Master Cylinder and that Felix character

The Mustang, as I brought it home, was a four wheel drum, non-power brake car. It wasn’t a white knuckle ride. I was more nervous about driving the car at night on account of its pitted and scratched windshield.

I was not in love with the drums. I never had any intentions of keeping them. I did intend to keep the car non-power though.

I had this odd sense of a punishing “Macho” car. I wanted the car to be as bare bones as possible; No power brakes, no power steering, manual clutch, carburetor, manual transmission.

I didn’t stick to that plan. Various reasons, none of which I can object to. Leaf through this blog and eventually you’ll find the reasons for the change of heart. On this post I’ll talk about the brakes.

I didn’t think anything special about when it was time to put the car back together. If the part unbolted, it should go right back the way it came off. I made some mods to the car and on those areas I expected some push back.

Getting the floor in the car signified that I could begin the task of putting the interior back together. For me, the best place to start was the drivers area. I dug out the pedal assembly and broke it down to clean and paint it. I bought a rebuild kit and put everything back together and installed the assembly in the car. The surprise came when I moved to the engine bay.

The engine was still in the car when I tried to put the brake master cylinder in. It didn’t fit any longer. This engine is way wider than I anticipated.

I did some measuring and found that there is 6 1/2” of space between the firewall and the back of the cylinder head. The M/C is 7 1/4” long from the mounting flange to the nose.

The master cylinder nose is resting on the valve cover. If this were a static display, it could probably pass but it’s not and the engine torquing over could do nasty things to the M/C or the valve cover.

Crap.

A lot of newer cars have Master Cylinders that are smaller than the one I had to replace but, here’s a little something I had to learn. Master Cylinders for manual brake cars have a piston diameter of an inch or less, anything larger and the pedal becomes more difficult to press. The later cars have pistons up to an inch and 3/8. These are for power assisted brake cars. These later model MC won’t work with my combination.

My friend Bryan has a 1974 Ford Courier. It’s a non-power brake car. I asked him to measure the MC on that car. It was just around six inches from the flange to the end of the piston chamber. I bought one and even removed the residual valves that a drum brake car requires.

After doing some additional research, I found out that the reservoir isn’t big enough to handle the requirements of a disc brake system. The reservoir IS smaller but it didn’t look all that much smaller. Well, we are talking brakes so if there is any doubt about a component in the system, I’ll avoid it.

I found some magazine articles on Mustangs with Cammers in them to see what these other cars used. Not impressed.

These other cars used a single port Master in them. They fit with plenty of clearance but the thought of having the power that the SOHC is capable of behind a single port master cylinder which means all brakes are gone if one line leaks or breaks. No thank you.

This is when I lie flat on my back in a dark room and stare at the ceiling.

There are odd ball options out there to raise the old MC up but then the linkage is compromised.

There is the Wilwood option, those aftermarket pedals that attach directly to individual cylinders. There is one that has two side by side cylinders off of one pedal. Save that for the race cars, this is a street car.

After weeks of reading and searching for inspiration, it dawned on me. The inspiration for this build is the Boskovich Mustang. Pop’s Toy started off as a legit 1969 Boss 429 Mustang before Pop’s swapped in a 427 SOHC. I swapped out the shock towers for Boss 429 repro shock towers, what else can I source from the Boss 9?

By looking at pictures, I can see that Pop’s car has a power brake booster.

I do some investigating and it turns out that ALL 1969/70 Boss 429 Mustangs had power brakes. Crap.

Don’t get me wrong, I’m not completely opposed to power brakes. All my other vehicles have them and I love them.

I have a dilemma with power brakes in this car with this engine though.

The 427 SOHC was designed for Balls out racing in NASCAR, I don’t think that would lend itself to a nice smooth idle with plenty of vacuum for a vacuum diaphragm power assist booster.

A Hydra Boost system ties into the power steering lines. Again, race cars from the mid 60’s, no mounting point on the engine for such luxuries as a power steering pump. I have no way of driving a Hydra Boost Brake system.

There are electric power assist brake boosters and they are ugly. I’ll come back to this.

Another dive into the internet and I discover that the Boss 429 had an aluminum adapter that bolted between the firewall and the power brake booster.

This adapter raised the mounting point slightly and caused the booster to angle upward off of the firewall.

I took a gamble on a picture from a magazine off of a computer screen and called my old buddy, Kevin Manley of Kevin’s Klassic’s. He’s the cat out in Minnesota who has a business restoring 1969 and 1970 Boss 429’s.

Kevin confirmed that the Boss 9 used this adapter and he even had some in stock. In order to use the adapter, the Boss 9 brake pedal was modified to work with the higher pivot point. Of course he had this as well so I gave him my credit card number and had the parts shipped out to me.

That was the easy part.

The Boss 9 used a modified vacuum booster and there aren’t many left to be found and if you do find one, $$$

The brakes are going to take a little while longer.