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First cyclekart build '20-'30s racer.

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chrisenamels Avatar
chrisenamels Silver Member Chris Brown
Llangadog, Carmarthenshire, UK   GBR
Great news René, enjoy your Summer of shows, look forward to seeing further progress with your cyclekart later in the year.

Chris

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Tom Knight Avatar
Las Vegas, Nevada, USA   USA
1911 CycleKart Racing "Yellow Peril"
GOOD NEWS....smileys with beer

Denny Graham Silver Member Dennis Graham
Sandwich, Illinois, USA   USA
That's got to take a big load off your shoulders Rene. I think a summer of
kicking back and just taking some relaxation is the best medicine you
can take after the battle you've had this year.
Stay well and those pups need a friend like you as much as you need them.
Denny Graham
Sandwich, IL USA

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Neto Ernest B
Berlin, Ohio, USA   USA
Hi René,

I'm new here, and just finished reading your entire build thread. I have a question for you about your chain drive - What is the distance between the two shafts in the second section? (From where you dropped down from the oil clutch to the rear short jack shaft.) Also, I see that that rear shaft is just ahead of the pivot point for the rear suspension. Is that different pivot point going to make any significant difference in the chain length as the suspension travels through its arc? (If I am thinking this through correctly, it will be tightest at the mid point, and a bit looser when compressed and when extended.)

Neto

Torro123 Avatar
Torro123 René Wesselius
Amsterdam, NH, Netherlands   NLD
The distance from both long chaines is almost the same,approx.72centimeter.
The pivot point is just near as possible the rear shaft,i don't know how much difference there is in length but the distance between pivot and shaft is the same as on a motorcycle so there will be no problem,the chain needs to move up and down about 12mm at unloaded position.
René


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Neto Ernest B
Berlin, Ohio, USA   USA
Thank you much for the response, and the pictures. Is that # 35 chain, or # 40? (Or is it even larger, or a metric size? I didn't make a point to make note of it when I read through your build reports thus far.)

I haven't any experience with motorcycles, so I didn't know that it would be OK to have the jack shaft center ahead of the swing arm pivot point. I am thinking along the same lines as what you are doing, and was thinking that I'd have to mount the swing arms on the jack shaft, and have bearings in the swing arm connection points, instead of just nylon bushings.

Torro123 Avatar
Torro123 René Wesselius
Amsterdam, NH, Netherlands   NLD
Ernest i am using just a light motorcycle chain,don't know the size.
The swing arm does not need bearings,the movement is only a few mm on the pivot point,nylon bushes will do.
On mine i use even nothing,just a strong bolt in a steel bushing and some grease,thats all.
Take care there is as little as possible sideways movement of the swingarm as every mm will be enlarged many times at the end of the arm.
Are you going to buil a front engine CK too?

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Neto Ernest B
Berlin, Ohio, USA   USA
In reply to # 24948 by Torro123 Ernest i am using just a light motorcycle chain,don't know the size.
The swing arm does not need bearings,the movement is only a few mm on the pivot point,nylon bushes will do.
On mine i use even nothing,just a strong bolt in a steel bushing and some grease,that's all.
Take care there is as little as possible sideways movement of the swingarm as every mm will be enlarged many times at the end of the arm.
Are you going to build a front engine CK too?

Yes, I was thinking that I would need bearings in the swing arms only because I thought that it had to be located on the identical pivot point as the jack shaft location, so that there would not be any variation in the distance between that shaft & the axles. So I was planning to mount the swing arms on the jack shaft itself. I had plotted out two arcs based on different mounting points, and saw that there would indeed be some slackening of the chain at the top & bottom travel points, Not having any experience with chain drives (other than bicycles), I didn't know how crucial that would be - I didn't know that motorcycles had different practical points for swing arm center & sprocket center.

One of my problems with designing something like this is that I can think of so many different options. I initially thought that front engine is the way to go, and was thinking of a shaft drive, with the engine up front and on a long sub-frame with an arrangement similar to the simple setup used on dugout canoes in the back water areas of Brazil (where we lived at missionaries for 17 years), what they call a 'motor de rabeta' in Portuguese, and I think 'peque-peque' in Spanish.
Then I started thinking of rear suspension, because I injured my lower back when I was in my early 20's (I'm 61 now), and while the seat could be sprung as some have done, I also saw that many builders have said to put padding along the sides in the cockpit. It would seem to me that that would chafe after driving that way very long, with the seat going up & down, and the side cushions fixed. So I thought to position the engine between the rear swing arms, down fairly low. (The frame rails would stop ahead of that, and the engine would be mounted on a sub-frame (or frame extension) that would go over the top. I don't know if that will make sense, especially with the language translation. (I know what it's like working in several different languages, from our years there in Brazil, where we not only had English & Portuguese, but the Indian language as well, and then my wife speaks a German dialect as her mother tongue, so we had that, too.)
Now, looking at your build process, I'm inclined back toward a front engine) because I just think 'The engine belongs in the front'), but with a differential also up front, and chains going back on both sides. At the rear I would have separate jack shafts for each side, but probably running together in a tube in the center, to help stabilize them. I was also thinking that a person could design a matching set of cogs that you could engage with a sort of clutch fork design, whereby you could lock the two axles together if you were in mud and one wheel just wanted to spin. If I recall your design correctly, I think you could do something like that, too, that would lock both wheels into a sort of posi-trac set up.

(I am self-employed, and I have to resist the temptation to spend my working hours on this hobby, so I'd better get back to work....)

