I am going to be rebuilding my 90 TII pretty soon. I just watched the Atkins rebuild video. I was wondering, does it matter if the rotors go back in where they came from? What about if i have a damaged rear rotor, can I use a S5 TII front rotor to replace it? Same with the housings. Is there a difference from front to rear housings?

Thanks!

 

rotors are identical (front/rear)

housings are not, but in some cases, could be swapped

 

in some cases? When would that be? Thanks

 

If you need to pass emissions, you need to keep stock front-rear rotor housings in their positions. IF not, it doesn't matter.

*You can pass emissions testing without the correct housings, also, its just a little harder*

 

The only difference between the front and rear rotor housings, that I can see, is where the air injection port is drilled. Correct me if I'm wrong. They appear to be the same castings.
The hole is drilled in the back-side of the port for the front rotor and the front side of the port for the back rotor.
I'm talking about the rotor housings and where air from the air pump enters the exaust fromthe air pump.
From the Air Control Valve?

 

Correct.
This is what allows the ECU to correct the exhaust AFR's to 14.7:1 before it enters the cat, even though the engine AFR's are closer to high 12's, mid 13's. Helps the cat work a little better.

 

I'm guessing it could be possible to plug the existing hole and drill a new one to be able to swap rotor housings from front to rear. Threaded pipe plug or weld would probably be best. Whata ya think?