20 Drum & Disc Brake Service Practice Questions & Answers

1. 1. A technician has the drums off a rear drum brake assembly and is preparing to clean the accumulated brake dust from the backing plates and shoes. Which method should be used?

   • A.Wipe the assembly down with a solvent-soaked rag and let the dust dry on the bench
   • B.Blow the assembly clean with shop compressed air while standing upwind of the wheel
   • C.Wash the assembly with an approved wet cleaning system or a HEPA-filtered vacuum✓ Answer
   • D.Brush the dust off dry with a stiff parts brush and sweep the floor afterward

   Brake dust may contain asbestos or other respirable particulate, so it must never be made airborne. Approved wet-cleaning equipment or a HEPA-filtered vacuum enclosure captures the dust at the source; compressed air, dry brushing and open rags all disperse it into the technician's breathing zone.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — drum brake cleaning and inspection safety proceduresReport a problem with this question

2. 2. A brake drum is machined and then measured. The drum measures 11.086 in. across its inside diameter and the maximum allowable diameter cast into the drum is 11.060 in. What action is required?

   • A.Machine the drum a second time to clean up the surface and then install it
   • B.Replace the drum, because it now exceeds the maximum allowable inside diameter✓ Answer
   • C.Install the drum and fit oversize linings to make up the additional diameter
   • D.Install the drum but back off the star wheel adjuster to compensate for the size

   Drums are machined oversize, so the discard figure is a maximum: 11.086 in. is larger than the 11.060 in. limit, so the drum is scrap. A thinner drum wall loses heat capacity and strength, and no lining or adjuster change restores it.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — measuring brake drums against the maximum allowable diameterReport a problem with this question

3. 3. During a drum brake reline, where should high-temperature brake lubricant be applied?

   • A.On the machined inner surface of the drum so the shoes do not grab when cold
   • B.On the entire face of the backing plate so the shoes float freely across it
   • C.On the friction face of the new linings so they seat quietly against the drum
   • D.On the raised shoe pads of the backing plate and the adjuster screw threads✓ Answer

   Lubricant belongs only where metal slides on metal: the six raised shoe pads on the backing plate and the self-adjuster threads and pivot. Any lubricant that reaches the lining or drum friction surface contaminates it and the shoes must then be replaced.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — lubricating drum brake shoe support pads and self-adjuster hardwareReport a problem with this question

4. 4. A technician pulls back the rubber dust boot on a rear wheel cylinder during a brake inspection and finds the inside of the boot wet with fluid and a small amount running out. What is the necessary action?

   • A.Replace or rebuild the leaking wheel cylinder and inspect the linings for contamination✓ Answer
   • B.Seat the boot fully on the cylinder body, since seepage past the lip is considered normal
   • C.Wipe the boot dry and recheck the wheel cylinder at the next scheduled service visit
   • D.Top off the master cylinder reservoir and bleed that wheel to reseat the cup seals

   Fluid behind the boot means the cup seal is passing, and a wheel cylinder that leaks will keep leaking and can fail entirely under pedal pressure. Any lining wet with brake fluid is contaminated and must be replaced along with the cylinder.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — inspecting wheel cylinders for leakage, operation and mountingReport a problem with this question

5. 5. Two technicians discuss the final steps after relining a rear drum brake. Technician A says the shoes should be pre-adjusted with a brake shoe gauge set to the drum's inside diameter before the drum is installed. Technician B says the parking brake should be adjusted only after the service brake shoe adjustment is complete. Who is correct?

   • A.Neither A nor B
   • B.A only
   • C.Both A and B✓ Answer
   • D.B only

   Pre-adjusting the shoes to the measured drum diameter gets the initial clearance close so the drum slips on and the pedal is not low. The parking brake shares the same shoes and linkage, so adjusting it first would take up the slack and hold the shoes against the drum; it is always set last.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — installing drum brake shoes and adjusting shoes and parking brakeReport a problem with this question

6. 6. All of the following findings on a drum brake assembly call for replacing the parts EXCEPT: (This question contains the word EXCEPT. Read the question carefully before choosing your answer.)

