A. All moving vehicle tests shall be conducted in accordance with the recommended practices referenced in §§B, C, and D of this regulation. All stationary vehicle tests shall be in accordance with the recommended practices of ISO 5130 1982 E.
B. The maximum sound emission test procedure for vehicles having a GVWR GCWR in excess of 10,000 pounds shall be that contained in the SAE Standard J986b, Exterior Sound Level for Heavy Trucks and Buses, except buses with automatic transmissions that cannot be manually held in gear. These vehicles shall be tested according to a modified J366 test which results in achieving the transmission shift from 1st to 2nd gear in the end zone during wide open throttle acceleration from a standing start.
C. For 1983 and subsequent model year street motorcycles manufactured after December 31, 1982, the test shall be that contained in Appendix I Subparts D and E, Title 40 of the Code of Federal Regulations Part 205 (40 CFR 205).
D. The maximum sound emission test procedure for vehicles having a GVWR or GCWR of 10,000 pounds or less shall be that contained in SAE Standard J876b, Sound Level for Passenger Cars and Light Trucks.
E. Deviation from ISO and SAE Standards and Practices.
(1) The Administration considers ISO 5130 1982 E and SAE standards and recommended practices to contain minimum requirements. In conducting tests in compliance with these procedures, the Administration may deviate from the literal requirements when it appears that the integrity of the test methods can be better preserved.
(2) Using instrumentation having greater precision or adding additional equipment to provide more accuracy in determining test conditions, and reducing the presence of objects in the test zone are examples of deviations from the referenced texts.
(3) The appendices attached to the referenced texts contain recommended sound level limits that are not appropriate to this regulation and are therefore deleted.