Exam 102: Disc Brakes Diagnosis and Service

On phenolic pistons, cracks that extend partially across the piston face are acceptable.

What is the technician doing in this illustration?

Use a screwdriver to remove caliper piston seals.

Technician A says that a steel piston should be cleaned with sandpaper to remove rust. Technician B says that brake assembly fluid or clean brake fluid should be used to lubricate the caliper pistons before installing in the caliper. Which technician is correct?

The surface finish is critical on the outside surface of caliper pistons.

What is not included with a loaded caliper?

Technician A says that a steel piston should have a greater piston-to-caliper bore clearance than a phenolic piston because the steel piston will expand when the brake fluid temperature increases during normal braking. Technician B says that the phenolic piston should have the greater clearance. Which technician is correct?

After removing the brake pads, hang the caliper by its brake hose.

A vehicle pulls to one side when braking. This could be caused by all of these EXCEPT ________.

A press-fit dust boot requires the use of ________ to install it.

A typical disc brake caliper overhaul (OH) kit usually includes what parts?

Rebuild the caliper if the dust boot is damaged in any way.

Which of these parts should be replaced when reassembling?

Technician A says that brake pad thickness is the only check that needs to be performed. Technician B says that pads can wear unevenly. Which technician is correct?

After a disc brake pad replacement, the brake pedal went to the floor the first time the brake pedal was depressed. The most likely cause was ________.

Two technicians are discussing ways of removing a caliper piston. Technician A says to use compressed air. Technician B says to use large pliers. Which technician is correct?

Technician A says that disc brake pads should be replaced when worn to minimal allowable thickness. Technician B says the pads should be removed and inspected whenever there is a brake performance complaint. Which technician is correct?

Uneven disc brake pad wear is being discussed. Technician A says the caliper piston may be stuck. Technician B says the caliper may be stuck on the slides and unable to "float." Which technician is correct?

A vehicle is hoisted during routine service and the service technician discovers that the left front wheel does not turn when force is applied. Technician A says that the hoist (lift) pads could be against the left front tire. Technician B says that there could be a brake fluid restriction between the master cylinder and the brakes. Which technician is correct?

A "chirping" noise is heard while the vehicle is moving forward, but stops when the brakes are applied. Technician A says that the noise is likely caused by the disc brake pad wear sensors. Technician B says the noise is likely a wheel bearing because the noise stops when the brakes are applied. Which technician is correct?