Preliminary Evaluation PE95-052: STEERING SHAFT SEPARATIONS

ODI OPENED THIS PE ON NOVEMBER 13, 1995 BASED ON AN OWNER COMPLAINT CONCERNING A SEPTEMBER 1995 ACCIDENT INVOLVING A 1995 1/2 TON GM PICKUP TRUCK.THE VEHICLE OWNER ALLEGED THE BOLT USED TO JOIN THE 2-PIECE STEERING SHAFT WAS MISSING.THE SHAFTS THEN SEPARATED AND STEERING CONTROL WAS LOST. DURING THE COURSE OF THIS INVESTIGATION, ODI HAS GATHERED INFORMATION FROM STAFF AT THE FOLLOWING: AUTO COLLISION INSURANCE COMPANIES, THIRD-PARTY PRODUCTS LIABILITY INDUSTRY, INDEPENDENT REPAIR SHOPS, INVOLVED VEHICLE OPERATORS, GENERAL MOTORS CORPORATION. ACCORDING TO GM, THE STEERING COLUMN AND SHAFTS WERE CHANGED FOR THE 1995 C/K MODELS AT THE START OF THE 1995 MODEL YEAR.THE CHANGE WAS MADE TO INCORPORATE DRIVER AIR BAG SYSTEMS FOR THE C/K10/20 WITH GVWR OF LESS THAN 8500 LBS.HOWEVER THE CHANGE WAS MADE FOR ALL C/KS. FOR THE 1995 MODEL YEAR, THE STEERING COLUMN SHAFT WAS CONNECTED TO THE UPPER INTERMEDIATE SHAFT WITH A BOLT THROUGH THE COLUMN SHAFT AND THE UNIVERSAL JOINT COUPLING.NO NUT WAS REQUIRED.THIS CONNECTION WAS MADE AT THE STEERING COLUMN ASSEMBLY FACILITY AND THE STEERING COLUMN IS SHIPPED TO THE VEHICLE ASSEMBLY PLANT.THIS JOINT IS LOCATED INSIDE THE VEHICLE CAB.THE UPPER INTERMEDIATE SHAFT WAS CONNECTED TO THE LOWER INTERMEDIATE SHAFT ASSEMBLY IS ALSO CONNECTED TO THE STEERING GEAR AT THE VEHICLE ASSEMBLY PLANT. THE CONFIGURATION OF THE UPPER INTERMEDIATE SHAFT WAS CHANGED AT THE START OF THE 1996 MODEL YEAR, WITH A SMALL NUMBER OF 1996 STEERING COLUMNS PULLED AHEAD IN THE 1995 MODELS ASSEMBLED AT THE OSHAWA AND FT. WAYNE ASSEMBLY PLANTS.THE UNIVERSAL JOINT OF THE UPPER INTERMEDIATE SHAFT WAS REPLACED WITH A POT JOINT.THIS CHANGE WAS MADE TO UTILIZE A JOINT MANUFACTURED INTERNALLY INSTEAD OF EXTERNALLY SUPPLIED UNIVERSAL JOINT.THE POT JOINT STYLE CONNECTION TO THE STEERING COLUMN SHAFT WAS MADE WITH A THROUGH BOLT AND NUT.THIS CHANGE WAS EFFECTIVE FOR 1995 VEHICLES ASSEMBLED AT FT. WAYNE AND OSHAWA IN OCTOBER 1995 AND FOR ALL 1996 VEHICLES. ODI'S ANALYSIS FOUND THAT, OF THE 24 FIELD REPORTS, 14 INVOLVE VEHICLES PRODUCED AT THE FT. WAYNE ASSEMBLY PLANT.ALL 7 OF THE ACCIDENTS INVOLVE TRUCKS BUILT THERE, AS WELL.HOWEVER, BECAUSE THE FT. WAYNE ASSEMBLY PLANT PRODUCES APPROXIMATELY THE SAME NUMBER OF VEHICLES AS THE OTHER SUBJECT VEHICLE ASSEMBLY PLANTS, THIS FINDING CAN NOT BE EXPLAINED ON THE BASIS OF VEHICLE POPULATION AND EXPOSURE.ODI, WITH THE INFORMATION CURRENTLY AVAILABLE, IS UNABLE TO EXPLAIN THIS PHENOMENON.ODI DOES HAVE INFORMATION INDICATING THAT THE PROBLEM OCCURS INFREQUENTLY AND VERY EARLY IN THE LIFE OF THE VEHICLE.FOR THE 24 FIELD REPORTS, INCLUDING THOSE REPORTING ACCIDENTS, A FAILURE OCCURRED, ON AVERAGE, 129 DAYS AND 3900 MILES AFTER THE TRUCK WAS BUILT.BASED ON INFORMATION FROM ALL SOURCES, CURRENT THROUGH NOVEMBER 1995, ODI HAS FOUND THAT ONE INCIDENT HAS OCCURRED INVOLVING A SUBJECT VEHICLE BUILT SINCE JULY 8, 1995, - A PERIOD OF 257 DAYS.THE DATA REVIEWED INDICATES ACCIDENTS, ALLEGEDLY DUE TO THE SUBJECT FAILURE, OCCUR EVEN EARLIER IN ACCIDENTS, ALLEGEDLY DUE TO THE SUBJECT FAILURE, OCCUR EVEN EARLIER IN THE LIFE OF A SUBJECT TRUCK, AT AN AVERAGE OF APPROXIMATELY 103 DAYS. FINALLY, BASED ON THE 115 WARRANTY AND FILED REPORTS COMBINED, THE INCIDENT RATE IS 12/100,000 VEHICLES.OF THE 115 REPORTS, 69 INVOLVE VEHICLES BUILT AT THE JANESVILLE AND FT. WAYNE ASSEMBLY PLANTS (35 AND 34 RESPECTIVELY).

THE JANESVILLE FAILURE RATE IS 15/100,000 AND THE FT. WAYNE RATE IS SLIGHTLY LOWER AT 14/100,000. A SAFETY-RELATED DEFECT HAS NOT BEEN INDENTIFIED AT THIS TIME AND FURTHER USE OF AGENCY RESOURCES DOES NOT APPEAR WARRANTED.ACCORDINGLY, THIS INVESTIGATION IS CLOSED.THE CLOSING OF T […]