Brakes 101 & Common Issues

We take our car brakes for granted, but they are a critical component of a car and can mean the difference between life and death in an emergency. Proper maintenance and a quick response to warning signs will ensure that your car will stop every time you hit the brakes.

How the brake system works:

Brake systems come in two forms, disc and drum. They both work by using friction and resistance.

Drum brakes get their name because the components are housed in a round drum that rotates with the wheel. Inside the drum are a set of shoes that force the shoes against the drum when the brake pedal is depressed. The shoes are made of a friction material that is heat resistant.

In a disc brake setup a rotor is connected to the wheel. Brake pads squeeze the rotor and cause friction, which stops the wheel from spinning.

Over time, this friction will wear down the brake pad, which is why they must be replaced on a regular basis. Calipers apply pressure to the brake pad. Calipers are powered by a hydraulic system.

The hydraulic system consists of a master cylinder, a network of hoses filled with brake fluid, and calipers and/or wheel cylinders. When you press on the brake pedal, the master cylinder multiplies that pressure and causes the brake pads to close on the rotors and bring the car to a stop.

Brake systems require regular maintenance to ensure optimal performance. A fresh brake pad can be 8, 10 or 12 mm thick. Once the pad gets down to 3 mm it is time to have it replaced. Failing to do so can cause damage to your rotors. Rotors will also wear down over time, and when the thickness is too low to dissipate the heat, they will have to be replaced.

Common issues faced in the braking system:

In most cases your car will warn you that it is time to have a mechanic come out and look at your brakes. It might be a dashboard light, a screeching noise, or a number of other indicators. Here are the most common warning signs and causes of brake trouble.

Emergency Brake Engaged

If your emergency brake is on, which is an easy fix, your dashboard light should come on to warn you. Depending on the vehicle the word “brake” or a circle with an exclamation point in it will light up.

Loss of Hydraulic Pressure

Losing hydraulic pressure in the front or rear of the brake system can be an indicator of a leak. Your dashboard warning system should illuminate if this happens.

Worn or Uneven Brake Pads

Brake pads are fitted with an indictor that will contact the rotor and make a squealing noise when the pads have worn too thin. You will hear a screeching, clicking or grinding noise when applying the brakes. When the squealing turns into a grinding sound, you have worn through your brake pads and the backing plater is grinding against your rotors. This can severely damage your rotors and dramatically raise the cost of the repair. Uneven brake pads can result in the car pulling in one direction when the brakes are applied.

Stuck Caliper or Slide Pin

If a caliper or slide pin is sticking, you will notice your vehicle is pulling to one side when you brake. This and a collapsed brake hose (see below) can cause an acceleration problem. You may feel like your car is dragging along.

Collapsed Brake Hose

This can result in calipers that move unevenly, which will pull the car to one side. This will present as an issue with the pads on one side thinner than the other.

Brake Line Issues

Air in the brake lines or damaged brake lines is a serious issue that should be addressed immediately. The major symptom of this would be a brake pedal that can be pushed nearly to the floor before the car stops. In order to check for a leak put an old white sheet or some cardboard under the car during the night. Look for a clear fluid that has the consistency of cooking oil in the morning.

Worn Parts

Faulty wheel cylinders, faulty disc calipers, a worn master cylinder or bad brake booster can all cause serious safety issues. Mushy brakes can mean one or more of these parts is failing or malfunctioning. You should call your mechanic immediately if the brake pedal goes almost to the floor before engaging.

Malfunctioning Brake Booster

This is the opposite of the soft pedal, if you must put a lot of pressure on the pedal before the brakes engages, there is a good chance your brake booster is malfunctioning or failing. Sometimes if you hear a whoosh noise when applying the brakes this, can be caused by the brake booster.

Dirty Brake Fluid

Brake fluid that has been contaminated by moisture or has gotten dirty will also cause your brakes to grab and pull to one side. Having the fluid changed should clear up this problem.

Warped Rotors

A rotor will warp when exposed to extreme stress for an extended period of time. Stress can be caused by towing, mountain driving or any other situation that would put abnormal stress on the brakes. Warped rotors will cause your brakes to vibrate. Be careful not to park your car next to where your sprinklers are spraying after driving. The cold water hitting the hot rotor will also cause warping.

Sticking Shoe Adjusters

This is a common drum brake problem and will cause the brake pedal to go almost to the floor before engaging. This is often caused by sticking or rusting shoe adjusters on a drum brake. While adjusting the drum brakes can fix this problem in the short term, it will return until the adjusters are replaced.

Worn Brake Shoes

This is the drum-brake version of worn brake pads. When the brake shoes wear too thin you will notice a squealing noise when you apply the brakes. Your brakes should be serviced immediately. If the noise turns into a grinding, the shoes are completely worn out and you are grinding on the drum. In most cases the drums will have to be resurfaced. Note that sometimes this squealing can be caused by brake dust. It is still better to have your brakes checked to make sure worn brake shoes is not the problem.

Broken Retracting Springs

If the retracting springs on a drum brake are broken you will experience a pull to one side. This condition can quickly accelerate the wear on the brake shoes and cause the brakes to run hot. This can also cause your vehicle to not accelerate as it normally would.

Bent Backing Plate

The backing plate on a drum brake can be bent if the brakes are serviced improperly. You will notice grabbing brakes, noise and even brake lockup. This can also happen on the front brakes, causing a high pitched squeal when the wheel is turning but not braking.