OK I bought a 95 Miata donor “Kart” so I’m off and running. Any comments are appreciated.
Attachment:
Miata-back lite.jpeg
I’m putting this build under “unconventional” because I plan to use the whole Miata roller skate, as several kits and other builders have done in the past. This will require a custom frame.
Here are the basics of this build.
Goals (I like to have project goals being a retired engineer):
- This will be a street car and probably never go to the track except maybe just for fun to see how it handles. So looks are more important than performance.
- I’m building the frame rather than buying a kit because I do not want an exoskeleton style body and also because my budget is small ($5k or so)
- I will probably have to build most or all of the body out of fiberglass
- I want to complete the project in less than one year. Nothing happens without deadlines.
- The design will allow the possibility of enclosing the cabin because I live in southern Arizona and may want to add AC later.
I have not done much car work since I restored a TR4 some time ago, so I’m a but rusty. For this reason I want to simplify the build to meet my time and budget goals. So I will use the whole roller skate to avoid building the suspension, mounting the engine, modifying the drive shaft, etc. I will reuse as many components from the donor as possible. I might replace the gas tank with a fuel cell for safety and add racing harnesses as the air bags are gone.
I will build a frame based on the classic Locost design using square tubing (except for the roll bar).
The donor. My 95 Miata that was being prepared as a Kart by the previous owner. For personal reasons (two small kids and a third on the way) he decided to simplify life and sell his nearly completed Kart. Kart people cut away as much of the Miata as possible to make it lighter. They then reinforce it to make up for the weakened unibody. Google “Miata based kart” if you want to learn more. Here is an example
https://jalopnik.com/track-day-genius-b ... 1762775599I paid $800 for the Kart but it runs and drives well. To transfer the title Arizona DMV made me do an emissions test. It passed!
My plan is to remove the rest of the body and make it Locost-like. It will not look exactly like a classic Locost but will have a similar body style.
Build approachMy basic approach is to strip the rest of the body off, measure and model the roller skate in CAD, then design the frame and body. Rather than creating a large build table I plan to build the frame on the roller skate. I’ll level the roller skate with four small jacks before I start. I will then use a strip of MDF, indexed to the mounting points on the sub frames, to build the side rails. Once I have the base frame built and mounted to the sub frames, I’ll add the rest of the frame while its on the car. This way I hope to keep everything square and lined up with the mounting points and shocks.
To simplify the body I’ll create foam forms on a large CNC machine at my local maker space. The forms will be build up from 2 inch thick foam layers and glued together. This is a common technique. I’ll then apply fiberglass to the foam and, when cured, cut the foam away. So the process does not require making molds. The hard work is smoothing the outside surfaces of the fiberglass.