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Manual To Power Brakes

*** (Download this article as a Word Document) ***

[Picture donated by Rich Okeson, thanks, Rich!]

Here is an option that many drivers take for granted today. The application of engine vacuum to braking power allows the driver to press the brake pedal with less effort, and still maintain the same, if not better, braking force. With the early Falcons being the compact cars that they were, not much room is available to squeeze a booster and master cylinder into the cramped area between the firewall and the driver's shock tower.

Power brakes were offered in Falcons as an option starting about 1963-4, but this unit consisted of a single reservoir master cylinder. These "fruit jar" master cylinders worked, but if they ever failed, the driver would loose ALL braking power. By the mid 1960s, dual reservoir master cylinders were used. These master cylinders create two braking systems instead of just one; the front brakes and the back brakes were independent systems. If one failed, the driver still has the other set of brakes to stop.

Not only does the fact that the Falcon's stock power brake unit uses a single reservoir master cylinder hamper their use, but they are also rare finds. Lately, some companies have begun to sell remanufactured or new units, but they are several hundreds of dollars. Other companies have also begun creating/modifying other master/booster combos to fit the Falcon. You can see one of these being installed at Joe Weaver's 64 Sprint Restoration site, along with a shorter summary of this section.


Because of these reasons, the hunt for a usable booster/master cylinder combination that would fit the Falcon was constantly discussed on the Falcon discussion group, and in time, a member found that this little unit discussed here would work: the unit off of a Geo Metro.

This setup has already been used on several cars, including my own. The cars that I am familiar with having this swap sport different brake setups as well. From drum brakes all around to disc brakes all around. So far I have heard nothing but shining reviews from incorporating this system.

My Opinion of this System

I, like many of you, am the skeptical type. I liked the idea of having power brakes, but off of a Geo?! Will it work? Can it actuate bigger brakes than it was matched to? There has to be brake fade, right? Maybe impossible bends needed in the brake lines to it?

In a word, no. The installation of this unit was fairly easy personally, and I never replaced/fit a power booster/master into a car before!

So do I feel that there are ANY downsides to this swap? Unfortunately yes, but in my opinion they are worth living with to have power brakes:

1.) You need to slightly modify the shock tower to firewall brace to fit the unit. The original instructions given to me on this swap call for "massaging" the brace with a hammer to gain clearance. I opted to cut a semicircle out of the brace, which you will see below.  The necessity of modifying the brace depends on what angle you mount the brake booster at.  The steeper the angle, the less necessary the brace mod.

Now that I have finished and have been driving the car with this system, I have seen the amount of flex in the firewall there is when the brake pedal is actuated. In all honesty, if one removes the small plastic clip that is molded into the front of the brake reservoir, there is enough room to fit the Geo system without need to modify the brace. The trick is to play around with the booster's placement angle to allow the reservoir to fit.

2.) I am picky when it comes to brakes. I like a certain feel to them. This setup has a small master cylinder bore, 13/16", compared to the Falcon stock 7/8", or the 1" bore of the Falcon optional power brakes master cylinder. The Geo unit does work, stops the car smoothly and evenly, and locks all four tires in panic stops. The only thing I don't like about them is the feel. It is a "soft" feel. The brakes begin to grab about a 1/4 of the way down, and I can lock them about 5/8 of the way down, but the pedal is too easy to push in my opinion. This "soft" feel, at least for me, had me stopping hard the first couple of times out since I hit the pedal expecting more force would be needed compared to what I truly needed.

Here we Go.....

1.) The 89-94 Geo Power booster and master cylinder are unlike American counterparts. This is a foreign part, and it has many differences compared to the typical Ford or Chevy master cylinder or booster. The master cylinder and the brake reservoir are separate pieces, with the reservoir being a tall cylinder with a screw off cap. The brake failure warning light is situated inside the reservoir, so plumbing of a switch is unnecessary. A simple plug comes off the reservoir to power the switch, and can be seen in the pictures of the unit below.

The booster is small, and seals with the help of recessed O-rings where the master plugs into the booster. The booster also has an adjustable rod: it can be adjusted at the pedal or slightly on the other side of the rod before the master is installed into it.

The Geo unit here is next to a 1967 Ford Mustang dual master cylinder, the unit that was on my car before this swap. Look at the difference in size. They're pretty close, eh?

2.) This system can be installed into 1963 1/2 to 1970 Falcons. As of yet I have not heard of this unit being installed into a 1960-1962 Falcon.

The middle/late1963 (or the 1963 1/2) Falcon engine bay was enlarged to be able to fit the 260 cubic inch small block. I personally measured a 1963 1/2 master cylinder area to find you can fit this swap, but a bit more brace modification *might* be necessary. The 1964/1965 "square" bodied cars, like mine, have one less inch of room than the 1964-6 Mustangs, but fit this unit. The 1966-early 1970 Falcons have enough room as well, with the late 1970 (1970 1/2) Falcon, based on the Torino, having ample room for this swap.

3.) I followed the instructions sent to me by the fellow discussion group member who discovered the compatibility of this unit and installed the Geo unit on his Falcon. Many thanks, Mark. The instructions posted here are his original directions, with some of my additions and modifications.

The directions do the brunt of the explaining, but since a picture is worth a thousand words, here are some photos of my installation:

inside car

The top left photo shows the original master cylinder removed, and the paper template described in Mark's directions taped in. With the help of my father, we used a grinding wheel and metal cutting hole saw to enlarge the original master cylinder's hole, as seen in the top right photo. The bottom photo is showing the use of the grinding wheel to clean up the semicircle I cut into the brace. I wasn't too worried about aesthetics here because I am replacing the original braces with a custom export brace. This is the main reason why I didn't take more time in seeing if modification of the brace was necessary.

After the hole in the firewall and the trimming of the brace, I installed the Geo booster/master combo. One of the most important things one must do when installing a master cylinder is to bench bleed it. There are generally two ways to do this: with the master on or off the car. I prefer to bleed the master while it is installed. Before the brake lines are connected to the master, go to the auto parts store and buy a master cylinder bleeding kit. It is simply plastic fittings that thread into the master with hoses that are placed into the reservoir. By pumping the brake pedal, all the air is expelled out of the master and fresh fluid fills the space. The bleeding kit is seen in action in the left photo.

The next picture is the removal of the pin out of the brake pedal. After grinding the pin flush with the pedal, a quick salvo of raps with a punch removes the pin, leaving a nice hole for the booster's pushrod.

The third photo shows the system plumbed and ready to go. Below are shots of the unit installed, but not yet plumbed:



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