ASE A5 Flashcards
What is the most cost efficient method of correcting excessive lateral runout on a disc rotor?
Indexing, it involves moving the rotor position on the hub and rechecking the runout with a dial indicator. The number of wheel studs determines the number of possible positions to correct runout.
Which disc brake caliper design allows the brake pads to be removed without removing the caliper?
A fixed caliper, because the pads can be removed while the caliper is mounted in place.
What should be used to clean a disc brake rotor after it is machined?
Soap and water.
Technician A says that surge bleeding is used in conjunction with manual or pressure bleeding. Technician B says that surge bleeding is used to remove air that is trapped in the brake hydraulic system. Who is right?
Technician A is correct because surge bleeding can be used when manual or pressure bleeding doesn’t work.
Technician B is also correct because, surge bleeding churns the air in the wheel cylinder in order to loosen any pockets of air.
Both technicians are correct.
What should be used to determine if an intermittent ABS problem is related to an erratic wheel speed sensor signal?
Digital storage oscilloscope because it samples the electrical signal over 250,000 times per second.
When replacing disc brake pads, you must bottom the caliper piston in its bore to create room for the new pads. What is the proper procedure?
- Connect a hose to the caliper bleeder screw.
- Insert the other end of the hose into a container.
- Open the bleeder screw.
- Use a C-clamp to slowly bottom the piston.
Fine filing can be used to apply a non-directional finish to a disc brake rotor. True or False?
False, files are not used to apply a non-directional finish on a disc brake rotor.
A customer says that he has just replaced his front disc brake pads himself and now the ABS warning light is on. What could be the cause?
Damaged/incorrect wheel speed sensor and stuck ABS solenoid valves.
A complete front brake service has just been performed on a vehicle with disc brakes: rotors turned, calipers rebuilt, new brake pads, bearings repacked and adjusted. However, when the vehicle is road tested, a pulsation can be felt through the pedal. Over torqued lug nuts are the cause of the problem. True or False?
True, over tightening the lug nuts can distort the rotor and create excessive run out.
What is the correct wheel cylinder repair process?
Loosen the bleeder screw, disassemble, clean and hone, and clean and assemble
Vacuum should exist on the booster side but not on the engine side. True and False
True
When rough machining a brake drum, the depth of cut and spindle feed rate should be?
0.010-0.015-in at high feed rate.
Tech A says that DTCs can be accessed from any ABS system using flash diagnostics. Tech B says that ABS system tests can be performed with a bi-directional scan tool. Who is right?
Technician B is correct because a bi-directional scan tool can be used to perform tests on ABS system components.
Technician A is wrong, only a few ABS systems are compatible with flash diagnostics.
Tech A says that DOT 5 brake fluid has a lower boiling point than DOT 4. Tech B says that DOT 4 brake fluid is silicone based and should never be used in an ABS system. Who is right?
Both techs are wrong because DOT 4 has a lower boiling point than DOT 5, and DOT 5 is silicone based and should not be used in any ABS system.
A seized caliper piston could cause a pulsation to be felt in the brake pedal. True or False?
False because a seized caliper piston can cause a brake pull or a hard pedal, but it would not cause a pedal pulsation.
A driver complains that the ABS system on his car engages every time he applies the brakes on a cobblestone roadway he uses going back and forth to work. This condition concludes that:
The system is operating normally and the wheels are traveling at different speeds because on a cobblestone road the signals coming from the wheel speed sensors are not in sync with each other, the ABS system sees this as wheel lockup and responds by engaging the system.
The purpose of an anti-lock brake system is to maintain tire (wheel) slip at what level?
Between 10-20% level to achieve maximum braking effectiveness.
Absorption of 3% moisture can reduce the boiling point of DOT 3 brake fluid by what percentage?
25%
After applying the brake pedal several times to deplete the fluid reserve in the accumulator of a Hydro-Boost system, a technician applies the brake pedal with moderate pressure and starts the engine. What should the technician feel at the pedal if the Hydro-Boost system is operating properly?
The pedal should initially move downward before rising up.
Runout measurements can be performed using a micrometer. True or False?
False because runout is measured using a dial indicator.
Parallelism, thickness and taper can be measured with a micrometer.
Brake fluid leaking from a cracked brake line causes the brake light on the dashboard to come on in response to the loss of hydraulic pressure. Which valve in the hydraulic system switched on the light?
The pressure differential valve.
What kind of problem would be caused by using a residual check valve in a disc brake master cylinder?
Increased brake pad wear because it would cause the pistons to keep the pads applied even when the pedal is released.
