I have done 3 FD rebuild all with the same problem, bad compression in the rear rotor.



All 3 are from different cars.



ALL HAVE THE SAME PROBLEM when I assemble them the rear rotor to rotor housing there is a huge gap{Here is a picture of the problem} to where i can rock the rotor in the housings. While the front rotor in all the engines have almost no play and measure fine with rotor to rotor housing clearance



I have done lots of engine before and really never had an engine that's rotor to rotor housing is to big.



The rotor to rotor housing is over .035 inch or more.



I fixed the problem one time by using a different front iron, but that does not seem to work all the time even with a new mazda front iron.



Before I thought that the rear housing with the rear gear would fix the problem maybe lineup the rotor and e-shaft, but no luck.



any insight for a correction

 

That's not your compression problem. When you assemble the engine the front stationary gear is what keeps the front rotor centered. That's why you have less gap on the sides. In the rear, the rotor has more movement because there is no gear in place to keep it centered. This problem is corrected as soon as you put on the rear plate and stationary gear. Ultimately if you have good housings, your side seal to corner seal clearance will make the biggest difference in your compression readings.

 

The rotor itself shouldn't be touching the housing anyway, that's what apex seals are for, but what ultimate 7 said is true, the stationary gear will tighten it up.