12a motor +13b flywheel ?
 

are the counter weights different and is it not advisable to do?. or will it work ok.

Pretty sure you use the counterweight that matches the flywheel (13B flywheel=13B CW).

Otherwise, it is a common upgrade. I think ALL of the guys local who rock 12a's have a 13B clutch set up in them.

sweet! thanks.

The only difference between a "12A clutch setup" and a "13B clutch setup" is the weight of the stock flywheel. '83+ (12A and NA 13B) uses a 225mm clutch disc and pressure plate, whereas up to '82 used 215mm, but the parts are interchangeable (you can use 225mm clutch components on an early flywheel or vice-versa).

thanks again. good to know

You can not use a 13B counter weight or flywheel on a 12A engine. The flywheel or counter weight is matched to the rotor weight. The 12A and 13B rotors require different weights. You will need a 12A flywheel or a 13B flywheel bolted to a 12A counter weight.

seems some one had to drop in and say that. lol it seems to make sense to me, as that was how I thought it went, now when you say a 13b flywheel with a 12a counterweight, that would only pertain to aftermarket flywheels because stock ones have the weight cast into it right?

lets make this a bit easier. I have a 12a car that was a auto, and a 13b parts car with a standard setup, and the plan was to swap the flywheel on to the 12a and bolt up all the 13b stuff. will this work. or do I need a 12a flywheel.

Correct.

That will work. Are you using a 13B turbo or NA flywheel? Not sure what the diameter of the 12A ring gear is off the top of my head, but I'm guessing the 12A and 13B NA are the same. If that's true, and you have NA stuff, you could run any mixture of the parts. If you're bolting up a turbo flywheel you will need to use a turbo trans. Basically, the bellhousing needs to match the diameter of the ring gear so the starter will engage.

Lastly, kinda obvious, you will need to use a clutch that matches the flywheel/trans combo and not the engine.

Im still a noob on the rotary stuff, totaly wiling to admit that. I am a Vw/mazda tech, but to be honest, we dont get alot of inner workings training or at least I havent, we mostly just replace the motor if anything goes "wroung". I was unaware that there is a front counterweight witch was aiding to my confusion.

after C. Ludwigs last post and my new knowledge I want to re ask just to get 100% on this.

12a motor with the stock 12a ft counter wieght, and a 13b flywheel with the 13b clucth and trans. this works and has been done correct.

I think I was getting confused due to all the aftermarket flywheels needing the auto flywheel counterweight witch bolts to the auto flex plate, and not knowing the motor had a ft counter weight.

Is the 13B flywheel in this example a "lightweight" flywheel bolted to the 12A rear counter weight or is it a stock 13B flywheel? If it's the stock flywheel then it's not right. The balance is off, badly.

Stock flywheels have counterweights built in. Aftermarket ones don't. That's why aftermarket flywheels need the automatic counterweight, and you can't mix-and-match stock flywheels from engines with different rotor weights.

Yep, the rear counterweight has to be matched to the year of the rotors. Otherwise you will get nasty vibrations that will eventually tear the motor apart.

For my 12a, I went with a lightweight steel flywheel along with the correct counterweight. Then added a nice clutch originally designed for a 13b.




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ok guys thanks I got it now, so I will need to buy a aftermarket flywheel and use my 12a auto counterweight, or buy the 13b I have a line on and get a carb on it. either way the 12a I have and the flywheel I have wont work together.

better then finding out myself. thanks all.