NHTSA Engineering Analysis EA09016

On January 4, 2012 Ford Motor Company submitted a Defect Information Report (NHTSA Recall No. 12V-006) to NHTSA regarding a defect in the performance of the transmission torque converter for approximately 205,896 Ford Freestar and Mercury Monterey vehicles.The supplier of the torque converter manufactured converters containing a pump shaft spline that did not consistently meet the specified heat treatment requirements.In normal use, the spline may wear excessively and eventually fails without warning.If a torque converter malfunctions due to a sheared pump drive spline, the vehicle will abruptly lose motive power.This problem affected model year 2004 and 2005 Freestar and Monterey minivans.During the investigation NHTSA identified 532 complaints alleging incidents of vehicle stall while driving due to torque converter failure.These failures were sudden and without any prior warning.Of the 490 complaints that reported the speed at the time of the failure:218 (44%) occurred at or above 55 mph; and 344 (70%) occurred at or above 40 mph.Of the 382 complaints that reported the position of the vehicle relative to traffic after it came to a stop following the loss of motive power: 122 (32%) alleged that the vehicle came to a stop in the flow of traffic and remained in the flow of traffic until pushed or towed out of the way; 225 (59%) reported that the vehicle was maneuvered to the side of the roadway and remained there until towed; and 35 (9%) reported that they were able to maneuver to a location away from the flow of traffic, such as a parking lot.Two crashes were allegedly caused by torque converter failure, including an incident in which a Freestar suddenly lost power in 65 mph traffic in an area where there was no shoulder available.As a result, the Freestar stopped in a travel lane and when trailing traffic maneuvered to avoid the stalled vehicle, a four vehicle collision occurred.In these types of circumstances NHTSA believes the defect presents an unreasonable ris