Simple Off road Kart- Project

[KasalmoR]

(Relisting the thread using google cached version)
Hello, everyone! I have been browsing the forum for a few weeks now and I will try to start my own thread. I really like the community and I think that there are many erudite people around here that will be glad to help. So after having said that I may continue with my ideas. First this is meant to be a small budget project. I have recently seen a kart on the internet which was quite simple and I pretty much like it as a design for my first kart. It uses solid axle and has rear suspention. It is small and uses 6.5 HP engine. I got the picture from a chinese site.

As they say a picture can say more than a thousand words



Now when you have seen the original you may understand me better.I plan to use 1,5 inch square tubing for the frame. I'm not sure if that is too big but it seams reasonable. Any suggestions? I think to use pedals and full circle steering wheel.
I also looked for an engine on ebay and I found this :http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=350425090461&ssPageName=STRK:MEWAX:IT What do you think? There is another option which would be an old Russian motorbike engine. I think it was 350 cc and it was supposed to be around 20 HP. But I will have to ask my grandfather if it still exists.

That is what I have on my mind in the moment and as it is winter and the weather does not allow me to work, the project will be in the planning/finding parts stage until the spring. Later I will upload my sketches/drawings of the kart. I will be thankful for any advice, suggestion, idea or whatever comes to your minds.

Thanks, Kristian!

 

[metalthrashinman]

I got an email with your question before the site went down.

The accelerator pedal is on the right, and the brake is on the left.

 

[Doc Sprocket]

Were you able to view my comments in the original thread?

 

[KasalmoR]

Were you able to view my comments in the original thread?

I can't remember exactly which comment was yours but if it was about the fabricating skills as well as tools i have provided I will anwser again. So partly this project is for me to learn basic skills and to try out if I can desing a good vehicle. I am learning how to weld with MIG (The one using wire and CO2) but I still haven't tried using the welding method using sticks of metal(sorry I don't know how it is called in English) I have access to many different tools as both kinds of welding machines, angle grinder, hand drill as well as stationary drill, lathe (although I don't know how to use it) different wrenches, files, screw-drivers.

Or if it was the comment about where I will ride the kart- I don't have a particular piece of land that I'm going to ride it. As far as I know here in Bulgaria I am allowed to ride it on fields, grass, dirt, forest as long as I am not on oficial roads or private land. For example there are large open grass spaces around the river which goes near my town that are perfect for this purpose. Otherwise I think it is nearly impossible for such a vehicle to be registered and driven on roads.

 

[redsox985]

i guess it looks gud for a china product...


Oh, billy, that's the one positive from this huge crash. It's like he never happened. I really like the swing arm idea and wish I would have put it on my kart.

 

[Rustydog2010]

I think some thing was said about using pedals?

And has Billy come back as honda-gx-power or something? If not his spelling and grammer is just as bad lol.

 

[Doc Sprocket]

Yeah- I can't remember exactly what I wrote either. I believe I commented on the fact that it's pretty hard to go wrong with a decent used bike engine, which will outperform industrial engines by miles. I might have also suggested that 1 1/4 or 1 1/2" tubing should be okay, but watch your wall thickness so it's not too heavy. I made that mistake.

 

[KasalmoR]

Yeah- I can't remember exactly what I wrote either. I believe I commented on the fact that it's pretty hard to go wrong with a decent used bike engine, which will outperform industrial engines by miles. I might have also suggested that 1 1/4 or 1 1/2" tubing should be okay, but watch your wall thickness so it's not too heavy. I made that mistake.

Can you suggest thickness? I am asking because I saw measures in another thread but they were in gauges? (don't know that) So I will be glad if you can tell me in mm (milimetres) that would be best. Thank you in advance!

Now I am thinking on a version of the kart with front suspention and the way it may be done. I will post some pics of my sketches tomorrow.

 

[Doc Sprocket]

2mm oughta be safe.

 

[KasalmoR]

So as I said here is what I have in mind.
The first alternative a kart with rear suspention only :
http://img88.imageshack.us/f/dsc03071m.jpg/

The other alternative, I added a front suspention with double A-arms. So here's the frame :
http://img135.imageshack.us/f/dsc03069g.jpg/

Now I have drawn a sideview of the rear suspention with suggested angles:
http://img194.imageshack.us/f/dsc03068kn.jpg/

And last I have drawn the front suspention both sideview and frontview. I'm not sure it will work flawlessly. So here it is:
http://img708.imageshack.us/f/dsc03074rz.jpg/

So that is for now. I am open to any critics, suggestions, ideas, etc. As I don't have experience in both designing and fabricating, people with years and years of knowledge can share some of the information they know. I will be glad to read what you think.

Thanks,Kristian

 

[Rustydog2010]

Looks good! But can I ask why double A arm? It seems like extra work without significant gain?

 

[KasalmoR]

Looks good! But can I ask why double A arm? It seems like extra work without significant gain?

One part because I'm not really familiar with single A arm setup. I think that when single A arms are used the bracket for the spindle is welded onto the A arm right? And it stays on it at a particular angle but when the A arm moves up and down the wheel will tilt from being straight up to the sides. I may be wrong but when I came to think of it that's what I think would happen. Otherwise it will be better because of the less weight and simplier construction.

