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Old 08-03-2011, 11:20 PM   #1
Wello
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Default Flywheel

During an abrupt stop, it would seem a lost bolt, which had apparently been lurking in the bowels of my trucks bell housing, dislodged and fell into the path of my flywheel ring gear. Following the heart stopping racket, I pulled the starter and my fears came true, the ring gear was badly damaged, to the point of needing replacement. Luckily the starter and bendix escaped harm.

In the next few weeks I will be pulling the motor for repairs. While in there it'll be a new clutch, pilot bearing, pressure plate and a good look at the transmission internals.

So here's my question. Is a lightened flywheel/V8 clutch set up worth it? My motor is stock with the exception of a Synder 5.5 head and a stock B cam. I've called the two local shops that work on, or rebuild, Model A engines and got two different answers concerning using a lightened flywheel with a stock crankshaft. One said the flywheel/clutch needs to be balanced with the crankshaft and the other said it does'nt. You folks have helped me work out so many other problems I was compelled to post my current dilemma.

All these are the issues I face with my 1929 CCPU.

Thanks, Dan
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Old 08-04-2011, 12:03 AM   #2
sonny30coupe
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Default Re: Flywheel

I have nasically the same set-up you have, I have the lightened flywheel. It is and does need to be balanced with the clutch after the assembly has been put together.
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Old 08-04-2011, 12:08 AM   #3
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Default Re: Flywheel

It depends on wether your crankshaft main journals are ground to the true centerline of the flywheel flange ----if the flange runs true a seperatly balanced flywheel will work, if the flange is off center the flywheel needs to be balanced on the crankshaft, or balanced off center to match the crankshaft.

When you take off the flywheel mark it so it can go on the same place. ( end of a dowell, flywheel next to dowell)

I don't usually replace a clutch just because it is out if it worked properly and isn't worn, but I do usually replace pilot bearing and to bearing.
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Old 08-04-2011, 12:52 AM   #4
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Default Re: Flywheel

Having the flywheel lightened is a debatable call, and is up to the individual. A few years back when many Borg Warner overdrives were installed it was said that a lightened flywheel would allow the overdrive gears to engage quicker. My personal opinion is to leave it the way Henry designed it.

You should have the flywheel balanced while mated to the pressure plate and then marked. If you are going to have the clutch surface machined have the shop also take material off where the the pressure plate mounts. The factory dimension is 1.123". The measurement should be restored anytime the flywheel is machined. The balancing should be done after any machining or other work is done to the flywheel.

Since you are going to be replacing the starter ring it is a good idea to have it "pinned". This will keep it from walking forward as some reproductions are prone to do. It is usually pinned in three places equal distance apart. The ring should be mounted on the flywheel such that the angled teeth face aft. You need to point that out to any machine shop you take it to as they are liable to install it backwards.

You can have this done at Jim's Automotive Services in Costa Mesa, CA 714-546-2969. Jim, the owner, is a Model A person. He can also supply you with a flywheel modified for a V8 clutch, as well as the V8 clutch and have it all balanced, if that is your desire.

Tom Endy
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Old 08-04-2011, 07:52 AM   #5
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Default Re: Flywheel

It is my understanding that a lightened flywheel is usually used with a counterbalanced crank. The crankshaft is heavier so a lighter flywheel is needed to keep the original rotating mass.

John
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Old 08-04-2011, 08:03 AM   #6
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Default Re: Flywheel

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lighten it
balance it with the clutch attached
install
love the difference in how fast it revs up
tk
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Old 08-04-2011, 11:02 AM   #7
Purdy Swoft
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Default Re: Flywheel

I don't run the heavy counter balanced crankshaft, so I can only speak from my experience with a lighter flywheel used with an unmodified, good cond. original crankshaft. My experience with a lightened 18 to 20 pounds flywheel will give near the same seat of the pants feel of adding a higher compression head, maybe better in the fact that the engine will rev quicker, accelerate much, much quicker and the gears will shift maybe 50% easier, without as much danger of clash. The extra weight removed will help the main bearings last longer. With the heavy original flywheen, when you try to accelerate from 40-45 mph you won't feel anything but the car, if properly tuned will SLOWLY gain speed. If a lighter flywheel is used you will be able to accelerate much like a modern car. Some will say that if you add a counter balanced crankshaft, you should only remove the same amount of weight from the flywheel as the extra weight that the heavier counter weights add.I disagree with this practice. If the weight removed from the flywheel is only the same amount added by the crankshaft there will be NO added performance in acceleration or shifting. More weight will need to be removed or it will remain status quo.
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Old 08-04-2011, 11:21 AM   #8
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Default Re: Flywheel

I feel its a worth while modification. Remove 20 to 25 lbs. from the flywheel; using a V8 pressure plate instead of A will save another 4 lbs.

Have the flywheel balanced, then bolt up the pressure plate and have the entire unit balanced.

