Automobile & Light Truck Certification Test A5 Brakes flashcards

A tool consisting of a set of blades of various calibrated thicknesses, used to measure small gaps or clearances between components.

• Measures small clearances.
• Blades are precisely sized.
• Used for non-self-adjusting brakes.

Memory trick: For a tiny gap, a feeler's lap, precise and no trap.

Hairline cracks in a brake drum indicate a severe structural integrity issue, often caused by excessive heat or stress.

• Cracks compromise drum strength.
• Can lead to drum failure during braking.
• Requires immediate replacement.

Memory trick: Cracked drum, don't be numb, replace it, or doom will come.

Non-uniform wear patterns on drum brake shoes indicate specific mechanical issues related to shoe movement, contact, or adjustment.

• Top/bottom wear on one shoe: often hold-down spring or backing plate issue.
• Uneven wear between primary/secondary: adjuster or wheel cylinder problem.
• Conical wear: bent axle flange or drum runout.

Memory trick: Wear on just one edge? It's often the shoe's seating, not the fluid's greeting.

An axle seal leak in a drum brake system results in black, greasy contamination on the brake shoes and drum, leading to reduced braking and potential scoring.

• Black, greasy residue
• Contaminates brake shoes
• Reduces braking effectiveness

Memory trick: Fluid is clear, oil is black, dust is just a powdery attack.

A leaking axle seal allows differential or axle lubricant to escape the axle housing, often contaminating nearby brake components like drum brake shoes.

• Causes grease contamination on drum brake shoes.
• Leads to reduced braking effectiveness and potential pulling.
• Requires replacement of the axle seal and contaminated brake parts.

Memory trick: Axle Leaks Grease, Brakes Lose Peace

Brake drum scoring refers to deep grooves or gouges on the drum's friction surface, typically caused by metal-to-metal contact due to worn-out brake shoes.

• Caused by worn brake shoes exposing metal components.
• Results in a loud grinding noise during braking.
• Requires drum resurfacing or replacement, and new shoes.

Memory trick: Metal on Metal Makes a Grinding Sound

A mechanism in drum brake systems that automatically compensates for brake shoe lining wear by adjusting the shoe-to-drum clearance to maintain consistent pedal height and braking performance.

• Operates during reverse braking or parking brake application.
• Prevents excessive pedal travel as shoes wear.
• Malfunction leads to low pedal, reduced braking efficiency.

Memory trick: Adjusters keep the gap just right, for a pedal that feels tight.

Rubber boots on wheel cylinders protect the internal hydraulic components from dirt, moisture, and debris, preventing corrosion and premature failure.

• Protects internal parts.
• Prevents contaminant entry.
• Cracked boots lead to corrosion.

Memory trick: Boot is torn, cylinder's forlorn, corrosion's born.

Specific contact points in a drum brake system where high-temperature lubricant is applied to facilitate smooth movement and prevent noise.

• Applied to shoe-to-backing plate pads.
• Reduces friction and noise.
• Must be high-temperature grease.

Memory trick: Lube the slides, where the shoe glides, no squeak hides.

The specified minimum thickness or maximum diameter to which a brake drum can be machined or worn before it must be replaced for safety and proper function.

• Nominal diameter: original manufacturing size.
• Maximum diameter (MAX DIA): absolute largest safe diameter after wear/machining.
• Always replace if diameter exceeds MAX DIA or if severely cracked/damaged.

Memory trick: Measure the drum, check the max, if it's in, resurface or relax, if it's out, then axe!

Brake drum scoring and grooving are often caused by the metal components of worn brake shoes (rivets, backing plates) directly contacting the drum surface.

• Metal-to-metal contact
• Reduced braking performance
• Grinding noise

Memory trick: When the pads are gone, the metal grinds the drum.

A weak or broken return spring prevents a brake shoe from fully retracting from the drum, causing continuous drag, overheating, and glazing.

• Causes continuous shoe drag.
• Leads to overheating and glazing.
• Results in brake pull or reduced efficiency.

Memory trick: Spring's weak, shoe can't speak, just drags and makes a streak.

