NHTSA Preliminary Evaluation PE07019

IN RESPONSE TO AN INFORMATION REQUEST (IR) LETTER SENT BY THE OFFICE OF DEFECTS INVESTIGATION (ODI), FORD STATED THAT THE PRIMARY CAUSE FOR THE MAJORITY OF THE REPORTED FRONT DIFFERENTIAL/DRIVE SHAFT FAILURES IS A MISALIGNMENT OF THE JOINT BETWEEN THE TWO COMPONENTS.CERTAIN LEVELS OF MISALIGNMENT MAY OVER TIME CAUSE AN UNEVEN WEAR OF THE SPLINES.CONTINUED WEAR OF THE SPLINES MAY RESULT IN A SHEARING OF THE SPLINES AND THE INABILITY OF THE DRIVESHAFT TO TRANSFER TORQUE TO THE FRONT DIFFERENTIAL. TO ADDRESS THE ISSUE IN THE FIELD, FORD INITIATED A SERVICE CAMPAIGN IN JUNE 2003 TO CORRECT THE MISALIGNMENT ISSUE AND, IF NECESSARY, REPLACE THE FRONT DRIVE SHAFT AND/OR DIFFERENTIAL.THE SERVICE CAMPAIGN COVERED MODEL YEAR (MY) 2003 AND MY 2004 VEHICLES BUILT FROM APRIL 18, 2002 THROUGH JULY 3, 2003.IN PRODUCTION, FORD INTRODUCED A CHANGE TO THE LUBRICATING GREASE OF THE JOINT IN FEBRUARY 2003 AND A CHANGE TO THE ASSEMBLY PLANT ALIGNMENT PROCESS IN JULY 2003 TO ADDRESS THE MISALIGNMENT AND WEAR ISSUE. ODI IDENTIFIED ONE CRASH RELATED TO THE ALLEGED DEFECT.THE CRASH INVOLVED A SUBJECT VEHICLE BEING STRUCK IN THE REAR AFTER BECOMING DISABLED BY A FRONT DIFFERENTIAL/DRIVESHAFT FAILURE AND PULLING TO THE SIDE OF THE ROAD. THIS PRELIMINARY EVALUATION HAS BEEN UPGRADED TO AN ENGINEERING ANALYSIS (EA07-012) TO FURTHER ASSESS THE SCOPE, FREQUENCY AND SAFETY CONSEQUENCES OF FRONT DIFFERENTIAL/DRIVESHAFT FAILURES IN THE SUBJECT VEHICLE POPULATION.