Engine mount bushing

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Posted (edited)

49AB1366-AEC7-483F-9C2A-C871B5885F04.thuI need to urgently replace my "582" type engine mount bushings. Looking for a reference and a supplier, preferably in europe... or dimensions and rubber characteristics (shores...) for make to order.

 

Edited by FredStork

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Posted

Leading Edge Airfoils sells them.

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Posted

Standard Lord mounts. Your old one should have a number on it. Mine used 150PD-30 and the "150" number is the series "Diamond" in my case. Yours pictured are not Diamond. I have an Avid Flyer with a 582 but who knows how many variations in mounts they have had? I have no idea if my original ones were the right ones. The radiator mounts were also bad on mine so I tracked down new ones for those too. Sometimes you can search Barry mounts and find them listed also. The Lord Company is a good place to figure out exactly what you need and then once you have their part number you can hunt down a vendor in your part of the world. E-bay part searches may work also. Link here: http://lordfulfillment.com/pdf/44/PC7000_IndustrialParts.pdf#page=72

 

PC7000_IndustrialParts.pdf#page=72

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Posted

The mounts that Fred needs came as a sheet of rubber with the kit, and you cut them out yourself into a round shape.  My C model builder's manual just calls it 5/8" thick neoprene.  Same name in the parts list.  JImChuk 

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Posted

I went up to the rubber store and had them cut out some. When I wanted a bit more preload, I had some thin ones cut and added them. When they asked what it was for, I told them mounts for an air compressor. I don't think they would have done it if I had said experimental airplane. :o

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Posted

The mounts can be hand made from 5/8" neoprene sheet, I found 1" sheet on Ebay which could easily be sliced down. Here are the instructions from Joey's build book, section 4:

engine mount absorber detail.jpg

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Posted

Thank you all.

With the exception of eventually Leading Edge Air Foils, I have not found anyone proposing an off the shelf solution. And yes, I have the indications about "5/8" thick neoprene" in the manual... but there is more than one sort of neoprene and there is no indication of hardness (shores).

Comparing with other bushings sold for this size 2 stroke I think the neoprene should be 40° shores. Anyone has a different opinion?

My old bushings were definitely too soft (and have not aged very well)

Bushings.thumb.jpg.9f03b55253e4a808a82a3

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Posted

LEAF sells soft, medium and hard mounts.

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Posted

 I think I still have a sheet of five eights that I use for my motor mounts, will check tomorrow and get back to you 

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Posted

 I think I still have a sheet of five eights that I use for my motor mounts, will check tomorrow and get back to you 

sorry, I only have 3/4"

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Posted (edited)

Thank you all for your feedback on this.

Comparing with bushings for other planes I have concluded that a shores hardness around 40 for the "rubber" used might be appropriate. I have found an industrial model that appears to match in terms of size and after talking to the manufacturer I have placed an order. I will test and keep you updated. 

image.thumb.jpeg.4b38a898fe521218d10807e

Edited by FredStork
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Posted

Fred, can you post up the part number for the mounts you ordered?

 

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Posted

Fred, can you post up the part number for the mounts you ordered?

 

I sure can...

Paulstra 530903-21 / Barry Control 22002-11

and as mentioned I will test when they arrive and post the outcome. They appear to be the right size, to be confirmed. And we will see about the hardness...

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Posted

Thank you.  I just ran the numbers they show and they seem to be a smaller diameter than the current neoprene ones that the book calls for.  I am going to swing by the rubber supply house tomorrow and see what I can find for the mount rubber to make new bushings for mine.

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Posted

Fred, can you post up the part number for the mounts you ordered?

 

I sure can...

Paulstra 530903-21 / Barry Control 22002-11

and as mentioned I will test when they arrive and post the outcome. They appear to be the right size, to be confirmed. And we will see about the hardness...

I think you will be fine with the industrial models. I didn't give a specific part number mostly because I calculated what I needed. I took the total weight of my motor, propeller, gear box, muffler and starter and added it up and divided by 4 to give me the static load for each bushing. Then I browsed through the sizes I needed until I found one with the weight and size requirement. Is that the right way? Maybe, maybe not. An airplane in a flight can pull several G's and a heavier rated mount may be needed. There's a range to these things so I guessed using the static weight as the low limit. I also think you could slightly vary the mounts with two of a different density to play with dampening sub harmonic vibrations from the propeller at low rpm's. If you guess too high you defeat the purpose of rubber mounts and the vibrations get passed along to the air frame.

Did you notice the video on the "Lord" mount website that had a camera watching the mount in an aerobatic airplane? The G forces do come into play on these mounts. A camera may be handy in finding the best rubber shore number for our type of aircraft.

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