Advice on lightened fly wheel

[Al 29Tudor]

I'm going through my drivetrain in the next few months. Rear-end, transmission and clutch. I also have the opportunity to install a lightened fly-wheel at that time.
My question is since I'm sure my crank is not counter balanced, will I be doing more harm than good by lightening the fly-wheel?
I suspect the heavy stock fly wheel is necessary to keep the engine somewhat smooth and using a light fly wheel will alloy a lot of vibration.
I sure would like comments on you experiences.
Thanks,
Al Leach

[jhowes]

I have the lightened flywheel and the v8 clutch. For me it was a mistake because none of the so called advantages are not obvious to me and I like the smoother running heavy flywheel. I think the vibration is less with the heavy flywheel . Just my opinion. Jack

[1930artdeco]

As long as everything is balanced together there should be no noticeable vibration increase. The engine will rev faster and easier so watch that.

Mike

[TerryH]

I had both the lightened flywheel and V-8 clutch and pressure plate installed about 12 years ago, and did not notice any increased vibration, and driveability has not been noticeably effected. I also happen to really like the lighter clutch pedal pressure, and would do both again.

[Jim Brierley]

The flywheel and internal engine parts are bolted together but not dependent on each other for balance or anything except the possibility of a smoother idle, and I doubt you'll notice any difference. What you will notice is more acceleration and quicker shifts. V8 clutches are often smoother than A clutches and easier to depress. I have run them for years, my latest engine has a diaphragm clutch on it, and is better still!

[2manycars]

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Mine is 40 pounds, which while being lightened, is still a very heavy flywheel by modern standards. The crankshaft is not counter weighted, but it is a very heavy strong crankshaft. I like the way it revs up a bit faster, and the V8 (not 8N tractor) clutch is easier to disengage. I think it also makes less stress on the rear main crankshaft bearing. If anything, the engine is smoother than it was, perhaps because I had the flywheel and clutch ballanced.

[2manycars]

Originally Posted by Jim Brierley

The flywheel and internal engine parts are bolted together but not dependent on each other for balance or anything except the possibility of a smoother idle, and I doubt you'll notice any difference. What you will notice is more acceleration and quicker shifts. V8 clutches are often smoother than A clutches and easier to depress. I have run them for years, my latest engine has a diaphragm clutch on it, and is better still!

More information the diaphram clutch and throwout bearing please.

[P.S.]

I went with the lightened flywheel and the stock Model A clutch when the motor in the tudor got rebuilt. What a mistake! Vibration wasn’t the issue, loss of hill climbing torque was the issue. About 6 months later, swapped the stock flywheel back in (changing nothing else) and what a difference!! It can climb the long hill up to my house in 3rd gear again! Used to have to downshift to 2nd because it would run out of grunt about half way up.

Makes a big difference.

When the motor in the fordor got rebuilt and the rebuilder mentioned that he would lighten the flywheel, I said NO!! Just surface it and that is all. Perfect!

[SSsssteamer]

Originally Posted by jhowes

I have the lightened flywheel and the v8 clutch. For me it was a mistake because none of the so called advantages are not obvious to me and I like the smoother running heavy flywheel. I think the vibration is less with the heavy flywheel . Just my opinion. Jack

Ditto. No lightened flywheels again for me either. Same reasons.

[Tom Wesenberg]

I wouldn't lighten my flywheel. If I went for a lighter clutch pedal, like Jim, I'd go with the diaphram pressure plate. My friend's 49 Chevy pickup had the nicest clutch I ever felt.

[BRENT in 10-uh-C]

We had an interesting discussion on this about 5 years ago. He is probably a little more than what most would like to read, however there are some good perspectives here;

Are Lightened Flywheels Overrated?

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[1930artdeco]

For me, I lightened the flywheel about 15lbs. Just enough to compensate for th increased weight of the Burlington crank. She revs a little faster but most of the low end pull of the heavy flywheel. Runs just fine.

Mike

[KansasRick]

I have an odd prospective about my lighten flywheel. Maybe I am nuts but my car with a 45 lb lighten flywheel engine does not sound like a model A. It doesn’t have the sound I liked after the engine was rebuilt. Call me crazy but to me I am disappointed to have lost that. That to me is part of the DNA of these wonderful machines. My rebuilder encouraged the lighter flywheel. Now don’t get me wrong my engine starts real well and has pulling power but as I said....it just ain’t meeting my expectation after a rebuild. It sounds more like a modern car. Any one else notice this? Anyone have a solution out there. I can set my car next to a Model A with the heavy flywheel and I can hear what I am missing. I wish I knew what I know now about it.

[AL in NY]

I regard to the diaphragm pressure plate in t a Model A, I used one out of a 86 Ford T-Bird 2.3 Liter L4 engine. It works with a 8-7/8 inch clutch plate. Really easy to depress the clutch.

[George Miller]

Originally Posted by BRENT in 10-uh-C

We had an interesting discussion on this about 5 years ago. He is probably a little more than what most would like to read, however there are some good perspectives here;

Are Lightened Flywheels Overrated?

.
.

I will stay with my light flywheel.

[Synchro909]

I'm rather ambivalent about lightening the flywheel but in your situation, I'd look at adding counterweights to the crank while you are in there anyway and lighten the flywheel enough to compensate for the extra flywheel effect of the crankshaft weights.
You're on the right track asking about this one before you do it. About the only way you could do more is to drive a car or two that has had a lightened flywheel fitted and see if it is what you want.

[wensum]

I have a substantially lightened flywheel and a Burlington counterweighted crank in my modified motor. Also a completely different exhaust system with free flow manifold and modern muffler. We did have quite serious vibration issues, simply solved with the harmonic vibration dampener pulley. It pulls like a train up hills and sounds remarkably like a Model A, although perhaps a little too muffled and slightly missing the crisp exhaust note of a totally original set-up.

[Terry, NJ]

Me Too! I read of Chumley's permutations (sp), Oquija board and Eisenfuss' dictums ETC and my head is still spinning with a definite yaw ! Using the intuitive method, I deigned that the car will run better with a lighter flywheel. There will slightly less wear on the rear bearing. Less rotational mass and easier installation. Picture this, you have two flywheels. One weighs 60 Lbs and one weighs 30 lbs. Your task is to mount on a freely spinning shaft and spin them up to 1000 RPM. My question is which one will more difficult, which is easier? Which will tire your arm out quicker? Your arm is analogous to the piston and rod. The RPMs are totally dependent on the amount of strength and energy you can put into it. So it's a fair assessment to say that the heavier draws off more effort than the lighter one. So that's energy that doesn't get to the rear wheels.
Terry

Originally Posted by George Miller

I will stay with my light flywheel.

[lake_harley]

I expect to get to my Model A project ('31 Coupe) in the next few months. I have started to gather some parts for mild mods to the engine and have considered a lightened flywheel among the things to do. I plan on using a 5.2:1 compression head I bought, a Model B distributor, perhaps a slightly "higher performance" cam, and a slightly larger carburetor and less restrictive exhaust. My question about lightened flywheels is whether the balance of the flywheel is independent of the crankshaft or are they balanced as a "rotating assembly". In other words, can the machining be done to the flywheel and then just the flywheel re-balanced, or does it need to be balanced together with the crankshaft?

Thanks, in advance, from this Model A virgin.

Lynn

[Jim Brierley]

Lake, In all 4 cyl. engines, all moving parts are balanced separately, crank, rods, pistons and flywheel. 6 cyl. and V8's are balanced as an assembly. You need to buy a copy of my book, 4-bangers and me before doing your rebuild. pm me or e-mail at [email protected]