How To: Replace Brake Hose and Line (Cutting, Flaring, and Bending)

How To: Replace Brake Hose and Line (Cutting, Flaring, and Bending)


Hey everybody… Pepe here from O’Reilly
Auto Parts to show you how to replace brake line and brake hose. Brake lines are steel
or copper tubing that carry brake fluid from the master cylinder to ABS units, equalization
valves, calipers and wheel cylinders. Rubber brake hoses have the same function, but are
flexible to allow for movement in the suspension system. Brake line and hose wear out over time. Steel
line corrodes, and rubber hose becomes less flexible over time and eventually cracks.
Brake hose can also collapse and not allow fluid through, which can make the caliper
stick, causing the vehicle to pull to one side during braking. Replacing brake hose
is more common than replacing brake line, unless you live in a northern climate, where
more frequent use of road salt can cause rust. Both brake hose and line can leak eventually.
You’ll usually see a leak on the ground near a wheel. Today, I’ll be working on this 2008 Toyota
Tundra, but the process will vary a little from one vehicle to the next, so be sure to
know the specifics for your vehicle before getting started. If you’re not completely
comfortable doing this yourself, we’d be happy to recommend a professional technician
in your area. Once you’ve got your supplies together,
here’s what you’ll do: Park on a level surface.
Jack up your vehicle and put it on stands. Brake hoses run from the wheel to the frame
of the vehicle… and metal brake lines run from the frame to the master cylinder.
If brake fluid is leaking near a wheel, you’ll need to remove the wheel where you’ll be
replacing hose or line. Whether you’re replacing hose or line or
both… when you detach an in-line fitting, you’ll want to use a plug or cap to keep
excessive brake fluid from leaking. There’s no specific way to plug the line…
In many cases a short piece of hose with a bolt in the end of it works well.
Leaving the lid on the master cylinder keeps dirt and moisture out of the brake fluid,
and slows the draining fluid while you plug the line.
Also, line wrenches are important for this type of job or any job where in-line fittings
need to be loosened… the open end of the wrench has six sides rather than four.
They work pretty well with frozen fittings, and it sometimes helps to try tightening slightly
before loosening… but if you run into excessive rust, you can use penetrating oil to help
loosen things up. So let’s start by replacing the brake hose.
Have a drain pan in place under the wheel well.
Use your line wrench to loosen the nut holding the hose to the junction box.
Plug the hole at the junction box to keep it from leaking brake fluid.
Use pliers to remove the retaining clip… then remove the other end from the brake caliper.
Let the fluid from the hose run into the drain pan.
Once the old hose is removed, attach the new hose at the caliper first.
Now, remove the plug at the junction box… attach the hose there… and clip it into
place. Be sure to tighten fittings to manufacturer’s
specifications to avoid leaks. Repeat these steps for each brake hose that
needs to be replaced. After you’re done replacing all brake hose
that needs replaced… if you’re not replacing brake line, you’ll need to top off your
master cylinder and bleed your brake system to remove air from the lines . Now to replace brake line.
Depending on your vehicle, you may be able to replace an entire line as one piece…
or you may need to replace shorter sections. Brake line is available in pieces from a few
inches up to several feet. Replacement brake line comes in steel, or
in some locations, copper, which is softer. The steel lines normally require a bending
tool so the metal line does not crimp. Copper lines can be bent by hand without any
special tools. O’Reilly Auto Parts also offers some pre-bent
brake lines designed to be installed in place of the original line… and no cutting or
flaring is required. We’ll start by addressing this scenario
and work our way toward cutting and flaring. With the vehicle on stands, open the hood…
and locate the master cylinder. Put a drain pan in place under the wheel well
you’ll be working in… and use your line wrench to loosen the nut on the brake line
at the master cylinder. Remove it from the master cylinder and plug
the hole to keep it from leaking fluid. Brake fluid is highly corrosive, so make sure
you don’t get any on your skin or paint. If you do, rinse it off immediately.
Now, loosen the other end of the line from the junction box.
The fluid in the line will start to drain. After it’s had time to drain, unclip the
line from the body and carefully remove it from the vehicle without bending it.
Use a rag or shop towel at the lower end of the brake line to soak up any brake fluid
as you remove it. If you’re going to be bending new line to
match the old, you’ll need the bends in the old line to remain intact so you can use
it as a guide to shape your new line. In a moment, I’ll show you how to bend the
line… and how to cut it and flare it, if needed.
If your vehicle is a model that has a pre-bent line available, the pre-bent replacement will
be the proper length, and comes pre-flared with fittings.
Carefully work the new line back up to the master cylinder.
Clip it back into the frame and reattach it to the junction box… then remove your plug
at the master cylinder… and reattach it there.
Again, be sure these fittings are tightened to manufacturer’s specifications.
You’ll repeat these steps for each brake line that can be replaced in this manner.
If your brake job is complete at this point, you’ll want to top off your master cylinder
and bleed your brake system If you’ll be doing any cutting, bending
or flaring… here are the steps you’ll take.
In some cases, you’ll be cutting a section of the old brake line out.
You’ll need to get a piece of brake line that’s long enough to replace the piece
you’re removing. And when you remove a piece of line from under
the vehicle, you’ll want to have a plug ready to keep the opening closest to the master
cylinder from leaking fluid. If you’re starting the process of brake
line replacement by cutting a brake line, you’ll do it with the tubing cutter. Here’s
how it works. Be sure to get a precise measurement if this
is a replacement piece, so that your cut is in exactly the right place.
If you’re going to be flaring the line, the flare will use the last quarter inch of
line. If you’re going to use a brass union to
link two pieces, subtract the length of the fitting from the length of line you’re cutting.