I made this modification in 1968 to my 28 Roadster which had pored bearings and no counter-balanced crankshaft; it really made a difference with excelleration and power when climbing hills to not have to get all that weight moving. With the type of roads we drive on today the low end torque is not needed like it was when the A was being produced.

Just my opinion,

Ron
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Old 08-04-2011, 05:12 PM   #9
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Default Re: Flywheel

The lightened flywheel is one of the best modifications you can make to your motor that affects the longevity of the crank and babbitt. Doesn't matter if you have a bone stock motor or a modified one, this is a good thing. I sell setups to people that have both and have never heard anything but good from any customer. I don't say to buy mine unless you want to but, buy one somewhere, you won't be sorry.
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Old 08-04-2011, 07:30 PM   #10
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Default Re: Flywheel

Like James says, it is a crank saver but, if you love the Model A sound, especially at shut down, it will be gone with a really light flywheel.
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Old 08-05-2011, 08:22 PM   #11
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Default Re: Flywheel

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Like James says, it is a crank saver but, if you love the Model A sound, especially at shut down, it will be gone with a really light flywheel.
That's why I stop at 17 pounds. Kind of a middle ground, enough to help the crank but not so much that the engine sound is different. The lightened flywheel makes gear shifts easier without as much grinding.
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Old 08-05-2011, 08:52 PM   #12
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Default Re: Flywheel

Why did Ford make the flywheel so heavy in the first place?
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Old 08-05-2011, 09:36 PM   #13
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Default Re: Flywheel

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Why did Ford make the flywheel so heavy in the first place?
Old school engineering and easier for Model T drivers to adapt to since they never had a hand shifter before. I don't know of many standard shifts that could be yanked into low gear without a clutch and keep running.
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Old 08-05-2011, 09:52 PM   #14
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Default Re: Flywheel

The biggest difference that I noticed when driving a car with a lightened flywheel is that the engine takes less time to lose revolutions when you let off the accelerator between shifts allowing you to get to the proper engine rpm to engage the next gear much quicker, and from a higher rpm. It seems to make the car quicker through the gears when trying to get to traffic speed.
I am sure the other affects, such as bearing wear and other torque affect are reduced. I am not sure what bad affects it might have, such as a less smooth idle etc.
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Old 08-06-2011, 07:50 AM   #15
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Default Re: Flywheel

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The biggest difference that I noticed when driving a car with a lightened flywheel is that the engine takes less time to lose revolutions when you let off the accelerator between shifts allowing you to get to the proper engine rpm to engage the next gear much quicker, and from a higher rpm. It seems to make the car quicker through the gears when trying to get to traffic speed.
I am sure the other affects, such as bearing wear and other torque affect are reduced. I am not sure what bad affects it might have, such as a less smooth idle etc.
I have found no bad effects even with a flywheel lightened to as little as 30#. I have one like this on my personal car and find it idles fine but with a slightly higher low idle. I don't think a low idle is good for the engine anyway.
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Old 08-06-2011, 04:39 PM   #16
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Default Re: Flywheel

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Why did Ford make the flywheel so heavy in the first place?
I was told in auto shop (1960) that it was heavy so the car could lug down and work harder.
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Old 08-06-2011, 06:19 PM   #17
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Default Re: Flywheel

Does the heavy 'wheel make the car easier to start with the hand crank? Seems like once you got all that weight moving it would take less effort to "pull through" and start without kicking back.
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Last edited by John S; 08-06-2011 at 06:29 PM.
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Old 08-06-2011, 07:28 PM   #18
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Default Re: Flywheel

The heavy flywheel allows the car to lug along without dying out. The transmission not being synchronized, you don't have to shift down and double clutch, you just lug it along after a corner and it creeps back up to speed. Try that with your modern manual transmission car and see how fast it kills the engine.
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Old 08-06-2011, 07:36 PM   #19
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Default Re: Flywheel

Quote:
Originally Posted by John S View Post
Why did Ford make the flywheel so heavy in the first place?

I heard once from a old timer that the engine turned the flywheel and the wight of the flywheel moved the car. I dont know if thats true but a interesting way to think about it.
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Old 08-07-2011, 06:41 PM   #20
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Default Re: Flywheel

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Why did Ford make the flywheel so heavy in the first place?
-------------------------------------

They made it so heavy to damp the impulses from the compression stroke and combustion stroke on the unslung (uncounterbalanced) crankshaft. If you add slings - or, obtain a slung crank - to your crankshaft, then you have partial damping under each piston and you do not need the weight of the original flywheel to damp the crank at the aft end of the crankshaft. Experiments we have done here indicate that removal of twenty pounds is the best practical amount to remove from the stock flywheel, thirty pounds if you want to produce a performance engine. One big caveat though: you are going to have to tune your ignition spark with the lightened flywheel. You can't just set it and forget it. Particularly retarding it a bit when on certain inclines. Happy Motoring!

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