We all know that high pitched squeal that sends shivers down the spine and attracts unwanted glares at as our brakes bring our car to a halt at a stoplight. Brakes have a way of making themselves known with unusual brake sounds when they are in need of maintenance.
High-Pitched Brake Squeal
Those all too familiar squealing, screeching, or chirping brake sounds come from the small metal wear indicators on your brake pads scraping against the large metal brake rotors. These brake sounds are a function engineered into your brake system to let you know that your brake pads have very little friction material left on them (2/32” or less) and need to be replaced before they wear out completely. If you heed the safety cry of your brakes by replacing your pads, you will not only silence the brake sounds, you may save yourself the cost of replacing your rotors as well (more on this later).
Low-Pitched Grinding Sound
If you keep driving your screaming car, you will find that eventually that high pitched squeal has grown up into a throaty growl. This is one of the more serious brake sounds, and a sure sign that you have made large metal-to-metal contact.
It doesn’t take long to wear through the 2/32” of friction material left on your pads after the screeching starts (the exact mileage you have left varies from driver to driver and car to car). Once the friction material is worn off the pad, the metal backing is forced against your car’s metal rotors every time you depress the brake pedal, causing the “metal-to-metal” grinding, that makes you feel like something is about to fall apart.
The friction material of brake pads is intentionally designed to wear away slowly as it rubs against the rotors at each wheel, changing the kinetic energy of your moving vehicle into heat, and stopping your vehicle in a controlled fashion. The metal backs of your brake pads have no such intention. The metal of your pad backings tear into the rotor at a breakneck pace while being thoroughly mangled themselves. The result – besides those awful scraping and grinding brake sounds- is that your braking performance has now disappeared, increasing your stopping distance dramatically. And since metal-to-metal wears so quickly, your rotors and pads will soon wear through altogether and lose their braking ability completely.
Your rotors are now collateral damage. Your brake job has grown from pads to pads and rotors. So as you can see it is well worth your while to pay attention to the brake sounds when they begin to happen.
Brake rotors have to be a certain thickness in order to absorb and dissipate heat properly. If they are overheated they will not allow you to stop as quickly and may become warped or unevenly worn, causing a lower pitched groaning or thumping sound as the pads and rotors alternatively grab and skip. That is why rotors are always measured for three things: run-out (wobble), parallelism (grooved or cupped), and thickness. If the rotor has suffered visual distortion on either of the first two areas, or if they are measured and found to be too thin, the rotors must be machined or replaced. If you are hearing these kinds of brake sounds you should get the brakes repaired as soon as possible to avoid even greater damage.
When you allow your pads to grind metal on metal, your rotors will almost certainly be worn thinner than specifications or so badly grooved and warped that they cannot be machined and so must be discarded. However, replacing pads before metal-to-metal grinding occurs does not always guarantee that rotors will not need to be machined. As improved brake pad technology increases the amount of time each rotor is used between servicing, and as low cost rotors become more abundant, the amount of wear on each rotor increases between changing pads. If you have been hearing these kinds of brake sounds, unless the rotors are of the highest quality (factory installed) and you are doing your first pad replacement since installing them, you will probably need to have your rotors turned or replaced.
Improved technology has brought the cost of rotors down compared to the continually rising cost of labor. Consequently, replacing rotors rather than machining them has become the popular choice of today’s drivers. If you drive a heavy duty or high-performance vehicle, however, you will find that the cost-to-performance ratio is better when you have your rotors machined.
Quality Brake Service
At Brakes and Beyond we give your brakes premium treatment in servicing. Our low cost does not mean low quality as it does with others.
A quality brake job includes: 1) thorough cleaning, 2) proper lubrication, 3) proper installation.
Thorough brake cleaning means making sure everything is rust free. The mating surface between the hub and the rotor cannot have rust, or else the rotor will not be true. Shims for the brake pads must be free of rust, or else the pads will be applied unevenly resulting in premature wear. Rust and brake dust on the shims can also cause unusual brake sounds – even if the pads and rotors are brand new. Caliper slide pins must be cleaned of old residue or they will stick, causing uneven wear and premature failure. Making sure that all parts are properly cleaned is the difference between a typical “good enough” job and a Brakes and Beyond “well done” job.
Properly lubricating the moving parts on brake systems ensures that everything will move as it is supposed to – not just for a short time after the job is completed, but throughout the whole life of the brake pads. Pads have to move freely in their brackets, and the caliper must move freely on its pins or else pressure will be applied unevenly, causing the vehicle to pull to one side. Uneven pressure also results in uneven wear, and premature failure of the brake pads.
Using the proper lubricator on brake systems is crucial. Normal anti-seize will destroy the dust boots and seals around the caliper slide pins and the caliper piston. This can result in rusted and seized caliper pins, or worse, a seized caliper in need of replacement. Many brake pads also need special grease applied to the back to eliminate abnormal brake sounds. Proper lubrication is the difference between even, long lasting braking action, and uneven action resulting in premature failure. The moral of the story is, if you want your brakes to last, make sure you get a mechanic who is understands and cares about brake lubrication!
Proper installation of brake pads includes the big things like tightening the bolts according to specifications, cleaning any manufacturers packing grease off the rotors, and properly resetting the caliper pistons. But it also includes little things like making sure the brake pad wear indicators are in the proper place, all shims are present and in order, and there are no twists in the caliper hoses. The difference between a professional and an amateur job lies in the little things.