Eighty percent of the brake rotors sold in this country are made outside the United States. A lot of the companies making these rotors are only concerned about fit. Their thinking: If the rotor fits on your Corvette, then it's a good rotor. The actual performance of the rotor is secondary. Then we have any number of Corvette owners who shop for the lowest price.
This brake rotor thing has gotten so bad that rotor companies are starting to sue each other. The Bingham Farms-based Affinia Group Inc. and its subsidiary Brake Parts Inc. recently filed suit in U.S. District Court in Richmond, Virginia, claiming Dura International is falsely advertising its brake rotors as meeting the specifications of automakers. Dura responded by stating, "No government standards exist specifically for rotors. Each and every manufacturer is independently responsible for producing quality product meeting acceptable standards in fit, form, and function." This one could be in court for years.
The arrows indicate the air...
The arrows indicate the air gap in this brake rotor. This is a critical dimension. Cheap, inferior rotors will have a wide air gap, as less steel is needed for a rotor with a wide gap. For a manufacturer, less steel means significant savings over millions of brake rotors. For a Corvette owner, though, this is a problem. The rotor won't have enough steel to properly absorb the heat from stopping. It also means the rotor does not meet original equipment standards. If you're buying new rotors to replace your originals, compare the measurements. If a shop is doing the work, explain that you intend to compare the measurements before you pay the bill. You'll need to say this nicely, though, or you might have to find a new shop (which may not be a bad idea if they get upset over your knowledge of brake rotors).
Eric Bolton, a spokesman for the National Highway Traffic Safety Administration, said the agency is aware of the controversy and is monitoring complaints and field data through its Early Warning System. Right.
Even Raybestos has jumped in. It's running ads that show the difference between its rotor and the rotors produced by the competition. Basically what you have to remember is that just because a brake rotor fits your Corvette doesn't mean that it's the equivalent of the original rotor. There can be significant differences in quality.
Some of the cheap brake rotors are much thinner than name-brand aftermarket and original equipment rotors. These cheap rotors are being sold to unsuspecting consumers as standard replacement rotors. They simply can't absorb the heat that's generated from aggressive braking forces.
Increasing the air gap between the rotor faces often reduces the thickness of the discs in these lightweight rotors. This saves about 4 to 5 pounds of cast iron per rotor and reduces the manufacturing cost per rotor. Unfortunately, this trick also reduces rotor strength and its ability to absorb and dissipate heat. None of these things is good.
The center hat here is aluminum....
The center hat here is aluminum. This means the rotor is much lighter than it would have been had the entire rotor been constructed of steel. Two-piece rotors are becoming much more common on Corvettes.
Cheap rotors are made from damped steel. You can test them by hitting them with a hammer and listening for a ringing sound. You might have to tap on a few rotors to hear the difference, but once you hear it, you'll know what I mean. It's sort of like tapping on a forged crankshaft and a cast crankshaft. Keep in mind that original Corvette rotors are made from better steel than the rotors in an S-10 pickup. That may not be the case with offshore brake rotors. Try tapping on several brake rotors as a test.
Some of you don't actually get involved in the purchase. You outsource the task to your local shop. Most people have never given much thought to the quality of the brake rotors on their cars. I can almost guarantee you spent more time thinking about the price than you did about the quality. Not good.
What Does a Brake Rotor Do?
Brake rotors provide a friction surface for the brake pads to rub against when the brakes are applied. The friction created by the pads rubbing against the rotor generates heat and brings the vehicle to a stop.
The basic scientific principle here is that friction between the pads and the rotor converts mechanical energy into heat energy. Just how much heat depends on vehicle speed, vehicle weight, and how hard the brakes are applied. For example, when I'm at Sebring my brake rotors normally reach about 1,200 degrees F.
The purpose of a brake system...
The purpose of a brake system is to convert mechanical energy into heat energy and then dissipate all of the heat into the atmosphere. If you have a lot of horsepower you're going to have a lot of heat. That's why you see three rather large cooling hoses on this C6 racecar.
Your Corvette brake system must be capable of absorbing a lot more mechanical energy (horsepower) than your engine produces. Remember the heat energy that's generated under braking happens over a very short period of time. Sixty to zero happens a lot quicker than zero to sixty. Corvettes stop faster than they accelerate. That means the brake system has to shed horsepower, or mechanical energy, very quickly.
Slotted or Drilled?
Drilled brake rotors became a huge fad a few decades ago. Today drilled rotors are generally considered a cosmetic item. They gained favor because of the belief that they prevented outgassing. Outgassing occurs at extreme temperatures when the bonding agents that hold the pad material together break down into a gas. This gas creates a pneumatic barrier between the rotor and the pad, reducing the amount of friction between them. Cross drilling, or slotting, creates a path for the outgassing that occurs during extreme braking conditions. These conditions are seldom reached on the street.
According to Baer Brake Systems, while cross-drilled or slotted rotors produce a strong visual appeal behind a modern open wheel, they have only a very slight performance edge when pad outgassing occurs. In other words, the holes don't matter all that much.