Lightened Flywheel

[DBSHELTON]

I mostly see lightened flywheels used with counterweighted cranks. Are they only useful only together, or will they work well with a stock crank? If you had to choose from a 33# or 42# flywheel, what would be the best choice and what would be the advantages of either? I would think the 33# would get the nod.

[BRENT in 10-uh-C]

Originally Posted by DBSHELTON

I mostly see lightened flywheels used with counterweighted cranks. Are they only useful only together, or will they work well with a stock crank? If you had to choose from a 33# or 42# flywheel, what would be the best choice and what would be the advantages of either? I would think the 33# would get the nod.

I thought you had already asked this same question a few months ago. If not, I apologize but here is a thread ( Is a lightened flywheel overrated? (I think so) )I posted a few years ago about the topic.

To answer your question specifically, they work well with stock crankshafts too. I would go with the 42# flywheel, ...and my reasoning is discussed in the link I posted.

.

[Mike Peters]

We had a flywheel lightened at a machine shop once and cannot tell the difference. from a stock flywheel. Stock crankshaft. No better and no worse.

[DBSHELTON]

Originally Posted by BRENT in 10-uh-C

I thought you had already asked this same question a few months ago. If not, I apologize but here is a thread ( Is a lightened flywheel overrated? (I think so) )I posted a few years ago about the topic.

To answer your question specifically, they work well with stock crankshafts too. I would go with the 42# flywheel, ...and my reasoning is discussed in the link I posted.

.

Brent, I am sure glad your memory and searching ability is better than mine. I thought I had asked this before but couldn't find it! Thanks!

[BRENT in 10-uh-C]

Originally Posted by DBSHELTON

Brent, I am sure glad your memory and searching ability is better than mine. I thought I had asked this before but couldn't find it! Thanks!

I did not search for it, and was only working off of memory that you had asked something about it. The link I posted is the one I started several years ago.

[DBSHELTON]

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Impressed! I can't remember what I had for supper yesterday!

[Jim Brierley]

Engines are beyond dumb, and well into stupid, the crank doesn't know or care what is behind it. I'd go with the 33 lbs. The lighter weight will accelerate and de-celertate quicker, and make quicker shifts possible. Do the math! It will not add horsepower.

[Patrick L.]

Must be another myth or old wives tale, but, I've always heard that at least 12# needs to be removed when using a counter weighted crank.

[1930-Pickup]

Originally Posted by BRENT in 10-uh-C

I did not search for it, and was only working off of memory that you had asked something about it. The link I posted is the one I started several years ago.

Dang, that's impressive. Especially with 9000+ posts and going strong.

[Bob-A]

My '29 roadster has a stock engine with a lightened (weight?) flywheel. It helps with engaging/disengaging a Borg-Warner overdrive.


Bob-A

[Dave in MN]

Brent,
We may have discussed this before so sorry if it is a repeat. For the rest, it may be of interest.

When using a lightened flywheel, I have had the experience of the "naturally occurring harmonic vibration" change rpm range.

A few years back, while doing some component testing for my touring car, I discovered the following: On an engine with a counter-weighted and balanced crankshaft, using an extremely lightened flywheel caused the vibration to present itself between 50 and 54 mph with a standard ratio rear end. Normally I see this vibration between 42 and 46 mph. Having the vibration show at 50 - 54 mph could not be worse for driving average roads with a touring engine.

The solution was to install a heavier flywheel, about 10#, and the harmonic vibration dropped back to between 46 - 49 mph which is much more drive-able. I believe if a standard weight flywheel were to be installed, the range would have dropped into the normal range of 42 - 46 mph. All the flywheels and matched pressure plates were balanced.

We even tried Ron Kelly's method of modifying a SB Chevy front harmonic balancer and mount it to the inside of a lightened flywheel. It actually worked the best in narrowing the vibration range. Voodoo or fuzzy logic I know but it was hard to argue with good results.
Good Day!

[BRENT in 10-uh-C]

Originally Posted by Dave in MN

We even tried Ron Kelly's method of modifying a SB Chevy front harmonic balancer and mount it to the inside of a lightened flywheel. It actually worked the best in narrowing the vibration range. Voodoo or fuzzy logic I know but it was hard to argue with good results.
Good Day!

I'm pretty confident that all Mr. Kelley's balancer did was add weight to the center of the flywheel. The flywheel mass (-of any weight) cancels any affect of the flywheel mounted balancer when they are both mounted onto the same flange. If it were mounted onto the opposite end of the crankshaft where it could dampen the torsional pulsations of the crank, then it would do a lot of good.

