Long, long, time ago I made a kart for my eldest son.
It all started because of his love for Lego, he was given a set of plans for different items, among which was a go- kart. He built this and played with it for sometime until other things came along.
Thoughts about bits
The idea stayed in the back of my mind until a guy I worked with said he had a 100cc motorbike engine spare and did I want it.
Of course I said yes, even though at the time I had no clear plans for it.
When he found the engine in the garage my son said “Dad…”
Bowing to the inevitable I said “OK you can have it”
One of his friends at the time had a father with a proper kart, so one day my son came home with a set of old kart wheels and tyres and so planning started that day.
Luckily I worked in engineering so bits and facilities were easy to obtain.
One of the prime requirements were that this kart had to have as near zero cost as possible so thinking cap on I gathered needed bits and made sketches.
Working out the design
To determine the overall sizes required he sat on the garage floor in an old plastic canteen seat with the engine located in roughly the right relative position. This seat was subsequently padded and used.
I marked out the positions of his feet (allowing for a bit of growth) on the floor and then the positions of the wheels. The chassis was marked around those items.
At no time had I found out any information about karts, it was intended to be a plaything and not to be raced, this was also pre-internet days as well.
After measuring the steering wheel position using an old wheel I still had from my Terrapin hill climber days, and also the gear-lever position, I converted these into proper dimensions.
The rear axle was a 25mm steel shaft with flanges for the wheels, Plummer block bearings for support and a sprocket for the drive.
The drive was a simple bike chain and the tension was adjusted by sliding the axle bearings rearwards.
The steering column was a 20mm steel shaft in bronze bearings with a short link at the bottom to move the front wheels.
The front wheels were mounted on simple flanges with pivots on the hubs and chassis to allow steering movement and a link system to connect them to the steering
The braking was a disc on the rear axle operated by a hydraulic cylinder on the chassis.
The clutch was operated by a similar cylinder system.
The gear-lever was mounted in the pre-determined position and connected to the gearbox by a simple link bar.
The chassis was fabricated from some 30mm tube I had spare and bent using a borrowed tube bender. We drew the chassis dimensions on the garage floor and bent the tube to suit.
This was welded up and the various mounting brackets added until all the components were in place.
A car silencer was mounted at the rear and connected to the bike exhaust.
When the kart was finished we decided to add a smaller extra sprocket to the rear axle to give a slower top speed when using the kart in more confined spaces.
Performance was surprisingly good for such a clapped out old engine (even with me on board, the extra pedal space really worked).
Some time later I had some plastic slat chain from a trial under my desk and instead of binning it I brought some home to use with the kart (as seen on the rear wheels). The slat chain was 7 1/2″ wide with connecting links underneath and a smooth top. This was used for the transfer of bakery goods.
We measured the circumference of the rear tyres and made up two complete chain circles just slightly smaller than the tyres.
After locating the slat chain circles on the tyres we pumped them up again to hold the slat chains in place.
Driving with these on was pure fun! It was like driving on ice! It was possible to completely spin the kart in the width of my drive – great fun for all.
The kart served my son and friends well for some years, having to put up with being driven along farm tracks, and into a farm gate post on one occasion until inevitably other things took over and the kart was sold on to another youngster.