Pull-back car builds

Pull the car backwards, let go and it zooms forward. A pull-back motor stores energy in a spring as you pull, then lets it out through the wheels. These builds use one to explore speed, gears and stored energy.

Start with Pull-back Racer for free

Turn your build into a fair test

Keep the car, surface and release method constant. Change one factor, repeat each trial and record where the car stops before drawing a conclusion.

Complete MightyCog booklet collection: 82 PDF booklets for $12.99. Instructions only; individual booklets remain free.

Explore the printable pack

Before you start: Mark a start line with tape and measure how far each car goes: an instant science experiment.

10 builds, easiest first

  1. Pull-back Racer🏁 Pull-back Racer: Pull it back, let it go — ZOOM! A racer with a spring for an engine. (level 2 of 5, about 12 minutes, 10 steps)
  2. 🛺 Pull-back Trike: A three-wheeler with a spring engine — twist the front wheel and it drives in circles! (level 2 of 5, about 20 minutes, 9 steps)
  3. 🔥 Big-Wheel Dragster: Giant back wheels, tiny front wheels — the same spring pushes this car much further! (level 2 of 5, about 22 minutes, 10 steps)
  4. 💨 Gear-Up Speeder: The spring engine sits up high and turns a BIG gear, which spins the wheels faster! (level 2 of 5, about 25 minutes, 11 steps)
  5. 🐢 Pull-back Tortoise: Slow but super-strong: a spring car that can climb up a book! (level 2 of 5, about 30 minutes, 12 steps)
  6. 🎚️ Two-Speed Pull-back: Choose your gear before the race: CLIMB or SPRINT! Slide the back axle to swap gears. (level 3 of 5, about 35 minutes, 13 steps)
  7. 🚀 Launch-Lock Racer: Wind it up, and a little catch holds the spring tight until YOU press the launch button! (level 3 of 5, about 40 minutes, 21 steps)
  8. 🐾 Twin-Spring 4×4: Two spring engines — one for the front wheels, one for the back. All four wheels push! (level 3 of 5, about 35 minutes, 16 steps)
  9. 🌀 Pull-back Diff Racer: A spring racer with a real differential, so it zooms round curves without skidding. (level 3 of 5, about 40 minutes, 23 steps)
  10. 🕰️ Spring Escapement Clock: A ticking pin-wheel clock powered by the pull-back motor's spring. Tick… tock… tick… (level 4 of 5, about 50 minutes, 22 steps)

More ways to choose