Bubble Flare vs Double Flare: Facts No One Ever Talked About

bubble flare vs double flare differences

Did you ever notice if there were leaks of brake fluid from the newly flared brake lines?

Various factors can be behind it, such as the kind of flare you used and the flare quality. You need to understand the critical details between Bubble Flare and Double Flare for brake lines before you start flaring brake lines.

If you’re interested in knowing more about bubble flares vs double flares, you are in the right place. Let’s get started.

The Difference in Appearance

The difference here is somehow subtle, but if you are familiar with brake lines, the distinctions become apparent.

The double flare has a funnel shape while the surface looks like a line inserted inward, towards itself. The look gives it a round feel with a noticeable thickness.

The bubble flare only looks different at the top, like the others. There is a screw shape at the top, and the circular edge has a relatively smaller diameter. It is generally described as a swollen hollow-topped flare.

Ease of Making

Both styles of brake lines require technical know-how.

It is generally agreed that double flares are easier. It is the go-to style of do-it-yourself technicians and workshop engineers. A lot of experts are very familiar with the process.

On the other hand, the bubble flares are quite technical, and the approach to making them are pretty different. It is not the go-to conventional style.

The Angle of Inclined Top End

This may fit into the description of looks, but it is quite different. The way these flares work is majorly dependent on the top end shapes and dimensions.

The double flare has a backside that is inclined at an angle of 45 degrees, giving it a unique operational process.

The bubble flare has a bottom end with an inclination of 90 degrees. 

Professional Denotations

The double flare brake line is also known as the SAE inverted 45-degree flare, while the bubble flare brake line is known as the DIN flare or ISO flare. 

How Common They Are

The double flare is the most common type, and it can be found in many modern automobiles. It has been prevalent since the 1980s, especially for cars that were made in the United States of America. This factor makes it easy to work with the double flare system.

The bubble flare is often mistaken for the double flare but less common than the double flare linings. The bubble flare also went viral in the 80s, mostly in Europe but still generally less common; it has a relatively less usage and technical understanding.

Techniques for Building the Flares

The essential tools for making a double flare can be manipulated to build bubble flares, but the processes are quite different.

The steps for making the double flare are:

–   The first step is cutting the Lines. Measure properly before cutting and make sure the cutting tool is well aligned, and the flare material is well tightened.

–   The second step is cleaning the cuts. The process is mostly overlooked but very important. You will need the appropriate cutters and avoid uneven edges.

–   The third step is setting up the brake flaring tool. It has two moving parts, and adequate pressure is needed to keep the tool steady.

–   The fourth step is applying hardware. You must prevent sliding of the hardware unnecessarily before flaring.

–   The fifth step is clamping the line with the tool. Proper alignment is a must here.

–   The sixth step is to lubricate the line. That is done using brake fluid or appropriate grease. Silicon-based lubricants should be avoided for this part.

–   The Seventh step is flaring the line. Use the fitting wrench to tighten the tool for flaring.

–   The eighth step is double flaring. It includes the repetition of the processes. But you have to be conscious of some differences. Inserts are avoided at this stage, and screwing stops when you sense some resistance. Make a third-quarter turn and ensure you have a 45 degrees’ standard double flare.

The steps for making the bubble flare are:

The use of a good tubing cutter with a sharp-edged cutting wheel that has no chip or deformity is the most critical thing to do when producing tubing flares. Four significant steps are:

–   Tubing Cutter use. If you are not incredibly vigilant, using a cut-off wheel is often a weak point that makes room for leaks. From the time you cut the line to flare, a leak may start. So that the flare may be standardized in shape, you need a clear, clean-cut on the tubing. 

–   Bubble flare. You are set to clamp the tubing into the flare after you’ve had the tubing cut perfectly. It is good to pick the die with the “DIN” stamp on one end because experience with European cars has shown how extremely effective they are. 

–   Lower half of the die mounting. Next, you want to set the brake line to the bottom half of the die to guarantee that the “DIN” end of the die is square and flat with the end of the brake line. You mount the top half of the die from there, turn the clamp down, install the pin in the clamp, and tighten the clamp, so the die halves are tightly clamped together (we don’t want that line back in the die wiggling!). Often, make sure that the brake line is lubricated where the flare is created. Some use grease while others use copper anti-seize, but it is great to go the easy way by spraying some lubricant on the line. One good example is WD-40.

–   Lubricating the Brake Line. Once the line is clamped and lubed, you literally pull the lever in one steady movement on the flaring tool before it stops (go for something around 90 degrees). One good thing is that the instrument has a certain point where it stopped when the flare was thoroughly developed; I can testify to that. It is just that easy! Just detach the die clamp, the top half of the die, and then the brake line, and it is ready for use with the car!

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Both the Bubble and Double flare in brake lines are utilized by automobile specialists. But the SAE double flare is the most widely used brake line flare. Also called the inverted flare, it is actually the single flare’s improved version.

A key aspect is the efficiency of the brake flares. Low-quality flares may cause brake fluid leaks, and because of the leakage, there is a chance of brake failure. You may need to use a suitable method to get high-quality flares.

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