J2784_202405 FMVSS Inertia Dynamometer Test Procedure for Vehicles Below 4540 kg GVWR



Issuing Committee
This document derives from the Federal Motor Vehicle Safety Standards (FMVSS) 105 and 135 vehicle test protocols as single-ended inertia-dynamometer test procedures. The test sequences enable brake output measurement, friction material effectiveness, and corner performance in a controlled and repeatable environment. This SAE Document also includes optional sections for parking brake output performance for rear brakes with hydraulic or Electric Park Brakes (EPB). It applies to brake corners from vehicles covered by the FMVSS 105 and 135 when using the appropriate brake hardware and test parameters. The FMVSS 135 applies to all passenger cars and light trucks up to 3500 kg of gross vehicle weight (GVWR). The FMVSS 105 applies to all passenger cars, multi-purpose vehicles, buses, and trucks above 3500 kg of GVWR. This document does not include testing for school bus applications or vehicles equipped with hydraulic brakes with a GVWR above 4540 kg.
This document does not evaluate or quantify other brake system characteristics such as wear, noise, judder, ABS performance, or braking under extreme temperatures or speeds. This document does not include minimum performance requirements. Consistency and margin of pass/fail of the minimum requirements related to stopping distance or equivalent deceleration levels of the FMVSS 105 or FMVSS 135 vehicle test can be assessed as part of the project in coordination with the test requestor when using the appropriate vehicle information and vehicle dynamics modeling. Nevertheless, this procedure and its results do not replace the vehicle-level test to demonstrate compliance with FMVSS for hydraulic brake systems or other mandatory regulations (e.g., ECE R13H or ECE R13).
Towing and trailering applications are not part of this document and require a separate assessment per SAE J2807.
The current version of this recommended practice corrects the calculations for brake effectiveness, provides a definition of average by distance, and clarifies the scope related to tow vehicles and trailering applications. This revision also includes several edits to improve readability. The technical content, the test conditions, and the test sequences from previous versions remain unchanged.
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SAE International Recommended Practice, FMVSS Inertia Dynamometer Test Procedure for Vehicles Below 4540 kg GVWR, SAE Standard J2784_202405, Revised May 2024, Issued December 2007, https://doi.org/10.4271/J2784_202405.
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May 24
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Recommended Practice