In the mid-'60s, many cars weren't even offered with front-only disc brakes as an option, so it caused a sensation when Chevrolet made four-wheel discs standard on the '65 Corvette Sting Ray (there was a strange drum brake substitution--for a credit of $64.50--option that 316 buyers of '65 Vettes opted to order). There's a late 1964 issue of Motor Trend that has a six or so page, in-depth technical article about the new brakes for the Sting Ray, and you don't begin to realize the enormous engineering advance these four-wheel discs represented until you read material from the era.
The deficiencies, particularly in competition or even "vigorous" use on public roads, of the earlier drum brakes were well known. Zora and Company had come up with various "band-aid" fixes over the years, beginning with the competition-oriented RPO 684 in 1957 through the so-called big-brake packages, the '63-only Z06 Special Performance Equipment group, and, finally, 1964's J56 and J65 sintered metallic brake packages. The new brake system, right out of the box, worked better than anything that had come before.
But, what had been a stunning fait accompli in 1965 was badly dated by the time the Mid-Year/Shark chassis was retired in 1982. The once state-of-the-art system, with its huge four-piston, cast-iron calipers was prone to leaky piston seals and the calipers were exceedingly heavy, especially compared to the calipers that appeared in early 1983 on the all-new '84 C4s. Compared to C4s--and in ensuing years C5s, newer F-Bodies, and others--the '65-82 factory brakes don't offer a particularly reassuring or confidence-inspiring feel (spongy is a common description for the pedal feel of these cars) when you need 'em the most.
A mini-industry has sprung up around fitting stainless steel sleeves in the leaky old calipers to stem the majority of the spillage. Stainless sleeves are a vast improvement over unsleeved '65-82 calipers. For anyone who owns a '65-82 Corvette that's either original or restored to stock, and who wants to keep factory appearance, stainless sleeving is heaven-sent. For the non-purists, it's a whole lot better than nothing, but sleeved calipers still leave something to be desired (we're dealing with almost 40 year-old technology) if you're looking for better than stock performance--which most certainly includes being able to stop in the shortest possible distance and under complete control.
What has really surprised Team VETTE is that, until recently, no one (we're talking about manufacturers, not individuals) has come up with a new brake system for these Corvettes. The '65-67 Sting Rays are among the most popular, sought after, and expensive of all Corvettes--and with over 74,000 built they're relatively abundant. You want Corvettes that were and are plentiful? Take a look at the Sharks. There were well over a half-million Corvettes built and sold between 1968 and 1982. There were in excess of 616,000 Corvettes built with the four-wheel disc brake system we're talking about. When it comes to modern brake systems, these Corvettes have pretty much been ignored, and all the while there have been front- and four-wheel disc conversion kits for Solid-Axles, front conversion kits for '63-64 Sting Rays, and a plethora of big brake kits, from reasonable to totally absurdly priced (who really needs a $7,500 system with 15-inch rotors and six-piston calipers for a daily driver?) for C4s and C5s.
The key here is "until recently." There finally is a genuinely contemporary, i.e. modern, brake conversion system for the '65-82 Corvettes. It's easy to sit here at Team VETTE Command Central and pontificate about the lack of brake updating kits or systems for the '65-82 Corvettes. It's not so easy for a company to make the manpower and money commitments needed to develop a new line of parts that'll actually fit onto these cars. And, once the bucks have been sunk into R&D and tooling, are enough customers going to buy the things to make it worthwhile? Stainless Steel Brakes Corporation took the gamble, and we've got a feeling that the "Force 10 Extreme Duty" brake system is going to be extremely popular.
Force 10 is a brake system upgrade that addresses the various deficiencies of the original brakes, and is engineered as a straight bolt-on. The heart of this setup is the all-new SSBC aluminum four-piston calipers. Aluminum? So what? The original calipers were cast iron and exceedingly heavy, that's what! These new 356-T6 alloy calipers weigh about about 7 pounds (original iron calipers weigh about 12 pounds each), are also four-piston like the originals, roughly the same size as the originals so they look "right," and bolt directly in place of the originals.
