Brake pads: What to look for
What you should know when having brake servicing done.
Last reviewed: April 2010
While the federal government sets performance standards for brake systems in new vehicles, there are no government regulations
covering replacement brake pads. Given that a large percentage of consumer complaints to the National Highway Traffic Safety
Administration (NHTSA) involves brakes—and the brake system is one of the most critical elements of vehicle safety—it's important
to understand the choices consumers face when taking their vehicles to a brake shop. The cheapest brake job may compromise
safety, and the most expensive parts may not make your vehicle any safer than the standard part.
Servicing brakes 25 years ago required few decisions other than choosing a mechanic. Disc and drum brakes used only two types
of friction materials—semimetallic and asbestos. The mechanic simply replaced the old pad or shoe with the same type. Aftermarket
suppliers rarely offered different performance grades or price points for either type of pad.
Today, however, asbestos has been all but eliminated, because it can't meet contemporary cars' higher performance standards
as well as concern over health hazards from asbestos dust. Automaker suppliers have developed additional friction compounds,
and the aftermarket now offers a dizzying array of replacement brake products under dozens of brand names.
The different friction materials in use today often have design compromises. While one may offer superior heat transfer—and
therefore better braking performance—it may also be noisier and more prone to depositing unsightly brake dust on the wheel
rims. Another friction compound may have a soft feel, and work quietly, but wear out much more quickly.
Do you need new brake pads?
Usually, the first sign of excessive brake-pad wear is a high-pitched squealing.This sound comes from a soft-metal wear indicator
that rubs against the brake rotor to alert the driver that a change is needed. Other symptoms can include the vehicle pulling
to one side under braking, the brakes grabbing or vibrating, and the brake pedal feeling softer to depress. A grinding sound
means that replacement is overdue and the worn brake pads may be damaging the brake rotors. Always check the owner's manual
for any brake-related recommendations, including pad replacement intervals.
Types of brake pads
There are four general types of brake pads for cars and trucks:
Semimetallic: This formula, containing about 30 to 65 percent metal, typically includes chopped steel wool or wire, iron powder,
copper or graphite mixed with inorganic fillers, and friction modifiers that bond all the ingredients together. These pads
are more durable and have excellent heat transfer, but also wear down rotors faster, can be noisy, and may not perform optimally
at low temperatures.
Nonasbestos organic: Sometimes listed as organic or NAO, this type of pad is made from fibers, such as glass, rubber, carbon,
and Kevlar, with filler materials and high-temperature resins. These pads are softer and create less noise, but they wear
faster and create more dust.
Low-metallic NAO: These are made from an organic formula mixed with small amounts (10 to 30 percent) of copper or steel to
help with heat transfer and provide better braking. With the added metal, there is more brake dust and they may be slightly
Ceramic: These are composed of ceramic fibers, nonferrous filler materials, bonding agents, and possibly small amounts of
metal. Lighter in color and more expensive than other brake pads, ceramic pads are cleaner and quieter, and offer excellent
braking characteristics without wearing down the rotors.
How to choose
While a large selection brings down prices, consumers can be confused by slick packaging, clever brand names, and pushy mechanics.
Some consumers are even unaware that asbestos replacement pads are still available. Unlike foods that have ingredient labels,
brake pads have no content labeling. In fact, the formulas are highly guarded secrets and can vary even within a manufacturer's
own line, depending on what type of vehicle the pads are intended for. Full-size pickups, for instance, may need more metal—for
additional stopping power and reduced brake fade—than compact cars, which can use organic materials just as effectively.
Most manufacturers offer a range of pads for each application, but consumers shouldn't be fooled into believing it's always
a good-better-best choice. Nor will a family be safer with the most expensive replacement pad. The standard pad, if certified
(see below), should meet the demands of normal driving. Upgraded pads for normal driving will likely be noisier, produce more
dust, and possibly respond with a harder pedal feel. But if you tow, carry heavy loads or numerous passengers often, live
in hilly or mountainous areas, or have a daily commute down a steep grade, you should consider an upgraded or severe-duty
What's the price difference? We looked at the line of pads from one major company for a late-model Chevrolet Tahoe. The standard
pad retailed for $68 per set (enough to cover two wheels) followed by an upgraded version at $87 and a severe-duty set at
$98. Ceramic pads are more expensive ($120 for the Tahoe), but the advantages may be worth the extra money to many, especially
those with custom wheels. Ceramic pads will help solve noise and dust problems as well as offer excellent stopping performance
and comfortable pedal feel.
Look for a certified label
New vehicles must meet federal performance standards—a minimum stopping distance in a variety of situations under a specified
pedal effort. Many consumers assume all aftermarket replacement pads will perform just as well or better than factory parts,
but that's not necessarily the case.
In an effort to improve the customer's comfort level—and also to avoid future government regulations—brake manufacturers can
test and verify their products under two voluntary certification standards. Both are designed to ensure that replacement brakes
are as effective as original equipment, and consumers should make sure that any pads being installed on their vehicle are
The first is an independent proprietary program developed by Greening Testing Laboratories in Detroit called D3EA—which stands
for Dual Dynamometer Differential Effectiveness Analysis. This procedure tests front and rear friction materials together
on dual dynamometers, then simulates vehicle weight and speed through a computer program to measure braking effectiveness
and balance for different applications. D3EA was introduced in 1996, and among the first aftermarket companies to achieve
D3EA certification were ACDelco, NAPA, Raybestos, and Satisfied.
The Brake Manufacturers Council (BMC) has a second certification standard called BEEP, or Brake Effectiveness Evaluation Procedure.
BEEP testing is conducted on a single dynamometer, and the numbers are washed through a computer program to compare brake
performance with federal standards for new vehicles. The BEEP approval seals appear on packaging as manufacturers submit products
The D3EA tests are proprietary and more expensive, but they're also completely independent and tougher to pass. Brake manufacturers
have contended that most consumers change only the front or rear brakes at one time, so a concurrent dual test is unnecessary.
But, according to officials from Greening, NHTSA tests in the 1980s concluded there was a significant reduction in braking
performance when there was a differential between front and rear replacement pads as compared with original factory parts.
That report provided some of the motivation for the brake industry to begin seeking a certification standard before the federal
government issued regulations for replacement pads. The obvious concern over BEEP testing is that the manufacturers themselves
oversaw the development of the certification standards. While the program received input from the Society of Automotive Engineers
and actual certification is currently conducted at an independent laboratory, BMC members can conduct similar tests on their
own single dynamometers and compute the numbers.
Consumers must remember that not all of an aftermarket manufacturer's lineup gets certified, only pads designed for a specificRead more at www.consumerreports.org
vehicle that passed the designated test. Also, since the D3EA tests are expensive, manufacturers may test just the standard
line for a particular vehicle. One can assume then that any upgraded line from that same manufacturer will meet the test standards.
That's why heavy duty or the new ceramic pads may not carry the seal. The best advice is to look for manufacturers that aggressively
test their standard line, then move up in grade if you need more performance or seek other advantages such as minimal wheel
Saturday, October 09, 2010
Consumer Reports: Brake Pads - What to Look For
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