Mr Di Lizio · Head Mechanic
This dragster keeps losing. The CO₂ cartridge is fine — the problem is friction stealing its speed. Four things are dragging it down. Help me find each one and fix it, and we'll get this car flying.
Friction is a force between two surfaces rubbing together. It always pushes against the direction the car is trying to move — so every bit of friction is energy stolen from your speed.
⏱ ~4 min🔧 4 repair missions🏁 Beat the clock
Mission 1 of 4 · Diagnose
The wheels won't spin
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Mr Di Lizio
Give that back wheel a spin. Feel how fast it stops? The axle is rubbing tight against the body. This is the biggest drag of all — it fights the car for the whole run.
Spins for: 0.3 s before stopping
⚙️Free up the axleHUGE EFFECT
Sand the axle, add a little graphite, and make sure it spins freely in the body. Drag the slider to loosen it.
stuckfree
Axle is jammed — barely turning.
Mission 2 of 4 · Diagnose
Something is scraping
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Mr Di Lizio
See that wheel pressing into the body? And the guide-string rubbing the screw eye? When parts scrape like that it's like driving with the brakes half-on. Push the wheel out so it spins clear.
🔩Stop the rubbingBIG EFFECT
Adjust the wheel spacing and line up the screw eyes so nothing touches the body or the guide string. Watch the contact point.
rubbingclear
Wheel is jammed against the body.
Mission 3 of 4 · Diagnose
The car pulls to one side
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Mr Di Lizio
The axle holes were drilled crooked, so the car steers sideways instead of straight. That drags it against the guide wire the whole way. Straighten the axle so it sits square to the body.
📐Square up the axleBIG EFFECT
A crooked axle is the cause behind a lot of rubbing. Rotate it until it's perpendicular to the centre line.
crookedsquare
Axle is off by several degrees.
Mission 4 of 4 · Diagnose
The ride is bumpy
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Mr Di Lizio
These wheels aren't perfectly round, so the car bounces instead of rolling clean. That bouncing wastes a little energy every turn. It's the smallest fix — but elite cars sweat every detail. Smooth 'em out.
⚫True the wheels roundSMALL EFFECT
Sand each wheel perfectly round and smooth so it rolls instead of bounces. Real, but the smallest of the four.
bumpysmooth
Wheels are lumpy — car bounces.
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
1Sticky axles were the biggest thief. A freely spinning axle fights the car the entire run — fix this first, always.
2Rubbing parts (wheels on the body, string on screw eyes) act like a half-pressed brake. Make sure nothing touches that shouldn't.
3Crooked axles steer the car sideways into the guide wire — they often cause the rubbing, so square them up.
4Bumpy wheels waste energy bouncing. The smallest fix, but champions still get it perfect.
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Mr Di Lizio
Remember the golden rule: friction always pushes against your motion. Every gram of drag you remove is speed you get back. Now go build a fast one.