Brake And Fuel Lines: When To Change Them Together

Whether brake lines and fuel lines should be changed together depends on the specific application and requirements. While both types of lines are crucial for the safe operation of a vehicle, they serve different purposes and have distinct characteristics. Brake lines are typically made of steel or stainless steel and are designed to withstand high pressures of up to 1000-2000 psi. On the other hand, fuel lines can be made of different materials such as steel, aluminium, or rubber, and they operate at significantly lower pressures of around 30-60 psi. It is important to note that using the wrong type of hose for brake fluid can lead to leakage and damage over time, so it is recommended to use brake fluid hose for brake lines. When building a street rod, kit car, or upgrading a classic muscle car's brake system, custom-bent and terminated hard lines for both the brake and fuel systems may be required. In such cases, having the right tools and practising the bending and flaring process is essential.

Fuel and brake lines are not interchangeable

While it may be tempting to use a brake line as a fuel line, or vice versa, it is important to remember that fuel and brake lines are not interchangeable. This is because there are important differences between the two types of lines in terms of their composition, diameter, and intended use.

First and foremost, fuel lines and brake lines are made of different materials. Fuel lines are typically made of mild steel, stainless steel, or aluminum, while brake lines are usually made of galvanized mild steel, soft steel, stainless steel, or a nickel-copper alloy. The choice of material is important because it affects the line's resistance to corrosion and its ease of bending and flaring. For example, stainless steel lines are impervious to rust but are more expensive and difficult to flare, while soft steel lines are easier to bend but may not offer the same durability as other materials.

Another key difference between fuel and brake lines is their diameter. Brake lines tend to have a smaller diameter than fuel lines, which means they cannot allow the same volume of fluid to flow through. This could potentially lead to fuel starvation if a brake line is used in place of a fuel line.

Additionally, fuel and brake lines serve different purposes in a vehicle. Fuel lines are designed to transport fuel from the tank to the engine, while brake lines are responsible for delivering brake fluid to the brake calipers or wheel cylinders. These different functions require different specifications and performance characteristics, further emphasizing the need for dedicated fuel and brake lines.

It is also worth noting that, while some people have reported using brake lines for fuel lines without encountering problems, this does not mean it is a safe or recommended practice. Brake fluid can seep through fuel lines over time, and using the wrong type of line could lead to leaks, deterioration, or other issues. Therefore, it is always best to use the appropriate type of line for its intended purpose.

In conclusion, while it may be tempting to substitute one type of line for another, fuel and brake lines are specifically designed for their respective functions and should not be interchanged. Doing so could compromise the performance, safety, and reliability of a vehicle's fuel and brake systems.

The difference in pressure between fuel and brake systems

The brake and fuel systems in a car are two distinct and separate systems, each with its own unique function and components. While it is rare to change the brake and fuel lines together, there are instances where one might consider doing so, such as when building a street rod or kit car, or upgrading an old braking system.

One key difference between these systems lies in the pressure they generate and operate under. Brake systems operate at much higher pressures than fuel systems. Brake line pressure, or the hydraulic force that actuates the braking system when the brake pedal is pushed, can range from less than 800 psi under normal conditions to as high as 2000 psi during a maximum effort. On the other hand, fuel systems operate at significantly lower pressures, typically in the range of 30-60 psi. This disparity in pressure is due to the differing functions of the two systems.

The braking system's primary purpose is to slow down or stop the vehicle by converting the car's kinetic energy into thermal energy during deceleration. This process generates a substantial amount of heat, which then needs to be dissipated into the surroundings and the air stream. To achieve this, the braking system relies on the hydraulic force created by the brake line pressure.

In contrast, the fuel system's function is to deliver fuel from the tank to the engine. This requires a lower-pressure system compared to the braking system. The fuel pump generates enough pressure to ensure a steady flow of fuel to the engine, but it does not need to reach the same levels as the brake system.

It is important to note that while the brake system operates at higher pressures, it does not mean that the lines themselves have different wall thicknesses. The difference in pressure is due to the specific requirements of each system rather than the physical characteristics of the lines.

In summary, the brake and fuel systems in a car serve distinct purposes, and the difference in pressure between them is a result of these differing functions. The braking system operates at higher pressures to facilitate the conversion of kinetic energy into thermal energy during deceleration, while the fuel system operates at lower pressures to ensure a steady flow of fuel to the engine.

