Instructions to install Geo Booster

These are the instructions that were sent to me. I have included my comments and modifications in red for easier reading. If you have not read my warning on my title page, please do so now.

Parts Required from Salvage Yard:

1.) Brake booster/master cylinder from '89-'94 Geo Metro or Suzuki Swift. Make sure to get the pin that attaches the booster to the pedal and the nuts that mount the booster to the firewall. Also get the foam gasket that is on the fire wall. Trace this onto a piece of poster board to make a template for installing.

2.) Wiring pigtail to stop lamp switch on '73-'79 Ford Pickup. Cut off as much wire as possible.

Parts required from the Auto Parts Store:

1.) One 3/16"x 2" cotter pin
2.) Two feet of 3/8" vacuum hose
3.) One stop lamp switch ( Standard Ignition Part #SLS 66)
4.)One male and one female "Bullet Style" wire connector (for '60-'64 cars, '65 use 2 male "spade" connectors)
6.) Two 3/8" x 1 1/4" bolts
7.) Twelve 5/16" flat washers
8.) One 8" piece of 3/16" steel brake line
9.) One 3/16" brake line coupler

10.)One pint of brake fluid


1) Disconnect battery, (I know, every thing starts out this way and usually for no reason. This time there is a reason.)

2) Remove hood and left hood hinge.( '60-'63 with prop rod may be able to leave hinge in place.)

3) Remove brake pedal (you probably needed to lube the pivot anyway)

4) Disconnect brake lines from junction at master cylinder. Remove the master cylinder. Install the two bolts that you bought in the holes where the master cylinder was. Loosen the two bolts that are above the master cylinder mounting holes. Give them a sharp rap with a hammer to loosen the spring clip type nuts that they are screwed into. Remove these bolts and the nuts that are inside of the car.

5) '60- '64 connect the two green wires together that were on the brake light switch. I cut and soldered them. '65 can disregard this step.

6) Tape template to firewall; upper holes in template line up with upper holes on fire wall. Drill two 3/8" holes at bottom of template.
Remove metal from firewall that is in center hole of template. This should be about 3/4" of metal.

7) Remove master cylinder from booster. Remove reservoir from master cylinder by pushing out rollpin.

8) Hold booster up to firewall. It should sit at a slight upward angle because of the two bolts that are in the old master cylinder holes. Figure out how many 5/16" washers are needed on the lower studs to hold the booster off of these bolts. I used 6 on each lower stud. This will vary as it depends on the thickness of the washers that you bought. On the inside of car, trim enough metal from the pedal support to allow the lower nuts to fit. When you get the spacing right, bolt the booster to the firewall.

(This is the trickiest part of the entire installation. I took the use of the 5/16" washers in this step as optional. The booster needs the shims on the bottom two holes to make room for the master and reservoir to fit, but the amount and type can vary. I used two 5/8 thick washers on my two lower bolts, and am glad I did. It allowed me to use the original master pushrod hole instead of drilling a new hole lower on the pedal.)

9) While the Geo master cylinder is still off of the car, screw the piece off 3/16" brake line into the front port that points up. Bend the line to the right and then under the master cylinder so that it points to the left side of the car. Attach the coupling to the free end of the line. Remove the line and set aside for the moment. It is much easier to bend this line while the master cylinder is still off of the car.

10) Install the master cylinder to the booster. Attach the line that comes from the right front wheel of the car to the front-side port. There is enough line on the car to do this if you bend carefully. Install the line you made and attach this to the line that comes from the left front wheel. Attach the remaining line that runs to the rear of the car to the rear port in the master cylinder.

(I ran all new lines. I suggest you do the same, since kinking a brake line is BAD. If you do what Mark suggests here, please be VERY careful. It doesn't take much to kink a brake line, and this can cause restriction of the brake fluid's flow or worse: a leak.

The Geo system also uses 3/16" line like the stock Falcon, HOWEVER, it has METRIC threaded fittings. Mark explained to me that he was able to thread the standard lines into the Geo master without any leaks developing. I decided on purchasing adapters to thread into the master so it absolutely mated with the standard brake line.

This Geo master has three lines running from it. The top line that feeds the front driver's side brake is a tight fit because of the brace running overhead. On this fitting I didn't have the room necessary to install the adapter that the other lower two ports have. Nevertheless, the standard line did thread into the metric port and tightened down. I have checked the line from time to time to find no leaks.)

11.) Set the reservoir in place and use the 3/16" cotter pin to hold it in place.

(I used the original rollpin on mine. In my opinion, it is much cleaner looking, and I haven't had any problems with it yet.)

You may have to indent the edge of the cowl brace slightly with a hammer. It doesn't need to move very far and is not noticeable when you are done. There are two wires that come out of the Geo reservoir that worked a low fluid light. They can be cut off or left on.

(I used a metal cutting blade in my jigsaw and cut a semicircle in my brace. See more of this in the Geo Brake section)

12) Remove the pin on the brake pedal that the old push rod connected to. This can be easily done by grinding the back of the pin flush with the pedal, and using a drift punch to drive it out. Remove the rubber bumper at the top of the pedal. Temporarily install the pedal. Mark the hole where the rod attaches. Remove the pedal and drill a 7/16" hole in this location. The hole should be about 3/4" below the hole that the pin was removed from. Install the pedal and connect the new push rod with the pin from the Geo.

(I did have to grind off and punch out the original pin that the old push rod attached to, but I didn't need to drill a new hole. My spacers under the booster allowed me to attach the Geo booster's pushrod in the original position of the stock manual pushrod.)

13) In '60-'64s, reconnect the battery. The brake lamps should be on. Find the dark green wire where the wires exit the steering column. Disconnect this wire and the brake lamps will go off. Crimp the "bullet" connectors on the Ford truck pigtail. Plug the pigtail into the green wire that you disconnected. Plug the stop light switch into the pigtail. The lights should now be on . Test the switch by pushing the button. The lights should go on and off. Install the switch into the hole that the rubber bumper was removed from. Adjust the two nuts until the lights are off.

On '65 crimp the "spade" connectors onto the pigtail. Plug these wires into the plug that was on the old brake light switch. Everything else installs the same as the early cars.

14) Bleed the brake system now. It's a lot easier to do it with the hood off.

15) Connect the vacuum hose to an unused port on the engine and to the booster. Reinstall the hood hinge and hood.

16) Take it for a test drive. This swap is such an improvement over the old system that it takes a little getting used to. The Falcon did not use a proportioning valve and I don't see the need to use one with this setup. My car stops very evenly, when I try to lock the wheels they all lock at the same time.

(Please note that Mark owns a Ranchero with four wheel disc brakes. I installed a Wilwood adjustable proportioning valve and am happy that I did. I am able to get much better braking out of my system, which is front disc with drum back brakes.)

I have tested this on wet roads and snow and ice covered roads. I have no problem with premature wheel lockup. This conversion may not be for every one, but anyone that drives their Falcon on a regular basis should consider it for safety reasons. If you have ever had the old style single reservoir system fail, you know why I did this.

Mark Dinzebach
March 1998

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