| From the time of the first V-8 installation in the early 1950’s, Corvettes out-performed their drum brakes. Finned drums, cool air ducts, metallic lining, and power assists only gave marginal improvements. It only took a few high-speed brake applications to induce fade, better known as “goodbye asphalt, hello tire wall!” Finally, Zora Duntov’s team gave the 1965 Sting Ray some real stopping power – 4 Wheel Disc Brakes! This system demonstrated straight, predictable stops time after time and was self-adjusting. It does have a few weak points that can cause today’s Corvette owner considerable headaches and expense. However, most of these problems can be remedied once they are pinpointed. Beyond the Corvette Disc Brake innovation, the chosen caliper design was quite complex. Each Corvette Brake Caliper employs 4 pistons; 2 inboard and 2 outboard that enlist Pascal's Law to insure that equal brake pad pressue is exerted on each face of the Corvette Brake Rotor. So what's this stuff leaking on the garage floor? By design, the Corvette Brake System is handicapped by the simple fact that there are 32 or more potential locations for fluid leaks to develop. In addition, the cast iron construction of the caliper and its 4 piston bores is prone to rust and corrosion build-up which causes pits or irregularities to form in the cylinder wall and a failure of one or more of the piston seals. This may be corrected by honing the cast iron piston bores and replacing the seals but eventually this scenario will recur. A more permanenet cure is replacement with Stainless Steel Sleeved Calipers. Each of the piston bores is lined with a stainless steel sleeve that resists virtually all rust and corrosion issues. Aging and breakdown of the rubber piston seals will eventually cause leaks to develop even within the stainless bores but lifetime is increased exponentially. Seal replacement alone would correct this problem. Never scuff or hone a stainless steel sleeved caliper bore. Caliper leaks also tend to be more common on cars that are innactive or stored for extended periods of time. Occasional pumping of the brake pedal in these cars can help the dormant seals to remain limber and prevent them from sticking to the piston bore. The brake fluid itself can cause problems. Most owners change the motor oil on a regular basis, but never think about the brake fluid until they experience a problem. Corvettes that sit idle for long periods should have their brake fluid replaced every two years or so. This will avoid the damage caused by water condensing within the brake system resulting in corrosion and leaks. An alternative is to drain the system and replace the fluid with silicone brake fluid. Silicone brake fluid does not have an affinity for water and helps to preserve internal brake parts and seals. Occasionally old, weak brake caliper hoses will balloon under pressure and cause a spongy response in the brake pedal. Some owners report that, despite repeated bleedings, the brake pedal soon “goes soft” due to air in the system. This is most often caused by worn or mis-adjusted wheel bearings, warped ("out-of-true") rotors, a bent spindle face, or any combination of these faults. Each of these faults result in brake rotor run out which causes an alternating pumping action of the inboard and outboard caliper pistons as the car is driven. This caliper piston pulsing causes air to enter the system without fluid loss. Here, the only solution is to correct the cause of the rotor runout. The maximum allowance for rotor runout for the 1963-1982 Corvette is .008". Lathing or "turning" the rotors may help but does nothing to correct the other causes mentioned earlier. Never "turn" the Corvette Brake Rotors beyond the minimum thickness which is stamped on the perimeter. Occasionally, one wheel will start dragging or pulling due to a caliper piston “hanging up”. This situation has two main causes and remedies. A worn piston and bore may allow the piston to wedge itself in the bore and not retract when brake pressure is released. A defective rubber brake line can balloon or collapse internally and maintain pressure even after the brake pedal is released. A quick diagnosis is to carefully open the bleeder valve on the stuck caliper. If the brake line has trapped pressure, there will be a rush of fluid and the caliper should be freed. If the piston is jammed mechanically, there will be little, if any, fluid and the caliper will remain jammed. The owner will now know where to start on repairs. Another common complaint is that either the front or rear calipers function, but the owner cannot get fluid to the other calipers. Once the master cylinder is checked and determined to function properly, the proportioning valve is usually the culprit. This is the rectangular block found between the master cylinder and the lines to the calipers. Its main function is maintaining partial braking control if either the front or rear brakes suffer a sudden loss of pressure, such as a ruptured brake line. A sliding valve will close the line that has a loss of pressure, allowing the driver to retain the use of the front or rear brakes in order to avoid an accident. This sliding valve may become jammed in the forward or rear position, thus effectively shutting off fluid to the calipers on the end of the vehicle. Replacement or repair of the valve often takes care of this problem. The key to getting the most from 1965-1982 disc brakes is regular inspection and maintenance. A little money spent here may keep you from buying a new front end! RELATED PRODUCTS YOU MAY WISH TO CONSIDER | 
