The flexible rubber brake lines that go from the frame to the brake caliper on the wheel can take on some wear depending on the type of climate you live in. Here’s how to change them out to give brake system the refresh it needs.By Jeff White – November 12, 2015
This article applies to the Jeep Wrangler JK (2007-Present).
Almost all vehicles come from the factory with flexible rubber brake lines that go from the metal line on the frame to the brake caliper on the wheel. These are made out of rubber so that they can move with the wheel and suspension as it travels over the road. Well, as you can imagine, these rubber brake lines can deteriorate over time, especially if you live in a harsh climate such as one with snow.
It is recommended to inspect these rubber brake lines every six months. You want to inspect them for cracks, chafing of the outer cover, leaks, blisters, and other damage. If your brake lines show any of these signs of wear, it’s time to replace it with a new one.
Figure 1. Jeep Wrangler.
- Millimeter wrenches sizes 10mm-15mm
- Flare nut wrenches sizes 10mm-13mm
- Torx bit sizes T25-T40
- Needle nose pliers
- DOT 3/4 brake fluid
- Clear plastic container with flexible hose or vacuum brake bleeder for bleeding brakes
The front and rear rubber brake lines are slightly different, so this how-to will go over how to replace each individually.
Front Brake Lines
Step 1 – Disconnect brake line from rubber brake line fitting
The flexible rubber brake line attaches to the frame where the metal brake line connects to it. You can see that in the image below. It is best to use a flare nut wrench to loosen the metal brake lines’ fitting, as this will keep the corners from being rounded off. If you do not have access to one, you can also use an open end wrench.
Figure 2. Brake line frame fitting.
Step 2 – Detach line bracket from frame
The rubber line has an integral bracket that allows it to be attached to the frame. A Torx bolt is what secures the bracket to the frame. This is where you will need the Torx bit to remove the bolt. After you remove the bolt, that end of the rubber line will be free.
Step 3 – Remove inlet fitting bolt from caliper
Now that the frame side of the line is free, you can loosen and remove the banjo bolt that secures the other end of the rubber line to the caliper. You will notice when you remove the bolt there are sealing washers that sandwich the line fitting. These sealing washers are one time use washers, so you will want to discard them and replace them with new ones. Below is an illustration of what it will look like.
If you are just changing one or both of the front brake lines, you can now bleed the brake system. The procedure for doing this will be at the end of the this article. If you are also going to change one or both of the rear brake lines, you will want to wait to bleed the brake system until after you have replaced them.
(Related Article: How to Bleed Your Brakes – JK-Forum.com)
Rear Brake Lines
The rubber brake line for the rear brakes is a different setup. Because the rear suspension has a solid rear axle, it doesn’t need a flexible brake line to go to each wheel. Because of this, there is only one rubber flexible brake line that runs from the metal line on the frame to a junction block on the rear end. Then there is two metal brake lines that run from either side of the junction block to each wheel.
Step 1 – Disconnect rubber brake line at the frame bracket
Using a backing wrench, disconnect the metal brake line fitting from the rubber brake line. Be careful not to bend the brake line bracket or the metal brake line.
Figure 4. Brake line bracket fitting.
Step 2 – Remove the U-clip
There is a U-clip that secures the rubber line fitting into the bracket. Using a pair of needle nose pliers, you can remove the U-clip, which will allow the rubber line end to be removed from the bracket.
Figure 5. Rear brake line diagram.
Step 3 – Disconnect rubber brake line at the junction block
If you follow the rubber brake line from the frame bracket, you will see where it connects to the junction block. Loosen and disconnect the fitting that secures it into the junction block.
Figure 6. Junction block fitting.
Step 4 – Install new brake line
Installation of the new line is similar to the removal. First, attach the brake line to the junction block and tighten the fitting. Next, making sure the line is not twisted, install the rubber brake line end into the frame bracket. Install the U-clip, which will secure the rubber brake line to the bracket. Finally, thread the metal brake line into the end of the rubber brake line and tighten using a backing wrench to ensure you do not bend the metal brake line.
Step 5 – Bleed the brake system
This is a basic procedure for bleeding the brake system. You only need to bleed the wheels of the brake lines that you have replaced.
Bleed brakes as follows:
- Remove residual vacuum (or hydraulic pressure) by applying brake several times with engine off.
- Remove cap and top off reservoir if necessary.
- Place tube of catch can over bleeder valve on wheel that you are going to be bleeding. Start with farthest corner from master cylinder first and work your way to the closest. This usually means working the calipers in the following order: passenger-rear, driver-rear, passenger-front, driver-front.
- Have an assistant slowly depress and hold the brake pedal in the depressed position.
- Open the bleeder screw enough to allow a flow of fluid to leave the valve. While doing this, keep an eye on the fluid being removed. It will be a dark color.
- Tighten the bleeder screw.
- Have an assistant release the pedal.
- Repeat steps 4 to 7 until you see fresh, lighter colored fluid coming out of the bleeder screw tube.