lightening a flywheel

Ed Saniewski

Ed Saniewski

Well-known member
I have a friend who is has a machine shop, and he said he could lighten an old flywheel for me and set up a V8 clutch for me. My question is how much is normally taken off? I see that most vender's will balance the flywheel, at 2500 rpm, is there a big difference if it is not balanced? Thanks Ed Saniewski.
 
You absolutely gotta have it balanced, with the pressure plate. It is common to take them down to 35 or so lbs, some take off more. Mine is 27 lbs, done by Dan Price. Check around for prices. The guys that do it regularly including some on this Board usually have them in stock and can probably beat the price of a one-off local machinist and you get the benefit of experience.
 
Here is a drawing, lots of published information here and at the H.A.M.B. Beware, the dimension in red in the drawing is a correction. DO NOT use the 5.735 dim. Catastrophic failure of the Flywheel could result. It was a retracted drawing error when Charlie Yapp at Secrets of Speed published the drawing. Charlie is a good resource for Banger Speed information.
 

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Definitely have it re-balanced! Those wheels are made of cheap cast iron and may have flaws inside of them. Any flaws will not affect anything except balance. Tell your friend not to take any off the surface the clutch disc rides on, just resurface it with a grinder, as done by any clutch rebuilding shop. Taking any off this surface will move the disc forward and the disc springs may rub on the flywheel bolts. A grinder is needed for this operation because hot spots may have developed on the surface. You gotta tell PC/SR (above) that there ain't no such word as gotta! :-)
 
Ed Saniewski said:
I have a friend who is has a machine shop, and he said he could lighten an old flywheel for me and set up a V8 clutch for me. My question is how much is normally taken off? I see that most vender's will balance the flywheel, at 2500 rpm, is there a big difference if it is not balanced? Thanks Ed Saniewski.
Click to expand...

Ed, I am of the opinion that just have your friend convert it for the modern pressure plate and no more. There is a "friendly discussion" here in the archives that discusses the Pro's Con's of lightening a flywheel.
 
BRENT in 10-uh-C said:
Ed, I am of the opinion that just have your friend convert it for the modern pressure plate and no more. There is a "friendly discussion" here in the archives that discusses the Pro's Con's of lightening a flywheel.
Click to expand...

If you have a counterweighted crank shouldn't the flywheel be lightened because you already have added reciprocating mass?
 
If you have a counterweighted crank shouldn't the flywheel be lightened because you already have added reciprocating mass?
end quote

The answer is yes.
 
I did the flywheel trick to my T.S. engine and I will probably do it to the engine I'm fixing now. By Indicating the flywheel very carefully, the only amount taken off to balance it again was a 5/16 x 5/16 hole. But who knew? You can't depend on it. I only removed about 6 lbs (63 lbs - 6lbs = 57 lbs) which isn't much. It was my fist one and I didn't want to screw it up. However, Macs is offering a flywheel/clutch combo in which the FW has been lightened by 7 lbs. When this is done, the purpose is to remove the weight off the circumference. This is to let the flywheel accelerate quicker. If the weight were taken from the flywheel's center, the effect would be less.
Terry
 
Ron Kelley did my flywheel. It came to net minus 20 lbs for the complete ballanced assembly -- Flywheel - Pressure Plate and Clutch Plate (plus adding the dynamic ballancer). As measured on my bathroom scale.
 
hefty lefty said:
If you have a counterweighted crank shouldn't the flywheel be lightened because you already have added reciprocating mass?
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Ok, but why are you saying that? :confused:



I think all too often we find recommendations on doing things only because we heard someone else say they did it, ...therefore it seems believable that is what needs to happen.

Adding weights to the crankshaft helps to ease some of the torsional flex (whip) but modifying the flywheel to accept the later pressure plate also removes rotating weight. The big argument is why does it need to be a certain weight? Again, in THIS THREAD we have discussed this at length.

Oh, ...and I STILL am waiting for someone to explain the theory on just how a "harmonic balancer" attached to a crankshaft on the same end as a heavier flywheel actually works.

.
 
THIS thread is always an interesting read when this balancer topic comes up. I wish some of the previous Fordbarn archives were still around from the late 90's and early 2000s when this was discussed then. The answers always turn out the same it seems.
 
Engines and engine parts are really dumb, the crank does not know what goes on behind it, not does it care. Dampers need to be on the front of the engine to be effective, not the rear.
 
That lost info is greatly missed. Seems more indepth conversations about all aspects and changes with the A took place then as compared to now. Rod
 
Ed Saniewski said:
I have a friend who is has a machine shop, and he said he could lighten an old flywheel for me and set up a V8 clutch for me. My question is how much is normally taken off? I see that most vender's will balance the flywheel, at 2500 rpm, is there a big difference if it is not balanced? Thanks Ed Saniewski.
Click to expand...
Ed, check my website and see if my price beats the price you got there.
 
I have many that have been modified for the V8 pressure plate which lightens the flywheel assembly by 17#. I also have one that is lighter but has not been weighed or balanced yet.
 
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