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The w154 "Vulture" build project

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1908Rick Avatar
1908Rick Rick Eggers
Cape Coral, FL, USA   USA
You're right Denny, but building a basic cyclekart doesn't present the same design and construction challenges I'm looking for. That's a big part of why I do this.

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andrewroudny Avatar
andrewroudny andrew roudny
peterborough, ON, Canada   CAN
1939 CycleKart German "The Vulture"
Wouldn't want to hurt your feelings Mike! hahahaha

No, not front engine. My original idea was a belt drive from a jackshaft to the rear axle so that the rear trailing arm suspension can move freely (go back a few pages in this thread to see what I mean). It almost worked. Just wasn't getting enough grip on the belt. It kept skipping at low speed acceleration. So now instead of the belt, I'll be going TAV to jackshaft to shaft drive to jackshaft (mounted to rear suspension) to rear axle. I'll make a video soon (like February probably) to give a better idea what I'm talking about.

In reply to # 36435 by MichaelR Just kinda catching the tail end of this, but are you trying to go front engine and use drive shafts with a swing arm for suspension? If so you could use a fixed position drive shaft from motor to rear and use the universal joint drive shaft from there to the diff. As long as you mount the center of the U joint at the center pivot point of the swing arm mount axles you won't need to worry about sliding. It won't have to. Look at the drive shaft unit on a Honda cx500 street bike to see what I mean. and if this isn't what you're trying to do just ignoring me won't hurt my feelings. lol



"I never lose. I either win or learn.”
-Nelson Mandela

andrewroudny Avatar
andrewroudny andrew roudny
peterborough, ON, Canada   CAN
1939 CycleKart German "The Vulture"
Hey, don't blame me, Denny! When I started this project I knew it was gonna be weird and put it in the Custom Karts forum. But the crowd called out for more, as it were. And I was relocated to the proper CycleKart Tech page.

I know it's not exactly Stephenson, believe me. But this is a world of safety certification and license plate stickers and insurance slips and government inspectors and insurance adjusters. Making your own insane vehicle, just the way you like, and launching yourself across a field in it is pretty liberating. The more insane the machine, the more subversive and freeing, don't you think?

In reply to # 36437 by Denny Graham Boy O boy, we sure are drifting further and further away from what the "Cyclekart" is
supposed to emulate. That is, the cars from the first Golden Age of the Automobile, the 1920's.
Or the age of the "Cyclecar".
dg



"I never lose. I either win or learn.”
-Nelson Mandela

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jcny Avatar
jcny Silver Member John Corey
Melrose, NY, USA   USA
1927 CycleKart French "Sam"
1934 CycleKart Italian "Tazio"
I wonder if the rear axle could itself be made springy enough to just flex up and down at each wheel, from a central, frame-mounted drive point. OF course some trailing arms would be needed for fore-aft location; and I suppose additional springing could be applied at the mobile end of those arms (or as torsion bars at their pivot ends), but the main point is, why not just let the axles shafts flex, thereby avoiding any need for U-joints or splines, etc. With a 38 inch track, the half-axles would be live over about 17 inches. IF the axles were, say, 1/2 inch in diameter, then bending one end by 2 inches, would require 112 lbs force, and result in a peak stress at the root of about 155 ksi. That stress is too high, but not crazy. Allowing just 1.5 inches deflection (for 3 inches total travel) cuts the max force to 84 lbs and the peak stress to 112 ksi. 4140/4340 Q&T allot steel rod has a strength of over 200 ksi, so that would work just fine. There you have it. A simple, independent lightweight suspension on a driven rear axle. Schematic sketch below. jc



Builder: John 'the Fierce' Corey, aka Lord Emile Salmson (or Lordy Miles On Some)


Attachments:
CK FLEX SUSPENSION SCHEMA.jpg    24.7 KB
CK FLEX SUSPENSION SCHEMA.jpg

1908Rick Avatar
1908Rick Rick Eggers
Cape Coral, FL, USA   USA
That's very similar to what I was considering, except for the flexible axles. I was thinking of using standard 1" axles shafts with U-joints.

Denny Graham Gold Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
Sure Andrew, home built is always more fun than a Factory Certified vehicle, on the ground,
or in the air. That's why I home built me my own biplane. In fact, when I first discovered CK's
I jumped in full throttle. I accumulated quite a collection of "insane" ideas the first year
or so. Such as a couple of motorcycle shaft drive rear units, a Peerless 100 dif., Honda GX270,
Predator 307, 420, 670, endless evenings trying to design real rear suspension and a bunch of
other things that I now agree, don't belong on a "real" Cyclekart.
Recently I've throttled back a bunch and am more prone to toeing the line and coloring inside
the lines.
But as many of the "purists" here have espoused, a true "Cyclekart" is modeled after the
"Golden Age", of the Cyclecar, at least that's the way I've interpreted the description over
the past couple of years that I've been monitoring this forum.
Other wise it's a fancy little car of sorts, more like the Shriners little cars with big wheels:

Denny Graham
Sandwich, IL

BaronVonKurtz Avatar
BaronVonKurtz Gold Member BaronVonKurtz Belshe
Huntsville, AL, USA   USA
John, your setup has a few inhearent inherent (where did that come from?) problems.

