April 30, 2021
Brakes are the most essential safety system on your car, as they stop your vehicle when necessary. Production automobiles have brakes on all four wheels. Some cars have a ‘drum’ brake assembly on the back wheels, but this configuration is notably less-efficient, and exist on vehicles in the lower price ranges. For this article, we’re going to discuss the more efficient disc brakes. (Motorcycles and even bicycles use disc breaks as well.)
Brakes work by clamping down a set of brake pads on each side of a brake disc. The disc, also known as the rotor, is mounted to your wheel assembly. For the most part this whole assembly is hidden behind your wheel rim and tire.
The process by which brakes are activated is simple. While you are driving, and you want to stop, you press down on your brake pedal. This motion creates pressure in a sealed hydraulic system. This system, or circuit, consists of two redundant reservoirs called master cylinders, which are filled with a non-compressible brake fluid. A network of brake lines, (metal tube) run from the master cylinders to each wheel, where hydraulic actuators expand, clamping the brake pads against the brake disc. This pressure creates friction, which slows the spinning of the wheels, and accordingly slows the card down. (NOTE: this is the simplified explanation. Most modern cars have a multiplying-mechanism that exerts exponentially-more pressure than your foot could ever exert alone.)
You may have heard someone say they had to “pump their brakes” to get them to work. This terms relates to the loss of brake fluid in the system, usually due to a minute, slow leak. As fluid is lost, it is necessary to repeatedly pump the brake pedal to create enough pressure to actuate the brake pads. At any point that you need to do this, you should immediately bring your car to a qualified brake mechanic.
Do you hear a squealing when you engage your brake pedal? While this could be a build up of rust or oil on the brake disc and pads, it’s more likely a warning system built into your brake pads. Many manufacturers embed a metal market in the brake pad at the level where the pad has worn down enough that it is time to replace it. This metal insert creates a whistling sound when it meets the disc surface. Again, this is the time to get those brake pads replaced.
A vibration when braking, from subtle to horrible, is a potential indicator that one of your brake discs has warped. Braking creates extreme heat. But, brake system components are designed to deal with dissipating that heat efficiently. (As you can see in the photos in this article, some discs are vented, with grooves or holes milled in them, and the pads have channels in them to whisk away debris and provide air for cooling.
Brake pads wear out. Plain and simple. There are different types of brake pads with varying degrees of effectiveness and longevity. While you can certainly put the cheapest ones on your car, you probably wouldn’t put the cheapest tires on, so here’s what you need to know:
There are generally two types of brake discs, (or rotors), flat and vented. Flat discs, as the term indicates, have no special indentations or holes in the metal. While vented discs can have anything from spiraling grooves, to dimples, to full-on holes bored in air-manipulating patterns. Essentially, flat discs are better for most driving because they offer a larger surface area for the pads to engage, and they are lighter. BUT, vented disc outperform flat ones in circumstances of prolonged braking, like descending a mountain incline for many miles.
Brake pads come in three general types.
Non-Metallic (aka Organic) Brake Pads: These are the softest, and fastest wearing pads, and are composed of a combination of glasses, rubbers, and resins. You can tell if you have non-metallic brake pads if there is an unusually high amount of brake dust around your wheel rims every time you wash your car.
Metallic Pads: These are the most typical pads found on new cars, and used in replacement. They consist of a blend of synthetic materials with metals to form a hybrid compound with extended life and reliability.
The metal composition make these brake pads more resistant to extreme heat and wear. In the realm of metallic brake pads, there are various levels of metals in the composition. The higher the amount of metals, including graphite and iron, in the pad, the better the braking.
Ceramic Pads: Sure ceramic brake pads are exponentially more expensive than their little cousins, the cost is recovered in the performance and longevity of the pad. Ceramic compositions often includes a small percentage of copper, which improves the high friction coefficient when cold, and enhances the exceptional strength and durability.
What is the right brake pad for you? A quality metallic pad for sure. But in some circumstances, like you live in the snow-capped peaks of Colorado and are constantly descending for long periods of time, ceramic could be a smart investment. As they are if you do a constant amount of towing with your vehicle, or happen to have a high-performance track in your backyard. Regardless, the different variations exist for a reason. Choose wisely.
Today’s cars offer ABS as a standard feature. This technology controls the brakes and prevents them from locking up in the instance of an emergency braking situation, or simply when traveling in inclement weather. When a wheel locks up due to extreme pressure on the brake pedal, the likely result is skidding, with which comes a complete loss of control. If you haven’t skidded on an icy road yourself, you’ve probably seen a multi-car pile-up on the TV news. Anti-lock Braking Systems ensure the car comes to a gradual, but as quick as safely possible, stop. This is something that the average driver simply cannot achieve in a stressful braking situation.
If you’re brake pedal ever plunges to the floor with no apparent slow down of the vehicle, you’re not necessarily doomed. What this indicates is that both the primary and the backup master cylinder, or the brake lines, or a fitting have failed completely and you’ve lost your brake fluid.
But, while most people think the Parking Brake handle, also known as the Hand Brake, or Emergency Brake, is just for keeping your car from rolling down a hill, in an emergency, this mechanism, which is connected to the rear brakes via a high-strength cable, can, and will, slow down your vehicle with enough exerted force.
Fraser Engine Co. is NOT recommending you use your parking brake for everyday situations, but it is also referred to as the Emergency Brake for the very reason that it can be used in an emergency.
Unless you hear or feel something ‘off’ about your brakes, the garage that does your annual inspection will let you know if your brake pads need to be replaced, and if a disc needs to be replaced as well. And here’s a helpful tip, not all brake pads and discs will wear down at the same rate. The calibration of your brake system may cause one wheel to work harder at braking or conversely, less. It is a general rule of thumb with disc brakes to replace both pads at the same time, but you don’t necessarily have to replace them on all four wheels.
Also, when you replace your brake pads, the garage will need to ‘turn’, or resurface the disc. This is a process of shaving the disc to a fresh, consistent, smooth surface. This ensures maximum performance of your new pads, and reducing premature wear.
And, of course, there will be the need, from time to time, to replace the whole disc. Don’t cut corners. Brakes are as important to your safety as tires are. Spend the money and feel good about it.
Thinking about building a replica with an american-made engine? Fraser has the right engine ready for you!