This project took about two years. It started off simple enough: it would be fun to try a build a kart, and maybe the kids would think it would be fun to ride around on. I wanted it to be a metalworking construction project, so the plan was that I would try to make as much of the kart as possible, instead of just buying parts from a catalog.
I started off cutting some square tubing I had laying around, and welded it together, and a typical ladder-style truck frame took shape.
After I had a few weeks into the project, I realized that fabricating wheels would be beyond me, so I made the fatal mistake of going to the local kart parts store to look at wheels. I found the wheels all right, but I also saw what a genuine racing-style kart frame looked like. The frames were beautiful. They looked fast just sitting in the shop.
Things took a serious turn.
I went home, and cut the existing frame into scrap while I pondered my next move. I could buy a last-year's unpainted chrome-moly racing frame for $450. Or, for $450, I could buy a tubing bender, a tubing notcher, and a bunch of chrome-moly tubing.
It was one of the easier decisions of my life, and I ordered myself a Model 3 tubing bender from JD Squared.
But it wasn't just the frame. The entire bar had been raised. The race karts had hydraulic brakes and aluminum floors and other cool features that would have to be duplicated.
Basically, the kids were going to have to wait another year to go for a ride.
For a plan, I got a brochure from the kart shop. It had a beautiful overhead shot of the bare frame and wheels. I knew that the wheels were 5" in diameter, so I got out my calipers and measured how big the wheels were in the picture. That gave me a conversion constant that I could use to determine all of the other dimensions in the picture. From there it would be a simple matter of bending tube and welding...
If there is any interest, I could put up more details on the various bits involved in creating the kart. If not, then these pictures will have to document the process.
It took a long time to make. Here is Ian doing a little wishful thinking early on in the process.
Here is another mockup. We are getting closer to mounting the rear axle.
The frame has most of its miscellaneous tabs welded on now.
The steering arm. Notice the fine hand-written plans. In the second picture, the pieces are ready for welding. The cylinder of aluminum serving as a jig to maintain proper spacing and alignment during welding.
I had a bit of trouble figuring out how to align the pedal pivots before welding them on. Basically, the problem is that you need to clamp a cylinder to a tube in just the right position and angle with a clamp that was not really designed for the task. I was proud of this solution: I used a long piece of drill rod to locate both pivots at the same time. The drill rod would not let either end slip out of alignment relative to each other, so it became a whole lot easier to clamp. After clamping came a tack weld, then I farmered the things on. You can see a bit of undercutting in the middle picture which proves that I am not a professional welder, nor do I play one on TV.
Rear brake caliper mount. The rounded form on the caliper mount was done with a hand file. The bolt holes in the leftmost picture are supposed to be a bit off-kilter. If I haven't already said so, everyone who reads this and likes to make stuff should beg, borrow, or buy a welder. Reason #27: I drilled the lower holes in the picture to the right in the wrong spot. Without a welder, you are screwed. With a welder, you clamp a copper backing bar to the back, and then fill the hole back up with metal. File it flush, and drill new holes in the right spot. No need to scrap all the other work to that point!
The rear axle mounts (below) were cut with the plasma cutter using a plywood tracing guide, then hand filed to final form.
Brake caliper is mounted.
These trick aluminum spacers were required to provide clearance for the even more trick spherical axle bearing mounts. The spherical mount means that the bearing mount can be misaligned to the rear axle and everything still works fine.
The master cylinder mount. This was my first attempt at TIG welding.
Master cylinder mounted.
Below: the brake pedal takes form. The pedals are made from stainless rod stock bent on the home-made bender.
The floor, rev 2.0. This time, it was made from some scrap diamond-plate aluminum. Plasma-cut, of course. An aluminum brace runs underneath, mainly for practicing TIG on aluminum. I was surprised at how loud A/C welding is with the inverter welder. Wear ear plugs!
It was about this time that the kart was ready for its first gravity tests. The house has a pretty steep hill right off the end of the driveway. Here is Ian, dressed for the occasion, looking as studly as only one can be who knows how to drive downhill.
After that, it was time for motor mounts. The motor is a Honda. Starts every time.
Gas tank mounts:
Throttle mechanism. The cable length adjuster on the left is a bolt that has been drilled lengthwise to let the wire pass through. The hardware store claimed it was a Grade-8 hardened bolt. My drill bit claimed otherwise: it went through it like butter.
And finally, after about two years of construction, it is ready for the big day.
Caitlin and Ian: looking sharp, and having fun.
It will be worth it in the end.
Wright Cyclone in full song.