Done! Ok, now for the complete list and how-to if anyone wants or needs it.
To convert to power brakes from manual on a 1973-1979 F100, you will need to following from the donor truck:
- Power brake pedal (the brake light switch mount is completely different [the manual pedal switch mount is 85-90 degrees to the pedal shaft, and the auto is 40-45 degrees] , and the pedal will be marked "auto"
- Power brake booster bracket AND "z-bar" actuator [the booster rod attaches to the actuator, which in turn passes through the firewall and connects to the pedal]
*make sure to keep the nuts and bolts from the donor truck, and clean and paint the donor parts to your satisfaction
Next, go to a reliable parts store and pick up a new or rebuilt power brake booster and a NEW master cylinder [always go new on the m/c as there is no telling how many times a used unit has been rebuilt and who wants to install something only to have it fail soon after] Also keep in mind; there were several power boosters over the years [78-79 used two different boosters depending on serial numbers], make sure that yours looks like the one from the donor truck]
Remove the pivot bolt from your current brake pedal, then remove the pedal itself. This guide assumes an automatic transmission setup. If using a manual transmission, get the power brake pedal and clutch combination from the donor truck.
Next, install the "auto" pedal [check the bushings and lube if necessary, any all purpose grease lightly applied will do] and reinstall your brake light switch ensuring proper lenght for correct operation.
Carefully remove the brake lines from the manual master cylinder [keeping in mind which line was front and rear] and cap them if possible while you work [brake fluid can be some nasty stuff]
Attach the booster rod to the actuator rod, then pass the actuator rod through the firewall, making sure to line up on the correct side of your pedal.
Attach the booster bracket to the firewall, then to the booster.
Next, attach the pedal pivot bolt from the actuator to the pedal, and lightly depress the pedal a few times to ensure fluid motion [take special care not to work the pedal hard as not to cause damage to the booster diaphram]
You now want to mount the master cylinder to the booster. Don't worry with adjusting the pressure rod at this time [if your unit has one]
Attach the brake lines to the new master cylinder taking special care not to kink or bend the lines excessively [you may need line adapters to complete this as the new master cylinder may have different sized threads than your lines, mine did]
At this point, your setup should be complete [take a step back and admire your work, your back is probably killing you
]
Next, fill both front and rear reservoirs within 1/4 inch from the top, and secure the cap on the master cylinder.
For the next couple of steps, you will need a partner!
Starting at the farthest point [passenger rear] break the bleeder valve open with a box end wrench or socket wrench, clean the valve with a towel, then attach a small, snug fitting rubber hose to the bleeder valve and run it into a clear glass jar or similar. Make sure the bleeder valve is snugly closed, and have someone pump the brakes 3-4 times, holding the pedal to the floor on the last pump. With the pedal held to the floor, open the bleeder valve with a box end wrench and watch as the fluid enters the jar. You are looking for a constant, steady stream of fluid not disrupted by an occassional burst of air. Repeat this step until you have a steady flow from the hose. Follow this procedure from the right rear to the left rear, then passenger front to the driver front. Check the master cylinder periodically and fill as necessary. DON'T allow the master cylinder to run empty or you will have to start over! Once all bleeders have a constant flow of fluid [repeat the rotation at least once to ensure no air was missed], check all valves to ensure they are tightly closed.
Next, remove the master cylinder cap, and fill to within 1/4 inch of the top of both reservoirs.
Have your helper SLOWLY depress the pedal 3/8 to 1/2 inch, watching for fluid to "boil" within the reservoir [if the pedal is pressed quicly, you will get a brake fluid bath, as will your truck].
In a dual reservoir [most common today] fluid may only boil in the front reservoir.
If you have no movement in the reservoir, or it takes more than 1/2 inch of pedal press to get movement, the push rod is too short. Replace the cap on the m/c and remove it from the booster. Rotate the adjusting nut [if equiped] outward to gain length. Do this in small steps as you can create problems with a push rod that is too long. Continue to repeat this step until optimal results are achieved. If the fluid boils before the pedal is pressed 3/8 to 1/2 inch, shorten the adjusting nut.
DON'T ROAD TEST YOUR VEHICLE UNTIL ALL STEPS ARE COMPLETE! YOUR LIFE IS WORTH A CHECK AND DOUBLE CHECK!
Once all the steps are completed, checked and rechecked, go for a spin around the block. Test your new brake system with several stop and goes, and build speed as you become confident with your work.
Last but not least, enjoy driving your classic truck without the aches and pains of manual brakes
