How To Install a Power Brake Booster

Several modifications are needed at the firewall. First, drill this hole in the firewall directly below the large hole where the pushrod passes through. There's a dimple in the firewall indicating hole placement. The dimple was for cars equipped with original power brakes, but the hole wasn't drilled with manual brakes.

The next task is to open up the large hole at the top to allow the power booster to fit. We used an air-powered grinder with a small grinding bit attached. The directions and a supplied gasket or template illustrate how much material needs to be removed. The directions also say to enlarge the two smaller holes on either side of the large hole to allow the brake booster to fit. By test fitting the booster/master, we discovered that we didn't have to do this with our car.

Before installing the brake booster and master, the supplied junction block needs to be attached to the car's existing brake lines and installed according to the Master Power instructions. Shown here are the two front brake lines joined at the rear of the block and the single rear line joined at the front of the block. The master cylinder is then joined to the junction block with the two lines installed on the right side of the block as shown.

Next, the master cylinder/brake booster is installed and secured to the firewall using the supplied nuts. These are installed from inside the car underneath the dashboard where the pedal support is located.

This view from under the dash shows the new pushrod attached to the new brake pedal. Also visible are three of the four nuts that attach to the studs on the booster. All that's left to do here is reattach the brake-light switch to the new pedal using the existing clip.

While we're upgrading the brakes, let's also replace the factory front drum brakes with Master Power's front-disc brake package (PN DB1521B for a '70). It's complete and an ideal choice for a regularly driven vintage Mustang. The main bits include the four-piston calipers, rotors, caliper mounting brackets, brake lines, and wheel bearings. All the related installation hardware is also included. The kits for all '65-'73 Mustangs are similar to this '70 kit with slight variations depending on the year of your car.

Complete the installation by connecting the new brake lines to the master cylinder, installing the new vacuum hose for the brake booster, and bleeding the brake system. The brake booster needs a vacuum source from the engine to make it work. Master Power supplies a vacuum hose that's shortened to fit, as shown. It's a simple attachment to run the hose from the booster to a fitting on the intake manifold. If no fitting is in place, Master Power supplies one for installation on the manifold.