Click + hold on the dragster body where you want the hole. Then keep the crosshair inside the green target for 3 seconds. Wobble = crooked hole = car steers off line.
🧑🔧
Mr Di Lizio
Axle holes need to be perpendicular and 5–10mm from the base. Press and HOLD. Don't let the bit wander.
How to playThe drill auto-finishes after 3 seconds of steady drilling. Reset and retry as many times as you want.
Drill time0.0 / 3.0 s
Drift0%
Step 2 / 4 · Assemble
Set the wheel position with collars
Drag each wheel along the axle until it sits in the green target band. Too close to the body = wheel rubs. Too loose = wobble.
🧑🔧
Mr Di Lizio
Use the collars to lock each wheel just clear of the body. Aim for the green band on both sides.
How to playClick + drag a wheel sideways along the axle. Release in the target band. Press Check Fit when both wheels are set.
Left wheel—
Right wheel—
Step 3 / 4 · Screw eyes
Align the guide-line screw eyes
Drag the front and rear screw eyes onto the centre line. The guide string runs through them — any sideways offset drags the string against the car.
🧑🔧
Mr Di Lizio
Drill a tiny pilot hole, then twist the screw eye in dead-centre. Both must sit on the centre line for the line to track true.
How to playYou're looking at the UNDERSIDE of the car. The dashed centre line is the target. Drag each screw eye onto it. Press Check Alignment.
Front eye—
Rear eye—
Step 4 / 4 · True
True the wheels round
Drag around the wheel's rim with the sandpaper until every red bump turns green. Hit 90% coverage and the wheel rolls clean instead of bouncing.
🧑🔧
Mr Di Lizio
Trace the outside edge slowly. Don't miss any spots — every red patch causes a tiny bounce that wastes speed.
How to playClick + drag around the wheel's outer edge. Coverage updates live. Hit Spin Test when you're happy.
Coverage0%
Workshop Test
Question 1 of 4
Car Rebuilt
Race Ready
2.80 s
↓ 2.60s faster than the broken car
What you fixed — ranked by impact
1Square axle holes are the foundation. A crooked hole = wheel wobble = car drifts off line.
2Wheel position matters — too close = rubbing on the body, too loose = wobble. Collars set the gap.
3Screw eyes on the centre line let the guide string run true. Off-line = string dragging the car sideways.
4Round wheels roll smoothly. Lumps cause a tiny bounce each turn that adds up over 20m.
Pit Crew · Friction Module
Welcome to the garage
You're building a balsa CO₂ dragster. Four steps decide whether it tracks straight and rolls free — or fights you the whole way.
Your goal
Beat 3.0 seconds on the 20m track. Right now this car runs 5.40s.
1Drill the axle holes — perpendicular, 5–10mm from the base.
2Set the wheels with collars — small clearance, no rubbing.
3Align the screw eyes — both on the centre line.
4True the wheels round — no lumpy bouncing.
Each step is a real workshop skill. You can retry any of them — practice until you're happy with the score.