brake repairer air Interview Questions and Answers

1. What are the main components of a disc brake system?

   • Answer: A disc brake system typically includes a caliper, brake pads, a rotor (disc), brake lines, and a master cylinder. It may also include components like a brake booster and anti-lock braking system (ABS) components.

2. What are the main components of a drum brake system?

   • Answer: A drum brake system consists of a brake drum, brake shoes, wheel cylinders, and adjusting mechanisms. It also relies on linkages and the master cylinder.

3. Explain the difference between disc and drum brakes.

   • Answer: Disc brakes use calipers that squeeze pads against a spinning rotor, providing better heat dissipation and generally superior stopping power, especially at high speeds. Drum brakes use shoes that press against the inside of a rotating drum. Drum brakes are generally less expensive but offer less stopping power and are more prone to fading under heavy use.

4. How do you inspect brake pads for wear?

   • Answer: Visually inspect the pad material thickness, comparing it to the minimum thickness specified by the manufacturer. Also check for uneven wear, cracks, or glazing.

5. How do you inspect brake rotors for wear?

   • Answer: Check the rotor surface for scoring, grooves, cracks, or excessive runout (using a dial indicator). Measure the rotor thickness to ensure it's within the manufacturer's specifications. Excessive runout indicates the need for machining or replacement.

6. What is brake fluid and why is it important?

   • Answer: Brake fluid is a hydraulic fluid that transmits pressure from the master cylinder to the calipers or wheel cylinders. It's crucial for braking performance and must be compatible with the brake system's components. It should be checked regularly and flushed periodically to prevent contamination and maintain optimal performance.

7. What are the signs of low brake fluid?

   • Answer: Low brake fluid level in the master cylinder reservoir, a spongy brake pedal, or a warning light on the dashboard usually indicates low brake fluid. These may be indications of a leak, brake wear, or other issues.

8. How do you bleed brakes?

   • Answer: Bleeding brakes removes air bubbles from the brake lines. This is typically done by opening bleeder valves at each caliper or wheel cylinder while an assistant pumps the brake pedal. A specialized tool or tubing can be used to collect the fluid.

9. What tools are necessary for a brake job?

   • Answer: Basic hand tools (wrenches, sockets, screwdrivers), brake caliper piston compression tool, wheel chocks, jack and jack stands, torque wrench, brake fluid, and possibly a bleeder kit.

10. Explain the importance of using a torque wrench.

    • Answer: A torque wrench ensures that lug nuts and caliper bolts are tightened to the manufacturer's specifications. Over-tightening can damage components, while under-tightening can lead to loosening and failure.

11. What safety precautions should be taken when working on brakes?

    • Answer: Always use jack stands to support the vehicle, never rely solely on a jack. Wear safety glasses to protect eyes from flying debris. Use gloves to avoid skin irritation from brake fluid. Ensure proper ventilation when working with brake cleaner.

12. What is brake fade?

    • Answer: Brake fade is the reduction in braking effectiveness caused by overheating of the brakes. This often occurs during prolonged or heavy braking.

13. How do you diagnose a spongy brake pedal?

    • Answer: A spongy brake pedal usually indicates air in the brake lines, a leak in the system, or worn brake components. Checking the brake fluid level and bleeding the brakes are initial steps. A thorough inspection of brake lines, calipers, and wheel cylinders is needed to identify any leaks.

14. What is ABS and how does it work?

    • Answer: Anti-lock Braking System (ABS) prevents wheel lockup during braking, allowing the driver to maintain steering control. It uses sensors to monitor wheel speed and adjusts brake pressure to individual wheels to prevent skidding.

15. How do you test a brake light switch?

    • Answer: The brake light switch can be tested with a multimeter by checking for continuity when the brake pedal is depressed. A faulty switch will not complete the circuit.

16. What is the function of a brake booster?

    • Answer: A brake booster assists the driver in applying brake pressure by using vacuum from the engine to multiply the force applied to the brake pedal.

17. How do you diagnose a brake squeal?

    • Answer: Brake squeal is often caused by worn or glazed brake pads, contaminated brake rotors, or improper pad installation. Inspecting the pads and rotors for wear, and cleaning the components are typical solutions.

18. What is the importance of proper lubrication in brake systems?

    • Answer: Proper lubrication of brake components, such as caliper pins and slide pins, ensures smooth operation and prevents seizing or binding. However, it's crucial to avoid lubricating brake pad contact surfaces.

19. How often should brake fluid be flushed?

    • Answer: Brake fluid should be flushed every 2-3 years or according to the manufacturer's recommendations. This helps to remove moisture and contaminants that can degrade performance.

