Our friend John and his son, Greg, have been driving this mostly stock '64 Coupe De Ville for a few years. The big boat weighs in at about 2 3/4 tons, and even more when big John climbs in and puts his heavy right foot to the gas pedal. The sum of all that mass more than exceeded the safe stopping power of the 43-year-old drum brakes. During some recent 60-0-mph testing, those drums were so toasted after a couple of hard practice stops that the car was too dangerous to drive and had to be trailered home.
The next stop was ABS Power Brake in Orange, California. In addition to manufacturing power-brake boosters, high-performance master cylinders, and power-steering boxes, ABS makes disc-brake kits for all kinds of late-'40s to early '70s cars and trucks. The company currently has the measurements to provide complete kits for approximately 50 different applications, including Tri-Five Chevys, Fairlanes, Impalas, Thunderbirds, most popular musclecars, '47-72 Chevy pickups, '48-70 Ford F-series trucks, and Cadillacs like this one. If ABS doesn't have brakes for your car or truck, the guys can fabricate them using your spindles, steering arm, and bolt pattern. This upgrade doesn't cost radically more than rebuilding the stock drums, and provides much better performance.
The Cadillac disc kit that went on John and Greg's '64 is a recent development and presented a challenge, since the center portion of the stock rims wouldn't clear the caliper. It's a familiar problem to early '60s Cadillac owners who sometimes solve it by switching to rims from disc brake- equipped Cadillacs. Since John wanted to retain the stock wheels, Pedro Gomez substituted 11-inch rotors for the 12-inchers he would use otherwise.
The improvement was significant. The front discs, combined with a new master cylinder, double-diaphragm booster, and disc/drum proportioning valve, made an impressive difference.
"The car drives much better now. The new brake system is very well-balanced and matched to a Cadillac," John says. "The brakes aren't touchy, so it's easy to stop without being jerky-and if I need to stop fast, the harder I push the pedal, the faster it stops."
More testing backed up that seat-of-the-pants impression. Although the drum-brake failure during the pre-upgrade testing prevented us from getting any hard numbers, we deduced the 60-0 stopping distance would have exceeded 250 feet. With the ABS discs, that shrunk to 167 feet and a stopping time of 3.87 seconds. That's impressive, especially with such a heavy car rolling on non-performance tires.
According to John, "The biggest improvement is something you can't measure-confidence in the brakes. Now I can relax and enjoy driving the car without worrying about rain or repeated stops in heavy traffic."
Photo by Mike Harrington
All ABS Power Brake conversion...
All ABS Power Brake conversion kits, including this one, are created for each specific application, and come as a complete ready-to-bolt-on kit.
One of the advantages of this...
One of the advantages of this package was that it allowed us to retain the stock spindles. The two-piece mounting brackets-created according to the vehicle's bolt pattern-adapted the spindles to the rotors. The two lower holes were used to fasten the piece to the spindle on the lower bracket; the upper holes were used to fasten to the upper bracket.
This '64 Cadillac requires...
This '64 Cadillac requires a pair of spacers to ensure the correct alignment of the pad over the rotor. The smaller-diameter spacers (A), located on the bolts fastening the upper and lower brackets, correctly position the caliper. The larger-diameter 3/16-inch spacer (B) correctly positions the rotor on the spindle.
Installing the bearings (shown...
Installing the bearings (shown here for illustration and not greased yet), grease seals, and the rotor itself onto the spindle was as simple as it gets. In order to get the early '60s Cadillac rims to clear, Pedro reduced the rotor diameter from the typical 12 inches to 11 inches. These newly fabricated rotors had not been cross-drilled when we showed up to photograph this installation; ordinarily they would have been.
For this application, ABS...
For this application, ABS used GM calipers from a late-'80 Cadillac. The caliper mounted to the upper mounting bracket. This is the moment of truth. Is it positioned correctly on the rotor? It is.
The brake lines on this Cadillac...
The brake lines on this Cadillac were still in good shape and the ABS brake hose from the caliper connected directly to them, saving the time and expense of replacing them. If the existing lines aren't up to the job, ABS can provide replacement lines.
Under the hood, the old master...
Under the hood, the old master cylinder and booster were disconnected and replaced with a 9-inch Delco-style dual-diaphragm booster and master cylinder with a proportioning valve for a 60/40 disc/drum pressure ratio better suited to provide plenty of pressure to the new disc brakes.
When the job was done and...
When the job was done and the brakes were bled, Pedro checked the pressure in the lines using a hydraulic gauge. The pressure measured between 700 and 800 psi under normal braking conditions. In a panic stop, the pressure will jump to 1,000 lbs or higher.