[Kartbuilding] wedling/racing cart

[Stephen Burke]

Hi Jakub,

Im glad you found the 3D CAD drawings of the racing go-kart useful. The 
actual kart itself was originally drawn using Autodesk Inventor, and 
exported to Solidworks, however all the sizes and information should be 
fine.

A 13hp engine is a fairly large engine. Depending on its weight, you might 
want to increase the tubing from 25mm to 30mm for the chassis. See: 
http://www.kartbuilding.net/racingkart/Free_Racing_Kart_Plans_PDF/Main_Kart_Complete_03_Chassis.pdf
30mm with a wall thickness of 3-4mm would provide better support for a 
larger engine.

In regards to welding the chassis together. On professional and commercial 
gokarts, the chassis is "brazed" together. This is a lower temperature 
weld which provides better flexibility on the chassis. Arcwelding can 
sometimes weaken and crack at its joints.
In saying that, YES - I did arcweld my chassis together carefully. I used 
a 100amp stick welder, and 3.5mm welding rods. See: 
http://www.kartbuilding.net/Freeplans/images/Photos/Welder.jpg
After a tricky start, and a 2 hour lesson, I learned how to weld properly. 
Once all the chassis is positioned together, it will only take 1-2 hours 
to weld together. But yes, I would ask your friends dad to either do the 
bit of welding himself, or ask him if you could borrow the welder, and 
perhaps get a lesson off him on how to weld properly.

Onto the brakes. Depending on the type of calliper you have, it might be 
cable or fluid operated.
This ( http://www.kartbuilding.net/Freeplans/images/Photos/DiscBrake.jpg ) 
is an example of a "cable" operated calliper. There are 2 levers where a 
cable goes through. It is secured at one end, and the other end is 
operated via the brake pedal. This is the easiest type.
If you have a fluid operated calliper, things will be a lot more 
interesting/difficult! With a fluid calliper, you need a brake fluid 
reservoir! This is typically mounted beside the operating lever. For 
example on a motorbike, the fluid tank/reservoir is attached to the brake 
lever. See: http://www.kartbuilding.net/Freeplans/brakeandsprocket.htm
If your calliper is fluid operated, you need to find out what 
equipment/machinery/motorbike it is designed for. You will then have to go 
to a motorbike repair shop and ask them for the hydraulic brake unit for 
use with your callipers.
Hopefully the callipers will be cable operated, as this will make things 
much easier.

As for the chain. If you use a good strong chain from a motorbike, you 
wont have any worries about tension! I initially started using bicycle 
chains and sprockets, and had a very tough time trying to keep the chain 
on. I tried putting side railings on the sprocket to try and keep the 
chain on. See: 
http://www.kartbuilding.net/gallery/v/Kart_Clearance_and_Memories/DSC01082.JPG.html
If you use a motorbike chain however - the chain will not come off! unless 
the sprockets are totally out of alignment. Motorbike chains are much 
stronger and thicker, and are not designed to come off easily. See: 
http://www.kartbuilding.net/gallery/v/Kart_Clearance_and_Memories/DSC01167.JPG.html 
This image shows the difference in chains. I suggest you visit a motorbike 
store/repair shop and ask for an old or replacement chain and sprocket. 
You will not have to worry about tension.
It would be an idea however, when mounting the engine, that you drill 4 
slots (instead of holes) when bolting the engine to the cradle. See the 
bottom of: http://www.kartbuilding.net/Freeplans/enginemounting.htm
This will allow for minor adjustments in the tension of the chain. I 
managed to get away without this, and I managed to remove a link in the 
chain to shorten it. I then used a split link in the chain to join it back 
together. See: 
http://www.kartbuilding.net/gallery/v/Kart_Clearance_and_Memories/DSC01230.JPG.html

I hope I have answered your questions.
Feel free to email on some pictures (of the callipers also) and I can put 
them on the kartbuilding website to help others also.

Best of Luck,
-steve


On Wed, 18 Jul 2007, Jakub Rogalewicz wrote:

> Hello,
> My name is Jakub and I am currently building a go kart. I really like your 
> detailed plans. I have solidworks and have done 3D CAD work in the past, so I 
> really appreciate your 3D drawings and want to thankyou for releasing them. I 
> am going with more or less your design, however my cart will be a bit wider 
> as it needs to accomodate for a 13hp honda engine. My question is: Today I 
> was at a custom metal fabrication place and they told me that it is not safe 
> to weld this thing together with an arcwelder... Did you use an arcwelder to 
> build your kart? What do you recommend I do. I am 17 years old and never used 
> a welder before but my friend is willing to lend me his as his dad does some 
> welding. Is it ok to use the arc welding process? What kind of stick did you 
> use? I am using a disc break and caliper that I purchased at some store... 
> However there is no hydraulic system or anything. All that comes is a disc 
> that is previously welded to a hub, a caliper and moutning bracket. Do I 
> simply use a line to attach the lever to my break pedal? Kind of like a 
> bicycle with disc breaks. I am sending you a few pictures of what this looks 
> like. A few more questions: How do I get the chain tension right.. how do I 
> know it is not too loose or tense? I know it is a lot of questions but I 
> would really appreciate your help as I find it difficult finding answers to 
> these questions on the internet.
> Thankyou very much.
> Jaukb