In nearly every form of motorsports, the focus seems to be on speed and horsepower. True, the fastest cars are often the victors, but any driver will tell you that lap times are just as equally affected by the car’s ability to brake as it is the car’s ability to accelerate. Races can be won or lost in the turns and a car that can brake well may just beat the one with more ponies under the hood.
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NASCAR brakes are different, depending on the track and type of race being run.
We contacted several brake manufacturers to learn more about what is involved in designing braking systems and friction formulations, as well as to pick up some tips we could use in the shop. The companies represented are recognized leaders in the industry, both as OE and aftermarket suppliers of braking system products.
Brembo boasts a long and proud racing tradition, starting back in 1975 when Enzo Ferrari assigned the task of outfitting his Formula 1 car with a high-performance braking system. Since then, Brembo-equipped cars have racked up more than 200 world championships, including Formula 1 and NASCAR. In addition, Brembo braking systems have been fitted to the winners of 21 (out of the last 24) 24 Hours of Le Mans events and were the brake system of choice on the 2012 Indy 500 winner. According to one Brembo representative, “The research and development performed for racing allows Brembo to apply the newest technology to street vehicles; technology that has already been tested and validated by the highest levels of racing.”
Brembo F1 calipers start off life as a solid piece of aluminum and are then machined to form the caliper.
Raybestos (an Affinia brand) is known for its involvement in NASCAR, where the stopping challenges vary dramatically. Cars running the long ovals will rarely use the brakes while the same cars competing on the short tracks and road courses will rely heavily on the braking system to give them that competitive edge. Wally Marciniak, director of technical services for Brake Parts, Inc. says, “Product selection changes between different race tracks. We research and supply different formulations to meet the (differing) demands. In many cases, we take race proven designs and incorporate them into products used for everyday.”
Honeywell Friction Materials (the company behind Bendix braking components) has its ties to drag racing, currently sponsoring Clay Millican, driver of the Parts Plus Top Fuel car.
And our last, but certainly not least, source represents a global leader as both an OE supplier and aftermarket brand, Federal-Mogul (parent of the Wagner brand).
Brembo brakes have been used in a variety of motorsports, including Formula 1 as shown.
The Challenges They Face
Developing a friction material is a challenging process and involves several aspects. Sarah Olson is the manager for Federal-Mogul’s formulation product development, Aftermarket Friction Group. She tells us that one of the factors is core research, that R&D that is ongoing in the quest to build a better brake pad. Another factor is regulatory requirements, like the future limitations on the use of copper (see sidebar article) and minimum stopping ability (federally mandated for heavy duty applications).
Like other OEM suppliers, Federal-Mogul is also charged with meeting the design requirements and other needs specified by its auto-making customer. Just as important is the feedback received from aftermarket consumers, like us. Improving wear, minimizing dust, and eliminating noise are all consumer-driven demands every brake manufacturer is trying to meet.
Grif Jordan, product marketing manager for Honeywell Friction Materials, says, “After understanding what your customer needs, it is really important to get to know what the customer wants as well. Clearly, the first concern is that the most important safety item on his or her car, the brakes, works properly. Beyond that, however, some customers may have other preferences.”
How would you like to do a brake service on this car?
And consumers worldwide are not created equally. Americans want quiet, clean braking over stopping ability while European drivers flying down the Autobahn focus on stopping ability over noise. In the U.S., concerns over brake dust (that nasty stuff that collects on those nice shiny rims) is beginning to become an even larger focus on the OE side since J.D. Powers added that concern to their customer satisfaction survey questionnaires.
The Challenges We Face
“Most technicians we talk with tend to indicate that addressing NVH (Noise, Vibration and Harshness) issues is their biggest concern,” says Jordan.
NASCAR short tracks use a lot of brake pad.
“Brake noise has always been an ongoing complaint,” adds Marciniak. “In many cases, this is caused by not doing the correct or complete brake job.” According to the advice offered by Marciniak, one key to reducing issues with noise is to make sure that the caliper slides are clean and lubed, that the pads are able to slide in their brackets, and to use a quality brake lubricant on the shim side of the brake pads to allow the shim to move within the caliper.”
“If you can keep the shim tight to the brake pad you will be able to reduce the brake noise.” Jordan agrees, encouraging techs to replace any worn hardware or abutment clips and to make sure to apply a high temperature lubricant on all metal contact areas. “This will help prevent any uneven pad wear, dragging brakes, and brake pulls,” Jordan explained.
Uniformity across the pad is critical to performance and is tested in the lab.
An often-overlooked contributor to comebacks involving noise issues is the lack of proper break-in as well and Jordan adds that proper burnishing after completing a brake job is a crucial step.
“We recommend the 30-30-30 method. Driving the vehicle at 30 miles per hour, perform 30 gentle stops, allowing a 30-second cool down period between each stop,” he states. “This transfers a film of friction material to the rotor surface and will result in quieter brake operation and longer pad/rotor life.”
In addition to these suggestions, Marciniak also adds, “If you are resurfacing the rotors, make sure your machine is calibrated correctly and that you surface the rotor correctly. Wash the finished rotor with hot, soapy water to remove any debris left after the machining process.”
Production pads are constantly checked for quality during their manufacture.
Peter Murnen, Federal-Mogul’s Global Marketing Manager for braking, agrees on the importance of proper cleaning. “Nine times out of 10, we find that noise complaints are a rotor surface issue and not a problem with the pads,” he says. He explains how they found that many technicians rely on an aerosol cleaning product to clean the rotors after machining instead of the hot bath every brake maker suggests.