20. What are the different types of brake pads?

    • Answer: Brake pads come in various materials, including semi-metallic, ceramic, and organic. Each type offers different levels of performance, noise, and dust generation.

21. How do you properly dispose of used brake fluid and pads?

    • Answer: Used brake fluid and pads should be disposed of according to local regulations. Many auto parts stores accept used brake fluid for recycling, while pads might be accepted at hazardous waste facilities.

22. What is the procedure for replacing a brake caliper?

    • Answer: Replacing a brake caliper involves removing the old caliper, carefully compressing the caliper piston, installing new brake pads, mounting the new caliper, bleeding the brakes, and testing the brakes.

23. What is the procedure for replacing a wheel cylinder?

    • Answer: Replacing a wheel cylinder (in a drum brake system) involves removing the old cylinder, installing the new cylinder, ensuring proper sealing and bleeding the brakes.

24. How do you diagnose a brake pull?

    • Answer: A brake pull (vehicle pulling to one side during braking) can indicate uneven brake pad wear, a seized caliper, or a problem with the master cylinder. Inspecting the brake system components thoroughly is crucial for diagnosis.

25. What is the importance of proper wheel alignment after brake work?

    • Answer: Proper wheel alignment is important for safe and efficient driving. While not directly related to brake work itself, significant brake work, especially involving suspension components, may affect wheel alignment and should be checked.

26. How do you check for brake line leaks?

    • Answer: Visually inspect all brake lines for any signs of fluid leaks. You can also use brake fluid dye and a UV light to detect leaks if necessary.

27. What is the purpose of a parking brake?

    • Answer: The parking brake (emergency brake) secures the vehicle when parked to prevent unintended movement.

28. How do you diagnose a parking brake malfunction?

    • Answer: Diagnosing a parking brake malfunction may involve checking the cable for damage or looseness, inspecting the brake shoes or drum/rotor for wear, and checking the parking brake mechanism itself.

29. What are the signs of a failing master cylinder?

    • Answer: Signs of a failing master cylinder include a spongy brake pedal, low brake fluid, brake failure, or a hard brake pedal.

30. Describe the process of replacing a brake hose.

    • Answer: Replacing a brake hose involves disconnecting the old hose, attaching the new hose with proper fittings, bleeding the brakes, and checking for leaks.

31. Explain the importance of using the correct type of brake pads for a vehicle.

    • Answer: Using incorrect brake pads can result in poor braking performance, excessive noise, increased wear on rotors, and even brake failure.

32. How do you determine the correct brake parts for a specific vehicle?

    • Answer: Use the vehicle's identification number (VIN) or consult a parts catalog to find the correct brake parts.

33. What is the procedure for inspecting brake lines for corrosion?

    • Answer: Carefully inspect all brake lines for rust, pitting, or any signs of weakening or damage. Replace any lines that show signs of significant corrosion.

34. What are the potential consequences of neglecting brake maintenance?

    • Answer: Neglecting brake maintenance can lead to reduced braking performance, brake failure, accidents, and potentially serious injuries or fatalities.

35. How do you diagnose a pulsating brake pedal?

    • Answer: A pulsating brake pedal often indicates warped brake rotors. Inspecting the rotors for runout and checking for scoring or uneven wear are key to diagnosis.

36. What is the process of machining brake rotors?

    • Answer: Machining brake rotors involves using a lathe to remove a thin layer of material from the rotor surface to restore flatness and remove minor imperfections.

37. What are the limitations of machining brake rotors?

    • Answer: Rotors can only be machined a limited number of times before they become too thin and need to be replaced.

38. How do you inspect brake calipers for leaks?

    • Answer: Inspect the brake caliper for any signs of brake fluid leakage around the seals or bleeder valve.

39. How do you check for proper caliper piston retraction?

    • Answer: Check that the caliper piston retracts smoothly and fully when the brake pedal is released. Binding or sticking indicates a problem.

40. What is the importance of using a clean work area when servicing brakes?

    • Answer: A clean work area prevents contamination of brake parts and ensures safe and efficient brake repair.

41. What is the difference between front and rear brake systems?

    • Answer: Front brakes typically handle a larger portion of the braking force due to weight transfer during braking. Rear brakes provide additional stopping power and assist in directional stability. They may use different designs (disc or drum).

42. Describe the process of installing new brake shoes.

    • Answer: Installing new brake shoes in a drum brake system involves removing the old shoes, cleaning the drum, adjusting the automatic adjuster (if present), installing the new shoes, and ensuring proper adjustment.