[wensum]

Originally Posted by BRENT in 10-uh-C

I'm pretty confident that all Mr. Kelley's balancer did was add weight to the center of the flywheel. The flywheel mass (-of any weight) cancels any affect of the flywheel mounted balancer when they are both mounted onto the same flange. If it were mounted onto the opposite end of the crankshaft where it could dampen the torsional pulsations of the crank, then it would do a lot of good.

Thanks for that observation Brent, It was my understanding that a harmonic dampener is most effective at the front end of the crankshaft? Having seen a a flywheel mounted dampener, not only did it look complicated, but one also has to remove the motor to fit it. Whereas the Harmonic dampener pulley is so much easier to fit, and in my experience, very effective.

[Synchro909]

While I'm no expert in this area, it seems to me that a heavy flywheel will cause greater torsional stresses in the crankshaft due to its inertia. For that reason, I have gone with a lightened one at the back and one of those Murray Horne (From NZ) harmonic balancers on the front. I have no reason to regret that.

[Pete]

I had to look for it awhile but this is a VERY good explanation of what torsional vibration is and how it is dealt with. The pics don’t show because it is a very old post but maybe MikeK can be persuaded to re-post it.

It is from 2-24-13. Post #32

[Jack Shaft]

50lb B flywheel, stock A crank,Murray's balancer..no more 'harmonic' rpm..smooth all the way..

[Jack Shaft]

During A engine development all the engineers involved with the work identified the torsional vibration,Harold Hicks had the temerity to bring it up to Mr Ford,who was a proponent of the heavy flywheel compensating for the issue..the engineers finally 'won' in '32,a mechanical advance distributor,larger crankshaft journals and later a counterbalancing addressed the issue..
Benson Ford research center oral histories..right from the horses mouth..

[Dave in MN]

Originally Posted by BRENT in 10-uh-C

I'm pretty confident that all Mr. Kelley's balancer did was add weight to the center of the flywheel. The flywheel mass (-of any weight) cancels any affect of the flywheel mounted balancer when they are both mounted onto the same flange. If it were mounted onto the opposite end of the crankshaft where it could dampen the torsional pulsations of the crank, then it would do a lot of good.

Brent,
I agree, it added weight and that was key in lowering the range of vibration. The same happend when a flywheel of approximate equal weight, that was solid...no balancer added, was tried.
The difference between the two was the range of vibration was much tighter and less in intensity to almost not noticeable. The mounted balancer appears to take the edge off the torsional pulse, when a cylinder fires or the maximum pressure is reached on the compression stroke. I now run that version of flywheel in my Phaeton.

I tested these varying flywheels with the engine on the dyno. By varying the load at the rpm the vibration was most evident, the vibration could be intensified and clearly observed. The battery of tests taught me how to better build and tune an engine. Again...some say fuzzy logic but the dyno and results don't lie.

I have tried one of Murray Horne's combination front pulley/dampers. It also helps lessen the observed harmonic slightly. I need to complete more tests on his product when I have time. Available time seems in short supply of late.
Hope you and family are doing well...Good Day!

[DBSHELTON]

This is all interesting. I enjoy the conversation.

What I have learned is that I can put my flywheel money into a new cam and will get more usable benefit.

[updraught]

Originally Posted by DBSHELTON

This is all interesting. I enjoy the conversation.

What I have learned is that I can put my flywheel money into a new cam and will get more usable benefit.

When you try to accelerate the flywheel will suck the energy created by the cam and release it when you decelerate.

[Bob Bidonde]

The flywheel dampens the torsional impulses in the crankshaft from the power stroke, the compression stroke, acceleration and deceleration of the crankshaft's RPM (changes in momentum: Force x length of time applied = mass x velocity). Putting a small damper on the front of the crankshaft is money wasted because it has a minuscule mass and radius of gyration relative to the flywheel.
The flywheel is also a gyro, so it opposes changes in its rotational axis and dampens the engine's tendency to rock vertically about the rear engine mounts.
Lightening the flywheel gives the engine a mechanical advantage to accelerate / decelerate quicker (change engine's momentum). So lightening the flywheel a significant amount (pounds, not ounces) improves acceleration, shifting, braking, reduces rear main bearing stress and should improve gas mileage. On the other hand, lightening the flywheel decreases its ability to dampen the engine's impulses and vibrations. Thus it is a trade-off to lighten a flywheel.
The trade-off is worthwhile in my opinion, so I favor lightening the flywheel for improvement of the car's performance. By the way, the weight of a stock flywheel and clutch is 80 lbs.