Murnen explains that, “Using an aerosol brake clean often causes more problems than it solves. The cold refrigerant used as a propellant in the aerosol can actually freeze machining chips to the rotor surface, rather than remove them.” Later, as the rotor warms, these chips loosen and become embedded in the pads, causing noise and impacting braking efficiency. Using hot water with a detergent additive opens up the machining grooves and helps insure all the chips are removed from the surface.
Vibration: The V in NVH
According to Brembo, vibration is one of the most common problems drivers complain of.
“There are two different types of vibrations; cold judder and hot judder,” says a Brembo engineer in response to our questionnaire. “Cold judder, which does not depend on the operating temperature, is generally caused by geometric imperfections of the disc (rotor) or installation of the same. These imperfections will produce pulsations during contact with the pads that will be transmitted to the pedal. Hot judder is caused by use at high temperatures and can be caused by different reasons; low-quality friction material or material which is not uniform on the entire surface of the pad, and malfunctioning brake calipers allowing the pads to remain in slight contact with the disc even after the release phase.”
Performing a professional brake job involves more than simply swapping pads.
To detect problems with alignment, every maker recommends checking the installed runout of the rotor. Excessive runout allows the pads to contact a portion of the rotor surface, even with the pedal released, wearing areas of the rotor unequally. After a period of time, these wear areas result in a surface that resembles a wave and when the brakes are applied, the pads must try and follow this constantly changing position leading to the pulsation in the pedal your customer feels.
“Be sure to clean the hub of rust and dirt and check the lateral runout of every rotor, whether new or resurfaced,” recommends Marciniak. It is also important to properly torque all related fasteners; caliper mounting bolts and wheel studs, and to check the bearings themselves for excessive wear. During disassembly, take the time to mark the wheel’s location relative to the hub and do the same for the rotor. Reinstall in the same orientation to minimize setting yourself up for a comeback.
Of course, the use of quality parts is important to insure a quality job. “Rotors are more than big hunks of metal,” advises Murnen. “Use only products from a known good manufacturer to insure OE-level or better braking. The metallurgy of the replacement is not something you can easily verify and it is critical to braking performance. Check the thickness of the new rotor. There are instances of cheaper manufacturers cutting corners and this is a known industry issue. Will there be enough material to refinish the rotor after its first life cycle?”
Ask your customer how they use their vehicle to help them select the best brake pad.
What About Dust?
American consumers are just as concerned with appearance as they are performance and often we have to deal with concerns over brake dust. So what do we do?
“Sometimes it’s the rotor causing the dust. It’s the iron in the rotor causing the black dust rather than the pads, typical on European designs where the rotors are often “softer” than other makes and the friction material is designed foremost with stopping power in mind,” Murnen shares.
Federal-Mogul’s Olson warns that switching to a ceramic over a Low Steel Euro formulation or semi-metallic won’t necessarily cure the problem. “Not all ceramic products are created equal. There are still plenty that will generate dirty wheels. Just because you use ceramics doesn’t mean (the wheels) will be clean.”
Brake manufacturers strive to test their products under the most grueling conditions they can, both on and off the race track.
A Few Tips
To ensure that you offer your customers a professional brake job and minimize your comebacks, follow this advice. Always use components of a known good quality. Manufacturers that also make the OE pad have an advantage over those that must reverse engineer, but all major suppliers strive to meet or exceed OE performance. Replace all hardware with new and clean/lubricate all metal contact areas with a high temperature silicone lube.
Resurface new and used rotors alike to the proper finish and use only hot, soapy water to clean them. Check the condition of the bearings clean the mating surfaces between the hub and rotor, as well as the rotor’s “hat”. Verify that lateral runout is below maximum allowable on the finished assembly at the least and finish the job by properly torquing down all fasteners, including the wheel lugs.
For more tips, watch our archived webinar entitled “A Professional Brake Job” in the AutoPro Workshop or on YouTube.
New Laws Requires New Formulations
Adding to the challenges of brake pad design is legislation passed in both Washington (state) and California, phasing out the use of copper and other “heavy metals.” According to environmental research, copper deposits from brake pad wear may account for nearly half of the copper contamination entering water resources in urban areas. Highly toxic to fish and other aquatic species, it is hoped the legislation will help clean up area waterways and help the states meet the mandates outlined in the federal Clean Water Act.
Federal-Mogul was among the first to develop pads with no or little copper content, calling their product EcoFriction.
The California bill bans brake pads containing more than trace amounts of heavy metals and asbestos in 2014 and also bans brake pads containing more than 5 percent copper in 2021. By 2025, the law reduces the allowable copper content to almost zero. The law also requires that manufacturers comply with laboratory testing and certify with a marking that their products meet with the restrictions set for brake pads.
Washington’s bill is similar to California’s. The Washington mandate prohibits brake friction materials made after Jan. 1, 2015 from containing asbestos and other specified materials but does allow shops and distributors to use existing inventory through 2025. It also limits the use of copper to the same 5 percent standard in 2021 but its phase-out plan is a bit more complicated.
It calls for the Department of Ecology to study the feasibility of copper alternatives, and if it determines that such an alternative exists, it gives the manufacturers eight years before requiring that no product containing more than 0.5 percent copper can be sold in the state.
Most of the manufacturers we spoke with are already hard at work phasing out the use of copper in their friction formulations, and none voiced any concerns over meeting the bills’ requirements.
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