43. How do you determine if a brake booster is faulty?

    • Answer: A faulty brake booster might result in a hard brake pedal, especially at low engine speeds, or a noticeable lack of assist when braking.

44. What safety measures should be taken when working under a vehicle?

    • Answer: Always use jack stands rated for the vehicle's weight. Never work under a vehicle supported only by a jack. Use wheel chocks to prevent accidental rolling.

45. Explain the importance of regularly inspecting brake components.

    • Answer: Regular inspection allows for early detection of wear and tear, preventing potential brake failures and ensuring safe operation.

46. What is the proper way to lubricate caliper pins?

    • Answer: Use a high-temperature, silicone-based brake lubricant specifically designed for caliper pins. Avoid using grease or other lubricants.

47. How do you diagnose a grinding noise coming from the brakes?

    • Answer: A grinding noise usually indicates metal-on-metal contact, likely due to severely worn brake pads, or foreign material in the braking system.

48. What is the process for replacing a master cylinder?

    • Answer: Replacing a master cylinder involves removing the old unit, bleeding the brakes, and installing a new unit and then bleeding the brakes thoroughly.

49. How do you check for leaks in the master cylinder?

    • Answer: Carefully inspect the master cylinder for any signs of brake fluid leakage around the seals or mounting points.

50. What is the importance of using the correct torque specifications when tightening brake components?

    • Answer: Using incorrect torque values can damage components, leading to unsafe braking conditions. Always consult a repair manual for correct torque specifications.

51. How do you check the condition of brake lines?

    • Answer: Visually inspect brake lines for damage, corrosion, kinks, or leaks. Squeeze lines to check for flexibility and resistance.

52. What is the proper procedure for removing a seized caliper piston?

    • Answer: Use specialized tools to carefully compress and remove a seized caliper piston. Penetrating fluid can help loosen a stuck piston.

53. Describe the different types of brake systems found on modern vehicles.

    • Answer: Modern vehicles often feature disc brakes on the front and either disc or drum brakes on the rear, possibly incorporating ABS, electronic brakeforce distribution (EBD), and other advanced systems.

54. How do you diagnose a soft brake pedal?

    • Answer: A soft brake pedal may indicate air in the brake lines, low brake fluid, a leak in the hydraulic system, or a faulty master cylinder.

55. What is the importance of proper wheel chocking?

    • Answer: Proper wheel chocking prevents the vehicle from rolling unexpectedly while working underneath it, ensuring safety.

56. How do you identify a leaking wheel cylinder?

    • Answer: Inspect the wheel cylinder for any visible signs of brake fluid leakage. Look for wetness, staining, or fluid dripping.

57. What are the safety hazards associated with brake repair?

    • Answer: Potential hazards include injury from moving parts, burns from hot brake components, eye injuries from flying debris, and exposure to hazardous brake fluid.

58. What are some common causes of brake noise?

    • Answer: Common causes include worn brake pads, glazed rotors, contaminated rotors, and debris in the brake system.

59. How do you prevent brake fade?

    • Answer: Prevent brake fade by avoiding prolonged or excessive braking, ensuring proper brake system maintenance, and using high-quality brake pads.

60. What is the importance of using a clean rag when working with brake components?

    • Answer: Using a clean rag prevents contamination of brake parts with dirt or other materials, ensuring efficient and safe brake repair.

61. How do you verify that brakes are working correctly after repair?

    • Answer: Thoroughly test brakes in a safe area, checking for consistent stopping power, absence of pulling, and proper pedal feel.

62. What are some signs that you need new brake rotors?

    • Answer: Signs include excessive runout, scoring, deep grooves, cracks, or exceeding the minimum thickness specified by the manufacturer.

63. Describe the procedure for installing new brake calipers.

    • Answer: Remove the old caliper, compress the piston (if necessary), install new brake pads, install the new caliper, bleed the brakes, and test the brakes.

64. How do you check for brake fluid contamination?

    • Answer: Check the brake fluid for discoloration, cloudiness, or the presence of debris.

65. What tools are necessary for bleeding brakes?

    • Answer: A wrench for the bleeder valves, clear tubing, a container to collect brake fluid, and a helper to pump the brake pedal.

66. What are some common mistakes made during brake repair?

    • Answer: Common mistakes include improper bleeding, incorrect torque values, improper installation of parts, and inadequate cleaning.

67. How do you check for leaks in the brake lines?

    • Answer: Inspect brake lines for fluid leakage, visual damage, and corrosion.

68. What safety precautions are necessary when working with brake components?

    • Answer: Wear safety glasses, gloves, and use proper ventilation. Use jack stands, and follow all manufacturer's instructions.

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