You will find the brake master cylinder located at the top of the brake assembly. It will be held in place by two nuts on threaded posts. Remove these nuts with an adjustable or open-ended wrench, and then remove the cylinder. This will allow you to get to the brake booster vacuum hose.
Make sure you have a safe place, such as a plastic bag or a bowl, to put all of the nuts removed in this process so you don't lose them.
Step 4 - Remove the Vacuum Hose
The brake booster vacuum hose will be in behind the master cylinder, held in place with one nut. Remove this and slide the hose out from the rear of the brake housing. Disconnect it from the brake line, and take it to your local auto parts store to make sure you buy a properly fitting replacement.
Step 5 - Install a New Vacuum Hose
Once you have the old vacuum hose off of the brake line and brake assembly, position the new one in its proper place and begin securing it. Reconnect the brake line as well as the assembly itself. Then, replace the nut for the brake booster vacuum hose.
Step 6 - Replace the Brake Cylinder
Now that the new vacuum hose is installed, you can slide the master cylinder back onto the threaded post. Secure with the two nuts that you removed initially.
Step 7 - Bleed Brake Lines
Any time you work with the brake lines, you'll need to bleed them afterward in order to release any air trapped inside. Open the bleeding nut on the back of the brake assembly and let the brake fluid flow until pure liquid comes out. Close the bleeding nut and add brake fluid to the reservoir to replace any that was lost.
Step 8 - Replace Tires and Lower Car
Replace the brake cover and tires. Tighten the lug nuts onto the wheel and lower the car back to the ground.