Soap box derby's ( billy carts, go-carts etc )
Discussion
my local motorsport club holds this every year at there classic car show and its awlays a good laught anyway this year im planning on taking part. i was planning mini moto wheels at the rear with the cable operated disc brakes hookes up and then sack barrow wheels at the front with pleanty on negative camber etc. with the frame made of 1inch mild steel tube, not going to bother with a body shell thats jus extra weight.
if its just for messing around on wood will be adaqute we use to make the all the time when i was younger.
barrow wheels are good just make sure you have good bearings or pleanty of grease on them to make them spin freely
if its just for messing around on wood will be adaqute we use to make the all the time when i was younger.
barrow wheels are good just make sure you have good bearings or pleanty of grease on them to make them spin freely
steering..
is something like this steering setup hard to replicate?
http://custom-gokart.blogspot.com/2008/05/front-en...
is something like this steering setup hard to replicate?
http://custom-gokart.blogspot.com/2008/05/front-en...
Edited by SystemParanoia on Tuesday 31st March 18:57
Did a project to design one of these in uni, for the chappie helping the gadget show guys 
He's since gone on to organise a few gravity racing events, got a webby here
(Our car is the VXR Firefly, some pics and tech info on there!)
Ours was built around rules for the Goodwood event but it was cancelled before it was built (insurance reasons, pushing 60-70mph down the hill and a few crashes in previous years...)
In terms of advice, think energy conservation. You have a fixed amount of potential energy at the top of the hill, the more the better so the car needs to be as heavy as it can be. You then want to waste as little of that as possible when travelling down the hill so as much as possible is converted to kinetic energy at the bottom.
So, minimum rolling resistance and aero drag. Smallest tyre contact patch you can manage, so thin bike tyres pumped up way beyond max pressure Think we got hold of kevlar inner tubes. Ball bearing with no seals or grease, we were planning WD40 but the guys on the gadget show mentioned using something else. Make sure the brakes don't drag, we went for drums as you can easily ensure they retract fully. Only had two plus parachute
Good luck, they're a lot of fun!
He's since gone on to organise a few gravity racing events, got a webby here
(Our car is the VXR Firefly, some pics and tech info on there!)
Ours was built around rules for the Goodwood event but it was cancelled before it was built (insurance reasons, pushing 60-70mph down the hill and a few crashes in previous years...)
In terms of advice, think energy conservation. You have a fixed amount of potential energy at the top of the hill, the more the better so the car needs to be as heavy as it can be. You then want to waste as little of that as possible when travelling down the hill so as much as possible is converted to kinetic energy at the bottom.
So, minimum rolling resistance and aero drag. Smallest tyre contact patch you can manage, so thin bike tyres pumped up way beyond max pressure
Think we got hold of kevlar inner tubes. Ball bearing with no seals or grease, we were planning WD40 but the guys on the gadget show mentioned using something else. Make sure the brakes don't drag, we went for drums as you can easily ensure they retract fully. Only had two plus parachute Good luck, they're a lot of fun!
The San Fernando Valley Illegal Soapbox Federation have some great films on youtube:
http://www.youtube.com/watch?v=ljOcB7Si5dw
http://www.youtube.com/watch?v=0C0sN34Ndxo
I think I'd use an old 100cc racing Kart chassis with nice tyres, steering & brakes myself!
http://www.youtube.com/watch?v=ljOcB7Si5dw
http://www.youtube.com/watch?v=0C0sN34Ndxo
I think I'd use an old 100cc racing Kart chassis with nice tyres, steering & brakes myself!
Edited by Roman on Tuesday 31st March 17:35
beejay said:
Smallest tyre contact patch you can manage, so thin bike tyres pumped up way beyond max pressure
only problem with that option, is that im not planning on regualry running on prepped race track surfaces.and cornering grip and braking ablilty are quite important to me also.
do this on the public highway means, glass, sharp stones, speed bumps, potholes, sharp corners, road that end in T junctions or major traffic light controlled junctions
thats why if you look at the Undergroud vids, most of them have wider rubber, rather than skinnys, so that they can corner, even though it means sacrificing some speed.
i guess ill just have to have a selection of wheels and see what suits me best
SystemParanoia said:
beejay said:
Smallest tyre contact patch you can manage, so thin bike tyres pumped up way beyond max pressure
only problem with that option, is that im not planning on regualry running on prepped race track surfaces.and cornering grip and braking ablilty are quite important to me also.
do this on the public highway means, glass, sharp stones, speed bumps, potholes, sharp corners, road that end in T junctions or major traffic light controlled junctions
thats why if you look at the Undergroud vids, most of them have wider rubber, rather than skinnys, so that they can corner, even though it means sacrificing some speed.
i guess ill just have to have a selection of wheels and see what suits me best
i would say to use sack barrow wheels with bearings etc, just pump they up a bit more than there ment to to get less rolling resistance. that kart steering pictured further up, should be easy to copy the easiest way to copy it is either find a kids pedal tractor or ket cart as there the say easily availble and easy to copy
Peter_1980 said:
Dont they have one of these every year down the hill at Goodwood?
Usually some pretty impressive engineering.
There is a budget of £150, but it isn't that strictly adhered to. Usually some pretty impressive engineering.
A classic racing dealer, the name of whom escapes me, turned up with two cars; one built for his son, the other for his daughter. They were quite simple things apart from the fact that one of them had borrowed a rear wing from a 1970s F1 car, and another had the nosecone from another! The same year an Austrian count turned up with a perfect replica (1/3 scale I think) of a classic Maserati (may of been an Alfa). It was thought to have cost £250,00 but he claimed his mechanics 'donated' the time!
308mate said:
SystemParanoia said:
£8.61 ea doenst seem like a bad deal
has a steel ballbearing too.. great. the plastic ones have brushings instead of bearings
Its also quite a flat profile. Im not so sure....
Thing is, yes its a flat profile... but isnt that what i would want for grip... the cart isnt going to lean into the corners.. so rounded rubber will never come into contact with the ground, and so just be wasted.. ?
I did a few soapbox races as a kid. We used an old-school pram chassis, (the kind Mary Poppins had) but with the top half cut off and a front axle fashioned from a plank of wood. I would lie on it on my front steering with my hands holding the font axle and with my right foot on the rear tyre to slow it down! Sounds bad but I found it kept the centre of gravity down and I could lean into the corners more effectively. The wheels were around 18/20 inches across with a kids mountian bike tyre on.
This sounds dangeous (and it was), but in the races I was the fastest cart by a considerable margin. In a Lotus stylee, the trick is as little weight as possible with decent sized wheels for maintaining the top speed. Getting up to speed isn't as important maintaining that speed, and larger wheels help, definately use bigger than a 100cc go carts. Tyre choice was cruical too as the mountain bike tyres helped us to maintain grip and traction around and through the bends when a lot of other carts were spinning out (as you can see in the vids).
Great fun, wish I still did it. Good luck!
HTH
Joe
This sounds dangeous (and it was
), but in the races I was the fastest cart by a considerable margin. In a Lotus stylee, the trick is as little weight as possible with decent sized wheels for maintaining the top speed. Getting up to speed isn't as important maintaining that speed, and larger wheels help, definately use bigger than a 100cc go carts. Tyre choice was cruical too as the mountain bike tyres helped us to maintain grip and traction around and through the bends when a lot of other carts were spinning out (as you can see in the vids).Great fun, wish I still did it. Good luck!
HTH
Joe
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