So I am converting to manual. I have a 2nd gen n/a tranny, clutch and flywheel (that I got for free) Can I use the 13b flywheel on my 12a if I get rid of the counterweight and use the automatic counterweight?

 

I believe that you would need the counterweight that matches the same year of the flywheel. Mazdatrix has a good page on flywheels and counterweights that should tell you which counterweight to use with your flywheel. Example: If your flywheel if from an 87 the you would need a counterweight from an 87. Not sure thought is a 13b counterweight would fit in a 12a or not. Someone else who has actually done or attempted this could better address that problem.

 

I thought the counterweight had to match the engine.

 

You can't use a 13B flywheel on a 12A.

 

Use a 12a flywheel, that matches the year of the motor, or a 12a auto counter weight with a light weight flywheel. Do not use the 13b flywheel.

Since you have an 84, the clutch assembly will be the same.

 

If I had money I would go the lightweight route, that is very expensive though.