 

[Doc Sprocket]

One part because I'm not really familiar with single A arm setup. I think that when single A arms are used the bracket for the spindle is welded onto the A arm right? And it stays on it at a particular angle but when the A arm moves up and down the wheel will tilt from being straight up to the sides. I may be wrong but when I came to think of it that's what I think would happen. Otherwise it will be better because of the less weight and simplier construction.

Yes, you've got it. The spindle bracket is fixed to the arm, as is the camber angle. As the suspension cycles, the camber changes. I belive that for the amount of suspension travel most karts/buggies would have, this really isn't that much of a problem. I'm working on a single arm setup, myself. I am working to have the arms sit parallel to the ground with the suspension at rest, and my weight on it. At this zero point, there is a few degrees of camber- the tops of the tires slightly tilted inward. The arms nearly reach the frame centre. The travel will be 3 or so inches up AND down from there. Playing with it, the camber change is noticeable, but not ridiculous. Since the suspension will be near the "rest" position more oftem than not, I am not at all worried about the camber.

The TRULY important thing is bump steer. The steering has to be designed in such a way that the suspension cycling does not cause the front wheels to steer. THIS is where things can get hairy, and this is a problem for single arm, double arm, trailing arm, you name it. To keep bump steer at a minimum, you want the tie rods parallel to the suspension arms. Try to make them the same length as the trailing arms, too. The idea is to have the tie rods travel in the same arc at the same time as the suspension. The further off that arc it is, the worse the bump steer, and the more accident insurance you need.

 

[theo]

For single a arms try to make them as long as you can. To eliminate bump steer the rod ends on the pitman arm need to be on center with the rod ends on the a arms. You might get some ideas from my kart.

[/IMG]

 

[KasalmoR]

For single a arms try to make them as long as you can. To eliminate bump steer the rod ends on the pitman arm need to be on center with the rod ends on the a arms. You might get some ideas from my kart.

[/IMG]

Thank you for the info and if I got you right you mean that the tie rods must be parallel to the A arms, right? So they will travel in the same way when suspention works.

That's one pretty nice looking kart. I like the construction and the paint you chose but I cannot understand why you use such steering. Isn't it easier with a steering wheel? Except from that your kart is killer

I wish I could find such turf tyres here in Bulgaria. They will be the perfect choice for my kart. Any suggestions on wheels/tyres anyone?

 

[Doc Sprocket]

Atv tires, whatever tread pattern you can lay hands on. I find truf tires are disappointing in loose traction conditions.

 

[metalthrashinman]

Were you able to view my comments in the original thread?

This is all I have:

Thank you everyone (except the little spam). So here I will try to answer some of the questions posted.


---Quote (Originally by Rustydog2010)---
That looks like a good first project. What are your fabrication skills like and what tools do you have available to use?
---End Quote---
As for my fabrication skills, I can weld with MIG (CO2) welder even though my welds are not so good. I'm still learning. This is one of the reasons of this project which would be like a learning course. As for the tools I have available: MIG welder, another welder with metal sticks (Excuse me, I don't know how it is called in English), angle grinder, a hand drill as well as a stationary drill (I'm not sure this is right also), many kinds and sizes of wrenches. I am coworking with my grandfather and learning from it so this tools are his but I can use them. The only thing that may be a problem is the fact that I don't have tube bender (I'm not familiar with names of tools, sorry ) but I think if square tubing is used I'll be fine.



---Quote (Originally by metalthrashinman)---
Are you planning on going with the hand controls as opposed to foot pedals? ....
---End Quote---
That's one thing I forgot to mention and thank you for reminding me. I'm planing on using pedals because they seem to be more comfortable as well as more reliable. The steering wheel will be a complete circle. And in general which pedals are which. Left- brake, right-throttle?


---Quote (Originally by cpt.skier)---
Anyways. Where do you plan on ride this cart. Do you have a large tract of land, or do the laws in Bulgarian allow you to ride that in a less restricted manner?
---End Quote---
In fact I don't have a particular place to ride it as for a private land but as far as I know I am able to drive it on fields,grass, forest, etc as long as I'm not on an official road. I think that in the USA laws are more strict and a person is not permited to drive it on many places. Or may be just particular states? I am sorry if I am wrong.

And that's for now. I'll picture my sketch and upload it later.
Thanks, Kristian.

 

[theo]

Not parallel, they have to be centered with the a arm rod end looking from the front. Mine is a tab lower then the front a arm rod end because my rear rod end is lower for rake.

I found steering with a little wheel is to stiff, with a pitman arm (ok with a rack). In tight fast turns this set up works much better.

 

[KasalmoR]

Here are two examples of possible construction of the suspension. In the second picture I made it so the camber can be adjustable. I'm not sure it will be sturdy enough but it can be adjusted. The other alternative the camber will be fixed and I think that the inner side of the tires will wear more.

 

[theo]

The adjustable camber setup will not make any difference. One of the bad things about single a arms is the positive camber, you don't want anymore then 1 deg.