The primary shoe in a duo-servo drum brake system typically wears faster than the secondary shoe due to its self-energizing action during forward braking.

• Self-energizing effect
• Located towards the front of the vehicle
• Does more work during forward braking

Memory trick: Primary leads the dance, secondary follows the trance.

The process of setting the correct tension in the parking brake cable to ensure proper engagement and holding power with appropriate lever travel.

• Prevents excessive lever travel.
• Ensures adequate holding force.
• Performed at the equalizer or cable ends.

Memory trick: Cable too loose, parking's no use, adjust the noose.

Internal parking brake levers in drum brakes can seize due to corrosion or lack of lubrication, preventing the parking brake shoes from being activated.

• Prevents parking brake engagement.
• Common cause is rust/dirt.
• Requires disassembly for service.

Memory trick: Lever stuck, parking's luck, no hold, just muck.

A malfunction in the wheel cylinder, often due to internal leaks or piston seizing, leading to compromised hydraulic pressure and braking performance.

• Common causes: worn seals, corrosion, fluid contamination.
• Symptoms: spongy pedal, fluid leaks, uneven braking.
• Requires replacement or rebuild (if applicable) to restore hydraulic integrity.

Memory trick: Spongy pedal? Think fluid, air, or a leak, my dear.

A malfunctioning automatic brake adjuster (e.g., bent lever) prevents the brake shoes from self-adjusting for wear, leading to excessive shoe-to-drum clearance and a low, spongy brake pedal.

• Increases pedal travel
• Reduces braking effectiveness
• Caused by lack of adjustment

Memory trick: No adjustment, no grab, just a long, soft stab.

Hold-down springs secure the brake shoes against the backing plate, preventing them from rattling, shifting, and ensuring proper alignment with the drum.

• Prevents shoe movement
• Maintains alignment
• Reduces noise

Memory trick: Hold-down springs keep the shoes in their place, preventing a noisy race.

A seized automatic brake adjuster prevents the brake shoes from advancing as they wear, leading to excessive shoe-to-drum clearance.

• Increases pedal travel.
• Causes low/spongy pedal.
• Reduces braking effectiveness.

Memory trick: Seized star wheel, pedal feels ill, braking's chill.

A system (typically vacuum or hydraulic) that multiplies the force applied by the driver to the brake pedal, making braking easier.

• Vacuum boosters are most common.
• Loss of assist results in a 'hard' pedal and increased stopping distance.
• Relies on a vacuum source (engine or dedicated pump).

Memory trick: Hard pedal, no vacuum medal.

The residual pressure valve in a master cylinder maintains a slight pressure (0-2 psi) in disc brake lines to keep caliper piston seals expanded, ensuring immediate pad contact.

• Prevents excessive piston/pad retraction.
• Stuck open: spongy pedal, increased travel.
• Stuck closed: dragging brakes.

Memory trick: Residual valve open, pedal's slow to know, where the pads need to go!

Excessive outer brake pad wear with inner pad remaining indicates a caliper's inability to float, often due to seized or missing guide pins.

• Common in floating caliper designs.
• Caliper body cannot move freely on its mounting.
• Results in uneven pressure application.

Memory trick: Outer pad worn thin, guide pin's where the problem begins.

A mechanical noise (e.g., clunk, click) occurring when brake pads move excessively within the caliper or bracket.

• Often heard during direction changes (forward to reverse).
• Caused by missing or incorrect anti-rattle hardware.
• Can also be due to worn caliper bracket abutments.

Memory trick: Listen closely, the parts speak loudly.

A procedure using a scan tool to cycle the solenoids and pump within the ABS hydraulic control unit (HCU) to purge trapped air that cannot be removed by conventional bleeding methods.

• Required for many ABS systems after repair or air ingress.
• Uses a scan tool to activate ABS components.
• Removes air trapped in the HCU.

Memory trick: Soft pedal, check for air, then ABS, then bigger repair.

Modern ABS systems may require a scan tool to cycle the hydraulic control unit (HCU) solenoids and pump to purge trapped air that traditional bleeding methods cannot remove.

