Northern VA Auto Repair


What's Stopping you?

These major components of your brake system are actually stopping you:

  • Rotors
  • Pads
  • Calipers

Your brakes operate through a hydraulic system that uses brake fluid to engage the calipers, cylinders, pads, rotors, shoes, and drums to stop your wheels from turning.

Most cars have disc brakes and work by pushing a ceramic pad against the brake discs, creating friction to slow the vehicle down.

This is what happens when you step on your brakes:

  1. As the pedal moves down it pushes a lever that increases your pushing force.
  2. The lever, in turn, pushes a piston into a narrow cylinder filled with brake fluid, squeezing the fluid down long, thin pipes to cylinders at each wheel.
  3. When the brake fluid enters these cylinders, which are much wider than the first, the piston inside each is pushed with greatly increased force.
  4. The pistons push the brake pads toward the brake discs generating friction to slow down the outer wheel and tire, stopping the car.

What you really need to know about your brakes:

  • If you experience any of these symptoms, get your brakes checked:
    • Squealing
    • Vibrating
    • Grinding – a “metal-to-metal” sensation. This is usually a clue that your pads are worn out
    • Pulling when you apply the brake
  • Most brakes last about 30,000 miles. This, of course, depends on your driving habits and conditions.
  • A typical brake job usually takes about 2 hours and can cost around $400-500 if done properly. This is for most cars. European and other high-end cars will cost more.
  • This is what is done for a proper brake job:
    • Replace Pads and Rotors
    • Lubricate the slide pins and calipers
    • Check the condition of the brake fluid and do a flush if needed
  • It’s current practice to NOT resurface the rotors. It’s actually more cost effective to just replace them. Resurfacing them can cause a thinner rotor which results in shaking and squealing and you’ll end up replacing them anyway. Resurfacing is just a temporary and expensive fix.
  • Never buy the cheapest brake pads. They just don’t hold up and can compromise your safety and car performance.
  • Hybrid vehicles brakes will normally go much longer than the recommended 30,000 miles.

Some more interesting details

Brake Fluid

Brake fluid lives in a reservoir which usually sits on top of the master cylinder under the hood of your car. When new it's often light brown or clear but darkens with age, becoming murky from water contamination. It operates in a sealed system and can last for years, but moisture can still work its way in through hoses and other areas. When this happens, your brakes become "squishy," and their stopping ability is compromised. Moisture can also lead to corrosion throughout the system which could require expensive repair work.

Flushing and replacing brake fluid is a vital part of keeping you safe on the road. It's very easy for your technician to check the quality of your fluid as part of your routine maintenance. Most vehicle manufacturers recommend replacing brake fluid every 20,000 – 45,000 miles, but you may need it done more frequently in high humidity areas and areas that get winter weather due to salt and other contaminants getting into the system. It's a relatively inexpensive, but critical, part of your vehicle's maintenance.

Brake Pads

Pads and shoes are the part of the brake system that squeeze against the rotors to slow your vehicle. They are designed to wear out, and a lot of factors determine when they need to be replaced, including:

  • Driving Habits: How hard you push your brakes greatly affects how long the pads last. Smooth, gradual braking increases their lifespan, while riding the brakes or abruptly stopping often can significantly shorten it.
  • Environment: Stop-and-go traffic and driving in mountainous terrain are much harder on your brakes than driving on long, straight roads where you don't have to brake as frequently.
  • Brake Pad Hardness: Brake pads are made of different compounds. Hard compound brakes last longer but are more expensive and are mainly used by high-performance cars, which operate at higher temperatures. Soft compound brakes perform better at lower speeds but wear out more quickly.

As a general rule of thumb, your brake pads will need to be replaced every 50,000 miles or so, but this number can vary greatly based on many factors. So, it's a good idea to have their thickness checked every time you have the oil changed or the tires rotated. Most newer pads have small metal hairs that create a squealing or scraping noise to indicate it's time to replace them.

Brake Rotors

The rotors are metal discs which are subject to a lot of heat because of the friction between them and the brake pads. They can warp as a result and will need to be replaced around 30,000 miles. If you notice your braking becoming jittery, then the rotors are probably warped.

Stopping Distances

When your car is moving, kinetic energy is created, and the heavier it is or faster it is moving, the more kinetic energy there is. To stop the vehicle, the kinetic energy must be stopped, so your brakes create heat in the form of friction to stop this energy.

The distance required to stop your vehicle is based on a calculation that factors your rate of speed, reaction time, and road conditions. The following information, based on data from the Los Angeles Police Department, shows how far your car will travel to make a complete stop on dry road conditions.

30 m.p.h. 33' reaction distance + 57' braking distance = 90' stopping distance

35 m.p.h. 38.5' reaction distance + 74' braking distance = 112.5' stopping distance

40 m.p.h. 44' reaction distance + 96' braking distance = 142' stopping distance

45 m.p.h. 49.5' reaction distance + 121' braking distance = 170.5' stopping distance

50 m.p.h. 55' reaction distance + 150' braking distance = 205' stopping distance

55 m.p.h. 60.5' reaction distance + 181' braking distance = 241.5' stopping distance

60 m.p.h. 66' reaction distance + 216' braking distance = 282' stopping distance

Seeing how long it takes to stop a vehicle, it is vitally important to maintain enough distance between you and the vehicle in front of you to bring your car to a stop without running into it. The most common safe distance is 3 seconds behind on dry, clear road conditions. On icy, wet, or curvy roads, you should increase the distance to 6 seconds. To determine your distance (in seconds), you can pick a building or road sign that's parallel to the car in front of you and count the number of seconds it takes you to arrive at the same point.

Another method to be safe is the car-length rule. This rule says to keep one car length between you and the car in front of you for every 10 miles-per-hour you're traveling. So if you are going 60 m.p.h. you should maintain 6 car lengths between you and the car in front of you. One other indicator is to look at the bottom of the other vehicle's wheels. If you can't see the bottom of the wheels in front of you, then you are driving too closely and need to slow down.


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