Balancing Flywheel and Pressure Plates

dwick01

dwick01

Senior Member
Is it really necessary to have the flywheel and pressure plate balanced on these old cars? My car is a '47 fordor. I don't remember doing this on any of my cars or friends cars back in the day. I know they did it on race cars. We got the flywheel off the other day and it will need machined as it is glazed over. The clutch and pressure plate are obviously shot and have ordered their replacements from Ft. Wayne Clutch.
 
As you say, never did it before,so why do it now?
Especially if it was removed from an engine with no balance issues.
 
Good practice to have it balanced by a reputable shop if you have it out.

Especially if there's going to be ANY machining on the wheel itself, like grinding a new surface!

With a flywheel/clutch ***'y you are working on a 7.000" (nominal) radius, any slight imbalance at that radius makes it more critical to have it right. For instance, if you have a 10/15 gram imbalance at the crank counterweight (3.000" radius) it would not be noticeable at all during the operation, take that same 10/15 grams at a 7.000" radius on the wheel and you will "feel" it.

Thanks, Gary in N.Y.

P.S. You'll get all different recommendations here on how to balance it exactly. On "independent" balanced units (Flatheads) we always balance both the wheel and the plate as a single unit, with all the correction on the wheel. This is considered "single-plane" balancing. It gets indexed before it goes on the balancer and we instruct the customer to make certain the marks are aligned when he installs it! Cannot be done with this method on any "dependent" balanced units due to an existing (built in) counterweight on the wheels. Here's a shot of one finished.
 

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Back in the day, as kids, we replaced many clutch and pressure plate assemblies on our cars and didn't balance these assemblies. Mainly because we didn't have the means nor the money, and in most cases we were not resurfacing or replacing the flywheel.
Now that I'm a lot older, and maybe a tad bit smarter, I would balance these assemblies, especially if machining or replacing the flywheel is part of the job.
 
JSeery, do you have any recommendations as to where to have it machined and balanced around here? I have no idea where to take them.
 
I have always used Chet Wilson, here in Wichita. Haven't been by lately, if Jerry is still there he knows flatheads.
 
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I made a balancer years ago that seemed to work real good. It was a lot of work for a one off job though.


9kA
 

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I still have the stuff to static balance some of the old Bell 47 tail rotors on knife edges. A person would have to make their own mandrels to do a flywheel with clutch but it works OK. Dynamic balance is better but a good static balance will generally be OK for regular service. It would be a good way to see if they are very far out for sure.
 
Jack E/NJ said:
It probably was then mounted in a table saw for dynamic testing. 8^) Jack E/NJ
Click to expand...

:D

I had my clutch and PP balanced together. They had to weld a 1" long piece of 1/2" rod to the cover to get it right. That's about 25 grams...
 
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It's not that costly to balance a motor, but makes a huge difference in how smooth it runs. It's well worth the extra money.
 
i static balance mine too on a home made thing like randyz shows. my friend made it, we use two model T transmission shafts bolted to the flywheel for an axle, as they are the same bolt pattern and very smooth, and well made. dowel pins line up too
 
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cas3 said:
i static balance mine too on a home made thing like randyz shows. my friend made it, we use two model T transmission shafts bolted to the flywheel for an axle, as they are the same bolt pattern and very smooth, and well made. dowel pins line up too
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Photos?
 
here's a photo of one shaft. this is the main shaft for a model T transmission. the flange is exactly the same as all T,A, and flat v8 crankshaft flanges. bolt pattern, dowel pins, and diameter the same. so we take a light cut on the lathe to make sure its flat and snug to the flywheel, and use two, one on each side. these are cheap at swap meets if you know what to look for, or a T transmission rebuilder guy would have a bunch with a bad keyway or other defect that will not affect this use. i have one to do in the near future, i'll get an action photo then!
 

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cas3 said:
here's a photo of one shaft. this is the main shaft for a model T transmission. the flange is exactly the same as all T,A, and flat v8 crankshaft flanges. bolt pattern, dowel pins, and diameter the same. so we take a light cut on the lathe to make sure its flat and snug to the flywheel, and use two, one on each side. these are cheap at swap meets if you know what to look for, or a T transmission rebuilder guy would have a bunch with a bad keyway or other defect that will not affect this use. i have one to do in the near future, i'll get an action photo then!
Click to expand...

Thanks like to see that. Always like to see DIY techniques
 
Ross F-1 said:
:D

I had my clutch and PP balanced together. They had to weld a 1" long piece of 1/2" rod to the cover to get it right. That's about 25 grams...
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Hi Ross, this method (welding on the cover) makes absolutely no sense to me, if you have the pieces bolted together and indexed it is so much easier and MUCH more accurate doing all the correction on the backside of the flywheel.

This is my take on it, you are working in a "single-plane" balancing mode, there's no reason to weld on anything??

When balancing a crankshaft you are balancing in a "dual-plane" mode! You have a "right" side and a "left" side. Not so with dampers, flexplates, flywheels, etc.

Thanks, Gary in N.Y.

P.S. If you balance pieces individually you will always have a very slight remaining imbalance on each piece (it has no "real" effect on the unit), this equates to 2 parts with some inherent imbalance, this gets all but eliminated when balancing the flywheel/clutch assembly as one!
 
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