The engine as depicted in your illustration is part of the sprung weight while the CVT transverses from the sprung side of the equation to the unsprung side. So imagine a simplistic view of both wheels attached to the axle moving up and down in unison (not probable but we will use it for this example). The axle stays parallel to the drive of the engine but the distance between the axle and the drive varies about the radius of the pivot arms. Not necessarily a lot at the axle but the variation at the circumference of the 60 or more tooth sprocket can be significant. This means that there would have to be a way to add to and subtract from the length of the chain. In theory that is possible but at a sacrifice of some HP. This effect could be minimized by having the centerline of the engine drive shaft match the centerline of the pivot arms thus maintaining the exact distance between the axle and the drive shaft. But in reality the the axle will not move up and down in parallel. Both wheels would move in accordance with the terrain they are in contact with thus tilting and moving the axle simultaneously and independently of the center line of the engine drive shaft. The tipping of the circumference of the 60 tooth in relation to the fixed drive shaft causes a significant mis-alignment of the engine drive sprocket and axle drive sprocket. Keeping a chain on would be difficult. Even if you could keep it on the chain wear on the respective chain, and sprockets components would be considerable.

So another take would be to move the engine and CVT to the unsprung side. That way the as the rear axle moves up and down and tilts the entire engine and drive train is also moving in the same directions. The relationship between the engine drive sprocket and the axle drive sprocket stays relatively constant. Sounds good except that it changes the sprung vs unsprung weight ratios. Unsprung weight must be designed to be tough enough to survive the constant shocks and vibrations and, as a rule, designers try to minimize unsprung weight. This would result in a significant increase.

It seems to me that if the ride is too tough on your backside that some more/better seat cushions is simpler. Experimentation here is relatively quick and cheap in comparison...

Just trying to keep it simple. =8^0

Baron



Edited 2 time(s). Last edit at 2018-12-01 03:48 PM by BaronVonKurtz.

Woodysrods Avatar
Woodysrods Silver Member Brian Woods
Westbank B.C., Canada   CAN
And we are glad to have you on the same page in the colouring book Denny!thumbs up
It is nice to have you here!smileys with beer
Brian

MichaelR Avatar
MichaelR Michael Richard
Albany, GA., USA   USA
If you want to reduce unsprung weight I came up with an idea to have the entire axle move up and down and tilt without affecting drive sprocket alignment. Just mount a CV joint and carrier on a separate swingarm in the center of the axle, and have the end of the axles on independent swingarms with a matching travel radius. The center sprocket remains vertical throughout its travel, but the axle is free to "hunt" ground contact on its own. This leaves the engine and CVT fixed and keeps them off the unsprung weight/movement list. It wouldn't be hard, and if done right wouldn't add too much weight to the Kart. As for the splined CV just use a joint large enough that you can cut the original splined shaft off and machine out a hole and keyway for the axle. Still working out some kinks. As for your original swingarm idea and the chain length variance needed you could use two chain tensioners. One inside the chain to maintain proper chainway play and one outside to take up the slack on those chainway variances. If you can build a motorcycle with 14 inches of rear wheel travel and keep a chain on it we can surely keep a chain on a cyclekart. Just ideas for now, but it looks like it would work. Maybe, sort of, I think.

Denny Graham Gold Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
Well like I said, lots of big ideas, not enough time or...for that matter, enough
real need at this time to pursue this one.
Since all this talk about springing the rear axle is popping up, this is where I left
that idea. The point that slowed me down on the design was coming up with a
simplified means of adjustment.
I'd mount the motor fixed to the frame and drive a jack shaft. Then swing the
axle on the same axis as the jack shaft. The swing arm would be a boxed section
with wide bearing surface for rigidity and to rule out the need for a transverse (Panhard) rod.
http://www.pbase.com/dennygraham/image/165169105
dg

jcny Avatar
jcny Silver Member John Corey
Melrose, NY, USA   USA
1927 CycleKart French "Sam"
1934 CycleKart Italian "Tazio"
Baron, I must disagree. The CVT is a rigid structure, rigidly mounted to the engine. It is all of a piece there and all sprung. IT is easier to see, if you imagine putting U-joints where the axle halfshafts attach to the CVT. This would be no different that early VW, Porsche, or Corvair layouts. The difference I propose is only to omit those U-joints and let the axle shafts flex to accommodate the relative movement of suspension travel, which is possible, given the small size and light weight of a CK vs those cited full-size cars.



Builder: John 'the Fierce' Corey, aka Lord Emile Salmson (or Lordy Miles On Some)

Racie35 Avatar
Racie35 Bruce T
Terre Haute, IN, USA   USA
The tav mounted to the swingset might work allowing the engine to remain fixed..the belt length wouldn't be as crucial as you think either...if off a tad it would just start or end slightly lower or higher ratio...and you can buy different length belts . It'll absorb minor alignment issues easier too.....to be clear, the tav driven unit ...you still have the driver on the engine....bye bye plate



Edited 2 time(s). Last edit at 2018-12-01 09:41 PM by Racie35.

andrewroudny Avatar
andrewroudny andrew roudny
peterborough, ON, Canada   CAN
1939 CycleKart German "The Vulture"
Whipped up a few ideas for "The Vulture" logos. Whadaya think?



"I never lose. I either win or learn.”
-Nelson Mandela


Attachments:
Vulture Logos.jpg    65.6 KB
Vulture Logos.jpg

jcny Avatar
jcny Silver Member John Corey
Melrose, NY, USA   USA
1927 CycleKart French "Sam"
1934 CycleKart Italian "Tazio"
I like the moon ones best, but you need to add some cut-out lines within the bird shadow to give is some more definition (maybe a red eye, and a mark for the wing?). Example here may not be right wing location, but gives the idea.



Builder: John 'the Fierce' Corey, aka Lord Emile Salmson (or Lordy Miles On Some)


Attachments:
v-2.jpg    14.2 KB
v-2.jpg

andrewroudny Avatar
andrewroudny andrew roudny
peterborough, ON, Canada   CAN
1939 CycleKart German "The Vulture"
Nice edit! My wife said the same thing. Needs more definition. I'm exploring options.



"I never lose. I either win or learn.”
-Nelson Mandela



Edited 1 time(s). Last edit at 2019-01-01 09:41 AM by andrewroudny.

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