MITO Light Auto L3 cheat sheet

Risk control hierarchy, highest to lowest: eliminate the hazard, substitute a safer method, engineering controls (guards, ventilation), administrative controls (procedures, training), then personal protective equipment.

Never work beneath a vehicle held only by a hydraulic jack; use rated stands or a hoist, and chock the wheels that remain on the ground.

Torque conversions: 1 N·m = 0.738 lb·ft; 1 lb·ft = 1.356 N·m; 1 kgf·m = 9.81 N·m.

Tighten wheel nuts in a star sequence in at least two stages, finishing at the specified torque; re-check alloy wheels after 50–100 km.

Chlorinated brake cleaner decomposes to phosgene when heated; use non-chlorinated cleaner anywhere near welding or hot components.

Refrigerant must be recovered with certified equipment; venting it to atmosphere is prohibited in most jurisdictions.

Segregate waste streams: used oil, glycol coolant, brake fluid, solvent, lead-acid batteries and refrigerant each go to a separate licensed collector.

A safety data sheet must be available for every hazardous chemical stored or used in the workshop.

Two-post hoist: position the arms at the maker's lift points, raise to working height, and confirm the arm locks are engaged before going under.

Four-stroke cycle: intake, compression, power, exhaust - two crankshaft revolutions per cycle, one camshaft revolution.

Compression ratio = (swept volume + clearance volume) ÷ clearance volume.

Stoichiometric ratio by mass: about 14.7:1 for petrol and 14.5:1 for diesel; lambda 1.00 equals stoichiometry.

Thermostats typically open at 82–90 °C; a pressure cap raises coolant boiling point by roughly 2–3 °C per 10 kPa of rating.

Valve clearances are measured at the base circle of the cam, engine cold unless the specification states hot.

Torque-to-yield head bolts are tightened by angle after an initial torque and must be replaced rather than reused.

Overall driveline ratio = gearbox ratio × final drive ratio; road speed (km/h) = (rpm × 60 × rolling circumference in metres) ÷ (overall ratio × 1000).

Interference engines have overlapping valve and piston paths, so a slipped or broken timing belt causes valve-to-piston contact.

Inner CV joints plunge to absorb suspension travel; outer CV joints are fixed and transmit drive through larger steering angles.

Gear ratio for a pair = driven gear teeth ÷ driving gear teeth; a ratio above 1 reduces speed and multiplies torque.

Planetary set members are sun gear, planet carrier and ring gear; holding one member while driving another gives a fixed ratio, and holding two locks the set.

Torque converter multiplication is greatest at stall and falls to 1:1 at coupling speed; the lock-up clutch removes slip at cruise.

Check automatic transmission fluid level with the engine running, selector in Park or Neutral, fluid at the temperature the maker specifies.

Open differential: driveshaft speed equals the average of the two wheel speeds; torque is split equally, so a spinning wheel removes drive from the other.

Hypoid final drives require GL-5 specification oil; limited-slip units may also need a friction modifier to prevent clutch chatter.

Part-time 4WD must not be engaged on high-grip sealed surfaces because the absence of a centre differential causes driveline wind-up.

CVT ratio change is achieved by varying the running radius of a steel belt or chain between two hydraulically controlled pulleys.

A dual-clutch transmission uses two clutches on separate input shafts, preselecting the next gear so shifts occur without torque interruption.

Hydraulic pressure P = F ÷ A; increasing caliper piston area raises clamping force but demands more fluid volume and pedal travel.

DOT 3 and DOT 4 glycol fluids are hygroscopic; absorbed moisture lowers the wet boiling point and risks vapour lock.

DOT 5 silicone fluid is not miscible with DOT 3 or DOT 4 and must never be mixed in the same system.

Disc thickness below the stamped minimum, or runout beyond specification, requires replacement rather than resurfacing.

Bleed order: begin at the wheel furthest from the master cylinder and work towards the nearest, keeping the reservoir above minimum.

ABS preserves steerable braking on sealed surfaces but can lengthen stopping distance on gravel or fresh snow, where a locked wheel builds a wedge.

Too little pedal free play can cause brake drag and overheating; too much free play increases travel before braking begins.

A diagonal-split dual circuit gives partial braking if one circuit fails; a pressure differential valve or warning lamp signals the loss.

Fade from overheating reduces friction; glazed pads and discs are replaced or deglazed, and the cause (dragging, overuse) corrected.

Steering ratio = steering wheel degrees ÷ road wheel degrees; a higher ratio reduces effort and slows response.

Camber is the vertical tilt of the wheel viewed from the front; negative camber improves cornering grip but wears the inner tyre edge.

Caster is the fore-aft tilt of the steering axis; positive caster increases straight-line stability and self-centring effort.

Total toe is the sum of both wheels' toe angles; incorrect toe causes feathered tyre wear and scrubbing.

Spring rate = load ÷ deflection (N/mm); progressive springs increase rate as they compress.

Dampers control spring oscillation and do not support vehicle weight; a worn damper gives continued bouncing after a bump.

Ackermann geometry makes the inner wheel steer a tighter angle than the outer wheel in a turn.

Tyre wear diagnosis: centre wear = over-inflation; both edges = under-inflation; one edge = camber fault; feathered = toe fault.

Check ball joints and tie-rod ends for play with the suspension at normal ride height and the wheel unloaded, and inspect the boots for splits.

Ohm's law: V = I × R; power P = V × I = I²R.

Series: total resistance adds and current is common. Parallel: voltage is common and total resistance is below the smallest individual resistor.

A healthy 12 V battery rests at about 12.6 V (six cells × 2.1 V); charging voltage is typically 13.8–14.8 V.

Voltage drop tests are performed with the circuit loaded; more than roughly 0.5 V total loss indicates excessive resistance.

Parasitic drain with all modules asleep should typically stay under about 50 mA.

CAN bus is a twisted pair terminated by two 120 Ω resistors, giving about 60 Ω across the bus, using differential signalling around 2.5 V.

Sensor types: inductive (crank and cam speed), Hall effect (position and speed), potentiometer (throttle and pedal), NTC thermistor (coolant and air temperature), piezoelectric (knock).

Hybrid and EV high-voltage systems use orange cabling at 60 V DC or more; isolate and verify dead before work, and never assume a cable is de-energised.

Fuses protect wiring rather than the component: fit the same rating and diagnose the cause of any repeat failure instead of increasing the rating.