I am pretty sure if your quick fix failed and got into an accident, and it was discovered that you used a compression fitting on your brake line, you would be FUCT.  Especially if someone was injured or killed.

Spend the time to do it right.  It is not that difficult.  Get some extra line and practice.

Compression fitting

Brake line



Yeah, go ahead!

If you don't want to do it yourself, just pay the mechanic's price. This might not be as bad as the guy that was bitching about the retread tires thread, but it sure is close! You shouldn't skimp on some things, not only because it's a terrible idea, but because the second you tell somebody that you do, they automatically know you're so cheap that you make terrible decisions to save a buck, and they'll never trust you fully because of that.

2 things on a vehicle you never go cheap on
Brakes and steering

I just replaced all of the brake lines on my wife's Tahoe.
I have a snap on double flare kit and a nice line bender. They were all rusted and I was just going to replace the bad section but it basically crumbled up so I went ahead and did all of them.
It wasn't too bad and I didn't have to hurry up so I took my time and let her drive my truck to work.
If yours are in good condition I would probably get a section of how much you need, Autozone has a big selection of different lengths and they are already flared so all you need to do is double flare your line and put in the new section.
Dan

True enough about the factory unions. I said it is half assed because if the line is weak in one spot, it is probably soon to fail in another. Especially up here with all the salt induced corrosion.

This is my favorite tool. I never could get a good double flare with the clamp together screw type tools. Can get a perfect double flare the first time even on stainless steel with this thing.

https://www.mastercool.com/product/72475-universal-hydraulic-flaring-tool-set/

Definitely second this as a favorite tool. Can be awkward to use on lines on the car but it makes beautiful flares. Also can get the dies to do push connect ends for transmission cooler lines and such.

The most important question no one asked is,"What vehicle?"
If the vehicle has ABS, absolutely NOT! Some ABS systems operate at pressures over 1000 psi.
A flare/ compression fitting is not rated for the pressures associated with modern ABS. Old school, 1960's cars, we did use flares and compression fittings. Not on today's vehicles.

If you do a non factory repair and have an accident, is it worth risking killing someone or seriously injuring someone?
Is it worth going to prison for manslaughter? Whenever someone gets killed in an auto accident, the person at fault goes to prison.

Pipe is not measured on the ID.  It has a standard OD.  Otherwise pipe fittings wouldn't screw on threaded pipe and weld fittings wouldn't fit either.  The OD is not the same as the nominal pipe size for sizes smaller than 14". Different schedules have different ID's.  At 14" and larger, the pipe OD and pipe size are actually the same.

Most modern brake lines are 3/16 diameter tubing.  Some older stuff is 1/4 diameter.  Sometimes there is an extra covering over the factory brake line that may make your measurement closer to 5/16.  It's seriously an easy thing to match up, but you need to take the line off of the car and take it to a parts store.  There can be different thread sizes on either end, if your replacing the whole line.  I've seen a lot of people use compression fittings, but I've only ever done it the right way.

Yep, as good as it gets for fabbing any lines..love mine as well...

Any auto part store has loaner flare tools

You're plan sounds sound.
If you'll be driving in DC.

FPNI

Compression unions are not 100% on new tubing. On corroded stuff, it will fail.

Double flare is the minimum, and with any significant corrosion replace the whole thing.

Fresh tubing is cheap.

Nope nope nope.  Too much pressure in the liner or a compression fitting to work.  You can buy sections of line, but you need a flare kit to flare the lines.  Done it plenty of times.  Most grossly underestimate how many psi is in the brake line when you mash the pedal

I can vouch for that Eastwood on car flair tool, works very well on regular lines, not so much on stainless steel though. You would need a pro tool to handle stainless lines.

FYI - you can get prebent replacement line kits in stainless from a few companies. I bought one for my tj and it was like $150 for every new hard line From the master cylinder to the calipers. You will need to straighten the long runs out (they come bent slightly to fit in a smaller box) and do some minor tweaks to get them to fit but it’s easy.

Depending on the vehicle, there are pre-bent and formed stainless lines available. Replace the whole line, and get home safe.

Compression fittings aren't designed to remotely cover the pressure or cycles you see in brakes.  They're made for air brakes, fuel lines, and truck air systems (max 300 psi) that don't even remotely see the PSI of a liquid hydraulic brake line (800-2000 psi).  Not to mention they were never made for steel line, they're made for nylon line.  Eventually they start pissing brake fluid around the nut and ferule.  Especially under hard braking.  Cletus got away with it long enough to sell you that shitty Toyota Camry, but you have no idea when it will let loose and leave you with no pedal.

If you're not familiar with flaring and repairing liquid brake lines I recommend consulting or hiring a certified mechanic.  There's no shame in it and he will have the proper tools and knowledge to do it right.  If your mechanic recommends compression fittings, they're a moron and risking a law suit.  

A lot of people see proper brass tube repairs and assume that compression fittings work the same way.  But the way they seal is totally different.  The fittings look similar but a compression fitting seals on a piece of brass this a couple of thou thick and can split under high pressure.  Brake line fittings seal steel to a solid cone of brass that is at least 3/16" thick from the inner bore to the outside diameter of the fitting.  That's a big difference of metal and how they seal.  

Harbor freight.

then cut out a longer section

Id at least slip some rubber hose over each end with some hose clamps.

Been there.
Did that earlier with some shrink tubing. Slipped on the connector, gave it just enough crimp to hold in place and soldered it up. As I was admiring my solder job and how badass it looked(I dont soldered much), I looked over and saw my shrink tubing just laying there all sad like.

Yeah, good luck on it arriving not balled into a circle

A simple compression fitting can work, but keep in mind that brake line pressure can hit several thousand psi. I've personally run a compression fitting on rear brake lines for several years on an absolute beater of a piece of shit before (pro tip: never buy a mechanic's car because we rig up the most ghetto shit on the planet). Saw the car again parked at a Kroger two years after I traded it, so I assume the compression fitting was still holding up fine. With that said, I still don't recommend it.

This. You will blow out other sections of the brake lines when you bleed the system and build pressure. At that point you are just chasing corrosion and pinholes.

I don't laugh easily, but that made me laugh.

I bought a hydraulic flaring tool a year or two ago. Every time I use it, I'm glad I have it.

If anyone buys one and you're flaring steel 3/8 line, ditch the little arm to tighten the die and just use a ratchet or wrench to get it tight enough to not slip.