My Quest to Build a Better Kei Car

It has been one whole year since I picked up my Autozam AZ-1, and over the last year I have been customizing the car to my liking.

For those unfamiliar, the AZ-1 is a mid-engine, rear-wheel-drive kei car not unlike the Honda Beat. Power comes from a turbocharged Suzuki F6A 660cc 3-cylinder through a 5-speed manual transaxle. To top off its quirky setup, it also has gullwing doors and weighs in at just 720 kg.

I purchased the car last year and picked it up in early June. It was a solid, rust-free chassis and was mostly stock. These cars originally only came in red or blue, so the gray is definitely a respray but it looked good, generally well done. The seats had also been reupholstered to match the exterior.

My first modification was the steering wheel. The stock wheel is about the same size as in a Miata, but with how much less space there is inside it rubbed on my legs. I made a custom steering column adapter to fit it with the MOMO steering wheel and Sweet Mfg quick release from my formula car. I designed a custom horn button to sit inside the steering column and be pressed by a switch I built into the wheel. This retained both horn and quick release function without needing an expensive connector in the column.

After that came the boost controller. The AZ-1 has a factory ashtray in the dash which was missing from my car. I decided to put that empty space to better use and carved a piece of pink foam until it fit the slot. I then 3D printed a nice little adapter which fit the factory mounts, curved with the dash, and mounted my boost controller.

My attention soon turned to tires. The K-sports my car came with were starting to dry rot and were really no longer safe. Finding a tire in stock size is difficult, so I opted to find some alternative options. After pouring over data for any small tire I could find, I decided upon the factory Caterham race tire - the Avon ZZ-S. This did, however, pose a slight problem. The narrowest ZZ-S was still 30mm wider than my old tires and came only in a 13, while my wheels were 14s. I would need new wheels to fit my new tires. I put together a simple tire flop model and combined with some calculations for how that affected track width, scrub radius, and some other basic vehicle dynamics, I settled on a wheel and offset I needed for these new tires to clear the suspension and provide the cornering performance I wanted.
These came in the form of BRAID Sturace lightweight formula car wheels.
These wheels have a flat mounting face and a 60mm hub bore, but since the AZ-1 has no hub ring I needed a way to center these wheels. This solution came in the form of 3D printed center caps with custom Autozam badges. They mount over the axle nut and provide a conical surface onto which the wheel self-centers.

With wheels sorted, I just had to figure out how to cover all of that poke. This time I partnered with RPM Speedworks to make a custom widebody. We started with some rivet-on NRF flares and chopped them up until they gave the right general shape for our needs. Rather than extend the flares down onto the bumpers and rockers, we trimmed them off and sculpted some end caps to blend them together with the factory body lines. After a short test fit, we attached and blended our custom fiberglass flares and set up for paint. I got an updated MS-style hood from SODO-Moto which we painted at the same time.

In July of last year I was also able to take my car to Pittsburgh for the Pitt Shootout as the official pace car since my formula car wasn’t running. I had a great time there too, and popped some pictures of that in as well.