Tech A says that a caliper seal installed in the caliper bore is called a stroking seal. Tech B says that when the brake pedal is released, the piston in the caliper moves back in its bore due to the action of the piston seal. Who is right?
Technician B is correct because the outward movement of the piston during braking causes the piston seal to distort. Once the brakes are released, the seal returns to its original shape forcing the piston to move back in its bore.
Technician A is wrong because a caliper seal installed on the PISTON is called a stroking seal.
Tech A says that all 3-channel ABS systems use only 3 wheel speed sensors. Tech B says that a 4-channel ABS system means that fluid pressure is independently regulated to each of the wheels during an ABS stop. Who is right?
Technician B is correct because a channel is an independently controlled fluid path from the hydraulic modulator to the wheel.
Technician A is wrong because a 3-channel system can have a speed sensor at each car wheel, even though there are only 3 individually controlled hydraulic circuits, two in the front and one in the rear.
Two technicians are discussing traction control systems. Technician A says that some traction control strategies do not use the brakes to control wheel spin. Technician B says that a fault in the ABS does not affect traction control. Who is right?
Technician A is correct, some manufacturers reduce power to the spinning wheels by retarding ignition timing, cutting off fuel injection to certain cylinders and mechanically closing the throttle.
Technician B is wrong, because the traction control uses the same components as the ABS.
Tapered wheel bearings are most commonly used on drive axles. True Or False?
False, tapered wheel bearings are used on NON-drive axles.
Tech A says that when rebuilding a caliper with a stroking seal, the condition of the caliper bore surface is critical. Tech B says that when rebuilding a caliper with a fixed seal, the condition of the piston surface is the most important consideration. Who is right?
Both technicians are correct because the caliper bore must be smooth to prevent leaks, and a fixed seal needs a surface in good condition to provide a good seal.
What is the purpose of the master cylinder residual check valve on vehicles equipped with drum brakes?
It prevents air from entering the hydraulic system by using low pressure to keep the lips of the piston cups tight against the cylinder walls.
When replacing an integral hub/bearing assembly on a fwd car, the steering knuckle must be removed. True or False?
False.
On a vehicle with single-piston floating caliper front disc brakes, the brake pads on the left side of the vehicle are almost completely worn while the right side is almost new. Technician A says that too much rotor runout could be the cause. Technician B says that a binding caliper piston could be the cause. Which technician is right?
Technician B is correct because a frozen caliper piston will keep its pads applied even when the pedal is released, this will also cause a front end pull.
Technician A is wrong because rotor runout will only cause a pulsating brake pedal.
Grease on the linings can cause disc brake squeal. True or False?
False, grease on the linings can cause the vehicle to pull when brakes are applied, but would not cause squeal.
Excessive slack in the parking brake cables can be eliminated on most vehicles by making an adjustment at the what?
Equalizer because by tightening its adjusting nut it is used to shorten one or more of the parking brake cables to remove slack.
A technician wants to check the condition of a vehicle’s brake fluid. Where should he get the sample to make the most accurate determination?
The brake caliper, because the heat generated while stopping breaks down the corrision inhibitors in the brake fluid.
During a brake inspection, an area of the vacuum brake booster below the master cylinder is found to be damp. Tech A says that this is normal. Tech B says that any evidence of fluid indicates a leak and the master cylinder must be replaced. Who is right?
Technician A is correct because a small amount of fluid present is normal due to the lubricating action of the master cylinder bore end seal.
Two technicians are discussing brake bleeding procedures. Technician A says gravity bleeding is a relatively quick way to bleed a brake system. Technician B says silicone brake fluid cannot be gravity bled. Who is right?
Both technicians are wrong.
Technician A is wrong because gravity bleeding is the easiest but more time consuming method of brake bleeding.
Technician B is wrong because gravity bleeding does not agitate the fluid and generate air bubbles, which is an advantage for systems with DOT 5 silicone fluid.
A blocked master cylinder compensating port can cause a vehicle to pull to one side when the brakes are applied. True or False?
False, a blocked master cylinder port could cause all brakes to drag but would not cause a brake pull.
Bench bleeding is a procedure for removing air from a hydraulic system. True or False?
False, bench bleeding is a procedure for removing air from the master cylinder only.
Leading-trailing type drum brakes are self energizing.
True or False?
False, because the fixed anchor on the backing plate prevents the shoes from transferring their force to one another.
The front disc brake pads are being replaced on a vehicle with composite rotors. The left front rotor is scored below the ‘machine to’ but not the ‘discard’ thickness. The right front rotor has minor heat checks but otherwise checks out OK. If cast rotors are the only available replacements, what is the proper course of action?
