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Pelican Technical Article:

Brake Line Replacement

Steve Vernon

Time:

4 hours4 hrs

Tab:

$50 to $200

Talent:

**

Tools:

14mm, 11mm flare-nut wrench, 17mm wrench, pliers

Applicable Models:

Porsche 944 Turbo (1986-89)

Parts Required:

New rubber or stainless steel brake lines

Hot Tip:

Make sure that corroded rubber from old lines didn't end up in your caliper

Performance Gain:

Better braking performance

Complementary Modification:

Rebuild calipers, replace brake pads, flush brake system, replace master cylinder

One of the most popular projects for the Porsche 944 is the replacement of the flexible brake lines that connect from the main chassis of the car to the brake calipers. These lines are made out of rubber and have a tendency to break down and corrode over many years. The rubber lines should be carefully inspected every 10,000 miles or so as they can exhibit signs of failure, such as bubbling and expanding prior to actually bursting. Needless to say, failure of these lines is a very bad thing, as you will instantly lose pressure in one half of your brake system. The lines can also fail from the inside where broken down rubber can end up getting into the calipers.

Faulty brake lines in the front of your 944 can cause all sorts of steering problems when braking including causing a car to dart from side to side. Bad hoses allow pressure to build up in the caliper, but sometimes do not release this pressure properly when the pedal is depressed. This can lead to uneven wear of the pads and unsafe operating temperatures, as the pad never comes off the rotor.

The first step in replacing your lines is to elevate the car. Please see our article on safely jacking up and supporting your vehicle. Remove the front wheels from each side of the car, as this will make it much easier to access the brake lines; you do not need to remove the rear wheels to perform this work. To prevent a large amount of brake fluid from leaking out, I recommend pushing the brake pedal down just to the point of engagement and block it there. If you do this, you will lose less brake fluid, and also less air will enter into the system. But no matter what you do you must properly bleed the entire brake system after replacing your brake lines. Do NOT attempt to drive the vehicle until you have properly bled the system.

The brake lines themselves can be very difficult to remove. The goal of this job is to remove the lines without damaging anything else. In this case, the easiest thing to damage (besides your paint) is the hard steel brake lines that connect to the flexible rubber lines. These lines have relatively soft fittings on each end and often become deformed and stripped when removed. The key to success is to use a flare-nut wrench. This wrench is basically designed for jobs like this one where the fittings are soft and might be heavily corroded. The flared end of the wrench hugs the fitting and prevents it from stripping. It is very important to use only one of these wrenches, as it is very easy to damage the fittings using a regular crescent wrench.

You must properly bleed the entire brake system after replacing your brake lines. Do NOT attempt to drive the vehicle until you have properly bled the system.

The rubber brake lines are often responsible for poor brake performance.
Figure 1

The rubber brake lines are often responsible for poor brake performance. As the car ages, the rubber begins to break down and can clog the lines, leading to very little pressure getting to the calipers. The brake lines should be renewed if they are old or if you are having problems with your brakes. The red arrow points to the flexible brake line on the front of the car that needs to be replaced. The yellow arrow point to the fitting on the hard brake lines that needs to be released using an 11mm flare-nut wrench on the hard line and a 17mm wrench holding the rubber line. The green arrow indicates where the flexible line connects to the caliper; you will need a 14mm flared nut wrench for this. You are going to want to remove the line at the fender connection and not the caliper first. If you try and remove it from the caliper first the line cannot turn freely and will bind.

Begin by pulling the line out from the mounting bracket on the strut (yellow arrow).
Figure 2

Begin by pulling the line out from the mounting bracket on the strut (yellow arrow). There should be a rubber grommet on the line to protect it (red arrow).

Remove the mounting clip that holds the lines to the body bracket by pulling it out with a set of pliers.
Figure 3

Remove the mounting clip that holds the lines to the body bracket by pulling it out with a set of pliers. Some people like to remove this after you separate the lines but I like to do it first. You are going to be supporting the lines with two wrenches. Once the line is open brake fluid will get everywhere. Brake fluid is very slippery. You don't want to make a mess trying to get this off once there is fluid on it.

A required tool is an 11mm flare-nut wrench (red arrow) that fully wraps around the brake line nut (yellow arrow).
Figure 4

A required tool is an 11mm flare-nut wrench (red arrow) that fully wraps around the brake line nut (yellow arrow). If you use a standard wrench, then there is a high chance of rounding off the corners and permanently damaging the hard brake lines. These fittings are not very strong and will become stripped if you don't use one of these wrenches. The other disastrous thing that can happen is that the fitting can get stuck to the rest of the hard line. The fitting is supposed to turn and rotate on the end of the line, but sometimes it becomes too corroded to break free. When this happens, the fitting and the line will usually twist together, and it will break the line in half.

Be careful when you are removing this fitting to make sure that you are not twisting the line.
Figure 5

Be careful when you are removing this fitting to make sure that you are not twisting the line. You should counter hold the flexible line with a 17mm wrench (red arrow) while turning the hard brake line with an 11mm flared nut wrench (yellow arrow).

With the line separated you can see the delicate flare on the end of the hard line (red arrow) and some of the corrosion that has built up (yellow arrow).
Figure 6

With the line separated you can see the delicate flare on the end of the hard line (red arrow) and some of the corrosion that has built up (yellow arrow). NEVER put any sort of Teflon tape or Loctite on the threads (yellow arrow) or fitting. With the line separated you can use a 14mm flared nut wrench and remove the other end of the line form the caliper.

The rear brake lines on the 944 have a hard line going into the caliper (red arrow) and the flexible connecting line is located up under the trailing arm (yellow arrow).
Figure 7

The rear brake lines on the 944 have a hard line going into the caliper (red arrow) and the flexible connecting line is located up under the trailing arm (yellow arrow). Even though these lines are out of the way of most road dirt, debris and weather they still need to be inspected and replaced.

The procedure is exactly the same as with the front lines; make sure to support the flexible line with a 17mm wrench and turn the fitting on the hard line with a 11mm flared nut wrench.
Figure 8

The procedure is exactly the same as with the front lines; make sure to support the flexible line with a 17mm wrench and turn the fitting on the hard line with a 11mm flared nut wrench. Installation is the reverse of removal. You must properly bleed the entire brake system after replacing your brake lines. Do NOT attempt to drive the vehicle until you have properly bled the system.


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