FMVSS 121 brake option review

FMVSS 121 brake option review

New stopping regulations encourage fleets to consider foundation brake choices for their current and future vehicles

The National Highway Traffic Safety Association (NHTSA) recently announced new stopping distance regulations for tractors. Effective August 2011, the maximum allowable stopping distance from 60 MPH for new Class 8 three-axle tractors is reduced by 30%. Existing vehicles are not affected, but should fleets consider upgrading brakes to meet the shorter distances anyway? And if upgrading, is there any advantage going from drum to air disc brakes?

Plan ahead nowabex brake shoe
The vehicle manufacturers is responsible for making sure its vehicles are compliant for 2011. However, fleets can prepare for the new stopping distance regulation now by working with their OEM suppliers to review their needs and determine if any changes might be required, says Alesha Erving, brake and steering product manager, Federal-Mogul Corp., manufacturer of Abex commercial vehicle friction products. “In many cases,” Erving notes, “larger steer axle brakes and potentially wider rear axle brakes will be required to meet the new law, in addition to new friction materials.” One of the advantages of upgrading to a wide brake system is that it generally operates at a cooler temperature, which can result in longer brake life and better stopping power, she adds.leland brake system

Federal-Mogul’s Abex team has been working with its OEM customers to develop new materials for the larger and/or wider steer and drive axles.

The new stopping distance regulation will certainly involve higher-torque steer-axle brakes, notes Brian Rassin, marketing product director for Leland Brake and Wheel Parts. “Fleets need to understand how this increase in load transfer will impact wearable items such as axle/suspension components and tire wear.” Other considerations include tractor-to-trailer compatibility, since the new tractors will have improved braking capability, and whether the new technology will require a change in maintenance practices.

Joe Kay, chief engineer for brake systems at ArvinMeritor, believes vehicle manufacturers will try to minimize additional costs to the overall vehicle to comply with the rule. “It is likely that only foundation brakes will be utilized to meet the new regulation. This means the size of the brakes will change to a product that produces more torque,” he explains. In some cases it may mean going to a larger brake size, and in other cases, it may require a friction material change. arvinmeritor q-plus s-cam drum brake

Kay warns of aftermarket-only friction and brake suppliers making claims that their products meet the new FMVSS 121 requirements. Fleets are going to be inundated with a lot of information and claims of “OEM approved,” he says, and customers will to have to sift through those claims and understand that the stopping distance requirement applies to the complete braking system on that vehicle. Friction and brake shoes are only components in that system and, as stand-alone components, cannot meet the new stopping distance requirement on their own. He adds the only way to be assured that the friction meets the new stopping distance is if it has been tested as a component in the braking system manufactured by that brake OEM.

Randy Petresh, vice president of technical services, Haldex Commercial Vehicle Systems, advises fleets to replace friction materials and shoes with OE-level parts or those with equivalent performance characteristics offered by trusted aftermarket suppliers. He says making the right choice is easy to do by consulting the list of aftermarket linings that meet FMVSS 121 criteria for OE linings in TMC Recommended Practice Aftermarket Brake Lining Classification (RP 628A).

In today’s economy, it’s tempting to try lower-cost products with unknown or unproven performance characteristics. The stopping power and structural integrity of the products are critical factors that need to be considered when replacing brakes, notes Federal-Mogul’s Erving. A cracked brake lining can put a vehicle out-of-service and can cause brake failure if the lining breaks loose from the shoe.

Ken Kelley, vice president, Webb Wheel Products Inc., says fleets need to work with their preferred vehicle OEMs to understand their plans to meet the new stopping distance and the respective component options. Each option will have a different cost and weight impact, and fleets should understand the OEM’s options and specify the stopping distance solution that best matches their fleet’s operating environment.

Drum or air?
ArvinMeritor’s Kay says it is not necessary for fleets to convert to air disc or air disc/drum combinations. He notes that the NHTSA estimates the incremental cost for drum brakes on a typical three-axle tractor would be $211, whereas the incremental costs to convert to disc brakes at all wheel positions would be $1,475. Drum brakes are highly popular, with parts commonly available at thousands of locations. Technicians know how to service them, he explains.

Leland’s Rassin advises that fleets should consider need and perform a cost-benefit analysis for each brake option. Disc brakes are an alternative to drum brakes but are more costly when OE-installed. A retrofit would be even more costly and usually not feasible. The typically cost OE-installed is approximately $1,000 per axle with little to no residual value upon resale. This is one of the reasons disc brakes have not entrenched themselves in the North American market, he explains. The other is need. “Many vocations, including over-the-road, don’t need the minimal additional braking stability at 70-plus MPH,” he states. “Test results have proven that drum brakes perform admirably at most speeds and are significantly less costly.”

Webb Wheel’s Kelley believes fleets have two options: retain drum brakes by using the wide profile 16 1/2 X Webb Wheel Products' Vortex drum brake
8 5/8-in. drive axles and 16 X 5-in. front axles, or as an alternative, choose air disc, which will also perform to the regulation but introduces new wheel end components and related maintenance procedures with added cost and little residual value.

Haldex’s Petresh agrees that from an aftermarket perspective, it is really costly to retrofit existing vehicles to air discs from drums. However, the new stopping rule is an opportunity for fleets to try air discs when spec’ing new. He suggests, “Don’t make a big change overnight. Try with a small percentage of your fleet, run them three-to-four years to see how they perform and to give your technicians time to understand them.”

Some fleets may change the brakes they are spec’ing and want to go standard with the change on their older vehicles as well, to keep parts proliferation down and make purchasing easier, says Kay at ArvinMeritor. He suggests that transitioning to larger brakes will provide some advantages, including increased lining volume to drive longer service intervals, lower operating temperatures, reduced fade and improved performance. He adds that ArvinMeritor has been working on a reduced stopping distance program for more than three years in anticipation of the new regulations. As a result, he says the company’s Q Plus S-cam drum brake will meet the new requirements with an additional 10% margin.

Webb Wheel’s Kelley says upgrading a select number of vehicles ahead of the mandate would allow more time to understand how any new braking components will impact the performance of other undercarriage components and give technicians more training time to iron out any new maintenance procedures.

Reman option
Reman shoes are the product of choice for most fleets, says Federal-Mogul’s Erving. “This has been primarily driven by the cost differential between reman and new shoes. A premium brake lining attached to a properly reconditioned brake core can provide the fleet with the stopping power and durability they need for cost-effective and safe operations,” she notes.

At any brake replacement, a truck operator should consider spec’ing remanufactured brake shoes, according to ArvinMeritor’s Kay.

Haldex’s Petresh says, “It’s a business decision more than anything else. It’s fine for a fleet willing to deal with the paperwork and process for stockpiling and returning cores as long as the same guidelines are utilized for supplier and friction material selection.”  FE

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