Must you have a counterbalanced crank to use the V8 pressure plate?

[buyitsmart]

I want to install a V-8 style pressure plate when I install my new transmission and I am hearing that you cannot use this unless you have a counterbalanced crank.

According to Bratton's catalog regarding "Part #11460 V-8 PRESSURE PLATE - Helps reduce the amount of pressure needed to depress the clutch pedal by about 2/3rds. To use this, the crank must be counterbalanced and the flywheel must be machined. No changes in the way the clutch pedal is adjusted. NO EXCHANGE NEEDED. Uses the same clutch disk (11400) as the stock one."

I also want to use a lightened flywheel.

Must I have a counterbalanced crank to use the V-8 pressure plate and a lightened flywheel?

What if I only want to lighten the flywheel?
Must the crank be counterbalanced to do that?

Ken in Orlando

[JoeWay]

Short answer is no. It is not NECESSARY to counterbalance the crank.

I would be reluctant to lighten the flywheel to less than about 45 lbs, but with that said many people have run very light flywheels on non-counterbalanced cranks with good results.

Joe

[buyitsmart]

Joe, a 45 lb flywheel is MUCH lighter than a 65 lb flywheel. That is about a 30% reduction in weight. I would be satisfied with that.

What is the most you would comfortably reduce the flywheel weight to if you DID have a counterbalanced crank?

[SteveB31]

You must lighten the flywheel to install A V8 clutch since it is significantly thicker.

[OoltewahSpeedShop]

Why wouldn't you want a flywheel lighter than 45lbs? Response might be to quick? I hear this all the time and have never heard a legitimate reason that a heavy flywheel is better than a lighter one.

If this were true, aluminum flywheels would not be on the market.

Enlighten me.....

[PC/SR]

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Be sure to call and verify with Brattons that the pressure plate you are getting is the flyweight type if you want the reduced spring pressure (at lower speeds. It is high pressure at higher RPM's.) A couple of years ago I bought a plate from Brattons, the catalogue showed the flyweight type. I had it shipped directly to the machinist for balancing with the crank and it was the tractor type. I did not know that until after it was balanced. I decided to keep it, and dont mind having it, it works fine, but it was not what I thought I was getting. The tractor type spring pressure is about the same as the stock Model A spring pressure. And the plate arms cannot be adjusted.
You have to at least remove the raised portion around the circumference of the flywheel so the V8 type rests entirely on the same face surface as the clutch. Other than that, there are choices of how much metal to remove from the A wheel. Les Andrew's Volume II has illustrations.

[mrtexas]

Originally Posted by buyitsmart

Joe, a 45 lb flywheel is MUCH lighter than a 65 lb flywheel. That is about a 30% reduction in weight. I would be satisfied with that.

What is the most you would comfortably reduce the flywheel weight to if you DID have a counterbalanced crank?

I thought the idea was to reduce the flywheel by the same weight as was added by the counterweights.

[James Rogers]

Originally Posted by PC/SR

Be sure to call and verify with Brattons that the pressure plate you are getting is the flyweight type if you want the reduced spring pressure (at lower speeds. It is high pressure at higher RPM's.) A couple of years ago I bought a plate from Brattons, the catalogue showed the flyweight type. I had it shipped directly to the machinist for balancing with the crank and it was the tractor type. I did not know that until after it was balanced. I decided to keep it, and dont mind having it, it works fine, but it was not what I thought I was getting. The tractor type spring pressure is about the same as the stock Model A spring pressure. And the plate arms cannot be adjusted.
You have to at least remove the raised portion around the circumference of the flywheel so the V8 type rests entirely on the same face surface as the clutch. Other than that, there are choices of how much metal to remove from the A wheel. Les Andrew's Volume II has illustrations.

Nobody sells a new, true original V8 pressure plate because it is not available in it's original form. The tractor style is the only type available. I have several originals and they are not for sale.To answer the original question, no you don't have to have a counterbalanced crankshaft to benefit from a lightened flywheel. I sell lots to people who just want to relieve some of the pressure on their hip and knee while lessening the weight on the rear main. If you were ever to watch an original flywheel being balanced, you would understand why the engine still vibrates after everything else has been meticulously restored.