   • A.Linings soaked with brake fluid from a seeping wheel cylinder cup
   • B.A backing plate with the shoe contact pads worn into visible grooves
   • C.Return springs that are discolored from heat and stretched out of shape
   • D.Light surface dust on the shoe webs and the backing plate around the pads✓ Answer

   Ordinary dust is cleaned with approved wet or HEPA methods and the parts go back in service. Heat-set springs no longer return the shoes, fluid-soaked linings cannot be cleaned, and a grooved backing plate lets the shoes hang up, so all three of those require replacement.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — inspecting drum brake shoes, springs, hardware and backing plates and determining needed repairsReport a problem with this question

7. 7. A brake rotor is measured with a micrometer at several points around the braking surface. The thinnest reading is 0.923 in., and the discard thickness cast into the rotor hat is 0.921 in. What should the technician do?

   • A.Machine the rotor, because the reading is still above the stamped discard thickness
   • B.Replace the rotor, since machining it would finish it below the discard thickness✓ Answer
   • C.Machine the rotor on the vehicle, since on-car cutting removes no measurable material
   • D.Install the rotor as is, because the discard figure applies only to a machined rotor

   Discard thickness is the minimum a rotor may ever measure in service, and machining always removes material from both faces. With only 0.002 in. above discard, any cut leaves the rotor under spec, so replacement is the only correct action. On-car lathes remove material just as bench lathes do.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — measuring rotor thickness against the minimum/discard specification and determining machine or replaceReport a problem with this question

8. 8. Which tool and setup is used to measure brake rotor lateral runout?

   • A.A vernier caliper spanning both braking surfaces at a fixed distance from the edge
   • B.A dial indicator on a rigid stand, its tip on the braking surface as the rotor turns✓ Answer
   • C.An outside micrometer taking paired readings at several points around the rotor
   • D.A feeler gauge inserted between the rotor face and the caliper mounting bracket

   Lateral runout is side-to-side wobble as the rotor rotates, so it can only be read by a dial indicator held stationary against the turning face. A micrometer measures thickness at a point and reveals thickness variation, not wobble.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — inspecting and measuring rotors for runout and thickness variationReport a problem with this question

9. 9. A rotor within thickness specification is going to be resurfaced. What is the main reason a technician would choose an on-car lathe over a bench lathe?

   • A.It removes far less material, so a rotor already at discard thickness can be reused
   • B.It restores a rotor whose surface is scored past the manufacturer's depth limit
   • C.It cuts the rotor true to that vehicle's own hub, correcting assembled runout✓ Answer
   • D.It is the only method approved for rotors that are cast in one piece with the hub

   An on-car lathe indexes off the vehicle's own hub and bearing, so the finished surface runs true in the position where the rotor actually operates, eliminating stack-up runout that a bench lathe cannot see. It removes material the same as a bench lathe, and it does not restore a rotor that is out of spec.

   Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — machining rotors on-car and off-car and selecting the methodReport a problem with this question

10. 10. While replacing front pads, a technician finds the outboard pad worn nearly to the backing plate while the inboard pad still has most of its friction material. Besides fitting new pads, what service does this finding call for?

    • A.Clean the caliper slides and pins, inspect their boots, and relubricate them to spec✓ Answer
    • B.Machine both rotors so the new pads have matched surfaces to wear against
    • C.Replace the flexible brake hose feeding that caliper and bleed the wheel afterward
    • D.Swap the caliper to the opposite side so the pads wear evenly over the next interval

    On a floating caliper the housing must slide freely for both pads to share the clamping load; uneven pad wear means the slides or pins are seized or dry. Cleaning, inspecting the boots and relubricating restores the float, and new pads on a bound caliper would simply wear unevenly again.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — inspecting caliper assemblies, mountings, slides, pins and bootsReport a problem with this question

11. 11. A vehicle has an electric parking brake integrated into the rear calipers. What must the technician do before the rear caliper pistons can be retracted for new pads?

