Larry Jewett
September 1, 2001

Wheel Cylinders
"Wheel cylinders are the first thing you need to look at," says Jim Inglése. "They tend to leak. Leaky rear-axle seals can cause malfunctions. They can lock up the rear wheels, so pull the shoe and check the linings."

You can rebuild your wheel cylinder, but the best solution is replacement. This gives the best performance from the seals, cups, and pistons.

Brake Fluid
The "blood" of the brake system is often misunderstood. It can truly affect the performance of the entire braking system.

High-performance enthusiasts are getting the gist of brake fluid quicker than the average consumer. Those who go fast need to stop quickly. Each time they brake, they put their faith in the system working properly.

"Racing fluid meets DOT (Department of Transportation) standards and has other processing for low aeration and low viscosity. You don't want the fluid to get air in it (aeration) when agitated," says Carl Bush of Wilwood Engineering. "Air makes it compressible and slow to work. Brake fluid will absorb moisture from the air and lower the effective boiling point.

For standard everyday use, a DOT 3 brake fluid is suitable. Heavier vehicles, like trucks, will use a DOT 4. There is also a DOT 5 silicone fluid, which isn't necessarily better in the progression, but involves a different material and, hence, a different designation.

"We recommend you change your fluid once a year and we recommend DOT 4," says Anastasio. "The fluid should be amber. If it's dark brown, it's contaminated. If it's black, it's burning up."

Brake Lines
In order for the fluid to do its job, the conduit from one end of the car to the other has to be free flowing. While there is certainly plenty of attention to the moving parts, the brake lines hold an important key.

"Inspect all your steel brake lines," says Inglése. "Those lines are running all along the car and they are subjected to the weather and the road. Steel lines can get rusty and leak. When we bring a car in for service, we like to replace the lines. We use stainless steel for our replacements."

Proportioning Valves These items need to be serviced or rebuilt. A bad proportioning valve can cause the rear brakes to lock up with pressure misapplied.

It's another area of misunderstood application. Anastasio notes a proper valve can take the "dive" off the front end of a car during braking. "It holds off the front brakes for a split second, allowing the rear to come in first," he said. Master Power valves come with a built-in residual pressure valve. In case of a lost line, the fluid will be shut off to that end and directed to the working part.

High-Performance Applications
The need for a high-performance racing car will be different from a daily driver. Wilwood Engineering directs plenty of attention to the sport end and has researched product to address the need.

"Our systems are based on car weight as much as speed," says Bush. "Our light-duty kits will fit the Pinto with the Mustang II suspension. We have kits for musclecars that will fit on stock spindles, and drag kits will come in light, medium, and heavy-duty.

In simple terms (call Wilwood for the best application), light systems will go on cars less than 2,400 pounds with rear disc brakes. These kits will take anywhere from 35 to 50 pounds off the front wheels. Medium kits are for cars in the 2,400 to 2,800 range, while the heavy-duty units are for cars weighing 2,800 pounds and up, especially those toting an iron big-block. The heavy kits are good for street and strip machines.

Pads
The development of man-made compounds has had a direct impact on the brake pad. The source of stopping friction, the brake pad continues to utilize material to best suit its needs.

Original brake-pad materials are hard to acquire and generally do not do the job as capably as today's materials. The asbestos pad has been replaced with materials of the carbon fiber family (such as carbon Kevlar). Pads need to be visually examined for wear and need of replacement.