[Kevin in NJ]

Which V8 pressure plate?

You have to be careful because there are 2 types. The tractor kind which does not have flyweights and uses heavy springs. Some rebuilders sell these types and might tell you that the flyweight types are not available, but other rebuilders seem to have no problem finding the flyweight types. The flyweight type have weights that increase the pressure on the clutch with RPM so they use lighter springs which means less pedal pressure with your foot.

At the very least you can buy your own. the flyweight types are around you just have to ask some V8 folks. The last one I bought was like $5 at Hershey 2 years ago (didn't go last year). They usually are hiding in piles cause they are heavy.

When into your engine you need to consider balance and quality of the grind on the crank. This all feeds into a smooth engine with more power to send to the wheels.

Here is a link to some comments on crank grinding.

Counterbalanced cranks are not required to have a smooth running engine. The counter balance will help as that is scientific fact, but a well balanced original A engine is all that is required by the vast majority of owners.

[Seth Swoboda]

Why is an original Ford V8 pressure plate so hard to find? I have many of them lying around. Are they that hard to find? I am running a V8 pressure plate and clutch on a lightned flywheel and the crank is not counter weighted. All the rotating engine components were balanced.

[James Rogers]

Originally Posted by Seth Swoboda

Why is an original Ford V8 pressure plate so hard to find? I have many of them lying around. Are they that hard to find? I am running a V8 pressure plate and clutch on a lightned flywheel and the crank is not counter weighted. All the rotating engine components were balanced.

The plate is not available in new form that can be sold with as many flywheel setups as I sell. I sell probably 30 setups per year.

If somebody here knows of a source where these can be purchased 20 at a time I sure would like to know it. I just don't believe anyone will step up and furnish a reliable source.

[Seth Swoboda]

I gotcha now James. Have you ever tried the early V8 swap page want ads? I bet you could find some V8 pressure plates for purchase. I'm keeping my stock now.

[James Rogers]

Originally Posted by Seth Swoboda

I gotcha now James. Have you ever tried the early V8 swap page want ads? I bet you could find some V8 pressure plates for purchase. I'm keeping my stock now.

I have and like I said, I need to purchase 20 at a time and cannot use anything that is not NEW. New are not available anywhere I have tried and used and reconditioned won't work.

[JoeWay]

Originally Posted by buyitsmart

Joe, a 45 lb flywheel is MUCH lighter than a 65 lb flywheel. That is about a 30% reduction in weight. I would be satisfied with that.

What is the most you would comfortably reduce the flywheel weight to if you DID have a counterbalanced crank?

Most of the ones I have done came in at about 35-37 lbs. I take most of the weight out of the inside of the rim, so that the thickness at the ring gear surface is about 7/16". I leave a step to locate the gear and turn the rest of the OD to the same diameter as the ring gear surface. I feel that machining the rim to less than about 7/16" thick is pushing the envelope too far in terms of strength. I'm probably over-conservative as the gear itself should hold the rim together, but I'd rather be safe than sorry.

Brent Terry posted some comments about flywheel weights a year or so ago. He wondered if the slightly hopped up engines most people build (balanced cranks, HC heads, etc.) wouldn't do better with flywheels in the (IIRC) 45-50 lb range. I think I agree with him.

Joe

[dlshady]

Originally Posted by OoltewahSpeedShop

Why wouldn't you want a flywheel lighter than 45lbs? Response might be to quick? I hear this all the time and have never heard a legitimate reason that a heavy flywheel is better than a lighter one.

If this were true, aluminum flywheels would not be on the market.

Enlighten me.....

The heavier flywheel mas more inertia, and inertia = stored energy. I don't know if Henry's engineers thought that the additional inertial energy of the heavy flywheel outweighed the additional wear on the rear main, or if they just didn't consider it.

