The Ultimate Guide to How to Double Flare Steel Brake Line: Tips and Tricks

Are you ready to tackle your brake line repair project with confidence? Knowing how to double flare steel brake lines is essential for any DIY mechanic or car enthusiast looking to achieve a professional-grade repair. This guide will walk you through the entire process, from understanding the fundamentals to mastering the technique.

Why Double Flare?

Before we dive into the details, let’s clarify why double flaring is the preferred method for steel brake lines. Unlike single flares, which create a single, 45-degree bend at the end of the line, double flares involve two distinct bends:

• First Flare: A 37-degree flare that creates a slight bulge at the end of the line.
• Second Flare: A 45-degree flare that forms a larger, more pronounced bulge, creating a secure and leak-proof connection.

This double-flaring technique provides several advantages:

• Enhanced Strength: The double flare creates a stronger and more durable connection, reducing the risk of leaks and ensuring a reliable braking system.
• Improved Seal: The two flares work together to create a tight seal between the brake line and the fitting, preventing fluid leakage and maintaining optimal braking performance.
• Reduced Risk of Damage: The double flare is less susceptible to damage during installation, as the thicker flare provides added protection.

Gathering Your Tools

Before you begin, ensure you have the following essential tools:

• Double-Flaring Tool: This specialized tool is designed to create the two distinct flares needed for a secure connection.
• Tubing Cutter: This tool provides clean and precise cuts on the brake line, preventing ragged edges that can hinder flaring.
• Pipe Wrench: Use this wrench to tighten the fittings onto the flared brake line.
• Degreaser: Clean the brake line and fittings thoroughly with a degreaser to remove any contaminants that could interfere with the seal.
• Safety Glasses: Protect your eyes from flying debris during the flaring process.
• Gloves: Wear gloves to prevent skin irritation from brake fluid or metal shavings.

Preparing the Brake Line

Now that you have your tools ready, it’s time to prepare the brake line for flaring. Follow these steps:

1. Cut the Brake Line: Use the tubing cutter to make a clean, square cut at the desired length. Ensure the cut is perpendicular to the line to avoid uneven flaring.
2. Deburr the Cut End: Use a deburring tool or a fine-grit sandpaper to remove any sharp edges from the cut end. This will prevent damage to the flaring tool and ensure a smooth flare.
3. Clean the Line: Thoroughly clean the brake line with a degreaser to remove any dirt, oil, or grease that could affect the flaring process.

The Double Flaring Process

With the brake line prepared, you’re ready to perform the double flare:

1. Insert the Brake Line: Place the brake line into the flaring tool, ensuring it’s securely positioned and centered.
2. Create the First Flare: Using the appropriate die for the first flare (typically 37 degrees), slowly turn the handle of the flaring tool to create the initial bulge.
3. Create the Second Flare: Once the first flare is complete, switch to the die for the second flare (typically 45 degrees) and continue turning the handle to create the larger, final flare.
4. Inspect the Flare: Carefully inspect the finished flare to ensure it’s smooth, even, and free of any defects. A properly flared end should have a distinct, pronounced bulge.

Installing the Flared Line

With the brake line successfully flared, it’s time to install it:

1. Prepare the Fitting: Clean the fitting thoroughly with a degreaser and ensure it’s free of any debris.
2. Thread the Fitting: Thread the fitting onto the flared end of the brake line, but do not tighten it completely.
3. Tighten the Fitting: Use the pipe wrench to tighten the fitting onto the flared brake line. Be careful not to overtighten, as this can damage the flare or the fitting.
4. Check for Leaks: Once the fitting is securely tightened, check for any leaks by applying pressure to the brake system. If you notice any leaks, re-tighten the fitting or re-flare the line if necessary.

Tips for Success

Here are a few tips to help you achieve a successful double flare:

• Use the Right Tools: Invest in a high-quality flaring tool designed specifically for steel brake lines.
• Practice Makes Perfect: Before working on your car, practice flaring on scrap brake line to get a feel for the process.
• Lubrication: Apply a light coating of brake fluid or special flaring lubricant to the line before flaring to reduce friction and prevent damage.
• Patience: Take your time and avoid rushing the process. A rushed flare is more likely to be uneven or damaged.
• Cleanliness: Maintain a clean work area and ensure all tools and components are free of debris.

Beyond the Basics: Additional Considerations

While this guide provides a solid foundation for double flaring steel brake lines, there are a few additional considerations for advanced applications:

• Line Material: Different brake line materials may require different flaring techniques and tools. Consult the manufacturer’s specifications for the appropriate flaring procedure.
• Line Size: The size of the brake line will determine the appropriate die and flaring tool to use.
• Fitting Type: The type of fitting (e.g., compression, flare, banjo) will influence the flaring process and the required tools.
• Safety: Always prioritize safety when working with brake lines and fluids. Wear appropriate safety gear and follow recommended procedures.

Final Thoughts: Embracing the Art of Brake Line Repair

Mastering how to double flare steel brake lines is an essential skill for any DIY mechanic or car enthusiast. By understanding the process, gathering the right tools, and following the steps outlined in this guide, you can confidently tackle brake line repairs and maintain a safe and reliable braking system. Remember, practice makes perfect, so don’t hesitate to experiment and refine your technique for optimal results.

Answers to Your Questions

Q: Can I use a single flare for brake lines?

A: While single flares are sometimes used for other applications, they are not recommended for brake lines due to their weaker seal and increased risk of leaks.

Q: What if I overtighten the fitting?

A: Overtightening can damage the flare or the fitting, leading to leaks or even a broken line. If you suspect overtightening, loosen the fitting and re-tighten it carefully.

Q: How often should I check my brake lines for leaks?

A: It’s a good practice to inspect your brake lines for leaks during regular maintenance checks, especially if you notice any changes in braking performance or fluid levels.

Q: Is it safe to drive with a leaking brake line?

A: No, it’s not safe to drive with a leaking brake line. A leak can lead to a loss of brake fluid, compromising your braking ability and potentially causing an accident.

Q: Can I use a flaring tool designed for copper lines on steel brake lines?

A: It’s not recommended to use a flaring tool designed for copper lines on steel brake lines. Steel lines require a different flaring angle and tool to achieve a secure and leak-proof connection.