Life has become easier for those of us who love classic Mustangs. In the old days-the '70s and '80s-we were limited in what we could do with a vintage Mustang. At the mercy of salvage yards and a limited aftermarket industry, we had to improvise at every turn.
Today, companies like Master Power Brakes make short work of upgrading your braking system. You can bolt on disc brakes at all four corners. And, you can install power brakes any number of ways in '65-'66 Mustangs that were never available with power disc brakes to begin with.
One of the greatest challenges for those with '67-'70 Mustangs is installing a power booster when there's a big-block underhood. Mix in those Shelby pent-roof valve covers, and the potential for obscenities becomes great. The stock power booster is virtually impossible to remove and install with the valve covers installed; it just doesn't fit. Master Power Brakes changes all that with a compact power booster/master cylinder combination that fits like a glove-without removing the valve cover.
Our Master Power Brake (No....
Our Master Power Brake (No. BM1521KA) booster kit arrived with virtually everything needed for installation: booster, master cylinder, distribution block with warning switch, vacuum hose, and installation hardware. Not shown here is the power-brake pedal assembly, also included. The GM distribution/proportioning-valve block combo shown here is optional. You may have to do your own line fabrication or purchase lines, with fittings and flares, already made. Any seasoned auto parts store or hydraulic-line shop can make lines for you.
This is the area we are dealing...
This is the area we are dealing with. To install the Master Power Brakes booster, drill out the existing threaded-nut plates to get the booster studs through the firewall. You also have to drill an additional hole at the six o'clock position.
At the six o'clock position,...
At the six o'clock position, relative to the master-cylinder opening in the firewall, drill a small pilot hole, followed by a 31/48-inch hole.
This accommodates the additional...
This accommodates the additional stud in the power booster.
We have actually removed the...
We have actually removed the brake-pedal support to show you the drilling process. Existing nut plates are drilled out to 3/8-7/16 inch to make way for the power-booster studs. You can do this with the pedal support still in the car.
The Master Power Brakes power...
The Master Power Brakes power booster and master-cylinder assembly is test-fitted in place. Installation, even with a huge FE big-block and Shelby pent-roof valve covers, is simple. It glides right in-our test fit is perfect.
Chuck Schnarr and Laurie Slawson...
Chuck Schnarr and Laurie Slawson install our power booster. Chuck holds the booster while Laurie runs the nuts down underdash.
Chuck tightens the self-locking...
Chuck tightens the self-locking nuts up under the dash. He has removed the steering column for visibility. Unless you do otherwise, you will have to contend with the column.
Installed, the master cylinder...
Installed, the master cylinder and power booster clear the Shelby pent-roof valve covers nicely. You can even remove the valve cover with the master cylinder installed.
We have removed the master...
We have removed the master cylinder for the brake hydraulic-line portion of this installation. Because our '68 Mustang fastback had manual drum brakes to begin with, we need to drill an additional 3/8-inch hole (arrow) as indicated. This clears the proportioning-valve clamp bolt with the stock '68-'69 front-disc brake distribution block.
The stock '68-'69 distribution...
The stock '68-'69 distribution block is installed, as shown. Two self-tapping bolts retain the block and proportioning-valve assembly.
This is the stock '68-'69...
This is the stock '68-'69 front-disc brake distribution block and proportioning-valve combo installed.
We like the compact nature...
We like the compact nature of the Master Power Brakes power booster. Check out the clearance. We installed this guy without removing the big-block valve covers.
The master cylinder is reinstalled,...
The master cylinder is reinstalled, as shown. Two self-locking nuts get the job done.
All brake hydraulic lines...
All brake hydraulic lines are tightened, as shown. All fittings should be checked for leakage after the brakes are bled. Remember that brake fluid will lift paint, so don't allow any fluid to leak onto your Mustang's paint.
The completed brake hydraulic-line...
The completed brake hydraulic-line installation at the master cylinder looks like this.
Next is the vacuum-line connection...
Next is the vacuum-line connection between the power booster and engine's intake manifold. If you are running a hot camshaft, which can reduce manifold vacuum, use a vacuum reservoir to store vacuum.
Looks sharp, doesn't it? The...
Looks sharp, doesn't it? The completed underhood installation looks stock, made for a Mustang! Underdash, attach the brake-light switch and rod to the brake pedal.
Give Yourself A Boost
Master Power Brakes has power-brake booster packages for all '65-'73 Mustangs. Here's the information you need to make an informed decision:
| '65-'66: |
BM1522K (no brake pedal) |
| '67-'70: |
BM1521KA
(brake pedal included) |
| '71-'73:
| BM1523(no brake pedal) |
| Plumbing kit: |
AC2000 |
| Combination valve: |
VL3350KF
(Also called distribution block) |
| Vapor trap: |
No part number
(keeps fuel vapors out of the power booster) |
| Petosin DOT 4 brake fluid |
| Electric vacuum pump: |
(Use when camshaft profile hurts manifold vacuum) |
Distribution Plan
When you order your Master Power Brakes power-booster package, which includes the master cylinder, you have choices. Optional is a GM distribution block, which includes a brake-pressure warning-light switch. This is a nice looking bolt-on that functions well if you aren't concerned with originality.
Here are three examples of...
Here are three examples of brake distribution blocks. The four-wheel drum-brake distribution block for 1967-'69 is "A." Front-disc brake applications for 1968-'69 received "B," with a built-in proportioning valve. For 1967, the proportioning valve was located above the rear axle. The Master Power Brakes' version is "C," which works well for custom applications, where originality doesn't matter.
If originality is important, you can opt for the factory distribution blocks for 1967-'68, which also have the brake-pressure warning-light switch. The warning light comes on whenever there's a pressure loss in either the front or rear braking system. Pressure from the working side moves a pressure differential piston in the direction of the "no pressure" side, which closes the switch and illuminates the light. Whenever we correct the problem and bleed the brakes, we need to create a pressure change, which moves the piston back to center, canceling the light. The pressure change comes when we open a bleeder slowly on the unaffected side. Pressure from the affected side returns the piston to center.
This is a bird's-eye view...
This is a bird's-eye view of the Master Power Brakes distribution block.
The Master Power Brakes distribution...
The Master Power Brakes distribution block can be mounted at your Mustang's inner fender using spacers, or you can use this bracket from the kit, which provides a mount that ties it to the master-cylinder mounting stud at the power booster.
Master Power Brakes provides...
Master Power Brakes provides this brake-pressure warning-light switch lead in the kit.