If you've ever spent much time around a drag strip then you've probably noticed that the only cars using an aluminum flywheel (successfully at least... the HonDuuuh boys don't count ) are very high powered cars. Take for example the ProMod cars. They have huge 500 to 700 cubic inch engines that can rev from idle to 7000 rpm and drop back to idle in a fraction of a second. It's an impressive sound for sure! The reason they can do that is because of ultra lightweight rotating assemblies (ultra light knife-edged cranks, aluminum rods & flywheels etc.) but they make 1000+ horsepower too, so they don't have to rely on the inertial energy stored in the flywheel to get the car moving. If you were to put the same lightweight rotating assembly in a low compression motor that makes 200 horsepower it would be much more difficult to get moving from a dead stop.

Roundy-round racers also have the same thing going on. If you've ever watched round track racing (local short track stuff, not Winston cup) you'll notice that some cars get off the corners a lot quicker than others. While gearing, tires and other things also contribute to this, one reason is because of the stored energy in the heavier rotating assemblies. The cars with lightweight parts tend to be lazier off the corners and take a little while to get wound back up whereas a car with a good steel flywheel will exit the corner harder (in most cases).

So anyway, sorry for hijacking the thread... Way more information than most FordBarners care about, but that's the reason. I'll be quiet now....


Deron

[buyitsmart]

Deron it seems that a heavier object would take more energy (and more time) to change to a higher speed. This seems the opposite of what you are stating. I am under the impression that a lightened flywheel in the Model A engine would allow for faster starts from standing still. It also seems that a lighter rotating assembly (i.e. flywheel) while not having as much stored energy (and therefore momentum) would still be easier for my 40-50 horsepower engine to get moving quickly as opposed to a heavier rotating assembly.

Wouldn't a lightened flywheel allow for quicker acceleration?

I'm confused.

[dlshady]

Well, you're kind of right... It's correct that the motor with the heavier flywheel will take more time to rev up but it will also store energy that can be used to help move the car from a dead stop. When you ask "It also seems that a lighter rotating assembly (i.e. flywheel) while not having as much stored energy (and therefore momentum) would still be easier for my 40-50 horsepower engine to get moving quickly as opposed to a heavier rotating assembly." it's true that it will be easier for the engine to get moving, but then you have to get the dead weight of the car to get moving. That's where the increased inertia of the heavier flywheel comes into play. In oversimplified terms, it's kind of like having more torque to help move the car.

Does that make any sense? Not sure that I'm doing a very good example of explaining this without getting into the physics aspect, but it's no different than using a longer lever to move an inanimate object.... kind of...

And when you ask "Wouldn't a lightened flywheel allow for quicker acceleration?" the answer would be yes, asuming that you have enough horsepower and rear end gear, but in a low powered car that's not always the case. A 500 horsepower drag car won't notice the light flywheel nearly as much as a 40 horsepower Model A.


Deron

[40 Deluxe]

A 70+ yr. old friend that's been around cars all his life says that for years the quickest car across an intersection was a stock Model A. It stands to reason: There's a lot of energy stored up in that heavy flywheel when the engine is wound up. When you pop the clutch, the car will jump across the intersection. Now, if you're letting the clutch out at an idle and then stepping on the gas, you'll be about the slowest car across, partly due to having to accelerate that heavy flywheel from idle instead of having it already "accelerated".

[Milton]

I don't know why they said that a counterbalanced crank was necessary with the clutch modification. Way back, a half century ago, I used a 45 lb flwheel and stock clutch and crank. Currently I am using a 27 lb flywheel with a counterbalanced crank and a Bratton clutch. The Bratton clutch has the desirable flyweights. Part of the idea, I guess, is the removal of the original clutch mounting ring from the flywheel. The extra crank weight will make up for the lighter flywheel so the motor will still be able to idle down and sound the same.

[Geo. H]

You can't have it both ways. A heavy flywheel works better while letting the clutch out. Once it's out, a light flywheel works better.