| Replacing Brakes |
| Worn-out brakes are replaced with new ones. |
From "Trade School"
episode DTRS-312 |
|
|
In this segment, student Jessica Kenney takes on a crucially important job—replacing a car's brakes.
1. To get started, Jessica raises the car on the lift, and then removes the front tire to expose the brake assembly (figure A). The assembly consists of two main parts; the rotor (disc), and the caliper. When the driver steps on the brake pedal, the caliper clamps onto the rotor, preventing the wheel from turning, which stops the car.2. At the parts washing station, Jessica gives the brake assembly a good cleaning (figure B). This chemical bath washes off any brake dust, making it easier to inspect the surface of the rotor. It's also important for the mechanic's safety--if inhaled, brake dust can be hazardous to your health.
3. After a quick visual inspection to check for pad wear and rotor damage, Jessica uses a socket wrench to unbolt the brake caliper. With the bolts removed, she lifts the caliper off of the rotor (figure C).4. Using a small pry bar, Jessica pops the old brake pads (also called brake linings) out of the caliper. If she can see metal rivets through the ceramic surface of the pads (figure D), they need to be replaced.
5. Before replacing the pads, Jessica inspects the brake rotor. She looks for rust, warping and other signs of wear. She then verifies the rotor's minimum thickness. This measurement is usually stamped on the inside of the rotor.6. After determining the rotor's minimum thickness rating, Jessica measures the actual thickness of the rotor using a micrometer (figure E). If the rotor is thicker than the minimum rating, she can resurface it with a lathe, and re-install it in the car. If the rotor has worn too thin, it will have to be replaced. This particular rotor is thick enough to resurface. 7. Jessica mounts the rotor securely to the lathe with steel cams, and then attaches a weight belt to the outside edge of the rotor (figure F). The belt insures that the rotor will spin evenly when the lathe is running.
8. Once the lathe is set to the proper measurements, Jessica turns it on (figure G). As industrial diamond cutting points grind the surface of the rotor, she keeps a close eye to make sure they are cutting evenly.9. Jessica shuts down the lathe, and then removes the rotor. It now has a new, even surface that's free of grooves or nicks (figure H), which allows the brake pads to grip more securely. She now replaces the resurfaced rotor on the car.
10. With the rotor back in place, Jessica can install the new brake pads. She coats the back of the pads with Brake Quiet, which is a gummy substance that prevents annoying brake noise.11. Before she can attach the new pads, Jessica needs to get the caliper piston out of her way. She uses a caliper piston retractor to push the piston back up into the caliper (figure I). 12. With the piston out of the way, Jessica installs the new pads. Metal clips secure the pad to the caliper—snapping in easily. She sets the caliper back onto the rotor, and then bolts it in place (figure J).
13. Jessica replaces the tire, and then tightens the lug nuts using a torque wrench. After replacing the process on the other front wheel, she takes the car out for a test drive. The new brakes work great, and the customer can look forward to many miles worth of use.
RESOURCES :
Emily Griffith Opportunity School
Website: www.egos-school.com
| 
)
)
)
)
)
)
)
)
)
)
