Anyone using lightweight Flywheels - Chevelle Tech
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post #1 of 32 (permalink) Old Dec 22nd, 04, 1:05 PM Thread Starter
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In the market for a new flywheel and clutch..and I was just wondering if there was a benefit in going with a 15lb billet aluminum flywheel vs. a 30lb billet steel. My 383 engine sees 6500+rpms and i'm running a muncie 4 speed. Its a weekend cruiser and 1/8th mile track runner once or twice a month.. What would you go with?

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post #2 of 32 (permalink) Old Dec 22nd, 04, 1:13 PM
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You won't like it in a street or street strip car.
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post #3 of 32 (permalink) Old Dec 22nd, 04, 1:18 PM Thread Starter
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Quote:
Originally posted by Mike Feudo:
You won't like it in a street or street strip car.
thats what I've heard....probably wouldn't give me very good 60ft. times.?

Herb
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post #4 of 32 (permalink) Old Dec 22nd, 04, 1:29 PM
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There are 2 schools of thought on flywheel weight.

A Heavier flywheel has more inertia and may launch the car harder resulting in a better 60ft time and possibly correlating to a quicker ET but the engine will accelerate slower trying to spin that extra 15-25lbs which in turn could result in a slower ET

The opposite is true for a lightweight flywheel

Billet steel flywheels are a waste of money. If your going to use the heavier type, stick with a factory cast flywheel. Cheaper and I've never know a factory flywheel to come apart. Even when they are machined way down past what I thought was safe.

The lightweight flywheel will not save your Muncie either. I went through 2 and a Super T-10.
Even with Liberty modifying it.
You're on borrowed time if you're launching at a decent rpm.

Rob
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post #5 of 32 (permalink) Old Dec 22nd, 04, 1:31 PM
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We use a 9.5# Fidanza FW in our road racer. 331" SBC with a 2.64 ST10 and 3.25 gears - no problems at all getting the car launched.

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post #6 of 32 (permalink) Old Dec 22nd, 04, 1:48 PM
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Chevy has a very tough 10.5" nodular iron flywheel available that weighs in the neighborhood of 14 lbs. It was used for all the Corvette L88 engines and '65 396 Corvette as well. I love mine on or off the strip but before you decide you need to take all aspects of your car, engine, and gearing into consideration.
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post #7 of 32 (permalink) Old Dec 22nd, 04, 1:56 PM Thread Starter
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Quote:
Originally posted by Rain Man:
Chevy has a very tough 10.5" nodular iron flywheel available that weighs in the neighborhood of 14 lbs. It was used for all the Corvette L88 engines and '65 396 Corvette as well. I love mine on or off the strip but before you decide you need to take all aspects of your car, engine, and gearing into consideration.
Rain Man
i've heard that the light flywheels put down more horsepower to the wheels, but also heard that i would sacrifice launch, and fast rpm drops. I'll be running it on my 69 vette...weighs in around 3400lbs(me in it), 3:36 rear, and wide ratio M20.(switching to 5sp Tremec later on)
I know this isn't chevelle related, but wanted some real opinions. I had a 70ss and sold to buy the vette.

Herb
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post #8 of 32 (permalink) Old Dec 22nd, 04, 2:22 PM
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383 vette, I had a 30lb hayes steel flywheel in my 73 355 camaro it hauled ass, I could smoke the tires for a whole block. Steel flywheel is my 100% vote. And never blew my tranny either, 3 years of abuse! (11 sec car)...mike
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post #9 of 32 (permalink) Old Dec 22nd, 04, 2:54 PM
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Quote:
Originally posted by mfsr:

Billet steel flywheels are a waste of money. If your going to use the heavier type, stick with a factory cast flywheel. Cheaper and I've never know a factory flywheel to come apart. Even when they are machined way down past what I thought was safe.
Using a factory cast flywheel in any kind of performance application is asking for trouble. They do come apart the the results are never pretty. If you've never personally had one come apart doesn't mean using one is a good idea.

If you want to use a heavy flywheel, go with billet, it's much more safe and not much more expensive than buying a new cast iron one (keep away from used cast flywheels, they more than likely have cracks you can't even see). An aluminum flywheels has more of an applciation in road racing where the RPMs are kept relatively high most of the time. If your engine make prodigious power, it might not have as much trouble launching a heavy car with an aluminum flywheel.

