How to Flare Brake Lines (Live Stream Episode)

In this video Matt shows us how use the Eastwood Professional Brake Tubing Flaring tool to perfectly form single, double and bubble flares in hard steel line. Other Eastwood products demonstrated, or mentioned in the video include the ratcheting tubing cutter, Triple Head 180 degree Tubing Bender, Brake Line Forming Tool, Brake Gray Paint, Aerosol-Injected Cleaner and Aerosol-Injected Lubricator. The lower cost “wingnut” style, and higher priced hydraulic flaring tool are shown and mentioned, but the how-to portion focuses on just the one flaring tool.

There are 3 basic types of flared ends you are likely to see on most cars: The single flare typically used on lower pressure fuel lines fittings, the double flare used on the high pressure brake lines of most vintage cars, and the bubble flare used on most modern and many older imported cars. In the picture the single flare is on the right, the double in the middle and the bubble on the left. With the proper Eastwood tools it is easy to make any of these flares.


The lowest priced tool to make these types of flares is the “wingnut” style, available at Eastwood and most auto parts stores. These are the trickiest to use and the hardest to make good flares with. Between the dies, the clamps and the press it seems as if you need 3 hands to work it properly. The one good thing about it, besides the price, is that its compact size allows you to use it while under the car if need be.


The Universal Hydraulic Flaring Kit can also be used under the car. It makes professional quality flares in all sizes and types, and uses the power of hydraulics instead of leverage and muscle. It can also make the special push to connect GM fuel line fittings. If you are a pro making custom lines all day long it is really the best choice. But it comes at a professional price, more than twice cost of the leverage powered Professional Brake Tubing Flaring Tool, and the flairs are the same quality.


So the Goldilocks choice of not too expensive, but still doing a great job is the Professional Brake Tubing Flaring Tool. Not only does it make all 3 common types of flares in 5 different metric and inch sized tubing, with the purchase of a separate set of dies it can even make AN fitting and JIC style flares.


Here is how to use it to make a double flare:

#1: Clamp the flaring tool in the vise – Since this tool is powered by leverage and your own muscle on the end of a handle you need to clamp it securely in a vise to use it properly. In a pinch it can be used loose, like while working under a car, but it is extremely awkward and difficult.


#2: Select the proper die – Different sized lines use different dies to hold them. Also bubble flares use a different die than regular single or double flares. Put the correct one for your tubing and flare type in the machine.


#3: Cut your tube to the proper length, using the proper tool – Cutting the tube the wrong way can leave a jagged, uneven edge. Cut the tube with a proper tubing cutter and not a hacksaw, cut off wheel or other method.


Here’s an example of how not to cut it, and the resulting less than perfect flairs it caused.


#4: Lubricate the end to be flared – Spray a little of the Eastwood Aerosol Injected Lubricator into a cup and dip the end of the metal line in. The lube will help the metal slide smoothly when you press the die into it to make the flare.


#5: Insert the tube in the die, and the die into the flaring tool – You don’t have to tighten it down yet, just leave it loose so the tube can still move freely.


#6: Make sure your fitting is on the tube and facing the right way – Remember, once you flare the end of the tube you won’t be able to put the fitting on. The bends in the line may keep you from being able to slide it on from the other end too. So make sure you have the fitting on the line, it is of the correct size and it is facing the right direction.


#7: Set the turret to “Op 0” and pull the lever – Operation 0 serves to set the tube at the perfect depth in the die for flaring.


#8: Tighten the tube in the die – Turn the handle and tighten the clamp down on the tube so it can’t move when you press the next shape in the turret into it. Be careful though, it is possible to break the die if you tightening too much.


#9: Set the turret to “Op 1” and pull – Choose the correct die on the turret for operation 1 of the double flare for the tube size you are using. Pull the handle and the first step of the double flare is done.

14No need to put your whole weight into it and try to bend the handle, just pull till you feel a little resistance, then keep pulling a bit more until it the lever stops.