Torro123 Avatar
Torro123 René Wesselius
Amsterdam, NH, Netherlands   NLD
Connecting the rear wheels by the axle is a bad idea if you have no diff.
If you go for front engine you can make a shaft drive silid axle to both sides and drive both rear wheel with 2 chains,one on each side,the slack in the chain drive will solve the diff problems,especially if you use a rubber cusion mount for the sprockets.
Mine will be one wheel driven as it probably only see tarmac,no dirt roads.
Seperate jackshafts connecting in a tube will cause problems with the chain tensioners because there will always be some difference in chain length.

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Neto Ernest B
Berlin, Ohio, USA   USA
In reply to # 24961 by Torro123 Connecting the rear wheels by the axle is a bad idea if you have no diff.
If you go for front engine you can make a shaft drive silid axle to both sides and drive both rear wheel with 2 chains,one on each side,the slack in the chain drive will solve the diff problems,especially if you use a rubber cusion mount for the sprockets.
Mine will be one wheel driven as it probably only see tarmac,no dirt roads.
Seperate jackshafts connecting in a tube will cause problems with the chain tensioners because there will always be some difference in chain length.

Regarding both wheels being driven
I thought that some guys here do that - it just doesn't do nice tight turns. But what I was suggesting would be only something you would engage if you were stuck, and the drive wheel was spinning. Then as soon as you got going again, you would disengage it. In Brazil we have a diesel microtractor (Yanmar brand) that we used to mow the grass airstrip. It has the drive wheels up front, and you steer with the hand clutches and a foot lever that turns the third wheel, located under the seat. The individual hand clutches are mechanical - they are matching cogs that lock the two drive wheels together when both are released. After the first time I opened the case there for maintenance, and saw how it was designed, I always made sure I was going straight again before releasing a hand clutch. If you did it while still in a turn, it would re-engage with a bang. Anyway, that's where I got the idea for this axle-locking system. In this case, it would be spring loaded to stay disengaged unless you pushed a lever. In the case where you were stuck in mud, you would do this when you were at a stand-still, with no power to the wheels. You would then turn the front wheels straight, and once moving again, release the axle lock. It may not work at all, but it was just an idea that came to mind.

Regarding unequal chain lengths
I was assuming that a fixed tensioner would be required in each chain run. From what I've read (all new to me), this tensioner sprocket should be at least as large as the drive sprocket, and positioned fairly close to the drive sprocket on the return (slack) side. I think that to avoid having 4 of these, I would allow for adjusting the middle sprocket (between the two chains on each side), then taking up slack with the fixed tensioner on the other run, on each side. So the front and rear points would be fixed.
Is it necessary to have tensioner sprocket(s) on the chain(s) between the jack shaft(s) and the powered wheel(s)? Or how do you take up slack there? I realize that on motorcycles they just slide the wheel back, but how will you do it on your Kart?

Torro123 Avatar
Torro123 René Wesselius
Amsterdam, NH, Netherlands   NLD
The rear axle on the drive side is adjustable,the middle shaft also and the front shaft too,first i do the chain from the motor to the first shaft,then the middle chain from the first to the second shaft and as last the rear chain by adjusting the rear axle.
It is the same as with a motorcycle



Edited 1 time(s). Last edit at 2017-06-28 12:52 PM by Torro123.


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Neto Ernest B
Berlin, Ohio, USA   USA
Hi again René,

In the weeks since this discussion, I have been doing a good bit of reading on issues that come up with chain drives on motorcycles, such as squat versus antisquat, and changing contact patch. Are any of these things of concern for a cyclekart with a rear suspension? For instance, is it best to keep the top of the chain from the jack shaft to the rear wheel(s) parallel to the road surface to minimize squat or antisquat, or is that even the way in which this could be done, if it is a concern?

My thinking is that if the top chain run, the powered side, not the slack side, is pointed up toward the front of the cart, it will tend to raise the rear of the cart on hard acceleration, and the opposite angle would cause it to squat, or compress the rear springs. I could well be over-thinking this, or being concerned over something that will never have any effect at the speeds these cars run at. I have no experience with any chain driven vehicle of any kind, including motorcycles, so I only know what I can pick up from reading, and the people talking about this are dealing with speeds in excess of 100 MPH, and a whole lot more power & acceleration.

Torro123 Avatar
Torro123 René Wesselius
Amsterdam, NH, Netherlands   NLD
Ernest with the amount of power a Kart will have there will be no problems with the chain or suspension.
On a 100hp+ motorcycle a chain don't have any problems,even moto gp bikes use them with 300hp and have no issues.
The only thing to beware is put your shaft as close as possible to the pivot point,that's it.
René

Torro123 Avatar
Torro123 René Wesselius
Amsterdam, NH, Netherlands   NLD
Last week i picked up the build a bit,during a testdrive the split rear axle did not do well so i made a solid axle which i can adjust to tension the chain.This works well and a serious test drive was made today.
I don't have a rear brake yet but the front brakes are very good so no problems there.
The steering was to direct so i made a bigger sprocket on the bottomside and now the steering i lighter and almost 3 quarter turn side to side.
Soon make some detail pic's


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Denny Graham Silver Member Dennis Graham
Sandwich, Illinois, USA   USA
Boy Rene, that's looking more and more like the real thing.
A few more touches and you'll be ready to enter it at
Shelsley Walsh, or Goodwood.

Denny Graham
Sandwich, IL

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