There are also lighter billet steel flywheels which can be a compromise between full weight steel and aluminum.
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post #10 of 32 (permalink) Old Dec 22nd, 04, 3:27 PM
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In the road race / autocross / canyon runner type cars the lightweight flywheels are great.... Going into a tight turn where it may be a bennifit to stay in the same gear.... a light flywheel will Decelerate the car quicker than a heavy flywheel will.... IE a light flywheel can almost act like a set of brakes......by dropping RPM when you let up on the throttle much quicker than a heavy flywheel would..... And then gain RPM quicker when you get back on the throttle..... Cornering is a huge part of that type of raceing.

On the street it's a different thing.... especially if you dont have alot of torque or lots of gearing.A heavier flywheel will be much smoother and driveable than a lightweight one would....especially if you are shy on torque and gearing.The Heavy wheel stores much more momenteum
and energy and wont drop as much RPM between shifts as a lightweight would.

In a lightweight car with alot of power and a close ratio box , you can get away with a lighter wheel.....If you assume a given engine makeing X amount of torque , then the lighter the car the lighter you can go with the flywheel , and teh heaver the car the heavier the flywheel needs to be for decient drivability.

IE 400LBS of TQ is fine to use a 15 lbs wheel in a 2500 lb car but to use a 15 lb wheel in a 3900 lb car wont ge nearly as much fun to drive as a 40 lb flywheel would....assuming the same gearing.This is one of the reasons that the 30 lb wheels seem to work so well in most applications

BTW I have to agree with RichL79 .... An aftermarket steel flywheel is a better piece than a stock wheel.... now Detroit a couple different types of iron in thier wheels , Grey and Ductile irons..... If given a choice I wouldnt use a grey iron flywheel even on a 4 cyl ... Yes they work but are not as strong as the ductile iron wheels..
The ductiles are better and strong but not as strong as an aftermarket steel wheel.

Al.
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post #11 of 32 (permalink) Old Dec 22nd, 04, 4:23 PM
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I definately second the don't use the factory flywheel for any sort of performance application. When I was in high school a friend had one let loose in a 55 Chev. It looked like a bomb went off. A large piece went up through the dash and out the windshield. He was lucky no serious dammage just a really sore right foot from the shock.
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post #12 of 32 (permalink) Old Dec 22nd, 04, 4:37 PM
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Rich,

I must respectfully disagree. Flywheels rarely if ever come apart on their own. They typically come apart after the bolts sheer, the pressure plate fails, or the input shaft lets go. (unless you're talking about prostock type RPM's) I had a factory flywheel in my 68 Camaro that ran 10.80's with the Muncie, had it machined everytime I put a new disc it (5+ times) and it still mic'd out thicker than the recommended minimum.

You're right, the end result wouldn't be pretty, but that's what a scatter shield is for, not the factory aluminum bellhousing. Ask Big Daddy Don G. Hopefully people dragracing will realize to change that item before it's too late.

383, If your spinning the tires on the launch, your tranny is less likely to break. But I can say from experience, and my friend and I having 6-8 broken Muncies lying around at one time, do not be surprised if something in that tranny one day says "I give up" A cluster gear is a crap shoot to find these days. Take it out and try that Tremec or a used Jerico and save it for restoration.

A steel flywheel is stronger than a factory one, but is not nessecary for this application. I was trying to give a couple of personal examples though. If money wasn't an issue, then I would use the aluminum flywheel with a 10.5" long style pressure plate and a 6 pad composite disc for mostly street / occasional strip use.

Rob
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post #13 of 32 (permalink) Old Dec 22nd, 04, 8:08 PM
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Anyone that would suggest a cast iron flywheel for any performance application has got to be kidding! Do not use an aluminum flywheel for anything but a light car.....Esp. in light of the fact that you have a car that weighs probably 3300lbs or so. You need a 30lb flywheel no ifs ands or buts.Stick cars are all I've ever known so stick with me on this one!

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post #14 of 32 (permalink) Old Dec 22nd, 04, 9:13 PM
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Gearing is the key here. Above 10:1 overall gearing in first, a light flywheel would be fine. A 2.2 first with a 3.08 rear (6.78 overall) would be a bad choice for a light FW.

Scott
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post #15 of 32 (permalink) Old Dec 22nd, 04, 10:02 PM
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Your leaving out two important things,power and weight.Ive got about 16:1 and still wouldnt run an aluminum flywheel.....and I'm not into slipping the clutch to make it work either....yes this is just my opinion but Ive seen what happens in a car similar to mine,the car died off the line and he would have had to take static out to recover some, but, in that application it would have been a bandage at best

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