This article supersedes TSB 22-2175 to update the Issue, Action, and Service Procedure. Some 2015-2022 Transit vehicles equipped with rear wheel drive (RWD), single rear wheel (only), and U-joints at the transmission flange and rear driveshaft may experience a boom/hum/moan noise from the rear while driving. This noise is most noticeable at highway speeds: 112-121 km/h (70-75 mph) for 4.10 axle ratio 121-128 km/h (75-80 mph) for 3.73 axle ratio 136-145 km/h (85-90 mph) for 3.31 axle ratio The noise may also be present to a lesser degree at roughly half of the noted speeds. This may be due to a 2nd order driveline frequency transmitted through the rear driveshaft, rear axle and into the body through the leaf springs. To correct the condition, follow the Service Procedure to install a driveshaft torsional damper. NOTE: The torsional damper will not resolve a vibration.