• Air can get trapped in ABS module valves.
• Scan tool activates ABS components.
• Necessary for complete air removal and firm pedal after system intrusion.

Memory trick: Spongy pedal, ABS light? Scan tool's the key to make it right!

Also known as parallelism, it describes the inconsistency in a brake rotor's thickness around its circumference, which can cause brake pulsation even if rotor runout is within specification.

• Causes pedal and steering wheel pulsation.
• Rotor is not uniformly thick.
• Often a result of improper lug nut torque or overheating.

Memory trick: Pulsation is a wobble, check the rotor, then the hub.

Uneven brake pad wear in a fixed caliper system, especially between inner and outer pads, often indicates a problem with individual caliper pistons, such as seizing or sticking.

• Fixed calipers have multiple pistons on both sides.
• Each piston independently actuates a pad.
• Piston issues directly cause uneven pad wear.

Memory trick: Fixed caliper, piston trouble, wear unequal, cause the rumble.

Reasons for a vibrating or pulsating sensation felt through the brake pedal or steering wheel during braking.

• Rotor runout (most common).
• Rotor thickness variation.
• Out-of-round brake drums (rear).
• Loose wheel bearings or suspension components (less common for pedal pulsation).

Memory trick: Pulsing feet, check front and rear heat.

A condition where brake components are so severely worn or damaged that the vehicle's ability to stop is dangerously compromised.

• Pads worn to backing plates.
• Severely scored or broken rotors.
• Leaking brake lines or calipers.
• Lack of pedal pressure.

Memory trick: Safety first, brakes are a must!

A mechanical failure where the electric motor and gearing mechanism within the EPB caliper actuator becomes stuck, preventing the parking brake from engaging or disengaging.

• Can occur due to corrosion, internal component failure, or debris.
• Often results in the parking brake being stuck ON or OFF.
• May or may not trigger diagnostic trouble codes (DTCs) immediately.

Memory trick: Electric Brakes Stuck, Actuator's the Suspect.

Small metal clips installed in the caliper bracket or on the pads themselves to hold the brake pads securely, prevent vibration, and eliminate noise during braking.

• Prevents pad movement and noise.
• Crucial for quiet brake operation.
• Missing/damaged clips cause rattling or grinding.

Memory trick: Noise means something loose, or rubbing wrong, listen strong.

Hat-type parking brake systems utilize separate drum brake shoes within the rotor's 'hat' and operate independently of the hydraulic service disc brakes, meaning their performance does not reflect the condition of the service pads.

• Separate shoes inside the rotor's hat.
• Mechanically actuated, not hydraulic.
• Does not indicate service brake condition.

Memory trick: Parking brakes, service brakes, separate ways they take.

Symptoms of a dragging brake include burning smell, reduced performance, excessive heat, and rotor discoloration, often due to mechanical binding.

• Caused by caliper not releasing, or parking brake issues.
• Leads to premature wear and potential brake failure.
• Can be identified by abnormal wheel temperature.

Memory trick: Hot wheel, burning smell? Parking brake cable's not doing well!

A brake caliper design where one or more pistons push a single pad, and the caliper body slides on guide pins to apply pressure to the opposite pad.

• Relies on guide pins for lateral movement.
• Piston(s) on one side only.
• Equalizes pressure between inner and outer pads.

Memory trick: Smooth slides keep the brakes aligned.

Hairline cracks, especially those radiating from lug holes or the rotor hat, indicate material fatigue and structural compromise due to excessive heat and stress, necessitating immediate replacement.

• Often caused by rapid heating/cooling cycles.
• Can propagate rapidly, leading to rotor failure.
• Even minor cracks require replacement for safety.

Memory trick: Cracks mean danger, replace with care.

Before servicing rear calipers with an integrated Electric Parking Brake (EPB) system, a scan tool must be used to place the EPB into service mode to safely retract the piston.

• Prevents damage to the EPB motor and caliper.
• Electronically retracts the piston.
• A critical step for vehicles with EPB.