Along with lopping 5 pounds of unsprung weight off of each corner, the aluminum calipers dissipate heat 30 percent more efficiently than do the stock cast-iron units, and utilize thinwall stainless steel pistons (43mm fronts and 35mm rears, with 48mm fronts optional) which also contribute to cooler caliper and brake fluid temperatures. The SSBC aluminum calipers are designed to be non-air pumping (if you've ever changed pads in those old Delco calipers and then had to bleed your Vette's brakes because of air getting into the system, you know what we're talking about), are fitted with large 3/8-inch bleeder screws, and all threaded assemblies use stainless steel helicoils and fasteners. Each front or rear caliper set comes with high-performance pads, new braided stainless steel flex lines for the front, and all necessary hardware.
Before going any further, let's take a quick look at how brakes work. Braking is basically a process of eliminating forward motion by friction, with heat produced as the byproduct. Within reason, the more friction area there is, the better the brakes--as long as heat produced can be dissipated. Brake fade is generally caused by brake system components getting too hot. Brake systems don't work well (or at all) when wet because there is little or no friction. Within reason, brakes work best when not excessively hot. Heat dissipation is why C5s all have those two little ducts that funnel air from the front valence towards the front brakes, why the '01 Z06 has air inlets on the rocker panels to feed cool outside air to the rear brakes, and why there are vanes or vents around the circumference of nearly all disc brake rotors. So, for good brakes, more surface or swept area is good, as is anything (again, within reason) that dissipates the heat produced by braking.
We wanted to put the Force 10 system to the test, in real world conditions, to see if it really does work as well as claimed. By Team VETTE's standards, that means a car that gets driven regularly, by someone who's familiar with all of the car's quirks and nuances. (This criteria immediately eliminated using Editor Bob's '76 project, the C5 Shark, nee (not so) Great White, since that soon-to-be-LS1-powered Stingray hasn't moved under its own power for over a year.) So, we turned to good buddy Loy McKenrick, whose '72 has served as a guinea pig for installing and testing quite a few items over the past two-or-so years, most notably for our "Size Matters" series and the do-it-yourselfer's 700-R4 trans swap. The War Bonnet Yellow '72 has served almost continuously as Loy's daily driver for over two decades, so we were confident that if the was a discernable difference between stock and the SSBC Force 10 brakes, he'd notice it, and, as almost always, he was game to experiment on ol' yeller.
SSBC was also game and sent us the entire package, including a pair each of A109AF (43mm pistons) front calipers and A109AR rear calipers, front braided stainless brake flex lines, and a quartet (PN S2311 front and PN S2303 rear) of their new ball-mill slotted 12-inch rotors.
Before we even considered beginning the swap, we "baselined" the original-style brakes with a series of 60-0 stops, measured with a G-Tech Pro accelerometer. The best stop we recorded was 170 feet; our best-of-three average was 171.5 feet. Then, it was time to tear into the conversion.
This installation is about as straightforward as it gets, as all we had to do was remove the old parts and replace them with the new. One thing to watch out for, however, is the direction of the slots in the rotors. We made a decision; based on previous knowledge, to mount the rotors with the slots slanted forward (you'll see what we mean in the pictures). We found out later, however, that Stainless Steel recommends that you mount them with the slots slanting towards the rear. They conceded, however, that any difference that resulted would be "minute." (Still, do as we say, not as we do, and follow Stainless Steel's recommendation.)
Where we did see a difference was in brake performance. Our three-run average was 143 feet, which lopped a good 27.5 feet off the old system's numbers. Incredibly, the new brakes actually got better as they heated up and Loy got the feel of them. Our last run, the last of five, and despite some minor locking-up, netted an outstanding 128 feet--42 feet better than the OEM system's best (which is, by the way, a 24.7 percent improvement. Once fully bedded in (200 miles is the recommended distance), and with a driver who knows the feel of the system on his car, the distances should be even shorter.
On top of the fact that Loy was still adjusting to the new brakes, we also didn't have time to properly bed them in due to our deadline constraints. The improvement was still marked. The bottom line is that this system works, and very well. The difference in performance--and safety--was phenomenal. And Loy was certainly jazzed about his new binders. "I can feel it," he said. "Big time. I had to get on them to keep from hitting someone right off the bat, and they were good." We think that in itself is worth the price of admission.