Thursday, October 7, 2010

When Brakes go Bad

“When a man opens a car door for his wife, it's either a new car or a new wife.”
Last week I took my car to a mechanic to examine why the maintenance light had come on. I figured it was just a routine warning for a check-up at 75,000 miles and had driven the car for several weeks, over 1000 miles, since the light had come on since everything seemed fine to me. Imagine my surprise learning that one of the front brakes had warped and locked-up. Now I knew braking was funny and I had to exert more force than normal but I thought it was the tires going bald. No clue that I was driving with just one working brake in front.
It can be argued that brakes are the most important safety feature on a car; seat belts and airbags are important but brakes are the first line of defense in NOT hitting something. Brakes wear out with use, but they do so slowly, meaning you may not notice they need attention until it's too late.
The most obvious indicator of brake wear is an incredibly high pitched squeal when you come to a stop; like fingernails on a chalkboard. Brake pads include a little piece of metal that rubs against the metal rotor when the pad wears down to ¼ inch or less. When you hear this sound, under normal driving, the brake needs to be replaced within the month. If you wait too long, the metal indicator in the pad will cut a groove and the rotor will have to be smoothed or replaced. Occasionally, the indicator falls off and the pad wears with no warning noise. If it takes longer to stop than it used to, or if the brake pedal travels farther down than it used to, get your brakes checked.
Rotors should last through two or three pad replacements. However if your steering wheel wiggles in your hands when you come to a stop, your rotors are probably "warped." A warped rotor causes braking vibration or pulsation. This is what happened to my car.
My mechanic attempted to "turn" my rotors by shaving off enough metal to make them smooth again but they were too warped and had to be replaced. Interestingly the “warp” can be very, very small; the faces of a disc brake rotor must be parallel (within .0005 inch on most cars) and flat (no more than about .002 to .005 inches of variance.)
One site described the rotor as the white center of an Oreo cookie being squeezed by the two dark cookie brake pads. The brake rotor can become "warped" due to normal wear and tear; most newer cars have very thin rotors which warp easily. Rotors can also warp by throwing cold water on a hot brake; for example driving through a puddle of water on the exit ramp after a long freeway trip and then applying the brakes.
Your brakes will last longer if you…
•Avoid "riding" your brakes.  Slow down with brief moderate pressure and release the brake to cool instead of keeping a long steady pressure on the brakes and overheating them. I’m guilty of riding my brakes – I like a smooth stop.
•On steep downgrades downshift your engine gear (but only do this when road traction conditions are good to avoid skidding.)  Downshifting lets your engine do some of the braking instead of your brakes.
Bottom Line
Top Ten Signs of Brake Wear:
1.   High pitched squealing
2.   Vibration in the steering wheel when stopping
3.   Grinding noises when stopping
4.   Increased braking distances
5.   Longer pedal travel
6.   Feeling the car "pull" to the left or right when stopping
7.   A weak emergency brake
8.   A bad smell after coming to a hard stop
9.   Pedal "fade"
10. Not stopping

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