[Kartbuilding] Thanks and queries

[Stephen Burke]

Hi Ben,

I'm glad you liked the www.kartbuilding.net website and found it useful. 
Indeed there seem to be few uk websites on karting, and even less events 
and the like on karting and downhill racing (well here in Ireland 
anyways).

I got great enjoyment out of going through your website, photos and videos 
of your soapbox race! 
http://albums.phanfare.com/isolated/ruEE5UzR/1/4186199
Wow is all I can say, and wonder why there aren't more of these. Ye seemed 
to have a brilliant time. The wheelbarrow kart was cool, and had a very 
brave driver! There seemed to be a great buzz and atmosphere. Having the 
tractor to take all the karts to the top of the hill was a bonus :-) I 
must write up a blog and link to your site from 
http://blog.kartbuilding.net

Your definitely looking to scale things up next year!
Yes, the hill did look bumpy. The last turn or slide at the end caused the 
most punishment on the karts. I see a few wheels broke on this turn in the 
videos.
It's hard to know. The bicycle wheels on the Bugattis kart seemed to go 
fast, however they would be weak on cornering, and liable to overturn.
I know small trailer (very small trailer or camper van) wheels would be 
strong and reasonably light.
As for brakes, the drum brakes would be fine. Make sure to be careful what 
way the hub rotates.
E.G. from my experience with drum brakes, when the wheel turns one 
direction, the braking action is smooth. However when the wheel turns the 
opposite way (in reverse) applying the drum brake causes a sudden brake.
I use wheelbarrow wheels myself, and they are very strong, cheap and easy 
to find. That coupled with plenty of air, and it would be a good choice. I 
then used solid axles and welded the axles to the wheelbarrow hubs.
Your going to want a low center of gravity with a wide wheelbase to 
prevent overturning. Ideally you want narrow wheels to go fast.
Details on the drum brakes I used can be see at:
http://www.kartbuilding.net/gallery/v/Off-Road_Kart/?g2_page=2
Wheelbarrow wheel with metal hub: 
http://www.kartbuilding.net/gallery/v/Kart_Clearance_and_Memories/DSC01055.JPG.html
Of course if you can get a small trailer wheels and hubs, you will have 
the brakes inbuilt.

As far as suspension goes, I never went with suspension. It complicates 
things and requires a lot of work. It may work well and provide a smoother 
ride. You want to do some testing. Perhaps if you made the kart first with 
no suspension, then sneak up one week and do time tests. Then you'd be 
really ready for next years race :-)

Regarding the 3D CAD model of the person in the wooden kart plans, I 
downloaded him from http://www.3dcontentcentral.com He was an assembly 
model which I could manipulate and move to suit the 3D Kart.

Let me know how the kart building goes. Happy Christmas and New Year too.

Best of luck,
-steve


On Tue, 8 Dec 2009, Ben Griffin wrote:

> Hi there,
>
> Firstly I just wanted to say thanks for your kartbuilding website. Last year some friends of mine organised a soapbox race on their farm here in the UK and I built myself a free-wheeling kart loosley based on the classic Bugattis of the 1930s! (see here: http://albums.phanfare.com/isolated/ruEE5UzR/1/4186199 ). Your website was very useful in giving me an idea of what was possible, and the best way to go about things. Sadly there don't seem to be very many similar sites based in the UK.
>
> For next year I'm planning some improvements to the kart, mainly stronger wheels and brakes. The hillside is pretty bumpy and the heavy steel chasis put a lot of strain through the wheel attachment points. I have been thinking about using 4" PCD trailer wheels/hubs on stub axles, which would be really strong, but then there is the problem of braking. Some trailer hubs come with cable operated drum brakes. Do you have any experience of these? I'm not sure if the braking action would be suitable for a kart or if it's more of an on/off type arrangement? It's also possible to buy trailer stub axles with an integrated suspension unit (ratings from 150kg upwards). Might these be a convenient way to add independent suspension to the rear of the kart?
>
> The final thing I wanted to ask you is this: where did you get the 3D model of the man, used in your 3D kart plans!? I have access to 3D CAD software which I was thinking of using to make my plans, but i've been unable to find a compatible human figure.
>
> Thanks again and happy building!
> Ben Griffin
>