Replace both rotors, because composite and cast rotors should not be mixed on the same axle.
Minimum thickness should be used to determine the serviceability of a drum brake. True or False?
False, minimum thickness is checked only when inspecting a disc brake rotor.
A technician has just overhauled the front brakes on a vehicle with front disc and rear drum brakes. However, when he attaches a pressure bleeder (pressurized to about 25 psi) to the master cylinder, he cannot get any fluid to come out of the disc brake caliper bleeder screws. What is the problem?
The metering valve release button is not activated, because 25psi is too low to open the metering valve so you must manually open it by pushing the button. 75 - 125 psi is the required minimum pressure to open.
The MOST common cause for premature front brake pad wear in a disc/drum system is?
Improperly adjusted rear shoes.
Technician A says that any imperfection found in a phenolic caliper piston warrants replacement. Technician B says that a phenolic caliper piston should be protected with a block of wood when installing it into the caliper bore with a C-clamp. Who is right?
Technician B is correct.
Technician A is wrong because minor surface imperfections are OK as long as they do not enter the dust boot groove area.
While on a road test, a technician notices that the rear wheels lockup and the car skids when attempting to stop quickly from a high speed. The most likely cause of this problem is a defective?
A defective proportioning valve, because it can cause the rear wheels to lock and skid because the fluid pressure to the rear wheel cylinder would be unregulated.
A vehicle’s brake pedal is pumped rapidly 20 times and then held down. The master cylinder cover is then removed and when the pedal is released, a spout is seen coming form the reservoir. Tech A says that this indicates that air is trapped in the system. Tech B says that this means that fluid is being forced out of the cylinder bore through the compensating ports and is normal master cylinder operation. Who is right?
Technician A is correct because when there is air in the system pumping the brakes compresses it and when the pedal is released, the compressed ait pushes the hydraulic fluid back through the lines, causing a spout.
Technician B is wrong because a small spout should appear over the reservoir, only when the pedal is applied, not released.
A frozen star wheel can cause drum brake drag. True or False?
False, a frozen star wheel would prevent the automatic adjuster mechanism from working which would cause lining wear.
A wheel cylinder has been disassembled and corrosion and light scoring have been found in the bore. Technician A says the bore can be refinished using a small hone lubricated with cutting oil. Technician B says oversize pistons and cup seals can be installed if the hone removes too much material. Who is right?
Technician A is wrong, use only fresh clean brake fluid to lubricate the honing stones.
Technician B is also wrong, if the piston can be inserted with a 0.003-inch feeler shim in place, the cylinder is oversize and cannot be rebuilt.
Both technicians are wrong.
Technician A says that an integral ABS system is an add-on system. Technician B says that a non-integral ABS system is a high-pressure system. Who is right?
Technician A is wrong because only non-integral systems are considered add-on’s.
Technician B is wrong because non integral ABS systems are low-pressure.
Both technicians are wrong.
What tool should be used to measure the thickness of a scored rotor?
An outside micrometer with pointed anvil and spindle because its pointed tips fit into the grooves of scored rotors, accurately measure the thickness.
With foot pressure applied, the brake pedal on a vehicle with vacuum assisted power brakes moves down slightly when the engine is started. Tech A says that this condition can be caused by a leaking power brake booster diaphragm. Tech B says that the cause could be a faulty power brake booster check valve. Who is right?
Both technicians are wrong because if the pedal moves down slightly on a vehicle with vacuum assisted power brakes, everything is operating correctly.
Two techs are discussing the duo-servo type drum brake design. Tech A says the brake lining on the secondary shoe is usually longer and thicker than the brake lining on the primary shoe. Tech B says the primary shoe is installed toward the rear of the vehicle. Who is right?
Technician A is correct because the friction developed by the secondary lining is greater than the primary lining. So the secondary shoe is typically longer and thicker than the primary shoe. Technician B is wrong because the primary shoe is installed facing the direction of forward motion.
A few minutes after the engine was turned off on a vehicle with vacuum power assist, the brake pedal is applied and it is hard to push. Tech A says that this is normal. Tech B says that the booster check valve is leaking. Who is right?
Technician B is correct because the lack of power assist indicates that the check valve is leaking.
Technician A is wrong because there should be at least one power assist before the pedal gets hard to push.
Brakes that drag or fail to release can be caused by which of the following conditions in the master cylinder?
A clogged compensating port, because if it’s clogged it will create a pressure build up, which is what causes the brakes to drag or fail to release.
