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Author Topic:   balancer
Dirt Full Roller

Total posts: 29
posted March 28, 2001 12:02 AM
Can any one tell me if i can run only the hub of a harmonic balancer and not the outter inerta ring ? The engine is a 377 that has been balanced with out the flywheel or balancer . I've been told I will brake the crank eventually. any input ...........

Dirt Full Roller

Total posts: 74
posted March 28, 2001 12:30 AM
juni ,

You will definitely break the crank !!! If your engine has been balanced without a flywheel/flex plate or harmonic balancer , you can take both to anyone who can balance engines , and have them zero balanced . You will run over your crank if you don't use some sort of harmonic balancer !!

Dirt Administrator

Total posts: 3279
posted March 28, 2001 08:06 AM UIN: 16262997
First of all what does a harmonic balancer do? It dampens the harmonic frequencies of a crankshaft throughout the rpm range. The outter balancing ring is a big part of that dampening process. If at any time, throughout your RPM range, the harmonic frequency of the crankshaft equals the rod frequecies or any other attached parts frequency, it will cause heat and basically rattle the part until it breaks. Very bad on bearings also. This is why you see some engine builders shooting their harmonic dampners with a pyrometers. They are checking the temps to see if any harmonic problems exist. Something similar happened to Tony Stewart's Winston Cup ride a while back. He had a problem with some valve train components and the pushrods were matching the frequencies of the springs and they were breaking valve springs. (inside source) Just an indication of how important it is in the engine department. One other thing....on a race motor, your moving through a broader band of frequencies because of the extended RPM range, which will make the requirement of a good harmonic even more necessary.


Dirt Full Roller

Total posts: 52
posted March 28, 2001 08:37 AM

If this motor has been internally balanced already then all you need to do is run a balancer (intenally balanced model) and a flexplate (internally balanced model)and you are ready to go, there is no need to re-balance at the machine shop.

I reccomend the Pioneer brand race balancer they are cheap and light. You can purchase the flexplate from them as well. I can give you part numbers should you want them.

YOu will need to run a balancer no matter what or yes you will destroy the crank.

Dirt Freak

Total posts: 219
posted March 28, 2001 06:18 PM
I'll say it's BEST to run the damper.....
If you want to save weight run a crank hub..don't bother taking a damper apart just for the can buy a crank hub with V-pully set up all ready. But life will be short on bearings.......around 15-20 shows.
And before everyone jumps on me.........what does a sprint car run for a damper????/ remember what the damper does.....Jammin explained it VERY well........I still say it's best for a weekend guy on a budget to run a damper........but if you got bucks and bucks you can gain in this department....that's all

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