Is there any difference between the 12a and 13b counter balancers? I have an adapter kit for my fiberglass dune-buggy that originally had a 12a on it but have this 13b sitting here.

-Mark

 

If you mean the bolt pattern that goes from the rear counterweight to the flexplate/aftermarket flywheel, no. That never changed, to the best of my knowledge. (People put TII lightweight flywheels on 20Bs and on 12As, after all, and IIRC even the RX-8 engine is the same)

The imbalance is not only engine-specific but year-specific, depending on rotor weight. The counterweight must be matched to the rotors in the engine.

I am *assuming* that your adapter kit came with a flywheel meant to bolt onto the automatic's rear counterweight.

 

Is there a way to find out what the counter-balancer is supposed to go to? Is there a source for CB's for other engines?

The adapter has a re-machined VW flywheel with a RX center. The CB then bolts to the backside of the flywheel. The CB is removeable so I assume it is the balancer from an auto RX although I have never seen one to know for sure.

-Mark

 

Manual transmission rotaries (not RX's, RX's are Subarus, I had one) had a one-piece flywheel/counterweight. Automatics had a separate counterweight that the flexplate bolted to.

 

Like I would be talking about a Scooby Doo on an RX-7 forum...

The question I need an answer for is how to determine which counter-balancer I need for my 13b and where to find one if the 12a one is different.

-Mark

 

The 12A one *is* different.

Find out what year your 13B is. Then get an automatic counterweight for that year engine.

 

There should be a number stamped on the counterweight. Rob at pineapple can tell you which one it is.

 

That does not hold true for the 84-85 GSL-SE 13b engine cars, cause they was not automatic GSL-SE made.

You have to get a Rx-4/ REPU unit since they use the same rotor weight as the GSL-SE cars.

John

 

Right. '74-85 13B are of the same "year".