title says it... im hopin a member can help me out here. i can go buy one from the junkyard for $35 plus tax but i only need it so the machine shop can balance my flywheel. other than that it will sit and never get touched again. if i have to buy one from the junk yard i spose i will but figured someone has one of these layin around they will never use.

i believe and dont quote me on this but every flexplate/flywheel is balanced according to your crank shaft so that youd have to get a specific weight for your according to your crankshaft. and i actually thought all newer motors were internally balanced.

[This message has been edited by Niterrorz (edited 10-18-2011).]

I have one. I would let it go for $25 shipped to your front door.

I'm puzzled. Why does your shop need a flexplate to balance the flywheel? In externally-balanced engines the flywheel and crankshaft are almost always balanced as a unit. In internally-balanced engines the flywheel should be almost perfectly balanced as-is, and it can certainly be balanced independently, but it's still a good idea to balance both the crankshaft and the flywheel independently and then verify proper balance as a unit.

[This message has been edited by Marvin McInnis (edited 10-18-2011).]

3800 engines are externally balanced. There is a counterweight on the flexplate/flywheel and also in the harmonic balancer. 3800 Series 2 and 3 SC (L67/L32) engines have MORE external counterweight amount than the N/A versions of these engines. Since the 3800 Series 2 N/A engine was the ONLY engine to ever be used with a manual trans (in a Camaro/Firebird application), that flywheel is going to be balanced for an N/A engine and not an SC engine.

A good machine shop can balance match the new flywheel to match the same amount of counter-balance as the stock flexplate (that came off the SC engine) had. Even though a balance-match job is not as good as a full engine balance, it should work just fine and be better than just slapping an "un balance-matched" flywheel onto the engine.

I've been told the amount of counterweight difference between N/A and SC engines is some 40 grams. Some people have just done the manual trans swap without having the new flywheel balance-matched to the stock SC flexplate and reported that they didn't feel huge vibrations. But even a minor imbalance can impact engine bearing life.

-ryan

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OVERKILL IS UNDERRATED

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

Thanks for the explanation. So the flexplate is only needed as a reference to determine the magnitude and angle of the required flywheel imbalance? That makes sense.

I think I've read of some people using unmodified L36 flywheels on L67 engines, but I don't remember any of the details. Maybe the balance was just "good enough" for them, or maybe the L36 flywheel isn't compatible with the transverse transmissions. Like you, if I were doing it I would want to be as close to optimum as possible.

[This message has been edited by Marvin McInnis (edited 10-18-2011).]

About a third of the way down this page shows how I did it myself. Must warn though, it's still not tested.

Edit: Please ignore the gay music in the video. The girlfriend was out there that day and she commandeered the sterio.

[This message has been edited by 1fatcat (edited 10-18-2011).]

quote Originally posted by Marvin McInnis: So the flexplate is only needed as a reference to determine the magnitude and angle of the required flywheel imbalance?

Angle isn't any different, but magnitude (amount of weight difference) is.