Automobile & Light Truck Certification Test A5 BrakesHydraulic System Diagnosis and RepairHard
A technician is installing new steel brake lines on a vehicle. They are using a double flaring tool to create the correct flare type for the connections. After creating the flare, the technician notices that the flare appears uneven and slightly cracked at the base. What is the MOST likely cause of this issue?
- AThe flaring tool was tightened excessively during the first stage.
- BThe flaring tool die was too large for the brake line diameter.
- CThe brake line was not properly deburred before flaring.
- DThe brake line material is too soft for a double flare.
Show answer & explanationAnswer & explanation
Correct answer: C. The brake line was not properly deburred before flaring.
An uneven or cracked flare, especially at the base, is often caused by a burr on the inside edge of the brake line. This burr prevents the flare from forming smoothly and can lead to stress concentrations and cracks. Deburring ensures a clean, smooth edge for flaring.
Why the other options are wrong
- A. Excessive tightening might deform the line, but a crack at the base is more indicative of material stress from an uneven surface.
- B. A die that's too large would likely result in an incomplete or loose flare, not an uneven/cracked one.
- D. Standard automotive brake lines (steel) are designed for double flares; if too soft, it might deform excessively but less likely to crack than with a burr.
Brake Line Deburring
Deburring the inside and outside edges of a cut brake line is a critical step before flaring to ensure a smooth, concentric, and crack-free flare.
- Cutting a brake line creates burrs on the edges.
- Internal burrs interfere with material flow during flaring.
- Burrs can cause uneven, weak, or cracked flares.
- Proper deburring ensures a strong, leak-free connection.
Memory trick: A rough edge makes a rough flare; smooth it first.