Memory trick: EPB's electric, scan tool's the trick, for safe piston retraction, quick!

A parking brake system where small drum brake shoes are housed within the 'hat' section of a disc brake rotor.

• Operates independently of the hydraulic service brakes.
• Activated mechanically by a cable.
• Requires periodic adjustment of the shoes.

Memory trick: Park it right, hold it tight.

Key signs that brake rotors need replacement rather than just re-surfacing or reuse.

• Excessive grooving or scoring.
• Warping (pulsation during braking).
• Cracks or heat spots.
• Reaching or exceeding minimum thickness specification.

Memory trick: Grooves and lips mean it's time for new trips.

The formation of fissures in a brake rotor, indicating material fatigue or stress.

• Always a critical safety concern.
• Can be caused by excessive heat, thermal shock, or manufacturing defects.
• Requires immediate rotor replacement.

Memory trick: A crack in the shield, a danger revealed.

Corrosion, dirt, or internal wear within the electric parking brake motor or actuator assembly can cause it to bind, leading to slow engagement/disengagement, partial release, or dragging.

• EPB is an independent system.
• Mechanical binding affects operation.
• Can occur without dashboard warning lights.

Memory trick: EPB slow, check the motor, then the cable, then the code.

A squealing noise when brakes are not applied, which stops with light pedal pressure, is typically caused by loose brake pads vibrating, often due to faulty anti-rattle clips.

• Indicates loose pad fitment in the caliper bracket.
• Anti-rattle clips (hardware) are crucial for pad stability.
• Noise stops when pads are held firm by light pressure.

Memory trick: Squeal when idle? Anti-rattle clips are vital!

Brake fluid weeping from the caliper piston boot signifies a failed internal piston seal, requiring caliper replacement or rebuilding.

• Piston boot is a dust seal, not a fluid seal.
• Internal seal failure leads to fluid loss and potential brake failure.
• Caliper must be addressed immediately.

Memory trick: Fluid on the boot? The piston seal's kaput!

A tight caliper after new pad installation, especially on floating calipers, often indicates seized or corroded caliper guide pins preventing proper caliper movement.

• New pads are thicker, requiring more caliper movement.
• Guide pins allow the caliper to center itself.
• Lack of movement causes constant pad-to-rotor contact.

Memory trick: Tight caliper's a fright, guide pins not sliding right!

The maximum allowable deviation from perfect flatness and concentricity of a brake rotor, typically 0.002 inches (0.0508 mm), beyond which brake pulsation and noise can occur.

• Measured with a dial indicator.
• Excessive runout causes brake pulsation (pedal feedback).
• Corrected by machining (resurfacing) or replacing the rotor.

Memory trick: Rotor's wobble limit: two thousandths, don't forget it!

The presence of oil, grease, or excessive heat causing a hardened (glazed) surface on parking brake shoes, leading to reduced friction, grabbing, vibration, and noise upon application.

• Reduces friction effectiveness.
• Causes grabbing or vibration.
• Requires cleaning or replacement of shoes.

Memory trick: Parking brake noise, shoes are the cause, check the surface, then applause.

A common diagnostic scenario where one pad wears significantly more than the other in a floating caliper system.

• Often caused by seized guide pins.
• Inner pad wears more if caliper can't pull outer pad.
• Outer pad wears more if caliper can't push inner pad (less common).

Memory trick: Stuck slides mean lopsided rides.

Common reasons for a high-pitched noise during brake application.

• Pad wear indicators.
• Glazed pads or rotors.
• Improper lubrication of pad backing plates/caliper contact points.
• Pad vibration due to poor fitment or missing anti-rattle hardware.

Memory trick: Squeaky brakes, check for mistakes.

Blue discoloration and hard spots on a brake rotor indicate excessive heat, usually from a dragging brake or severe overheating. This can lead to rotor warpage and reduced braking efficiency.

• Caused by temperatures exceeding rotor's design limits.
• Hard spots are areas of martensite, making rotor brittle.
• Leads to pulsation and reduced friction.

Memory trick: Blue means hot, hard spots mean a lot, of heat that the rotor got!

