Anyone using lightweight Flywheels [Archive] - Chevelle Tech

: Anyone using lightweight Flywheels


383Vette
Dec 22nd, 04, 2:05 PM
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?

Mike Feudo
Dec 22nd, 04, 2:13 PM
You won't like it in a street or street strip car.

383Vette
Dec 22nd, 04, 2:18 PM
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.?

mfsr
Dec 22nd, 04, 2:29 PM
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

onovakind67
Dec 22nd, 04, 2:31 PM
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.

Rain Man
Dec 22nd, 04, 2:48 PM
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

383Vette
Dec 22nd, 04, 2:56 PM
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.

69ralleygreen
Dec 22nd, 04, 3:22 PM
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

Rich-L79
Dec 22nd, 04, 3:54 PM
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.

69LS1
Dec 22nd, 04, 4:27 PM
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.

Mike Feudo
Dec 22nd, 04, 5:23 PM
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.

mfsr
Dec 22nd, 04, 5:37 PM
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

joespanova
Dec 22nd, 04, 9:08 PM
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! :cool:

70GS455
Dec 22nd, 04, 10:13 PM
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.

joespanova
Dec 22nd, 04, 11:02 PM
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 :cool:

pdq67
Dec 22nd, 04, 11:17 PM
Imho, a stock, big flywheel with a big "N" cast in it to tell that it is nodular-iron is fine for most street rides..

pdq67

Wolfplace
Dec 23rd, 04, 12:02 AM
Originally posted by mfsr:
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 =
Rob,
No disrespect intended but I will have to agree with Rich, Joe & Al here.
I personally feel telling anyone to use a cast flywheel in a performance application is some of the worst advice I can think of short of telling them a scattershield isn;t necessary :(

Cast flywheels can & do fail & it does not necessarily have anyting to do with the bolts attaching it or the clutch although these can fail too & it is usually on launch or a shift & if you had ever seen one come apart you would not consider using one in a performance application.

Just because it worked for you for a number of years does not in itself mean anything except yours didn't come apart.
People play Russian Roulette for years too but telling someone you did & never had a problem so it's a safe sport probably isn't the best advice either :D

I have posted this before but here are my opinions on both flywheels & scattershields in general ;)

Cast Iron or Billet, they can all come apart & almost always do it at RPM & it can be on the starting line or during a shift but it can be at any point.
My own personal opinion is anyone who runs a clutch car, especially one that can RPM without a scattershield is about 26 cards short of a full deck :D

I had one come apart in a car almost 40 years ago at Fremont Raceway & it made shrapnel of the stock cast iron bellhousing & took part of the floorboards & part of the dash out of a 55 Chevy.
I was VERY lucky to say the least.

I watched one come apart in a blown alcohol dragster at Bakersfield & it broke every bolt holding the can to the engine & the inside of the can looked like a grenade went off in there.
Watched a well known Top Fuel car cut damn near in half at Orange County & there were pieces of his clutch in the pits on the other side of the grandstands.

My best suggestion is to run a quality flywheel, clutch & scattershield.

joespanova
Dec 23rd, 04, 9:45 AM
Amen :D

69ttop502
Dec 23rd, 04, 9:59 AM
I am running a McLeod aluminum flywheel in my 3200 pound Vette and love it. I have no trouble with having to slip the clutch and it revs much quicker than the nodular iron one it replaced. I am also running the street twin clutch and it is great. No more pedal than stock.

Harold Sutton
Dec 23rd, 04, 10:17 AM
Originally posted by mfsr:
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 Rob, A steel flywheel is (not) a waste of money. If you like your legs and what they an do for you then by all means buy a 30 pound steel flywheel. I have a friend who blew up a "good" factory cast iron flywheel. It was not a pretty sight. This was a 375-396 with slicks and was on the one - two gear change. The exploding flywheel fortunately had a lakewood scattershield or else it might have cut his legs off also. Since it also had a block plate the first thing it did was to pull all the bolts out of the back of the engine with the bosses still attached and cut the input shaft off of the Muncie transmission. It then seperated the block plate from the Lakewood and cut the right header in half. The transmission then hit the Dragstrip taking the shifter with it, turned sideways and tore the Hurst shifter into two pieces at the heaviest part and trashed the driveshaft. When he got home and took everything apart he found he had also blown up the motor. So not having a steel flywheel cost him every piece from the radiator to the rear end. No piece of safety equipment is more "important" than a good flywheel, period. I've also seen a Ford blow up a "good" nodular flywheel but that one only mushroomed the bellhousing. Heat is what kill cast iron flywheels and no car with street tires is likely to bite well enough to blow one up but the resulting damage is indescibable.

