For classic truck enthusiasts, one of the most popular modifications is to upgrade the brake system. A good, reliable brake system that gives the driver the feeling of complete control is very important. The popular '67-72 GM trucks came with various brake set ups. The '67-70 models were equipped with drum brakes while the '71-72 featured a disc/drum combination. The power boosters were the same for disc or drum equipped trucks. Manual brakes were very common as well.
Classic Performance Products cut its teeth on designing replacement power brake upgrade kits for trucks and still to this day one of their most popular products is the Power Brake Booster kit. This kit features a replacement 11-inch diameter power booster as well as an improved master cylinder and proportioning valve for either disc/drum or disc/disc brake set ups. The assembly is a direct bolt on replacement for the factory equipment. Some modifications to the existing brake lines are required depending on what your truck's current brake set up is. This is an ideal upgrade from manual drum brakes to power discs.
To give the consumer some idea of what is involved with this power booster kit upgrade the following steps illustrate pretty much every detail of the installation that can be done at home in the driveway. This particular truck was an original manual drum brake truck. The brakes were upgraded to disc/disc so the system needed to be upgraded to support the new brakes. Regardless of your brake set up, the installation steps are the same. It is recommended to use a good set of line wrenches for the brass fittings. Be sure the vehicle is properly secured before removing the brake system.
CLA SSIC PERFORMANCE PRODUCTS, INC.
175 E. FREEDOM AVE., DEPT TEN
ANAHEIM, CA 92801
(714) 522-2000
 The first step is to begin removal of the factory brake lines from the prop-valve. |  |  Remove the brake system indicator wire from the sender in the prop-valve. |
 Remove the rear brake line from the prop-valve. |  Unbolt the master cylinder from the firewall. If your truck has a power booster, unbolt the bracket from the firewall. |  Once the nuts are removed from the firewall studs, remove the master cylinder. |
 With the assembly removed you should see four studs and the brake push rod sticking through the firewall. |  The new CPP Power Brake Booster Kit utilizes one of the bolt holes that secures the steering column, found just under the lower driver's side firewall stud. This bolt needs to be removed so that it can be used as a fifth mounting point for the booster bracket. |  Remove the brake pedal clevis from the brake pedal arm inside the truck and pull the brake push rod out. |
 Remove the clevis from the factory brake push rod. |  Install the factory clevis onto the new push rod attached to the power booster assembly. The proper position of the clevis will be determined later when attaching to the brake pedal. |  Install the new rubber firewall seal onto the push rod. |
 Install the power booster assembly onto the four firewall studs while inserting the push rod through the center hole. |  |  A 9/16 wrench is used to tighten the four nuts onto the studs, permanently securing the bracket. |
 |  The bolt removed from the steering column bracket in step 8 is installed through the bracket and into its original hole. This will complete the installation of the booster assembly to the firewall. |  From under the dash, connect the push rod clevis to the brake pedal. Adjust the clevis on the push rod so the brake pedal is as high as possible without preloading the brake booster and the brake lights are off. |
 A new brake sensor wire needs to be spliced to the old wire to make it long enough to reach the prop-valve. Cut the old wire, leaving plenty of room to work. |  |  Crimp the new wire lead with the existing wire. |
 Remove the frame clamp that secures the brake lines. |  Pre '71 drum brake trucks will need to modify the existing lines and use brake fitting adapters. If you are not familiar with how to cut and manufacture new brake lines, seek a professional to have them cut and bent for you. Properly bends and fitting seating is very important for the performance of your brake system. Here we begin with a tube cutter to cut the line approximately half way up the vertical rise of the line. |  A new fitting is placed onto the line before the new line flare is created. |
 A flaring tool is used to create the need flare in the line. |  At the prop-valve, measure the desired distance before the necessary bend towards the cut rear line. |  Double check your desired length to be sure the brake line will be straight at the fitting, yet bend with enough clearance to avoid the booster. |
 The pre fabricated new brake line is inserted into a hand line bender. Before proceeding, double check the measurement. |  You will want the first bend to be 90 degrees to allow the line to lead straight over to the old cut line. |  Here we used two 90-degree bends to get the line over to the old line. Mark the final bend starting point for the line to meet the old brake line about one inch from the vertical intersection point of the two lines. |
 |  Make the final 90-degree bend. |  Mark the cutting point on the new line. Make this mark approximately ¾-inch up from the cut on the old line to compensate for the length of the union fitting that will be used to connect the two lines. |
 Install the line fitting then make the final cut and flare to the new line. |  Attach the new rear line to the prop valve. |  Install a union fitting onto the new rear line fitting. |
 Attach the fitting on the old line to the union fitting. |  Repeat the steps on the rear line for the front line by cutting the front line at roughly the same location as the rear line. |  Install the line fitting then flare the line. |
 Like the new rear brake line, the front line starts with a 90-degree bend and then is angled approximately 45-degrees from the prop-valve over to the old front brake line so the bend point to the line can be marked. |  Install a line fitting, flare the line then install both the new line fitting and old line with new fitting into a union. |  Specifically using line wrenches, tighten the new fittings to the prop-valve. |
 |  Permanently tighten the line fittings to the unions installed where the new and old lines meet. |  |
 Before proceeding any further, use the line wrenches to check all of the master cylinder and prop-valve fittings. |  Remove the master cylinder cover and place in a clean location so as to not get any debris on the cover gasket. |  Pour DOT 3 brake fluid into both the front and rear master cylinder reservoirs. |
 Fill to approximately 3/8-inch from the top. |  CPP recommends bench bleeding your master cylinder prior to installation. Since many consumers are not familiar with how to bench bleed a master cylinder, here is an alternative and equally successful method. Locate a syringe with a small tip, or a larger syringe with a rubber tip and small hole. |  You will notice two small holes in each reservoir. The rear holes in each reservoir serve the fluid into the master cylinder and brake lines. The front holes are where the pressure comes from that pushes the fluid through the master cylinder and into the lines. Insert the syringe tip into the brake fluid and extract fluid to fill the syringe. |
 Place the tip into the rear holes and press the fluid slowly through. |  You should see small bubbles rise up if you are doing it correctly. Repeat the process until there are not bubbles, only fluid rising through the front hole which will be visible at the surface of the fluid. |  Top the master cylinder off with fluid before continuing. |
 There are various ways to bleed. See the brake bleeding guide or visit the ''How To Bleed Brakes'' on the CPP web site for more information. Here we attach a vacuum bleeder onto the passenger side rear brake caliper bleeder valve to provide suction while using the previously illustrated method of bleeding the master cylinder. |  Once each line has been effectively bled and you are confident there is no air in the line, the master cylinder is topped off again and the master cylinder cover installed. |  Power boosters require vacuum to operate. Locate a vacuum source on the intake manifold. |
 Install a threaded fitting into the vacuum source and attached a vacuum rated hose onto the fitting. |  Attach the vacuum hose to the vacuum fitting on the power booster. (note: If the engine cannot produce at least 18-inches of vacuum then a vacuum pump may be needed in order for the booster to function properly.) |  Here is the finished installation of the CPP Power Brake Booster Kit. |
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