⚙️ Clutch-Gear 2-Speed Car: step-by-step build

Push the gear lever and a driving ring grabs a different gear: 1st climbs, 2nd races!

Real cars have a gearbox, and now yours does too. The motor turns two gears on the input shaft all the time: a tiny 8 and a 16. On the back axle sit two clutch gears with round holes — they spin freely, so nothing happens… until the driving ring slides into one of them. Push the gear lever one way and the ring grabs the big 24 clutch gear: first gear, slow and strong. Push it the other way and it grabs the 16: second gear, fast! In the middle is neutral — the motor hums and the car stands still.

Level 3 of 5 (medium)
About 45 minutes
18 steps, 50 parts
Powered by: Motor
Series: Gearbox & Drivetrain Cars

What you will learn

Gearbox: A box of gear pairs where you choose which pair works.
Clutch & Driving Ring: A part that connects or disconnects a gear from its axle.
Gear Ratio: Fast or Slow: A big gear turning a small gear makes it spin faster.
Mounting a Motor: A motor must be pinned tight, or it spins itself instead of your wheels.
Idler Gears & Direction: A gear in the middle flips the direction back.
Plugging In: Power Functions: Battery box → (switch or receiver) → motor. Plugs stack like bricks.
Electric Circuits: Electricity flows from the battery, through the motor, and back.
Triangles Are Strong: A triangle cannot be squished — a square can.

Build these first

🔋 Motor Buggy: Your first car that drives by itself — with a forwards/backwards switch and headlights! (level 3 of 5, about 30 minutes, 20 steps)
🧪 Gear Speed Lab: Two cranks, two gear pairs: one makes things FAST, one makes things STRONG. (level 2 of 5, about 20 minutes, 13 steps)

Parts you need

2 × Beam 15
10 × Black pin (grippy)
4 × L-beam 3×5
2 × Axle 12
5 × Half bush
4 × Bush
1 × Clutch gear (16 teeth)
1 × Driving ring
1 × Clutch gear (24 teeth)
1 × Axle 10
1 × Small gear (16 teeth)
1 × Tiny gear (8 teeth)
1 × Gear shifter
4 × Yellow-hub wheel
1 × M motor
2 × Axle 3
3 × Medium gear (24 teeth)
1 × AA battery box
4 × Blue long pin
1 × LED lights

Steps

Stand a 15-hole beam on its edge — the left chassis rail.
Front battery post: black pins in holes 3 and 4 of the rail (inside) and a black L-beam pressed onto them, long leg standing up.
Back battery post: black pins in holes 10 and 11 (inside) and another L-beam, long leg up, corner towards the back.
Push a 12-long axle through the 2nd hole and the front post's corner (front axle), and another through the 14th hole (back axle), one hole further out on the left. A yellow half bush on the front axle, outside the rail, and a grey bush on the back axle, inside.
Now build the right side on the table: a second 15-hole rail with black pins in holes 3 and 4 and an L-beam post pressed onto them, long leg up.
Black pins in holes 10 and 11 of the right rail and the last L-beam post, corner towards the back.
Slide onto the back axle from the right, next to the bush: the 16 clutch gear, the driving ring, the 24 clutch gear and another bush to lock the stack.
Input shaft: hold a half bush, a bush and a 16 gear in a row next to the back post, and push a 10-long axle through the 12th hole of the left rail, the post's corner and all three.
Then another bush and a tiny 8 gear. The 8 meshes with the 24 clutch gear, the 16 with the 16 clutch gear. Clip the gear shifter over the driving ring — its fork sits in the ring's groove.
Slide the right side onto the car: its posts go over the input shaft and the front axle, the rail over all three axles. Push the right front wheel onto the front axle — it holds the right side on.
Push black pins into the 5th and 7th holes of the left rail, from the inside. Press the M motor's front onto them: the round holes on each side of its orange output take the pins.
Push a 3-long axle through the 6th hole into the motor's output, put a 24 gear on it outside the rail and a half bush on the end so the gear can't slide off.
A short axle through the 9th hole with a half bush on the inside end so it can't fall out, a 24 idler gear outside and another half bush on the outside end.
A third 24 gear on the input shaft — three gears in a row. Push on the back wheels: the left one keeps the 24 gear from sliding off.
Push on the left front wheel.
Lower the AA battery box between the posts. Push blue long pins through the top holes of the two left posts into the bottom holes of its end flaps.
Two more long pins through the right posts into the flaps. Plug the motor into the battery box.
Push the two LED lights into the 2nd and 4th holes of the front right post — headlights! Stack their plug on the motor plug.

Play time

Put the lever in the middle (neutral) and switch on: the motor hums but the car stays put. Push the lever into 1st and race a friend up a book ramp. Then try 2nd on the flat. Which gear wins on the ramp? Which on the flat?

Real-world inspiration

Constant-mesh manual gearboxes and the LEGO driving-ring gearboxes explained by Sariel. https://sariel.pl/2009/09/gears-tutorial/ · https://www.youtube.com/watch?v=kznEFrMxZf8 · https://en.wikipedia.org/wiki/Manual_transmission#Constant-mesh

Build next

↩️ Reverse-Gear Truck: The motor only spins one way — the gear lever decides forwards or backwards! (level 4 of 5, about 55 minutes, 18 steps)
🏁 Three-Speed Car: Two little gearboxes in a row make a big one: crawl, cruise or fly! (level 4 of 5, about 60 minutes, 20 steps)