Introduction: How to Replace Brake Lines

Video tutorial on how to replace the brake lines on your vehicle. Over time brake lines are exposed to the exterior elements and eventually they will rust away, creating a rupture, therefore losing braking power. If the line does fail, you will lose a substantial amount of braking performance and the brake pedal will feel spongy along with longer pedal travel. If a line were to fail on one section, you will still have half or less of braking performance which will allow you to pull over, but the vehicle is unsafe to drive.

Tools/Supplies Needed:

  • line wrenches
  • flaring kit
  • new brake line
  • brake line fittings
  • line cutter
  • file
  • brake fluid
  • rags
  • jack and axle stands or ramps

Step 1: Source the Leak & Remove the Faulty Line

Picture of Source the Leak & Remove the Faulty Line

You’ll notice is either an oily residue on the ground or somewhere underneath the vehicle, with close relation to the brake lines, besides the reservoir level dropping. Using a line wrench is recommended, as they are able to grab onto a larger area of the hex which prevents it from stripping. The line can also be cut off if you’re replacing the whole run and insert a socket. Remove the lines and try not to bend the existing shape too badly as we will be using this after. Next is removing the line from the master cylinder that goes to the driver’s side. It’s always good to have a rag handy to prevent any fluid from dripping.

Step 2: Bending the New Line

Picture of Bending the New Line

Replacement lines will vary, you can buy a length or buy a roll depending on the material. Copper tends to be easier to work with, is corrosion resistant, but can work harden or fatigue easier. Steel on the other hand is susceptible to corrosion so coatings are applied such as an epoxy or zinc. Stainless steel lines are also an option which can be harder to work with, yet is corrosion resistant. You will need to match the existing brake line diameter along with fitting type along with the lines being metric or imperial. It’s best to use a bender so you don’t risk kinking the line. Match up the old and new line, place the bender in the correct position and continue to bend the line.

Step 3: Cut the Line to Size

Picture of Cut the Line to Size

Using the cutter tool, set it in place, remember to cut about a 1/4” longer to account for the flare, then tighten the knob, spin the cutter until it’s loose, tighten again, spin, and repeat until the end separates. De-burr the cut line by simply sticking it in the center of the line and rotate back and forth until the burr is gone. Hit the end with a file to clean the cut a little more.

Step 4: Flare the Line

Picture of Flare the Line

For the flare, this is a double flare connection. First we will need to ensure the clamp is clean, both the jaws where the line sits and the surfaces that face each other. Install the fitting first, the side which is being flared must be on the chamfered side of the clamp. The line should be exposed the same thickness as the large side of the die. There are various dies available based on what size line is used which is determined by which fits best within the inside of the line. Tighten the clamp, ensure it is tight as we don’t want the line slipping. Apply a small amount of oil to the end of the die which helps with achieving a high quality flare. Insert the dowel end in the line and install the cone tool which will push the die into place, forming the line, the cone will have a depressed area it sits into on the die. Tighten the cone tool until it stops, remove the die and reinstall the cone tool so the flare can be folded down. Tighten until it stops and if desired apply a touch more oil. The final flare done and ready to be installed.

Step 5: Install the New Line

Picture of Install the New Line

Considering the master cylinder takes a bubble flare which I do not have the tools to produce it, I will be using an adapter than can be purchased from an auto parts stores that thats the double flare and allows you to connect it to a bubble flare female connection. Install the line and the line may need to be adjusted in the bends slightly, ensure they do not rub on any adjacent objects which may damage the line.

Step 6: Bleed the System of Air

Picture of Bleed the System of Air

Ensure everything is tight and finally we can move onto bleed the system. Fill the master cylinder reservoir with fluid and finally bleed the brake system of air.

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Comments

wrenchtoo (author)2017-05-22

Copper is a bad idea. Every manufacturer I have seen expressly states copper is unacceptable. Due to the issues with copper, In some areas with a required safety inspection copper is cause for failure. There is a copper nickel alloy line that has been approved by the US Department of Transportation for use in brake lines. The alloy lines are usually a dull copper color and will develop a green patina over time, this can make it difficult to differentiate between an alloy and a pure copper line. Brakes are nothing to take a chance with.

4DIYers (author)wrenchtoo2017-05-22

I believe you have a misunderstanding here. These are a copper alloy line, these are actual DOT approved brake lines purchased from an auto parts supplier. Not what is found on say a housing application for water lines. Yes a standard copper line will fail under the pressure of the hydraulic brake system, therefore it cannot be used. Here is the link to the product http://www.jegs.com/p/JEGS-Performance-Products/JEGS-NiCopp-Nickel-Copper-Brake-Lines/2111534/10002/-1

wrenchtoo (author)4DIYers2017-05-24

I had wondered if you were using cunifer (NiCopp) lines but the reference to copper was worrisome, particularly if the instructions were to be used by a novice. With that cleared up I like the instructions, a good overview on how to successfully replace brake lines. Thanks

lawagoneer (author)2017-05-18

Copper should never be used in brake systems. The work hardening is not the problem, it's the way copper tubing is made. Copper tubing will separate at the seam and fail. To Tytower, good for you for using copper, I wouldn't ride in the rig as it is a rolling time bomb of brake failure. Take a look at the rules for all types of racing-NO COPPER LINES. Why? because they fail. Use steel or stainless please.

4DIYers (author)lawagoneer2017-05-22

I believe you have a misunderstanding here. These are a copper alloy line, these are actual DOT approved brake lines purchased from an auto parts supplier. Not what is found on say a housing application for water lines. Yes a standard copper line will fail under the pressure of the hydraulic brake system, therefore it cannot be used. Here is the link to the product http://www.jegs.com/p/JEGS-Performance-Products/JEGS-NiCopp-Nickel-Copper-Brake-Lines/2111534/10002/-1

tytower (author)2017-02-23

I have always replaced old brake lines with pure copper on my Landrovers which get shaken and vibrated more than most road cars . Lines I replaced 50 years ago are still as good as when I did them so properly attached , copper will not work harden . Allowing for those that say it will then OK I'll replace them in another 50 years with new copper ones . Just need to live to be 135 now.

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