The NP244 Transfer Case Chain Noise Reduction Using a Gemini HyVo® Chain System

Major revisions for a 2004 model year Sport Utility Vehicle (SUV) included body, suspension, mounting systems, NVH package upgrades, and drivetrain including a new transfer case - the Magna Drivetrain NP244-Gen2 (2^nd Generation). During vehicle development, an objectionable level of transfer case chain whine was experienced over a narrow speed range. From vehicle and component testing, the noise was determined to be a transfer case to vehicle systems integration issue excited by the transfer case chain mesh order. The noise issue was solved through passive noise cancellation using a Gemini HyVo® phased sprocket and chain set. The half-pitch phasing of the sprocket and chain pair resulted in near total elimination of the fundamental chain mesh frequency. The NP244-Gen2 is the first transfer case to utilize a phased chain and sprocket system resulting in a best in any class performance for transfer case chain mesh noise.