Double Flare vs Single Flare: Comparison of Two Brake Lines

This double flare vs single flare brake line comparison is for car owners who might be confused about their distinction. Brake lines are vital components of the braking system of every vehicle, and they are mostly attached to the cylinders and engine.

Double Flare vs Single Flare

These lines are either flexible or rigid, and flares are used to keep them in place. Double flares and single flares are options that share some similarities and differences, all of which we have highlighted in this comprehensive guide.

Features Double Flare Single Flare
Material and Durability Made from steel or galvanized pipes, which makes them reliable, durable, stable, and strong Made from stainless steel and galvanized steel pipes, which means they are less durable
Pressure Resistance Resists cracks due to high pressure Cannot resist cracks caused by high pressure
Reliability More reliable because of its strength and durability Less reliable

What Are the Differences Between Double Flare and Single Flare?

The main difference between double flare and single flare brake lines is that double flare provides superior leak prevention and resistance from the brake line’s pressurized environment. Using a single flare in this highly pressurized environment is dangerous. They are illegal to use on the brake lines of cars.

There are other factors that distinguish the two flare plugs, and we’ll have a deeper look at these factors to enhance your understanding.

These factors include the following:

– Material and Durability

Single flare plugs are not used for braking due to their inability to withstand high pressure. The preferred materials for this purpose are galvanized steel and stainless steel pipes.

On the other hand, double flare plug materials are made from galvanized or steel pipes, which gives them higher reliability, durability, stability, and strength. This is also a reason why they are popular and an ideal option for withstanding high-pressure within braking systems.

– Pressure Resistance

The main factor that determines their pressure resistance is the materials they are made from. As mentioned earlier, double flares have a higher pressure resistance than single flares.
Therefore, you’ll expect the single flare to break and crack easily when subjected to high pressure, while the double flare can effectively resist the effects of high pressure without breaking or cracking.

– Alternative Names and Temperature

The alternative name for a double flare plug is DIN/ISO, while single flare doesn’t have other names. Also, the temperature of a single flare is generally lower than that of a double flare, which is why they are generally not recommended for use.

– Popularity

Single flare plugs are generally insufficient when it comes to how they handle braking system pressures. This affects its popularity, as not many people know about the flare. Also, it has a higher potential to cause brake failures and leaks to occur. On the other hand, double flares are robust and can withstand different extreme conditions, and this is why they are more popular.

– Best Brake Lines

As mentioned earlier, double flare brake lines are more reliable, more durable, and stronger, and their ability to withstand extreme pressures causes them to last for a longer period. On the other hand, single flares are low-pressure brake lines and outdated technology. They generally underperform in extreme conditions, and this is why they are not in use today.

Brake lines should not be single flare because they won’t provide a secure connection, and it’s more susceptible to rust and corrosion build-up. Also, they can easily crack, thereby causing the brake fluid to leak and decrease in braking power. Today, most cars come with double brake line flares, especially those from the Asian and US markets. These flares are also referred to as SAE or inverted flares.

– Reliability

Single flares generally offer more sensitivity to thermal stresses and vibrations, and this application in automotive is limited because they are unreliable. That’s not the case with double flares, as they are strong and reliable. They are designed to be strong and robust, which further enhances their reliability.

– Identifying Brake Flares

Knowing how to identify the two flares is important, especially when you want to replace them without consulting a mechanic. If your car uses a single brake line flare, you’ll need to get a replacement as fast as possible for your safety and that of other road users. This is because the protection offered by a single brake flare is not sufficient to withstand leaks, and it makes them more susceptible to damage.

The first thing to look out for when identifying the flares is the presence of a cone shape at the top. This is an indication that it’s a single flare, especially if the seal around the brake line is not tight enough. On the other hand, double brake flares feature a doubled-over top lip with a 45-degree angle at the back.

You can also identify them easily from the port that connects the brake lines. Another thing to note is that the interior part of the connection port in double flare features a tread pattern similar to an erupting volcano. If your car is from the Asian or US car market, it will most likely come with double brake line flares.

What Are Double Flares Characteristics and Specifications?

Double flares characteristics and specifications include its application in braking systems together with a female socket and an inner side that pops like a volcano. This is to provide a tight seal and prevent leaks from occurring. It also allows for superior resistance in environments with high pressure.

Characteristics of Double Flares

They are now one of the most popular brake line flares that are applied in most American and Asian vehicles. The double brake line flares feature a 45-degree backside with a connection that is like that of a funnel extending to the tubing. They are also called inverted or SAE flares, and like the single brake line flare, they have the same cone-shaped lip.

However, the lip in the double brake line flare is folded into and over the flare, and this allows it to create a secure connection point. Another reason why it is popular and the most preferred choice used on most vehicles is because of the unrivaled durability and strength it offers, especially when it is correctly secured to the female socket. With this connection, they can easily and effectively withstand pressures of high levels.

What Are Single Flares Characteristics and Specifications?

Single flares characteristics and specifications include a single lip that is not folded over like in double brake line flares. However, it can fit similar sockets like double flares, but they are not always applied in braking systems for safety reasons since they can’t withstand high pressure.

Single Flares Specifications

In some places like the United States, the use of single brake line flares in vehicles is illegal. Even though they are widely available on the market, it’s important to note that they are not a safe addition to include in your braking system. Unlike double flares, this type of flare does not resist high pressure, and this causes it to leak and crack easily.

Brake fluid leakages through the flare connection make it harder to apply pressure to the brake pads and caliper. With that, stopping the car becomes difficult. The shape of the single flare is like that of a double, but their lips around folded over, and they take the shape of an open cone.

Even though they are generally not used in the brake lines of cars, they are great for conditions that don’t require high pressure. An example of a low-pressure application of a single flare is in plumbing systems.

Frequently Asked Questions

– Can You Drive With a Broken Brake Line Flare?

Yes, you can drive with a broken brake line flare, but stopping the vehicle is where the problem lies. The brake lines transfer brake fluid from below the hood to the wheel calipers and cylinders. If the brake line breaks, the compressible pedal will cause the brake fluid to leak.

Even in cases where only a single brake line fails, it will still be released, resulting in serious leaks and brake failure. Therefore, the best thing is to avoid driving with a broken brake line and get a repair done as fast as possible.

Brake line damage or leaks occur due to many reasons. Flexible rubber lines can cut easily, and this can cause leaks and other damage. Also, corrosion and rust caused by water and salt on the road can weaken the brake lines. A car crash can also cause car brake lines to damage and leak.

Inspecting your brake lines is easy, and it starts by raising the car to view the underparts easily. All you need to do is to follow the lines under the hood to the wheels. The main things to look out for include dripping fluid, holes, or watermarks.


Brake line flares enhance the secure connection of lines in the braking system of cars. Flares come in different styles, which are double, single, and bubble flares. In this article, we have highlighted the differences between single flares and double flares to enhance your understanding.

Single flares are generally unsafe, and they are not legal for use in vehicles, especially in the United States. This is because of their inability to withstand high pressure, lower durability, and strength. On the other hand, double flares are the most popular option, and you can find them on most vehicles. This is because of their durability and ability to withstand higher pressures.

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