Whatever you do, don’t cut your line too short.
Once the tubing cutter is in place on the line… take your time, and turn the knob
on the tubing cutter one quarter to half a turn at a time… or until it’s tight.
Turn the tubing cutter three hundred sixty degrees clockwise… then counter-clockwise…
each time you tighten the knob. It could take you as many as ten times tightening
the blade before the cut is complete. When you get close to completing the cut,
go slower to make the cut as clean as possible. The tube needs to be smooth inside and out
before attempting to flare. If there’s a place that isn’t smooth,
it’s worth it to redo the cut. Any time you cut brake line, you’ll need
to use a metal file to take the burrs off the cut end… and file it to a slight chamfer,
or angle, up around the opening… so it can be properly flared. If you’re cutting line under the vehicle,
you may be cutting a piece out of the middle of the line… removing the upper portion
of the line coming from the master cylinder… or removing the lower portion of the line
connecting to the junction box. Regardless of which of these you’re doing,
cut or detach the end closest to the master cylinder first… and plug the opening so
it doesn’t leak. Place a drain pan under the lower end of the
piece you’re removing before cutting or detaching it, so you’ll have something to
catch the fluid from the line. Use a rag at the bottom end of the line you’re
removing to catch any excess brake fluid once it’s drained. Now that you have the old section of brake
line removed, you can get a measurement for the piece of line that will replace it.
Use a piece of string that’s at least as long as the section of brake line you’ve
removed, and starting at one end of the line… carefully work your way along each bend for
the length of it to determine how long you need your replacement line to be.
You can measure the string with a tape measure to determine length… or if you already have
a section of brake line, you can lay it against the line and mark the spot where it needs
to be cut. Depending on the measurement, it may be possible
to purchase a piece of replacement line that’s the exact length you need.
If not, get a piece of line that’s longer than what you need, and use your tubing cutter
to get it exactly right. Again, if you’re going to be flaring the
line, the flare will use that last quarter inch of line… and subtract the length of
a double-flare union, if you’ll be using one to join two pieces.
Once it’s cut… use your metal file to deburr it… and chamfer around the opening. Whenever possible, avoid flaring brake line
yourself… but when it’s necessary, here’s how you’ll do it.
Before flaring or bending, put the fittings you need on the line.
Only use fittings designed specifically for brake line… and never use compression fittings.
If you’re going to be flaring, you’ll want to make sure you’re double-flaring
by using a double-flaring tool. To start this process, make sure that end
is cut square… and that it’s deburred and chamfered.
If the new end and flare aren’t made properly, the brake line will not seal and you could
have a leak. If you’ve never flared a line before, practice
on a piece of spare line to make sure you know how to get the process right.
Place the line in the correct hole of the flaring tool… leaving a small length of
the tubing exposed. The length of exposed tubing should be equal
to the height of the adaptor… this length is very important to get a good flare.
Tighten the flaring bar firmly, starting with the nut closest to the tubing… just make
sure it won’t slip. Fit the adaptor stem into the tubing.
The adaptor is specific to the brake line, so it should be snug when fit into
the tubing. Place the anvil over the adaptor and turn
it down until the adaptor contacts the flaring bar… then remove the adaptor.
The end of the tubing should be bell-shaped. Now, place the anvil over the bar and turn
the anvil down until the tubing folds in on itself.
Remove the tool… and the tubing should be double-flared.
Compare your flare with an end of brake line that came pre-flared. They should look identical.
The flared opening should be smooth all the way around and rolled evenly.
If the flare doesn’t look right, do not install the line. Now that you have a piece of line that is
the proper length with fittings and double-flared ends… you’re ready to bend it to match
the original line. Make sure the fittings stay at their proper
ends as you start to bend, so they don’t get stuck in the middle of the line behind
a bend. We’ll work on the steel line first.
Slide your bending tool into place… Start at one end and match each bend in the
line you’re replacing. Take your time and work precisely… you want
this piece of line to be shaped in exactly the same way as the one you removed.
By situating it in the same way it was when you took the old one out, you’ll assure
it isn’t too close to exhaust or any moving parts. Copper line is not available at all O’Reilly
Auto Parts stores, but it can be ordered from OReillyAuto.com and shipped to you.
Because it’s so much softer than steel, it can be bent by hand.
The process is the same… but you won’t need the bending tool to get it into shape.
Like you would for the steel line, take your time and get the bends precisely the way they
are on the line you’re replacing… One big difference here is that once you bend
the steel line, it’s bent… and bending it back is likely to ruin it.
But the copper line allows you to correct mistakes that are made during bending… and
remains just as strong. Once your line is bent to match the one you
removed, you’re ready to install it. Install the end farthest from the master cylinder
first… then remove your plug… and install the upper end.
If you’re attaching it to another line under the vehicle that you’ve cut and double-flared,
that’s where you’ll use a double-flare union to connect the nuts of the two lines.
Again, make sure the fittings are tightened to manufacturer’s specifications to avoid
leaks. Lastly, you’ll want to fill the master cylinder
with new brake fluid… and bleed your brake system.
Check out our video on how to properly bleed brakes.
Replace your wheels… and lower your vehicle. And that’s it. You’ll find everything
you need for this and other jobs at your local O’Reilly Auto Parts store or OReillyAuto.com. Our DIY videos are designed to help answer
questions we get in our stores every day. If you found this one helpful, subscribe to
our channel to get all the latest. We’ll see you again soon.

About the Author: Michael Flood

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