1/2 vw engine vibration

[Dan_]

How many IPS is acceptable with this engine when a dynamic balance check is preformed, does anyone know?

I don't know the answer to your question, but if you are sure the bob weight is where it is supposed to be and the crankshaft journals were drilled hollow and the prop tracks within 1/16th inch then you may want to try a Balance Masters...

[Dan_]

Also leave your wooden prop sitting horizontal, else if it is vertical moisture can migrate to the bottom blade and throw it out of balance.

[mikeheckler]

Forgot to mention, a couple months ago had a dynamic prop balance done, initially 3.5" and then added washers to spinner and got it down to 1.5" I could not feel any difference

[mikeheckler]

The dynamic balance was done and a week after that I installed a balance master, and it is still on, there  is less vibration with it on than with it off. The vibration is still bad though..

[Dan_]

Mike,
I found this on the 1/2 vw group... apparently he changed props to get different rpms.  Was not able to find the Dynavibe 1/2 vw case study.

Bob Wood
Oct 17 6:00 AM

Yes, the biggest issue I had was a rougher power setting around 2800 rpm. I flew with the dynavibe attached and documented the power bands so I could avoid them. The needles in the Mikuni vm26’s must have been hopping around. I would get a bogging in this band and it was not fun. That all went away when I got below .5. If the prop tracking is not dead on it will not work. I changed props to get there.



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In both axis?

On Oct 16, 2019, at 11:33 PM, Bob Wood rwood@... [HalfVw_Engines] <HalfVw_Engines@yahoogroups.com> wrote:
 

 
I was able to get .42 with a perfectly balanced prop. Took some time but well worth it
 
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 On Oct 16, 2019, at 9:18 PM, Pete peterz@... [HalfVw_Engines] <HalfVw_Engines@yahoogroups.com> wrote:
 

Use it always on mine, but its nog possible to get better/lower than 0.6IPS in both the vertical (rotational) and the horizontal (rocking couple), as they are competing.

On Oct 16, 2019, at 9:29 PM, Bob Wood rwood@... [HalfVw_Engines] <HalfVw_Engines@yahoogroups.com> wrote:
 

 
DynaVibe dynamic balancing works very well. See their on line 1/2 vw case study
 
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 On Oct 16, 2019, at 7:33 PM, Pete peterz@... [HalfVw_Engines] <HalfVw_Engines@yahoogroups.com> wrote:
 

Not possible to balance out the rocking couple of the offset two cyl.

On Oct 16, 2019, at 6:29 PM, John Hartgerink johnhartgerink@... [HalfVw_Engines] <HalfVw_Engines@yahoogroups.com> wrote:
 

 


You can get very good balance on a 1/2 VW but you need to take it to a
Performance Machine Shop that can do high speed balances by adding
heavy metal to the crankshaft counterweights. V8 race engines are balanced
this way and are none as neutral balanced engines.
Jan

[Sweet B]

Well we tried to balance the prop today however as we went up on power the software told us to shut down vibration was "dangerously high", to that effect. We managed to get a reading @1500 at about .46 ips. I believe somewhere below <.07ips is acceptable for GA.  Next step, we are going to make a 8" disk or spinner back to with holes every 30deg to give us more flexibility when adding or splitting weight. More to follow. . .         

[mikeheckler]

Interesting,, let me know how it goes!

[Theodore]

Jeopardy
cat. LSA & 103 class aircraft
No blue pill needed for this engine...
What is VW Type 4?

(flywheel drive of course)

Peace.

[Dan_]

Type 4 was used in several models.  By the time they quit making them they came with 2000 CC stock.

[Theodore]

good link

the Bosch CIS injection is hard to find mechanics that will work on 'em. Most will convert back to carbs. No emission tests for the old vanagons and buses

[Dan_]

Well we tried to balance the prop today however as we went up on power the software told us to shut down vibration was "dangerously high", to that effect. We managed to get a reading @1500 at about .46 ips. I believe somewhere below <.07ips is acceptable for GA.  Next step, we are going to make a 8" disk or spinner back to with holes every 30deg to give us more flexibility when adding or splitting weight. More to follow. . .     

Take a look at the balancing methods in the attach pdf.

[13brv3]

FWIW, this is the chart that's in the Aces prop balancer manual. 
Rusty