Torsional Damper on motorcycle transmission

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1684zach

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Feb 3, 2011
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Bellflower, MO.
My biggest concern with using the Suzuki SV650 as my power-plant and PSRU is, trying to figure out what if any torsional damper is needed. I am leaving the clutch in the tranny, and stripping out all gears, but what I need to reduce the rpm to swing my prop. I have thought of putting a cog belt setup on to act as somewhat of a damper, but that adds quite a bit of weight. As far as I can tell, not many guys have tried to use the transmission as the PSRU; or at least not easy to find info on their experience. One thought I had was, to add a "harmonic balancer" between the prop and the tranny; but I am not sure of how to for lack of a better term, "size" the balancer. I have read a tremendous amount of info on this subject, but not being an engineer leaves me feeling like I would like to have more knowledgeable guys put in their thoughts. -Zach
 

orion

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I don't recall where this was but some time back i read about someone using a Honda Goldwing engine in this manner and the conversion was fairly simple. He did not use any form of additional damper - just the tranny and clutch.
 

PTAirco

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Sep 20, 2003
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Same with the Virago V-twin engine conversion some people did way back; simply added a prop hub/bearing set up at the output end of the transmission and flew it in first gear. First gear eventually broke and they switched to second gear. The first gear cog was not designed to be in continuous use and was of lower quality than the rest, but it did swing an 84" prop!
 

1684zach

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Feb 3, 2011
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Bellflower, MO.
Orion & PTAirco, -thanks for the responses! I wondered if there would be need for a damper, since the transmission and the clutch would both act in some way as a damper. But wanted some other opinions.

I hadn't seen this article before, you might be interested in reading: http://ibis.experimentals.de/downloads/torsionalvibration.pdf

Thanks again, it's so nice to have access to a forum like this to bounce ideas off others and glean from their knowledge. -Zach
 

Dana

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It's a much smaller engine, of course. but I left the torsional damper (rubber bits on the clutch bell) in place when converting a KX100 engine for PPG use. I took the clutch out, and put the prop shaft where the clutch had been (3.4:1 first stage reduction).

-Dana

A truly wise man never plays leapfrog with a unicorn.
 

1684zach

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Feb 3, 2011
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Bellflower, MO.
It's a much smaller engine, of course. but I left the torsional damper (rubber bits on the clutch bell) in place when converting a KX100 engine for PPG use. I took the clutch out, and put the prop shaft where the clutch had been (3.4:1 first stage reduction).
-Dana

Hey Dana, Do you have any pictures of the process you did? Thanks, -Zach
 
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Dana

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I took a lot of pictures. What do you want to see?

-Dana

The number of elected federal officials is limited to congress, the president and the vice president. That's only 537 people. The federal bureaucracy numbers in the millions...
 

1684zach

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Bellflower, MO.
I took a lot of pictures. What do you want to see?

-Dana

The number of elected federal officials is limited to congress, the president and the vice president. That's only 537 people. The federal bureaucracy numbers in the millions...
Really any that pertain to the engine being converted. Don't feel like you have to waste a ton of time uploading pictures, it's just that I am very interested in what you have done with that project. -I made a paramotor from scratch using a Honda gx200 tore it down to the case, and rebuilt it like the gocart engines are done. It is supposed to put out about 14-15 HP, I suspect in real life it is more like 10-12 HP. I am currently experimenting with a V-belt redrive that I made, and making my own propellers to figure out what works the best for my setup.

On a side note, I love reading your little quotes on the end of your posts! Most are right on!

If it's easier, my email is: zach.tekton@live.com
 

Dana

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Here's a couple. This first is from the CAD model:

shaft_assy.jpg

On the left, the red disk, green gear, and light blue basket are part of the original clutch assembly. The six gray parts are the rubber dampers, which allow the gear a bit of wiggle relative to the clutch basket.. The clutch basket then bolts to the light green disk, which is keyed to the [yellow] prop shaft. Then the light blue plate replaces the original clutch cover, the red is the bearing mount, and the green prop hub on the upper right.

Here you can see the assembly mounted on the engine:

pressure fitting.jpg

-Dana

We all know that engineers love to play with expensive toys. Especially when someone else is paying for them.
 
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