[Licensed to kill]

[QUOTE=Bob Bidonde;1917902]The flywheel dampens the torsional impulses in the crankshaft from the power stroke, the compression stroke, acceleration and deceleration of the crankshaft's RPM (changes in momentum: Force x length of time applied = mass x velocity). Putting a small damper on the front of the crankshaft is money wasted because it has a minuscule mass and radius of gyration relative to the flywheel.

OK, so how about putting a damper on the front AFTER removing much of that excess mass from the flywheel??

The flywheel is also a gyro, so it opposes changes in its rotational axis and dampens the engine's tendency to rock vertically about the rear engine mounts.
Lightening the flywheel gives the engine a mechanical advantage to accelerate / decelerate quicker (change engine's momentum). So lightening the flywheel a significant amount (pounds, not ounces) improves acceleration, shifting, braking, reduces rear main bearing stress and should improve gas mileage. On the other hand, lightening the flywheel decreases its ability to dampen the engine's impulses and vibrations. Thus it is a trade-off to lighten a flywheel.
The trade-off is worthwhile in my opinion, so I favor lightening the flywheel for improvement of the car's performance. By the way, the weight of a stock flywheel and clutch is 80 lbs.

On the "plus" side of the heavy flywheel is that it seems near impossible to stall taking off. All that mass rotating helps the engine to get these little cars going from a dead stop. This is one of the reasons i plan to teach my grandkids to drive on the A. Easier to learn to take off, nat as easy as a synchro trans but not too difficult to shift, if they can drive this they can drive anything and how many kids these days can say they learned to drive on a Model A.

[Jack Shaft]

Every modern engine uses a useless harmonic balancer.A flywheel stores kinetic energy and dampens impulse. On one end of the crankshaft....what about the other? Henry Fords heavy flywheel cure for torsional vibration was seen by his engineers as ineffective by years ago,it remains today..

[Jack Shaft]

the next time you change a cracked or broken front pulley ask yourself " why did this happen?"..think about the effect that cracked the cast pulley has on main bearings..dont just run out and buy a two piece pulley to make the "next time" easier...fix the root cause

[Pete]

12 lb.

[Jack Shaft]

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Buddy of mine has a Kong Jackson aluminum lightweight flywheel,it looks like a salad plate.

[Pete]

Originally Posted by Jack Shaft

Buddy of mine has a Kong Jackson aluminum lightweight flywheel,it looks like a salad plate.

I use SBC 12 lb. flywheels. Re-drill is easy. They are 100 bucks on eBay.
The closer you can get the weights on each end of the crank, the
less TORSIONAL vibration and the longer the crank lasts.

[Y-Blockhead]

Originally Posted by Jack Shaft

Every modern engine uses a useless harmonic balancer.A flywheel stores kinetic energy and dampens impulse. On one end of the crankshaft....what about the other? Henry Fords heavy flywheel cure for torsional vibration was seen by his engineers as ineffective by years ago,it remains today..

FWIW, I use a Murray Horn harmonic balancer on my Town Sedan.

[Licensed to kill]

Originally Posted by Y-Blockhead

FWIW, I use a Murray Horn harmonic balancer on my Town Sedan.

What is your experience with it??.

[Jim Brierley]

Every modern engine uses a useless harmonic balancer.A flywheel stores kinetic energy and dampens impulse. On one end of the crankshaft....what about the other? Henry Fords heavy flywheel cure for torsional vibration was seen by his engineers as ineffective by years ago,it remains today.

If they are ineffective, why to the penny-pinching manufactures put them there? Think about it!

[Y-Blockhead]

Originally Posted by Jack Shaft

Every modern engine uses a useless harmonic balancer. A flywheel stores kinetic energy and dampens impulse. On one end of the crankshaft....what about the other? Henry Fords heavy flywheel cure for torsional vibration was seen by his engineers as ineffective by years ago,it remains today..

Not sure I understand why you make this comment? In another thread you state you installed a Murray Balancer?? Or were you being facetious and it went over my head?

Your comment; "Put one of murrays on my car.. can feed a B width belt sideways to install. Bronze cam gear chatter minimized.Logic says reducing harmonic vibration should help extend main bearing life with a dynamically balanced crankshaft..time will tell."

https://www.fordbarn.com/forum/showt...monic+balancer

Originally Posted by Licensed to kill

What is your experience with it??.

See this thread: https://www.fordbarn.com/forum/showt...monic+balancer