1/2 vw and vibration...

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N8053H

Well-Known Member
Joined
Jan 31, 2013
Messages
2,523
Location
Right here in front of my computer
My little 1/2 vw ran silk smooth. Then I replaced the prop with a Tennessee prop. She had a Culver prop, and I removed the starter and everything that goes with it. After doing all this she had a vibration.
I double checked everything and nothing was a miss. So I reinstalled the flywheel. This made the difference. This engine once again runs silk smooth at all throttle settings.

Tony
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
12,845
Location
Memphis, TN
I'm helping a friend build a Legal Eagle so have been doing lots of 1/2 VW reading. Seen counter weights on the crank, and at Oshkosh, was told how the thickness of the prop can make a difference. I guess sympathetic vibrations with too thin a prop. His will be hand prop so we want it smooth as possible without too much extra weight. I do have access to dynamic balance equipment so we can test ideas.
 

nheistand

Member
Joined
Mar 4, 2011
Messages
23
Location
Vinton, Iowa / USA
A counterweighted crank is mandatory for a half VW. After that you still need some dynamic balancing to get it smooth. I think there is a trade-off where a $150 Balance Master on the prop is less or similar cost to taking the crank assembly and having a dynamic balance done. I am building a 82mm x 94mm half VW right now. If it vibrates too much to suit me, I will try the Balance Master. The neat thing is it balances the entire crank assembly including the prop.

Norm Heistand my .02
 
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