This is a DIY open-source 24 V 4WD ride-on car for kids, with power steering, custom gearbox, and full programmability built in. I got the idea when I bought a ride-on for about $500 — it looked good, but the steering was terrible. Even an 11-year-old neighbor couldn’t reliably steer it. Then the original gearbox broke — a tooth sheared off. I decided to build something better: a ride-on that actually steers, lasts longer, and you can tinker with.

I designed a stackable 4:1 gear module (more stacks = higher gear ratio) and 3D printed it. In the drive and steering systems I placed rotary encoders to detect motion and a potentiometer in the steering wheel to feed control. The stock gearbox shaft was cut and integrated into my custom steering module. The motion system still uses a foot pedal for throttle.

Electronics are controlled via a custom PCB I built: rear motors go to one motor driver, front motors to another, and the steering motor to a third. It also includes inputs for sensor feedback and control logic. The brain of the system is a Teensy microcontroller programmed via Arduino IDE — you can modify how it behaves.

A key safety feature: a parent remote override. If the parent controller is sending steering or throttle, the kid’s controls are locked out. After the parent stops, there’s a 5–10 second delay before the child’s controls re-engage, to avoid sudden misbehavior.

Images show the 3D-printed gear modules, internal mechanical assembly, PCB layout, and live driving in action. Videos will demonstrate steering, torque, remote override, and the robustness of the build.

What sets this apart is that it’s fully hackable. You can tune steering assist levels, adjust speed curves, change gear ratio, expand battery voltage, or even convert it to fully autonomous. All firmware, schematics, and 3D files will be open source — so you can build it, adapt it, and share improvements.