Harold Sutton
Dec 23rd, 04, 10:38 AM
pdq67, The "Nodular" one is no safer than regular iron one. I had a speed shop in the early seventies and had a friend who blew up a nodular one in a 427 Ford. It only mushroomed the Lakewood but it still blew up. Stay away from iron flywheels, just like playing with high explosives. I've had several billet steel wheels and have never had any problems with any of them but i avoid cast iron flywheels like the "Plague". It's also a good idea to resurface a steel flywheel when replacing a clutch.

JIM
Dec 23rd, 04, 10:54 AM
:eek: You guys are making me nervous!

mfsr
Dec 23rd, 04, 10:56 AM
To All,

All your points are well taken. I too have seen ONE come apart, but the scatter shield held everything in tact. I must digress then, I went back and read the first post and assumed it was a 1 or 2 times a year at the drags, not a month, so I will defer to all of the good posts here.

Harold, Your statment about the flywheel being the most important piece of safety equipment has to be taken in context though. No piece of equipment is more important than another as long as it saves your life, not just your car parts. And that's why I defer to all of your appropriate comments(good points). The roll cage does no good without the harness or the helmet, aftermarket wheelstuds do no good if their too short, a racing seat does no good if it's not properly mounted to the cage or bar, and so on.

I still feel that the Muncie will give out before the flywheel does though....:)

How do you guys get those stupid graemlins to work?

Rob

383Vette
Dec 23rd, 04, 11:03 AM
I agree with the billet steel flywheels over the cast iron flywheels. For my application, and my heavy car, and the amount of torque, it looks like my best bet is a billet steel flywheel.
Thanks for the feedback guys!

Harold Sutton
Dec 27th, 04, 2:54 PM
Mfsr, No disrespect meant here. It's just that i saw the carnage that an exploding flywheel left behind. It did about as much damage to the drivetrain as you could possibly imagine. This car had a muncie transmission and it was far stronger than the flywheel until the flywheel exploded. When a flywheel turns loose it generally does more damage to the passenger side of the car but seeing all the bellhousing bolt bosses ripped off the back of the engine just makes you realize how much energy is stored in that flywheel. It's a real ugly sight.

427L88
Dec 27th, 04, 4:37 PM
Was given the advice from a ProMod crew chief and his brother the clutch setup guy on that car, STEEL ALL THE WAY for a street/strip car. More important than a scattershield even.

Harold Sutton
Dec 28th, 04, 1:57 AM
Amen 427L88... My friends car even had a block plate and it still separated the engine and what was left of the transmission. It broke the bolt bosses right off the back of the block at all five or six places that the scattershield was bolted on. I'm sure that Lakewood saved some personal injury as one piece of the flywheel went up and into the hood, going between the block plate and scattershield, taking the distributor cap with it. That Lakewood still had some of the attaching bolts securely attached but there were no bosses left on the block.

engineguy
Dec 28th, 04, 10:30 AM
NHRA rules prohibit the use of "stock-type cast iron flywheels and/or pressure plates". Aftermarket flywheel/clutch must be used and must meet SFI spec 1.1, 1.2 even in Stock and Super Stock classes. Flywheel shield (steel) must also be used in any vehicle with V-8 and clutch.
There are no viable compromises for safety issues.

In my opionion, steel flywheel should be the choice for any street and street/strip car and also for most bracket cars. Lightweight aluminum flywheel will work well in a fairly light car with very low rear gear ratio (5.14 or lower), very high RPM capabilities (which will result in a very narrow RPM band).

Nickel333
Dec 28th, 04, 7:29 PM
I would probably go steel also. I have an aluminum in my street Nova and hit a 1.67 60' wich i bet would be a smaller number yet if i had steel.... theres a bog that i cant get rid of unless i launch WAY up there in RPM, like 5,500 then i just spin..... hence the aluminum flywheel. But on the other hand my little 350 raps up in a hurry with that aluminum flywheel on there!!! Go steel...its cheaper anyway

joespanova
Dec 28th, 04, 7:58 PM
Nickel333 , what gears do you run in the rear? Take the aluminum wheel out and put a thirty lb. one in there and your sixty foots will come down. :cool: whats the first gear in the 5speed?

Nickel333
Dec 28th, 04, 11:41 PM
I had 4.11's and a 3.27 first gear. It's a richmond 5. Its geared so low because i WAY over cammed {268/278@.050} and it had crap for torque. I believe in 4th gear it was the equivelent to a 5.14 gea. But thats all going to drop because im changing cams to somthing much more optimal. Im going to try 3.89 gears but im thinking im going to have to go with 3.55's or 3.70's for best ET.

joespanova
Dec 30th, 04, 8:59 PM
your a candidate for a 30lb wheel for sure!