On a 12a is the front and rear rotor different or are they interchangeable. And if they are diff. how do you tell them appart?

Thanks, I have searched but could not find anything.

 

If you look at the pic you see the combustion bowl, if you switch a front rotor with a rear rotor, the bowl will be upsidedown.
Not interchangeable.




To tell if it's a front or rear rotor you have to know which side the gear is on.
I can't remember off the top of my head by I can let you know tomorrow unless someone else already has.

 

You have an '83 to '85 rotor sitting there.

 

Sure do. It's an '85. I don't think I've seen pre '83, what do they look like?

 

sorry for the noob question but how can you tell?

 

iirc
combustion bowel is a little narrower
and the "f" "r" lettering is diff.

 

It has an N and a large cast R. The N means '83-'85.

 

This is a rear rotor. The gear is on the right side so when it is rotating in the engine the bottom or larger part of the bowl reaches the combustion chamber first.
A front rotor will have the gear on the opposite side.

 

Thanks guys for the help. I am tearing down my first rotary tomorrow. So the larger bowl is always facing down towards the oil pan.

 

Woah sweet i never knew they put imprints into the bowls. Is it typical to have that much build up on the rotor?

 

acumulated over 22+ years yes ... take the rotor face onto a wire brush attachement on a grinder and should take care of it all. Make sure the wire bruch is brass to not hurt the surface.

 

Just got done Dissasembling my 12a. Took about an hour. The front hub bolt was a little tight and the rear stat gear was a biotch to get out. Took one hour and that was fighting sticking components like the dowl pins- I need to make a tool for that.

Quick question. I only have one apex seal spring for each apex seal. Is this normal on 12a's? On the 13b's I know they have two springs- one small and one larger one for each apex.

 

3mm seals use one spring.

 

Thank you. I figured as much because there is only 1 ridge on each side of the seal but I wanted to make sure.