    • A.Pull the parking brake fuse and press the switch to release the actuator motors
    • B.Open the caliper bleeder screw so displaced fluid escapes as the piston is pushed
    • C.Force the piston straight back with a large C-clamp and a pad as a spacer
    • D.Use a scan tool to put the parking brake into its service or maintenance mode✓ Answer

    On an integrated electric parking brake the actuator motor drives the piston through a screw mechanism, so the piston cannot simply be pressed in. The scan tool's service mode retracts the actuator and holds it there; forcing the piston damages the actuator and the gear train.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — adjusting/retracting calipers with integral parking brakes per manufacturer procedureReport a problem with this question

12. 12. Two technicians discuss lug nut installation after a brake job. Technician A says a torque wrench should be used and the nuts tightened in a star (crisscross) pattern. Technician B says the nuts should be run down with an impact gun and then checked with a torque wrench to see if any are loose. Who is correct?

    • A.Both A and B
    • B.Neither A nor B
    • C.B only
    • D.A only✓ Answer

    A star pattern with a torque wrench draws the wheel squarely against the hub and loads every stud evenly. An impact gun cannot control final torque, and checking afterward only finds nuts that are loose, never the over-torqued ones that distort the rotor and cause pedal pulsation.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — reinstalling the wheel and torquing lug nuts to specificationReport a problem with this question

13. 13. A disc brake job is finished and the vehicle is about to be road tested. What is the purpose of the burnish or break-in procedure the manufacturer specifies?

    • A.To purge residual air from the caliper so a second bleeding is not required
    • B.To transfer an even friction film to the rotor and mate the pad surfaces to it✓ Answer
    • C.To seat the caliper piston seals so the pedal comes up to full height
    • D.To let the wheel bearing grease redistribute after the hub was disturbed

    Burnishing is a series of controlled moderate stops that heats the pads gradually and lays down a uniform transfer layer of friction material on the rotor. Without it the film is patchy, which produces noise, uneven bite and early judder. Air is removed by bleeding, not by driving.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — final checks, road test and burnishing/breaking in pads per manufacturer recommendationReport a problem with this question

14. 14. When new disc brake pads are installed and the caliper pistons are pushed back into their bores, what happens to the fluid level in the master cylinder reservoir?

    • A.It falls, so the reservoir must be refilled before the vehicle is road tested
    • B.It stays put, because the caliper bores are sealed off from the reservoir
    • C.It rises, so the level must be checked and corrected to the marked full point✓ Answer
    • D.It drops briefly and then returns on its own once the pedal is pumped up

    As the pads wore, the pistons moved out and fluid from the reservoir filled the space behind them. Retracting the pistons pushes that fluid back up the lines, so the level rises and can overflow if the reservoir was topped off earlier. The level is set to the full mark after the job.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — filling the master cylinder with recommended fluid and resetting the system after pad serviceReport a problem with this question

15. 15. A technician needs to add brake fluid after a pad replacement. Which practice is correct?

    • A.Use the DOT grade the vehicle specifies, taken from a previously unopened container✓ Answer
    • B.Use a DOT 3 and DOT 4 blend to raise the boiling point above either grade alone
    • C.Use fluid saved in a labeled shop container from the bleeding job done that morning
    • D.Use any DOT 5 fluid, since its higher number always exceeds a DOT 3 requirement

    Glycol-based brake fluid is hygroscopic, so an opened or salvaged container has already absorbed moisture that lowers the boiling point and corrodes the system. DOT 5 is silicone and is not interchangeable with the glycol fluid used in most systems, and grades are never blended to invent a rating.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — brake fluid DOT classification, handling and storage requirementsReport a problem with this question

16. 16. On a rear drum brake with a cable-operated parking brake, the self-adjuster mechanism is found seized with rust and will not turn. What is the correct repair?