If a caliper piston is difficult to compress even with the bleeder screw open, a blocked brake hose is the most probable cause, preventing fluid escape.

• Bleeder open should allow easy fluid flow/piston retraction.
• Internal hose collapse acts as a check valve.
• Can lead to dragging brakes and overheating.

Memory trick: Piston stuck, bleeder open? Hose is choked, no fluid flowin'.

Uneven wear between brake pads on the same caliper is often caused by mechanical issues preventing proper caliper or piston movement.

• Indicates a problem with caliper's ability to float or piston movement.
• Common culprits include seized guide pins or sticky pistons.
• Can lead to reduced braking efficiency and premature pad replacement.

Memory trick: Wear and tear tells the tale of the caliper's fail.

An internal collapse or blockage within a flexible brake hose, typically acting as a check valve.

• Allows fluid to flow to the caliper, but restricts return.
• Causes brake drag and potential overheating.
• Diagnosed by opening bleeder to relieve pressure.

Memory trick: Hard push, easy bleed, hose in need.

The elongation of a parking brake cable over time due to repeated use and stress, leading to increased lever travel, higher effort required to apply, and reduced holding force.

• Common wear item.
• Increases cable slack.
• Requires adjustment or replacement.

Memory trick: Cable long, grip bad, adjust or replace, don't be sad.

Wear patterns in fixed caliper systems, often indicating issues with individual pistons or their seals.

• Caliper body is rigid, does not move.
• Pistons on both sides of the rotor.
• Uneven wear often points to piston issues.
• Guide pins are not used.

Memory trick: Fixed pistons mean balanced decisions.

When a single-piston floating caliper's piston seizes, it fails to extend properly, causing the inner brake pad to wear less (remain thicker) than the outer pad, as the inner pad doesn't apply sufficient pressure to the rotor.

• Piston pushes inner pad.
• Caliper slides to engage outer pad.
• Seized piston means inner pad wears less.

Memory trick: Floating caliper, one pad thick, piston or pins, find the trick.

Visible signs of brake rotor overheating include blue or purple discoloration (heat spotting) and localized hard spots (glazing) on the friction surface, often indicating aggressive braking or system issues.

• Blue/purple color indicates high heat.
• Glazing is hardened, friction-reduced material.
• Reduces braking effectiveness and can cause noise.

Memory trick: Blue means hot, glaze means stress, brake hard, you'll make a mess.

A brake booster check valve test involves measuring vacuum retention after engine shutdown. A rapid vacuum drop indicates a faulty check valve.

• Check valve holds vacuum in booster.
• Vacuum allows power assist when engine is off.
• Failure causes hard pedal after engine off or during low engine vacuum.

Memory trick: Vacuum drops fast? The check valve's passed its last.

Brake fluid (glycol-based) is hygroscopic and absorbs moisture from the air, which can cause it to appear cloudy or milky and significantly reduce its boiling point.

• Hygroscopic nature.
• Milky/cloudy appearance indicates water.
• Lowers boiling point, leading to vapor lock.

Memory trick: Cloudy fluid? Water's in the brew, making trouble for you.

Application of high-temperature, anti-seize lubricant to specific contact points on the drum brake backing plate.

• Ensures smooth shoe movement
• Prevents binding and sticking
• Reduces noise (squealing, chattering)

Memory trick: Smooth slide, no brake pride.

A parking brake cable that has elongated over time, leading to excessive lever travel and reduced holding force.

• Requires adjustment or replacement
• Causes poor parking brake performance
• Not resolved by drum brake shoe or adjuster service alone

Memory trick: Cable stretched, brake's fetched.

High resistance in the ABS pump motor circuit can reduce power to the pump, causing it to draw excessive current or operate weakly, leading to system voltage drops and potential malfunction.

• Can cause 'system voltage low' fault codes (e.g., C1210).
• May lead to intermittent ABS/ESC activation issues.
• Diagnosed by checking voltage drop and resistance across the circuit.

Memory trick: The 'Low Voltage' is a tricky foe, hiding in high resistance flow.