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Class 3 chassis (3級シャシ) exam topics

The 3級シャシ paper covers everything between the engine and the road: driveline, suspension, steering, brakes, tyres and body electrics. This page lists the main systems, what is often asked and the Japanese terms you need.

Last updated: 2026-10-19

Systems in the chassis paper

System	Japanese	Often asked
Clutch	クラッチ	Clutch disc construction, pedal free play, slipping
Gearbox	トランスミッション	Gears, synchromesh (シンクロメッシュ), gear ratios, automatic transmission
Driveline	プロペラ・シャフト, ディファレンシャル	Universal joints, differential, final drive ratio (終減速比しゅうげんそくひ)
Suspension	サスペンション	Leaf springs, coil springs, shock absorbers (ショック・アブソーバ)
Steering	ステアリング	Steering gear, power steering, wheel alignment (ホイール・アライメント)
Brakes	ブレーキ	Master cylinder, disc and drum brakes, servo (倍力装置ばいりょくそうち), brake fluid
Tyres and wheels	タイヤ, ホイール	Tyre markings, pressure, wear, wheel balance
Body electrics	灯火装置とうかそうち	Headlamps, turn signals, fuses, relays

Clutch and gearbox

A friction clutch passes torque from the flywheel to the gearbox input shaft. Items often ask how pedal free play changes as the disc wears, or why a clutch slips. For gearboxes remember gear ratio = driven teeth ÷ driving teeth: the lower the gear, the larger the ratio and the greater the driving force.

Wheel alignment

キャンバ (camber): tilt of the wheel seen from the front.
キャスタ (caster): tilt of the steering axis seen from the side; helps the wheels return to straight ahead.
キングピン傾角けいかく (kingpin inclination): tilt of the steering axis seen from the front.
トーイン (toe-in): the front of the wheels is closer together than the rear, seen from above.

Brakes

Hydraulic brakes use Pascal's principle: the pressure from the master cylinder reaches every wheel cylinder equally. Remember: brake fluid absorbs moisture and is replaced periodically; air in the line makes the pedal soft with long travel; disc brakes shed heat better than drum brakes. A vacuum servo uses the vacuum in the engine's intake manifold.

Tyres

Read a marking such as 195/65R15 91H: 195 mm wide, 65% aspect ratio, radial (R), 15-inch rim, load index 91, speed symbol H. Under the safety standards a passenger car tyre needs at least 1.6 mm of tread, shown by the wear indicator (スリップ・サイン).

Practise chassis papers

The app has 20 Class 3 chassis papers, papers 1–3 free. Items have redrawn figures where needed (clutch cross-sections, brake diagrams) and explanations in English and Vietnamese.

VIP unlocks papers 4 to 20 in all three subjects (51 papers), the per-item tips and the detailed explanations for missed items. VIP is bought inside the iOS app with Apple payment, and Apple shows the price. The App Store version is coming soon. You can try the free exams on the web now.

Sources checked on 2026-10-19: the JASPA registration test page and its 2026 (令和8) guide, the JASPA results for the 2025 first session, the JASPA past papers page and the MLIT press release on the new mechanic qualifications. Rules can change, so check the latest version at these sources.

FAQ

Is Class 3 chassis harder than gasoline?

There is no official difficulty ranking. In JASPA's 2025 first-session results the two pass rates were close (chassis 70.8%, gasoline 69.2%). Pick the subject closest to your work.

Is wheel alignment tested often?

Yes. キャンバ, キャスタ, キングピン傾角 and トーイン are basic steering topics in the Class 3 textbook.

Does the chassis paper include electrics?

Yes, body electrics such as lamps, horn, switches, fuses and checking circuits with a circuit tester.

Take a 30-item mock paper and see right away which items you missed and why.

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