Back in the 1930s soap-box carts were just that; the heavy wooden crates that soap powder cartons came in,  fitted with second-hand pram wheels and rudimentary steering, made an ideal basis for a low-cost kid’s car.

And of course, as soon as boys of any age invent anything with wheels on it, they race them - in this case down the nearest steep hill. The annual All-American Soap Box Derby, now in its 85th year, is held on a purpose-built track in Akron, Ohio, and the fastest racers reach speeds of more than 80km/h in just 300 metres.

But the convenors of the Red Bull Box Cart Races simply refuse to take themselves that seriously; for them it’s all about having as much fun as possible building something totally outrageous and running it down the course, hopefully in one piece!

On 16 September Red Bull Box Cart racing will return to South Africa for the first time in eight years (the last time was in Soweto in 2010), to be run on a street course in Sandton that will be laid out by off-road racing legend Giniel de Villiers. Which is a warning bell in itself; no course laid out by ‘The Real Giniel’ is ever going to be straightforward, simple - or slow.

Following the application phase, 80 teams have been shortlisted to compete; they now have eight weeks to build their hand-made, non-motorised machines fuelled by sheer courage, the force of gravity and perhaps a little Red Bull. To help you understand why some carts flip, some flop and some fall apart, here’s Rob Marshall’s guide to what goes into a racing box cart that’s slick enough to get down the hill in a hurry and sturdy enough to arrive at the bottom in one piece.

1 Use a solid base

Start with proven technology; many box carts are based on bicycle or go-kart designs, or elements of both. You need strong wheels and axles, because it’s not going to be a smooth ride - there are bumps and jumps, and it’s on landing where most buckled wheels and chassis failures occur. Ideally they need to be robust, not too heavy and with free-running bearings.

2 Get the basics right

If you start with a robust frame, four wheels and a means of steering it, you can stick anything on top of it, from something a slick as a jet fighter to a three-metre Christmas cake. One look at some of the really elaborate ones tells you they aren’t going to make it to the bottom of the hill when there is just too much going on.

3 Pay attention to weight distribution

From the point of view of going quickly, you need to get your bodyweight as low as possible, and between the wheels, rather than up high, which makes the cart prone to topple. The ideal box cart looks like an old school (before wings!) Formula One car, basically a teardrop with four exposed wheels. Not fancy, but it works.

4 Airflow is important 

Aerodynamics do play a part. If you have a lot of flat surfaces and things sticking up in the air, it will slow you down. If you build your cart so that your position is nice and low, then you are going to minimise drag - and that’s a good thing.

5 Have Some Serious Fun

The final element to building the ultimate box cart is having fun and this requires precise attention to details from any team determined to go down in memory as the epic Box Cart Racers.

The event is free for all participants and spectators, so don’t miss the action on 16 September at Sandton Drive. Follow the action online at #RedBullBoxCartRace, and visit the Red Bull Box Cart Race website to learn more about the teams.

IOL Motoring