erwe
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| posted on 12/10/04 at 05:43 PM |
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propshaft goldwing or BMW cycle
Anybody thought of using the propshaft (or parts) from a Honda Goldwing or BMW bikes?
I'm started on my secon project: GSXR1000 with a lightweight chassis inspired by the Rush MC and caterham RS400. For the chassis (totally
V-shape) I only want to use round tube, 25 x 1,5 for the outer tubes, 18 x 1,5 for indirect stressed tube and 15 x 1,5 for diagonals. Sierra
(scorpio)rear, Westfield upright front. rear bike brakes alongside the diff.
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sgraber
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| posted on 15/10/04 at 04:09 AM |
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Iresearched this about 2 years ago when someone offered me a shaft-drive Yamaha V-Max engine.
The most basic problem with the shaft drive engines is that the output shaft rotates reverse to a standard engine. I investigated flipping a
differential upside down and running it backwards, but the gears in all modern automotive differentials are hypoid, which means they are cut to run
primarily in one direction. Which is why when you drive your car quickly in reverse it makes a god-awful whine. Imagine that whine happening while
going forwards and that's what you would end up with. Besides that, the gears would wear out quickly because they would be running on the
'coast' side of the gear. Which also makes the gears try to push out of the housing.
Here's a photo of hypiod gears
I once saw (and I think he's here on this forum) a guy that built a trike with a shaft drive bike engine, but it was front wheel drive with the
shaft facing forwards. I don't know how that worked out for him. I have also seen that some of the big American Trikes use a VW transaxle with
reinforced gears, but this combination is typically too long to package effectively in a smallish car.
In the end I gave up on the idea as being too much trouble for the value and I have to imagine that the difficulty in adapting these engines to a
standard differential is the reason you don't see them being used in this application too often, if ever.
Steve Graber
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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Mave
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| posted on 15/10/04 at 06:32 AM |
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Steve, I think you mis-read. He's only talking about using the propshaft. The rest of the car will be "standard BEC".
I think one of the concerns is the length. Without doubt you'll need to lengthen the bike's propshaft. The diameter of the bike-prop is
very small, and with an increased length, the risk of resonance will increase: In other words, it might break itself due to vibration....
This could be solved by using multiple center-bearings, so the unsupported length is small. (but then you might loose the weight benefit).
Marcel
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sgraber
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| posted on 15/10/04 at 02:38 PM |
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quote:
Originally posted by Mave
Steve, I think you mis-read. He's only talking about using the propshaft. The rest of the car will be "standard BEC".
I think one of the concerns is the length. Without doubt you'll need to lengthen the bike's propshaft. The diameter of the bike-prop is
very small, and with an increased length, the risk of resonance will increase: In other words, it might break itself due to vibration....
This could be solved by using multiple center-bearings, so the unsupported length is small. (but then you might loose the weight benefit).
Marcel
Yep, now that I re-read the original post I see what you mean. <sheepish grin>
<just ignore me > 
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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erwe
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| posted on 16/10/04 at 01:51 PM |
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pics
On the pic you can see the difference between the Ford an a bike one.
Ford weights 1 kilo and the bike 300 grs.
I want to use 38 x 1,5 mm round tube.
Ford propshaft is 52 x 1,5 mm.
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erwe
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| posted on 16/10/04 at 01:56 PM |
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http://locostbuilders.co.uk/upload/EPSN0005.jpg
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Gripenland
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| posted on 16/10/04 at 02:37 PM |
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If my calculations are correct then:
A 38x1.5 mm mild steel tube will only be able to withstand 380Nm of torqe.
With an unsupported length of 800mm your critical rpm will be 7600.
If you use a two peace prop you'll be ok regarding critical rpm but I think that torqe will be a problem.
kokos-racing.com
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sebastiaan
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| posted on 4/11/04 at 06:31 PM |
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Prop / UJ's from bike
Erwe,
If you only want to use the universal joints from the bike, why not knock up an adapter to go from 38*1.5 (35 inner diameter) to something like 50*1
(48 id). This should handle the torque OK, and should cause no problems with vibrations.
(I think, but am too lazy to do the maths....)
Should also give you less "interface trouble" at the diff end of the prop. I'd also go for a two piece prop, or at least one with a
centre bearing (though that'll be VERY difficult to engineer properly)
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