flywheel balancing

Bottom End (crankcases and crankshaft)
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nmaineron
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flywheel balancing

#1

Post by nmaineron »

I have been reading in the knowledge base and elsewhere about the ins and outs of balancing the crank on my 63FL.The formula for determining what is needed and how to get to the point of taking weight from the flywheels is straight forward.My question is ,what weight is used if you prefer to balance each wheel separately,especially if they weren't mated in the initially? Half of the standard one rod and all its rigging or the whole load?Thanks,Ron
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Re: flywheel balancing

#2

Post by 1950Panhead »

The flywheel is balanced as an assembly, usually equal weight is removed or added from both wheels, in reality it does not matter.
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Re: flywheel balancing

#3

Post by 1962FLH »

Yes you can; as a matter of fact I have only static balanced wheels one at a time on the balance beams. If you have unmatched wheels I would recommend doing them one at a time because you can have a wheel assembly that collectively is balanced but separately they are unbalanced you end up with unexplained Harmonics and vibrations that seem to show up at wider range of RPMs. I know many people dynamically balance wheels and say its better and hey maybe it is. I cannot disagree because I have never used that method and just don’t know. Hopefully others will help with the dynamic balancing methods.
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Re: flywheel balancing

#4

Post by 1950Panhead »

because you can have a wheel assembly that collectively is balanced but separately they are unbalanced
Left wheel pounds more then right wheel, describe your process.
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Re: flywheel balancing

#5

Post by nmaineron »

Thanks 62,do I use the total bob weight on each wheel??
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Re: flywheel balancing

#6

Post by Bigincher »

I'm no expert, but I've never heard of balancing flywheels individually. How does that work when you assemble the two wheels into a unit? You'll have to explain that, otherwise I only see balancing as an assembly.
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Re: flywheel balancing

#7

Post by nmaineron »

That is my question also Big.I was watching a you tube bit with the bob weight was attached to the pinion side wheel and was perfectly balanced and I think it was one of Saddlebagray's.So I am trying to convince myself that if you balance each wheel with the same weight,connect them and they should be in balance to that weight.It hurts to think that hard nowadays :?
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Re: flywheel balancing

#8

Post by hogboy52 »

In short, take 54% of total mass (for 74 in.), then take half of that amount and balance each wheel separately. If both are not exactly same balance there will be shaft flutter.

Good luck.
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Re: flywheel balancing

#9

Post by socalrider »

[quote="hogboy52"]In short, take 54% of total mass (for 74 in.), then take half of that amount and balance each wheel separately. If both are not exactly same balance there will be shaft flutter.

Good luck.[/quote]
Can you please explain what shaft flutter is ? Thanks
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Re: flywheel balancing

#10

Post by Buddhahoodvatoloco »

Hogboy,
now you have my undivided attention
what is shaft flutter.
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Re: flywheel balancing

#11

Post by hogboy52 »

If the wheels are balanced together as a unit, one wheel will have more balance weight than the other. The rotational (dynamic) force of this wheel upon its bearing/half-shaft will be greater in one direction while that of the lighter will be greater in the opposite direction, resulting in a side to side (angular) shaking motion, increasing with RPM.
I think in terms of identical wheels, while early HD's have one regular and one much more massive wheels. Don't know what dynamic effect that would have, but these aren't high revving machines.
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Re: flywheel balancing

#12

Post by Buddhahoodvatoloco »

Hogboy, interesting.
Thanks...................
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Re: flywheel balancing

#13

Post by Curly 64 »

I use the form from S&S and use the same weight for the bobweight on each wheel, done separately. I had a job to do on a '74" once that would shake itself across the floor on the sidestand when idling. I'm positive the two halves of the flywheels came from completely different engines so they weren't even close to the same balance factor when they were reverse engineered. I balanced them with the same weight and it was like a completely different engine when it was done. I've watched them balance flywheels at T&O, and it might be better, but I don't have the kind of money a balancer like that would cost...I think doing them separately is more than acceptable for most people. Jerry
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