    • A.Replace the parking brake cable, since a tight cable is what seizes the adjuster
    • B.Clean or replace the adjuster, then lubricate its threads and socket✓ Answer
    • C.Set the shoes by hand at the widest setting and let the linings wear in to fit
    • D.Soak the adjuster in penetrating oil and reinstall it without removing the residue

    A seized adjuster cannot take up lining wear, so clearance grows and the pedal goes low. The adjuster screw is disassembled, cleaned or replaced, and its threads and socket lubricated so it turns freely; leaving penetrating oil on it attracts dust and it seizes again.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — inspecting and lubricating drum brake self-adjuster mechanisms and related hardwareReport a problem with this question

17. 17. Two technicians discuss brake rotor service. Technician A says a rotor should be machined to remove light scoring even when the finished thickness will fall below the discard specification. Technician B says an anti-lock system requires a rotor to be replaced any time the pads are replaced. Who is correct?

    • A.B only
    • B.A only
    • C.Both A and B
    • D.Neither A nor B✓ Answer

    A rotor may never be put back in service below its discard thickness, because the thinner casting cannot absorb heat and can crack, so cosmetic scoring is not a reason to cut past the limit. And a rotor that measures within specification with an acceptable surface is reused with new pads whether or not the vehicle has ABS.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — inspecting, measuring and servicing rotors; machine or replace decisionReport a problem with this question

18. 18. After a brake caliper is removed for pad service, what is the correct way to support it while the pads and hardware are out?

    • A.Rest it on the tire or the lower control arm and let the hose take up the slack
    • B.Clamp the flexible hose shut and set the caliper on the floor beside the rotor
    • C.Hang it from a hook or wire tied to a suspension member so the hose carries no weight✓ Answer
    • D.Let it hang by its flexible brake hose, which is built to carry the caliper's weight

    The flexible hose is a pressure line, not a support: hanging the caliper on it stretches the reinforcement and can crack the inner liner, producing a hidden restriction or a leak later. Hanging the caliper from a hook keeps the hose slack and unstressed.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — removing and replacing calipers and rotors, and inspecting brake hosesReport a problem with this question

19. 19. A technician has installed new pads and calipers and topped up the master cylinder, and the vehicle is still on the hoist. What must be done before the vehicle is driven?

    • A.Pump the brake pedal until it is firm so the pistons take up the pad clearance✓ Answer
    • B.Run the engine at idle for a minute so the booster builds its vacuum reserve
    • C.Rock the steering from lock to lock so the caliper slides settle into position
    • D.Apply the parking brake several times to centre the front pads in their brackets

    The pistons were pushed fully into their bores, so the first pedal apply only travels to close that gap and the pedal goes to the floor. Pumping the pedal before moving the vehicle seats the pads against the rotors and restores a firm pedal; skipping this step means no brakes on the first stop.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — installing pads and calipers, making final checks and adjustments before road testReport a problem with this question

20. 20. All of the following are correct steps when installing new disc brake pads EXCEPT: (This question contains the word EXCEPT. Read the question carefully before choosing your answer.)

    • A.Coating the friction face of each new pad with brake lubricant✓ Answer
    • B.Cleaning rust and scale from the caliper bracket abutments where the pads sit
    • C.Torquing the caliper and bracket fasteners to the manufacturer's specification
    • D.Fitting the new anti-rattle clips and abutment shims supplied with the pad set

    Lubricant never goes on a friction surface; grease on the pad face destroys the coefficient of friction and the pad must be discarded. Noise is controlled by new hardware, clean abutments and a thin film of lubricant on the pad backing ears and slides instead.

    Source: Official ASE Study Guide, Automobile Maintenance and Light Repair (G1), Brakes content area — installing pads, calipers and attaching hardware and lubricating the correct pointsReport a problem with this question

Practice questions based on the Test Specification and Task List published in the Official ASE Study Guide for the Automobile Maintenance and Light Repair (G1) test. ASE is a mark of the National Institute for Automotive Service Excellence; this site is not affiliated with or endorsed by ASE. ASE certification requires passing the test and documenting relevant work experience, and appropriate vocational training may count toward that experience — confirm current requirements with ASE before testing. No question here keys a manufacturer specification: torque values, clearances, pressures and capacities differ by vehicle, so any figure a question needs is given in the question itself, exactly as you would read it off a service manual on the job. About the ASE G1 test →