Brake Problems and Noises

Disc and Drum Brakes

A car's brakes are often ignored until a problem crops up. Some of the most common signs of brake problems on cars are:

· Poor braking performance, hard to stop the car
· Squealing or grinding noises during braking
· Pulling to one side, or grabbing
· Loss of brake pedal
· Pulsation of the brake pedal during braking
· Clicking noises during braking
· Excessive drag during acceleration.

Here are some of the things that can cause those symptoms.

Glazed brake pads and/or shoes: The brakes have been heated up to the point that they become hardened and are no longer create enough friction on the brake drum or rotor.

This condition can occur after the brakes have been overused, either because of excessive panic stops, riding of the brake, lots of city driving or in some cases driving on steep hills. The braking material must be soft enough to wear and grab hold of the drum or rotor to stop the car. Excessive overheating hardens the braking material beyond its ability to do this. This condition can cause the brakes to make all kinds of noises, from squeaking to grinding. It will also reduce braking performance.

Other things that cause disc brakes to be noisy is warped rotors or rotor surface problems, dirt and debris, cheap or wrong brake material for the application and pad hardware missing.

Oil or grease-soaked brakes can cause pulling, grabbing and noises. Oil from the rear differential or front transaxle can get on the brakes from an oil seal that might have failed. Grease from a failed rubber boot on a front end component (such as a ball joint or tie rod) can find its way onto the brakes and cause this symptom as well.

Loss of power assist from the power brake booster is another cause for poor braking performance. It can occur due to a loss of engine vacuum, or deterioration of the vacuum brake booster diaphragm. This condition causes excessive pedal effort.

Worn out brake pads or shoes. This can cause squealing or grinding noises coming from the brakes along with poor braking. Sometimes the brakes wear away and you're into the metal without any noise though. That is why it is good to inspect them periodically.

Pulling or grabbing to one side can happen for a number of reasons. Pulling can occur from mis-adjustment of the brakes, a bad caliper or wheel cylinder, hydraulic problems, mis-matched components, brake fluid leakage, frozen emergency brake cables, or oil or grease leakage on the brake shoes or pads.

Loss of brake pedal usually is a result of bad master cylinder or brake fluid leakage due to failure of a brake hose or rusted metal brake line, worn wheel cylinder or brake caliper or possibly an ABS problem. This is a very dangerous condition and the car should be towed.

Pulsation or vibration of the brake pedal when braking is usually caused by warped rotors or rotor thickness issues. Heat and mechanical wear thin out the brake rotor, or drum, causing warping. This warping translates into a pulsation (up and down motion) of the brake pedal or vehicle vibration while applying the brakes. Machining or replacing the rotors will be needed for this problem. This condition can cause noise, excessive caliper wear and poor braking when the condition gets severe.

Clicking noises during braking is usually caused by a brake hardware or installation problem. The disc brake pads are held in place by pressure from the caliper against the brake rotor. The factory installs "anti-rattle" devices to stop movement of the brake pads, which will stop the clicking noise. These devices are made of spring steel and over time become brittle and break, allowing the brake pad to loosely ride in its seat, causing rattling.

Excessive drag: Brakes not releasing can cause this problem. Sticking or seized caliper pistons, deteriorating brake hoses, sticking caliper guides, mis-adjusted drum brakes and park brake cables frozen due to rust or dirt buildup can cause this. Periodic brake fluid flush and change will help avoid caliper problems, using your park brake regularly can prevent park brake cable problems.

Have your brake system thoroughly checked regularly, so there are no surprises. You can "head off high dollar brake work at the pass" by keeping a watchful eye on your brakes.

Wayne's Garage
27 E 27th Ave. in Eugene
333 Q Street in Springfield



BRAKE FLUID is very hydroscopic, it absorbs the moisture out of the air like a sponge. When moisture mixes with brake fluid it creates a caustic acid and lowers the fluid boiling point. The acid will rust or corrode metal brake parts and dirt and debris that flakes off can wreak havoc on the Anti-lock Brake System.

Moisture is the hydraulic system's biggest enemy. Moisture enters the system through minute holes, or pores, in the rubber brake seals, as well as when the master cylinder cap is removed. Research has confirmed that, on average, 2% moisture is absorbed by brake fluid on an annual basis. Now consider what happens to brake fluid after use over a period of time. At a rate of 2% per year, the boiling point of DOT 3 can drop over 9% the first year, and nearly 20% after two years.

A lower boiling point can result in the moisture boiling off after heavy braking, especially on a very hot day and creates air in the system which will cause diminished braking ability.

Brake systems should be flushed and refilled every 3 years on non ABS systems and every 2 years with ABS. Never use brake fluid out of a container that has been left open to the air for a long period.

Be very careful to never allow oil of any kind to get in the brake system as it will ruin all of the rubber components in the brake system.

Brake Fluid temperature chart

How it Works
When stepping on the brake pedal, the brake master cylinder transforms mechanical force into hydraulic pressure. Being non-compressible, brake fluid is responsible for transferring hydraulic pressure through brake lines and hoses down to the brake components and ABS system.

Being non-compressible, brake fluid acts as a "solid" link between the master cylinder and brake assemblies. With high braking temperatures and a low boiling point, brake fluid may boil and produce vapor in the system. If this occurs, the solid link is broken, as a vapor will compress. A driver applying the brake in this condition would experience a spongy, unresponsive pedal.

Another important characteristic of DOT 3 fluid is that it is non-corrosive to internal parts. Corrosion inhibitors are used in the make up of brake fluid and aid in the protection of the internal surfaces. Over time, these inhibitors break down and can no longer protect the internal surfaces adequately. Depleted corrosion inhibitors allow brake fluid to attack the system. Worn surfaces produce a degree of copper and other particulates that can collect in ABS solenoids and motor valves causing them to malfunction. This unit can be very costly to repair.