How to Identify and Choose the Right Brake Line Fittings

Written by Vince Lockwood | Fri, Mar 30, 2012 @ 10:43 PM

Understanding how to identify and choose the right brake line fittings is crucial for maintaining your vehicle's brake system. This guide will walk you through the different types of brake line fittings, how to identify them, and tips for selecting the best options for your needs.

Types of Brake Line Fittings

Standard Brake Line Fittings

Typically used in domestic vehicles, these feature straightforward designs compatible with most brake systems in North American cars.

Metric Brake Line Fittings

Common in European and Asian vehicles, measured in millimeters with different thread pitches compared to standard fittings.

AN (Army-Navy) Fittings

Used in high-performance and racing applications, known for precision and durability under extreme conditions.

ISO Flare Fittings

Often found in European and Japanese vehicles, these fittings have a 45-degree flare and are used with metric brake lines.

Double Flare Fittings

Common in domestic vehicles, these fittings involve two flares to create a stronger seal, often used in high-pressure applications.

DIN Flare/Mushroom Fittings

Used in some European vehicles, these fittings have a distinctive mushroom-like shape and are critical for certain hydraulic systems.

Brake Line Fitting Identification Table

Fitting Type	Description	Common Applications	Measurement Standards
Standard	Hexagonal shape, simple design	Domestic vehicles	Imperial (inches)
Metric	Precise measurements in millimeters	European and Asian vehicles	Metric (millimeters)
AN	Flared design, high precision	High-performance and racing	Imperial (AN specs)
ISO Flare	45-degree flare, metric lines	European and Japanese vehicles	Metric (millimeters)
Double Flare	Double flare for strong seal	Domestic vehicles	Imperial (inches)
DIN Flare	Mushroom-shaped flare	European vehicles	Metric (millimeters)

How to Identify Brake Line Fittings

Visual Identification

Look for specific markings or shapes that differentiate the types of fittings. For example, standard fittings often have a simple hexagonal shape, while AN fittings might have distinctive flares. ISO and DIN flares have unique flare shapes that can be visually identified.

Measurement Techniques

Use calipers to measure the diameter and thread pitch of the fitting. Accurate measurements will help determine the exact type of fitting needed.

Diameter Measurement: Measure the outer diameter of the fitting.
Thread Pitch Measurement: Measure the distance between threads.
Compare Measurements: Use standard sizes to identify the fitting.

Detailed Brake Line Fitting Specifications

Fitting Type	Diameter (inches/mm)	Thread Pitch (TPI/mm)	Application
Standard	0.25 - 0.5 inches	20 - 28 TPI	Domestic
Metric	6 - 12 mm	1.0 - 1.5 mm	European/Asian
AN	0.25 - 0.5 inches	16 - 24 TPI	High-performance
ISO Flare	6 - 10 mm	1.0 - 1.5 mm	European/Japanese
Double Flare	0.25 - 0.5 inches	20 - 28 TPI	Domestic
DIN Flare	8 - 12 mm	1.0 - 1.5 mm	European

Tips for Choosing the Right Brake Line Fittings

Understand Your Vehicle's Requirements: Check your vehicle’s manual or consult a professional.
Consider the Application: High-performance or specific European applications may require AN, ISO, or DIN fittings.
Quality Matters: Choose high-quality fittings for safety and longevity.
Compatibility: Ensure compatibility with your brake lines and other components.

Conclusion

By understanding the different types of brake line fittings and how to identify them, you can ensure your vehicle's brake system is properly maintained. If you have any questions or need further assistance, feel free to leave a comment below.

Posted by Marek Bobik & Vincent Lockwood

This article was originally published March 30, 2012, and was last updated September 6, 2024.

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