Jim Smart
September 1, 2000

Brake System Question & Answer

Q: Why do we coil steel brake lines in some locations?
A: Stainless Steel Brakes says to give the brake system plumbing flexibility. Coiling allows the lines to flex with fluid pressure inside, plus any movement of body and chassis.

Q: How many different kinds of brake fluid are there?
A: There are three basic brake fluid requirements mandated by the U.S. Department of Transportation (DOT). They are DOT 3, DOT 4, and DOT 5. DOT 3 and DOT 4 are glycol-type fluids. DOT 5 is silicone based. Because DOT 3 and 4 are mineral based, they tend to absorb moisture. When brake fluid absorbs moisture, the moisture boils when placed under high pressure. The moisture boils within the brake fluid from the heat of braking pressure. When it boils, it creates air pockets in the fluid. Silicone-based DOT 5 does not absorb moisture. Therefore, it is a more stable fluid, especially during hard use. Never mix DOT 3 and 4 with DOT 5.

Q: Why do we bleed a master cylinder off the car?
A: Baer Brake Systems says we “bench bleed” a master cylinder to ensure the piston has purged all of the air in the bore. If you bleed the master cylinder on the vehicle, the brake pedal doesn’t always move the piston the full length of the bore, which can leave some air behind. When we bench bleed a master cylinder, we want to route the fluid back into the reservoir. Bench bleeding kits are available for this purpose. New and rebuilt master cylinders also sometimes include bleeding tubes for this purpose.

Q: Which is better? Single-piston or multi-piston disc brakes?
A: Without question, a multi-piston caliper is better, according to Stainless Steel Brakes, because four or six pistons apply uniform pressure on pads and rotors, giving us better braking efficiency. Single-piston appears to be more popular because people perceive it to be a better brake. From a maintenance standpoint, the single-piston caliper wins because it is simple, with fewer parts.

Q: Why do disc brake rotors warp?
A: Baer Brake Systems tells us disc brake rotors warp because they’re not properly seasoned to begin with. Simply put, once a disc brake rotor warps, the battle is lost, even with a trip to the brake lathe. Baer strongly suggests properly seasoning brake rotors when they’re new, which prevents warpage.

Q: Which is better? Front disc/rear drum, or four-wheel disc?
A: According to Stainless Steel Brakes Corporation, four-wheel disc brakes provide the best stopping power in most applications. But performance depends largely on the vehicle, SSB says. If you’re going to road race, four-wheel disc brakes experience less fade than front disc/rear drum applications. Drum brakes are prone to fade in severe duty situations. Street vehicles that are light in the rear end benefit very little from the installation of rear disc brakes. The nice part about rear disc brakes is simplicity and ease of maintenance.

Q: When we say “Stainless Steel Brakes,” what does the name mean?
A: The company, Stainless Steel Brakes Corporation, was founded to improve Corvette and Mustang four-piston front disc brakes more than 20 years ago. According to Stainless Steel Brakes, disc brake pistons were chromed to help prevent corrosion, but chromed disc brake pistons never did perform well. Chrome would flake off, cutting seals, causing leaks, and sticking pistons. Stainless Steel Brakes concluded a stainless steel piston would perform better. The company and its idea have been something of a legend ever since.

Q: Why do we turn brake rotors and drums during a brake job?
A: Because we want to give new pads and shoes a uniform surface to mate with. If you don’t turn rotors and drums, the pads and shoes will have a hard time wearing into an already glazed surface. Baer Brakes advises against turning disc brake rotors because you compromise the structural integrity of the rotor. In taking metal away on the brake lathe, there’s less metal in the rotor, which can lead to warpage. If you have a scored or warped rotor, we advise replacement if the scoring is deep. Always ask the machine shop to cut the rotor as minimally as possible. All we want to do is eliminate any irregularities and give the new pads/shoes a rough surface in which to seat.