the same. But just want to make sure, before actually putting a new bearing in.

Story with this motor. Guy bought it from a person in WA, he swapped it in claiming it was rebuilt. Tried to fire it up, and no go. Both front and rear seals were shot. Coolant pouring out of the exhaust when turning by hand.

I hope the person who "rebuilt" doesn't have it mix and match. This is my first turbo keg. If all else fails back to high compression turbo, but with a tune.

J9 thanks for clearing that up. I meant the side of the rotor. The face I have no worries about. Just making sure that this might be ok. I don't want to put it together and have it throw a rotor.

I don't know the full history of the motor. But if you guys think it's ok then OK by me.

The rotors are within a letter of each other. This is going to be motor number 11, project chance. I might actually do a build thread...