The importance of using the correct tools when fabricating lines

Power and Weight Considerations:

An undersized or underpowered tool may struggle to heat the material sufficiently, resulting in incomplete or weak welds. While decreasing the speed of the machine can sometimes compensate for a lack of power, it often leads to subpar results. The thickness of the fabric being welded also plays a role, as more weight is required to ensure a proper weld. Adding supplementary weights beyond the manufacturer's recommendations can overwork the machine, leading to frequent breakdowns.

Speed and Precision:

The correct tools enable faster and more precise fabrication. For long, straight welds, a machine capable of higher speeds is advantageous. Conversely, for welding curved seams or shorter lengths, a slower machine that allows for fine-tuning can be more suitable. Additionally, the right tools ensure precision in creating bends, flares, and connections, reducing the risk of leaks and ensuring optimal fluid flow.

Efficiency and Cost-Effectiveness:

Using the correct tools can also improve efficiency and reduce costs. Specialized tools, such as tubing cutters, create clean cuts and help maintain a debris-free environment, reducing the risk of damage to sensitive components. Utilizing tools like tube benders and flaring tools allows for accurate bending and flaring, minimizing the need for adaptations or corrections.

Safety:

Using the correct tools is crucial for safety. For example, in brake and fuel line fabrication, using the wrong type of hose can lead to brake fluid seeping through and deteriorating the rubber over time. The correct tools and materials help prevent leaks and ensure the integrity of the lines, reducing the risk of accidents and costly repairs.

In summary, using the correct tools when fabricating lines is essential for achieving high-quality, safe, and long-lasting results. It improves efficiency, reduces costs, and ensures the proper functioning of the fabricated lines. By investing in and utilizing the right tools, fabricators can deliver reliable and dependable products.

The types of flares used for brake and fuel lines

There are two basic types of flares used for brake lines: the SAE/double (inverted/45-degree) flare and the DIN/ISO bubble flare. The SAE flare is the most common, found in all American and Asian cars, while the DIN flare is typically found in European cars. The SAE flare has a tiny funnel shape at the end of the brake line, with the backside of the flare at a 45-degree angle. On the other hand, the DIN flare has an end that resembles a button, with a 90-degree backside angle.

For fuel lines, the type of flare used depends on personal preference and experience. The 37-degree flare is a single flare process that requires a tube sleeve to support the backside of the flare, while the 45-degree inverted flare is a two-step process that creates a double-walled flare seat. The 45-degree flare is the most common style used in automotive hard lines like fuel lines. It is important to note that the 37-degree flare is often associated with high-performance components, while the 45-degree flare is more common with stock components.

The process of bending lines to match your template

Bending lines to match your template is a process that requires careful planning and the right tools. Here is a step-by-step guide on how to do it:

Firstly, it is important to have a template to work with. If you are replacing an existing line, you can use it as a template. If not, you can create one using a wire coat hanger, a stiff wire, or welding wire. These materials are ideal because they hold their shape and are easy to handle. When creating a template, consider any potential hazards the line might encounter, such as rubbing points on the frame or moving suspension parts.

Once you have your template, you can start planning the bends in your new line. Mark the tubing at the start of each bend and use a tubing bender to carefully bend the line to match the template. It is important to be patient during this process, as it may take a few attempts to get perfect bends, especially if your line has multiple twists and turns. Take your time and work precisely to ensure that your new line matches the template as closely as possible.

When bending the line, start at one end and work your way down, matching each bend in the template. It is crucial to get the bends in the correct places to ensure proper fitment and prevent interference with other parts. Take measurements and double-check your work as you go to avoid mistakes. Remember that copper or copper-nickel brake lines can be bent and adjusted by hand, but steel brake lines require special tools to prevent kinking.

After you have bent each section of the line, compare it to your template to ensure they match. Check that the bends are in the correct positions and that the line has the proper flares and flare nuts on both ends. If you are satisfied with the results, you can proceed to the next step of installing the new line and bleeding the brake system.

Finally, always check for leaks after installing a new line or brake components. Any leaks in the brake system are dangerous and should be repaired immediately.

Frequently asked questions