Picture of Soap Box Derby Cart
This a simple soap box cart that my son and I built for my 9year old daughter so she could enter the Trowbridge Carnival Soap Box derby
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Step 1: Basic Frame

Picture of Basic Frame
We used planed softwood, 2.1m x 74mm x 18mm for the frame and 2.1m x 50mm x 18mm for the front axle.  The king pins for the steering will be M10 x 100mm bolts

The cross brace at the front is 400mm as is the the brace that forms the "radiator" whilst the rear is at 600mm

The wooden pole is from a beach wind break and is used to estimate where the driver will be sitting.

The body frame work is made using 25mm x 25mm softwood and its size was based on my 9yr old

Step 2: Bodywork

Picture of bodywork
Cheap, fine plywood.
In order to minimise waste and keep costs down the frame was wrapped in craft paper. We used this to calculate how much ply was needed. 
The paper also formed the templates for each panel

The wheels, again just as a guide

The grill, seat and floor are made from pieces of chipboard I had lying around in my shed, you might also notice that the dumb irons at have been shortened.  I thought this improved the proportions of the cart.

Step 3: Steering

Picture of Steering
After much experimentation the steering system finally consists of:

1. Steering wheel from an old games console
2. Steering column made of tubular clothes rail
3. A bicycle front crank
4. two 15mm brass plumbing equal T pieces
and a couple of go-kart track rods bought from e-bay

In one picture you can see we used the bike chain to check we had the frame, king pins and steering square.

The tube was cut in half and a another piece found to fit snugly inside. the was clamped using U bolts so that we created a rudimentary collapsible steering column. One end bolted to the steering wheel and the other welded to the bike crank.
Ultimately the crank was drilled  to allow the track rods to be fitted, creating in effect a Pitman arm.
guidess 1 month ago

Beautiful! Thanks so much for the plentiful and super clear photos, especially the close-ups of the steering arrangement. Makes this really doable!

GarethMorris (author) 1 year ago

That looks fanatastic, I love the steering wheel

a5tor1 year ago
just wanted to drop a comment to thankyou for a great 'ible. followed it pretty closely (albeit with a few personalised tweaks) and it bagged me a trophy in a recent event. good stuff and keep them coming
244 Jake1 year ago
Gee in about 1960, I made my down hill run in derby, in those days in Tampa Florida we had to use standard tire / wheels, that derby guys idea on brakes. And a straight front and rear axles.
Your project does bring back some good images of family and friends.

Thanks and best of luck!

Big Jake
GarethMorris (author) 1 year ago
Thank you all for your kind comments.
You sir are a man among men it did my heart good to see you (and daughters) project kudos to you
(From a dad of two grown girls)
bhardy61 year ago
Looks good!!! We just went past Derby Downs here in Akron this part weekend.... Hope to see you there next year!!!
growing up I always wanted a soap box but there were no derbies near me. now the city I live in started derbies. looks like I will have to recruit a neighbor kid to drive so I can make one
I always wanted a soap box derby cart!