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Knowing When to Replace Your Brakes
It's a good idea to know when your brakes need replacement. For one thing, brakes are how you stop your car. (See our other article, Knowing What the Heck Your Brakes Even Do, if you weren't already aware of that.) So, they're pretty important; you can't just put your car in neutral and coast the last two hundred feet of everywhere you go.
So when should you replace them? There are a few good ways to keep abreast of your brakes' needs and to take care of them before they become a problem. First, let's discuss the main parts of your brakes and what to look for when they're not a problem.
Disc or Drum
Your brakes are one of two types: disc or drum. (Unless you're driving a commercial truck or something similar using an engine brake, but we'll discount that in anticipation that you know what you're doing if you're in that position.) Cars manufactured before 1970 or so may have drum brakes in the front and in the rear. Cars manufactured after then will either have disc brakes on the front, drum brakes in the rear, or disc brakes on all four wheels.
When you apply the brakes, the clamp latches onto the disc, which slows the wheel, slowing and stopping the car. Same thing with the drum brakes, except:
The drum brake is inside the wheel cylinder and pushes out against it when you apply the brakes. It saves a bit on fuel economy but is a bit harder to get to.
Check the Condition
So, the thing you can do first is to know what your brakes look like when they're in good shape. Get down on the pavement next to your wheel and peek inside. In most cars, the wheels are designed to let you see the brake pad, to gauge whether or not it needs attention.
A good brake pad will be relatively clean, with little accumulation of brake dust. That's the actual material of the brake pad being worn off by friction with the disc or drum. It's fine; it's meant to do that, but too much means that it's wearing down too thin to be effective. In fact, if you've had some brake dust buildup but have noticed there is less of it, it could easily be because there's not enough brake pad material to scrape off, meaning your brakes are in dire need of replacement.
Some brake pads have an indicator groove that lets you know how much of the material has come off; there should be at least a quarter inch thickness of the material. Most brake pads have a metal pin buried inside that is exposed through wear, then scrapes and pings on the disc to let the driver know the pads need replacement. The groove is visually noticeable; the pin is audibly noticeable.
The disc or drum should be in good condition, not sporting any scrapes or gouges; those will decrease the brake responsivity and should in such a case be replaced. The action when you press the brake pedal should be smooth and ought not produce vibration in the pedal or the steering wheel. Either of those could be a sign to replace sooner rather than later. While driving, notice whether the car is pulling to one side or another; that could be a sign that a caliper is sticking, decreasing brake responsiveness while making it harder to steer.
A vibration could be a larger problem than a sticky caliper, of course; it could indicate a warped rotor. That could stem from severe overworking of the brakes or misaligned wheels. Regardless, it's a good idea to check what the cause is.
While you're in the car pushing on the brake pedal, you'll want to look out for the brake being too slow to engage, requiring it to be almost to the floor before braking. That might indicate a fluid leak, which you can check by putting a piece of cardboard under the car overnight. Any brake fluid leaking will be almost colorless, and it will give the position roughly away.
A brake being too quick to engage, barely being tapped before throwing the car into a standstill, might indicate that you need to replace the brake fluid. A brake being too hard to engage might indicate that you have a brake line blockage. Any of these are potential reasons to get your brake systems checked.
In most cases, you should have your brakes checked when you go in for routine service; roughly every six months. But now that you have an idea of what to look for, you can keep track of your brakes in between.