Automobile & Light Truck Certification Test A5 BrakesDrum Brake Diagnosis and RepairEasy
A technician is inspecting a drum brake assembly. They notice that the brake drum has several hairline cracks radiating from the hub area. What is the MOST appropriate action for the technician to take?
- AMachine the drum to remove the cracks, as long as it remains within the maximum diameter specification.
- BFill the cracks with a high-temperature epoxy and reinstall the drum.
- CContinue using the drum if the cracks are less than 1/4 inch in length.
- DReplace the brake drum, as cracks indicate structural integrity loss.
Show answer & explanationAnswer & explanation
Correct answer: D. Replace the brake drum, as cracks indicate structural integrity loss.
Hairline cracks in a brake drum indicate a loss of structural integrity and can lead to catastrophic failure. Machining will not remove the underlying stress points, and filling them is not a safe repair. Replacement is the only safe and appropriate action.
Why the other options are wrong
- A. Machining will not remove cracks that indicate structural weakness; it can worsen the situation.
- B. Epoxy is not designed for the high temperatures and stresses of brake drums and will fail.
- C. Any cracks, regardless of length, compromise drum integrity and necessitate replacement.
Brake Drum Cracks
Hairline cracks in a brake drum indicate a severe structural integrity issue, often caused by excessive heat or stress.
- Cracks compromise drum strength.
- Can lead to drum failure during braking.
- Requires immediate replacement.
Memory trick: Cracked drum, don't be numb, replace it, or doom will come.