A leaking check valve can cause a problem in the Hydro-Boost system. True or False?
False, a check valve is used on a vacuum power booster, hydro boost system uses power steering pump fluid.
Which component in the Hydro-Boost system provides power assist if there is a loss of hydraulic pressure to the system?
The accumulator, it can supply enough power assist for two stops if there is a loss of hydraulic pressure.
What 3 brake symptoms can be caused by wheel bearing problems?
Pedal pulsation, brake pull and grabbing.
Technician A says the rear brake shoes should be properly adjusted before adjusting the parking brake. Tech B says the parking brake lever should be disengaged before adjusting the equalizer. Who is right?
Technician A is correct because the brake shoes must be correctly adjusted for the parking brake to work properly.
Technician B is wrong because the parking brake lever must be engaged a number of clicks before adjusting the equalizer.
A seized wheel cylinder could cause a parking brake to not hold a vehicle on a grade. True or False
False, the parking brake system engages the rear brakes mechanically; a seized wheel cylinder would not affect parking brake operation.
The hydraulic system on a vehicle with integral ABS is to bled. Tech A says that the front brakes can be bled in a conventional manner. Tech B says that both front and rear brakes can only be bled using the pressure from a fully charged accumulator. Who is right?
Technician A is correct since it is the booster piston that supplies fluid to the front brakes.
Technician B is wrong because only the rear circuit needs a fully charged accumulator.
Two technicians are discussing Electronic Stability Control (ESC) systems. Technician A says the ESC control module uses inputs from the steering wheel rotation sensor and wheel speed sensors to calculate the driver’s intended path. Technician B says the ESC control module uses inputs from the lateral acceleration and yaw rate sensors to calculate the vehicle’s actual path. Who is right?
Both technicians are correct.
Technician A says as brake fluid ages, it can corrode ABS control valves. Technician B says brake fluid corrodes the copper in the brake lines. Who is right?
Technician B is correct.
The driver of a vehicle with power disc/drum brakes says that the brake pedal moves slowly to the floor while maintaining pedal pressure at a stoplight. What could cause this problem?
A leaking primary piston cup in master cylinder
A front brake hose is being replaced. On this type of hose, the male end threads directly into the caliper. Technician A says the end of the hose that attaches to the steel brake line should be connected first. Technician B says that a new copper sealing washer should be used when the hose is connected to the caliper. Who is right?
Technician B is correct.
Technician A is wrong because the male end of the hose should be connected and tightened first. If the female end of the hose is connected to the brake line first, the hose will twist when it is threaded into the caliper.
A leak in the brake hydraulic system could cause a hard brake pedal on a vehicle with power brakes. True or False
False because a leak would cause a soft pedal. A frozen caliper would prevent retraction of the piston resulting in a hard pedal.
Tech A says that ABS wheel speed sensor gap should be adjusted with a non magnetic feeler gauge. Tech B says that a paper spacer can be used to adjust ABS wheel speed sensor gap but the paper must be removed before the vehicle is operated. Who is right?
Technician A is correct.
Technican B is incorrect because it is not necessary to remove the paper spacer, it is designed to wear off during vehicle operation.
A vehicle’s ABS warning light is on and a DTC for the left front wheel speed sensor is found in the computer’s memory. When check with an oscilloscope, the waveform for the left wheel speed sensor is erratic and uneven. Technician A says the sensor air gap is excessive. Technician B says the tone ring is probably damaged. Who is right?
Technician B is correct, a tone ring with chipped or damaged teeth will cause an erratic, uneven waveform.
Technician A is wrong, excessive air gap would cause a low amplitude wave-form.
A customer complains that the brake warning light comes on whenever the brake pedal is depressed while driving. A short to ground in the warning light circuit is the issue. True or False?
False because a short to ground would cause the light to stay on all the time even without the pedal being pressed.
A leak would cause the light to come on when the pedal is pressed because it causes unequal pressure to be applied to one side of the pressure differential piston.
A customer complains that their vehicle pulls to the right when the brakes are applied. Tech A says a restricted brake line to the left caliper can cause this problem. Tech B says a malfunctioning proportioning valve is probably the cause. Who is right?
Technician A is correct because a restriction will cause a drop in fluid pressure to the affected caliper which will cause the caliper to not have as much force as the other side, so the car will pull to the side where the brake force is greatest which would be the right side.
A customer complains that the parking brake will not keep his car stationary. The car has four wheel disc brakes. Technician A says the caliper levers could be out of adjustment. Technician B says the brake shoes could need adjustment. Who is right?
Both technicians are correct.
