Barry engine mounts

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Malcolm C

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I need to get some Barry engine mount rubbers for my Global 1/2 VW engine, I called the Lockwood help line but they would not advise me on what hardness rubbers would be suitable. They come in various hardness from soft to extra hard, has anyone out there got any advice on what type to order? thanks in advance...Malcolm.
 

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wsimpso1

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Lots of folks have been building and flying half VW engines, we should have a decent bit of empirical knowledge already out there of what works well with this engine.

Will someone out there please share the part number for Hutchinson/Barry mounts that have been recommended and found to work well at mounting and isolating the half-VW from the airframe.

Understand that this is coming from long experienced powertrain engineer who did torsional vibration isolation as a big part of his job, but never worked with engine mounts professionally. I do however understand that besides basic theory, there are almost always some "gotchas" out there to complicate things for you. The experience of what has worked and what has not worked is a valuable thing to take advantage of...

As to the Hutchinson page cited, the basic method is textbook and works fine for stuff vibrating up and down as all you need is machine mass and vibration frequency and amplitude. However in engines, well, this one will have torque reactions opposite the accels placed upon the crankshaft by firing and the pistons being accelerated back and forth in their bores. Then the prop will also have n/rev pulses due to P-factor as the n prop blades cycle through their varying angle of attack. Then there will be a vibration of the engine in the yaw axis of the airplane due to the two pistons being offset longitudenally from each other while being driven back and forth in their bores, also happening at two per rev. The vibration problem is thus multivariate - while it might be solved using analytical methods, it might be hard to get a good result on...

The half VW has two primary vibration modes to use in the Hutchinson process: Firing is the biggest one with one firing pulse per revolution of the engine. The second biggest vibration input is two pulses per revolution, if you get the first, second is covered.
As the process goes, the natural frequency must be enough below the lowest of these to isolate. 0.707 times the fd is a good place to start.
The hard part is not shown - fn is proportional to the square root of k/m. You would need the spring rates k of the mounts and the m for the masses supported by them... I suspect that the torsional spring rate and the torsional mass - that is the mass moment of inertia of the engine about the crankshaft centerline - are the more important ones to use in the equation. While doable and perhaps even doable with a good outcome, my inclination is to instead go for the monkey-see monkey-do approach.

Yep, copy what other people have found to work. So we are back to the opening two paragraphs of this post.

Billski
 

Malcolm C

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Thanks for responding both of you, If I don't get any feedback from people who have actually mounted their 1/2 VW's on Barry mounts I will just order the medium and go up or down depending on the results. They are only about $50 for four so it won't break me. Would still like to hear of others experiences though, all the best. Malcolm.
 

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Burgher

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I used some soft rubber I had and cut out the dougnuts using a hole saw! Am now looking into using the lord type mounts I ordered for a jabariu engine in a zenith. Will try to post progress but have other stuff in front of working on MoJo........ :( I have to keep the engine as close to the front of the airframe for W/B reasons. On another front I am considering a composite boom to replace all the chrome moly tubing and chop off some substantial weight.....but that's another story.
 

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Flyguyeddy

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I need to get some Barry engine mount rubbers for my Global 1/2 VW engine, I called the Lockwood help line but they would not advise me on what hardness rubbers would be suitable. They come in various hardness from soft to extra hard, has anyone out there got any advice on what type to order? thanks in advance...Malcolm.
There is a guy who has the original mounts made for that engine. Has a bunch of them. I think a whole set is like 60 bux. Check out the n3 pup group
 

Malcolm C

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Thank you both for the tip, I got medium Barry mounts from Lockwood and have some Chevy rubber mounts coming but I will call the Mosler mount guy tomorrow and buy some of his. You can't have enough rubber mounts when you are experimenting can you?
 

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Burgher

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Thank you both for the tip, I got medium Barry mounts from Lockwood and have some Chevy rubber mounts coming but I will call the Mosler mount guy tomorrow and buy some of his. You can't have enough rubber mounts when you are experimenting can you?
Glad to see her running! Also fully approve of your choice in MC's...........my road bikes a R80RT.
 

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Malcolm C

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She runs really well, no smoke or noises and 60 lb oil pressure, I got the correct rubber mounts from the guy with the bin full of them and will make an engine mount when my Flea is more complete so that I can get the center of gravity in the right place. Yes the BMW is a nice bike, I have 3 of them and 31 other motorcycles from 1909 to 2005, I have a
serious bike addiction problem.....
 

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Burgher

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She runs really well, no smoke or noises and 60 lb oil pressure, I got the correct rubber mounts from the guy with the bin full of them and will make an engine mount when my Flea is more complete so that I can get the center of gravity in the right place. Yes the BMW is a nice bike, I have 3 of them and 31 other motorcycles from 1909 to 2005, I have a
serious bike addiction problem.....
Did you put the Jag in to seduce me????
 

Malcolm C

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Ok, so I welded up in a jig , an engine mount to get the C of G in the right place. I had to do it in my garage as welding is prohibited in Torrance airport hangars due to fire regulations , I used the Barry medium rubber ones and they worked out fine. No excessive wobbling or vibration even at idle . On the solid engine test stand it would vibrate badly at low rpm. So medium it is, thanks for your input HBA ers the Flea will soon take to the skies vibration free.....
 

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