By Jim Smart
How To Convert To A Dual Braking System
Although the federal government can be a pain in the neck to automakers and individuals in terms of tougher safety and emission standards, it has contributed greatly to both vehicle safety and improved emission standards for the past half century. Much of it began with seat belts, padded dashboards, collapsible steering columns, impact absorbing crush zones, catalytic converters, and better braking systems.
Most classic Mustangs rolled off the assembly line with four-wheel manual drum brakes. Prior to '67, Mustang braking systems consisted of a single reservoir master cylinder tied to all four brakes. Drum brake systems got a smaller master cylinder borrowed from the Falcon. The few cars with optional disc brakes, including factory GTs, received a higher capacity master cylinder with a factory-adjusted proportioning valve to modulate rear drum brake performance. The problem with the single-reservoir approach to hydraulic brakes is the risk of complete and total brake failure should you experience wheel cylinder, brake caliper, or master cylinder hydraulic failure.
Beginning with the '67 model year, the federal government mandated dual braking systems with dual-reservoir master cylinders, meaning one cylinder, or bowl, for the rear brakes and another for the front, with both systems separated by a distribution block and warning light switch. If you experienced the misfortune of front or rear brake hydraulic failure, a piston dividing the two systems would slide in the direction of the failed system to trigger a "BRAKE" warning light. Even better, you retained some braking function from either the front or rear brakes to help get you stopped.
If you own a '65-'66 Mustang with a single brake hydraulic system and drive your Mustang on a regular basis, it's time to consider converting your brakes to a dual hydraulic braking system for a safer ride. Quality components are available from Stainless Steel Brakes, which can set you up with a dual reservoir master cylinder for a disc brake system, and Classic Tube, which offers pre-bent lines. If your Mustang has four-wheel drum brakes, seriously consider at least a front disc brake upgrade to improve safety. And if you can afford it, go for disc brakes at all four corners.
The Force 10 from Stainless Steel Brakes is a high-performance disc brake for the street. However, more affordable systems are available from SSBC to fit your Mustang's factory spindles.
Your single to dual braking system can be configured in at least two ways. You can use a '67-up dual braking system distribution block to divide the two systems and even set up a "BRAKE" warning light for system pressure differential. All you need is switched and fused power from the ignition switch.
1. This is the type of single reservoir braking system you can expect to see underhood on most '65-'66 Mustangs. This one is power-assisted for four-wheel drum brakes. Mustangs & Fast Fords OC is going to convert it to a dual braking system with four-wheel Force 10 disc brakes from Stainless Steel Brakes along with plumbing from Classic Tube.
2. Factory dual braking systems were federally mandated beginning with the '67 model year. In a dual braking system, braking is divided into two systems-One for the front brakes and a second one for the rear. The master cylinder's forward reservoir and cylinder operates the rear brakes and the aft reservoir and cylinder work the fronts. Disc brake master cylinders have a larger rear reservoir to operate the front disc brakes, which need more fluid capacity. With four-wheel drum brakes, you will see a dual reservoir master cylinder with equal size reservoirs. The illustration here shows a disc brake master cylinder.
3. Here's a typical power boosted dual braking package from Stainless Steel Brakes with a dual reservoir master cylinder for disc brakes. To the far left is an adjustable proportioning valve for rear drum or disc brakes. The proportioning valve adjusts rear brake pressure so you don't have too much rear brake pressure, which would be unsafe. You want the front brakes to begin to apply first.
4. Stainless Steel Brakes includes this brake distribution block (left), which divides front and rear systems, with its dual system kits. It routes pressure only to the front brakes. On the right is a '65•' 66 distribution block, which vectors brake pressure from the master cylinder to all four brakes.
5. You can purchase rolls of brake line and fabricate your own. Or you can order them prebent for your application from Classic Tube. For example, if you're converting a '65-'66 Mustang to dual braking with power-assisted front disc brakes, Classic Tube has galvanized or stainless steel lines ready for installation with the correct fittings in kit form. Stainless steel lines are more difficult to work with because they are not as flexible. Classic Tube also offers pre-bent line.
6. Bend your own lines using a large socket or opt for a tube bender from The Eastwood Company. Always make sure to have fittings in their proper location before you bend. Using a large socket prevents line kinking. Take it nice and slow.
7. Use a paper clip or coat hanger wire to map out line routing. Then bend your lines accordingly.
8. A tubing bender like this one from The Eastwood Company makes light work of tube bending. Follow the proper number of degrees on your tube bender and you can't miss.
9. Brake lines mandate the use of a double flare, which calls for a flaring tool. Before you flare, it's important to clean up the line end gently with a grinder to achieve a clean flare.
10. This is a flaring tool, which performs a double flare by first rolling the walls inward, then putting a flare on them to create a double wall. High brake pressures call for the double flare.
11. Unless you have one of the dual braking system line kits from Classic Tube, you will have to fabricate your own lines. Again, use coat hanger wire to establish a path from the master cylinder to the distribution block and proportioning valve. Bend your lines from the coat hanger template. Lines you pre-bend yourself make it easier to install. The forward reservoir and cylinder connect to your Mustang's new adjustable proportioning valve. The aft reservoir connects to your Mustang's front brakes via the distribution block.
12. The adjustable proportioning valve is a one-way only pressure regulator and check valve, with "IN" and "OUT" markings. The rear brake reservoir (front bowl) feeds the "IN" proportioning valve port. "OUT" goes to the rear brake chassis line.
13. If you're opting for a Stainless Steel Brakes power booster, it makes things tight for line installation, which is why you want to use a coat hanger wire template for your line fabrication.
14. We like the craftsmanship that Mustangs & Fast Fords OC has demonstrated here. They did a nice job with a custom-fabricated proportioning valve bracket for stability and security. The proportioning valve is easy to reach and adjust. Brakes will be flushed and bled, then the car is road tested for both operation and brake bedding.
15. Earlier, we told you about Stainless Steel Brakes' Force 10 high-performance disc brake system for classic and late-model Mustangs. These four-piston binders sport 11.25x0.8125-inch slotted, drilled, and plated rotors, with calipers powdercoated in just about any color you desire. They bolt to a drum brake spindle, which makes conversion simple.
16. Pad replacement is a cakewalk with Force 10s. No need to remove the caliper unless you're going to have the rotors turned.
17. Force 10 rear discs are four-piston units with 11.25x0.9375-inch slotted, drilled, and plated rotors with emergency brake feature.
18. Classic Tube improves your Mustang's factory rubber brake hoses with Stop Flex stainless steel braided brake hoses. These guys are virtually the last brake hose you will ever have to buy for your Mustang.