American Motorcycle Dealer AMD 230 September 2018 - Page 55

TECH EXTRA DOT BRAKE HOSE AND BRAKE LINE ASSEMBLY TESTING Part 2 - The Torture Tests Scott Hurwitz, founder and CEO of Pittsford, New York based Magnum Shielding, continues his two-part series examining the very particular challenges of the motorcycle brake hose business. s mentioned in the last article, Motorcycle Brake Lines Part 1, published in the June edition of AMD Magazine, brake hoses and brake line assemblies are among the most regulated components on a motor vehicle and all manufacturers of brake line assemblies for highway use must be registered with the Department of Transportation (DOT). In addition, these brake hoses, fittings and assemblies must conform to FMVSS-106 and SAE J1401 standards, both of which outline grueling and demanding tests, which are designed to exceed what a vehicle will actually experience in the real world. This intentional overcompensation is necessary to protect us considering real life variables in manufacturing, installations and usage. This standard ensures that brake hoses stay flexible in a wide range of temperatures while having a predictable expansion rate, so that the pedal feel and ABS response is the same in winter as it is in the summer. It also requires that the hoses are able to bend and twist at certain angles without fatiguing, collapsing, kinking or bursting and that the critical crimp joint, where the hose is permanently connected to the end fitting, is robust enough to withstand all mechanical, chemical and temperature influences. Let’s now talk about the testing itself. It is no surprise that the sophistication of the testing equipment usually requires that manufacturers send brake hose assemblies out to third party testing labs for DOT validation, along with formal supporting documentation. This can be very costly - in excess of $20,000 each time a complete validation is conducted. As a Tier-1 Supplier to Harley-Davidson P&A, Magnum Shielding takes rider safety very seriously and has placed this at the top of its priorities. Our brake line manufacturing expertise, process and quality controls ensure brake line compliance with all DOT requirements, i.e. NHTSA’s FMVSS-106 Compliance Standards. To support this initiative, Magnum Shielding has duplicated the majority of the equipment needed to conduct the tests described below at their Upstate New York facility in accordance with the TP-106-10, U.S. Department of Transportation National Highway Traffic Safety Administration Laboratory Test Procedures for FMVSS-106 Brake Hoses. Per Magnum’s Quality Management System, all brake hoses and assemblies are tested on an ongoing basis to guarantee both compliance and consistent product quality. A Reviewing the entire standard can be quite time- consuming, so it has been distilled down for the sake of this article - let’s get started. Volumetric Expansion FMVSS-106 Standard Tests Labeling Depending on whether the hose assembly is OEM or NON-OEM (aftermarket), there is more than one alternative for labeling compliance. The Standard requires a visual inspection of the hose and/or fittings for proper labeling requirements as previously discussed in Part 1. Constriction This is a "go" or "no go" test where a drop ball, such as a metal ball bearing, is inserted in the upper end of a vertically held hose assembly and expected to drop down by gravity through the hose and out of the other end fitting. For 1/8” I.D. brake hose, the size of this sphere is .079”. This is an important test to ensure that the end fittings are not over-crimped and that there are no other possible blockages in the assembly that might be created as a result of the manufacturer’s assembly process. Volumetric Expansion This is a test of the true strength of the brake hose’s construction. The lower the brake hose’s volumetric expansion, the better the braking response (and feel) will be. On very long OE routing applications, sections of the assembly have metal tubing incorporated to reduce this expansion. This is one of the reasons braided brake lines are preferred over rubber hoses, whether they be braided with stainless steel or better yet, high tensile aramid fiber, which is sometimes referred to by DuPont’s trademarked name, Kevlar. In both scenarios, the hose’s expansion rate is directly related to the tensile and elongation characteristics of the braided materials used, along with the specific construction of the braid. Braid construction is also controlled by the gauge and number of wires or strands used, along with the tightness of the weave. The Standard states that the maximum expansion of a low expansion (LE) hydraulic brake hose assembly shall not exceed the values specified in its referenced “LE” table at three particular pressures, 1,000 psig, 1,500 psig and 2,900 psig. The fixture which tests for this requirement pressurizes an isolated brake hose that has an upper valve connected to a graduated glass cylinder. Prior to the hose being pressurized, the level in the graduated cylinder is set to zero. After pressurizing the hose, the valve is opened and the fluid level is allowed to rise into the cylinder, which then measures the amount the hose expanded at that pressure level. Testing for hose expansion rates can be especially important given the combination of today’s sensitive computerized ABS controller modules with aftermarket extended length brake lines required for tall “Ape hanger” handlebars. If the brake line construction exhibits high expansion levels, the readings may be outside the controller’s functional range to actuate the ABS as originally intended and programmed. Tensile Strength This test consists of subjecting the hose assembly to a gradually increasing tensile load at two AMERICAN MOTORCYCLE DEALER - SEPTEMBER 2018 55