#10: Turn the turret to “Op 2” and pull the lever – Operation 2 completes the double flair. Just pull the handle again the way you did in operation 1 and you are done.


16#11: Remove and inspect your brake line – It may take a wiggle or a tap to get it free from the die that is holding it, but you should now have a perfectly formed double flare on the end.



#12: Clean out the inside of the line – Spray some Aerosol Injected Cleaner to clear out any residual oil, or metal particles in the line from cutting and flaring.


That really is all there is to it. Flaring hard lines is one of those jobs that is nearly impossible without good tools, but easy once you have them. A bubble flair line is exactly the same process, just with different dies on the turret. A single flare line is even easier, it only take the “Op 2” die and one pull of the lever.

Here are two examples of flares gone wrong. On the right is a double flare that was done with too much of the line left sticking out of the die before flaring. Notice how it’s got an extra wrinkle in it. On the left is a single flare that was over flared. The metal has been pushed out so far that it has begun to tear at the edge.


Besides flaring Eastwood has other tools to make custom brake and fuel line plumbing easier, too.

For making bends in full custom lines, nothing is easier than the Triple Head 180 degree Tubing Bender. Just grab the tube in the correct size head and start bending. It’s got an easy to read angle gauge right on it to help you get the perfect bends.


The Brake Line Forming Tool is perfect for tweaking old line, or even new ones. When you are under the car and just can’t get the brake line fitting to thread in straight it can be aggravating. This tool can save a lot of frustration and stripped threads.


If you don’t have either of these tools, and need to bend your line ASAP, any old can, socket or piece of pipe can become a handy form in a pinch. Just be extra careful not to kink the lines when using improved tools like these.


And here’s a pro tip for bending custom line when you don’t have an old line to use as a template: Use a straightened out coat hanger, or a length of TIG wire.  You can easily bend a stiff wire to follow the route the tubing should take, even while under a car. Then just bend the line to match your wire pattern and you’re done.

Lastly, a word about Eastwood’s specially formulated Brake Gray Paint. Brake Gray paint is impervious to brake fluid. It is actually more resistant than powder coating. Eastwood has tested it by letting painted parts sit in brake fluid over night and the paint was still perfect afterwards and showed no signs of softening.


Eastwood has also recently introduced a low price, handheld brake line straightener. This simple tool makes it much easier to start out with an actual straight tube, instead of the roll you get when buying bulk lengths. The time saved is easily worth the price of the straightener.

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  1. with making these flares for brake lines do not use any mineral based lubes. any contamination will cause brake failures with the reaction of the mineral oil… using a water/soap lube is better and will easy be gone by the time it is installed.

  2. You miss the sales opportunity these “instructional” photos provide. Add a “link” to each frame for the Eastwood product mentioned. I am too lazy, er um, busy to go shop the catalog for the gray paint or the dies for bubble flares but if there was the instant gratification of a shop it, buy it now feature I would gladly have spent money this morning. As it is, don’t have the time to get a feel good now as the dentist is waiting…..

  3. I like everyone else I have struggled for years with the wingnut clamp on flaring tool trying to get a good SAFE flare. I took the plunge and bought the Eastwood Pro Flaring tool and I can honestly say it is one of the best tools I’ve ever invested in. Gone is the guessing if the tubing is out far enough, trying to clamp it without damaging the tube and hoping the l flare will come out correctly. It takes longer to get the tool out, clamp in my vice and put it away than it does to make a perfect flare every time. So fast and excellent results making it well worth the investment in this fine tool.

  4. I have stainless steel custom brake lines for my 1969 olds 442. I had to change out fitting sizes and make new dbl flares using your rotating die setup tool. I found it very difficult to make a good dbl flare on ss tbg. I broke the handle on your bending tool. What’s the secret with dbl flaring SS brake lines?

  5. Lubrication is definitely key, our professional flaring tool flares double lines well I’ve found if you lubricate everything before flaring.

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