NHTSA Complaint #10393193 — 1991 BUICK REGAL

ABRUPT, TOTAL LOSS OF STEERING CONTROL: AS THE VEHICLE ROLLED TO A STOP AT A TRAFFIC SIGNAL, AND LOUD "BANG" WAS HEARD AND FELT COMING FROM THE FRONT END OF THE CAR. CAUTIOUSLY MOVING OFF FROM THE STOP, THERE WAS A COMPLETE LOSS OF STEERING CONTROL; THE STEERING WHEEL JUST SPUN FREELY, WHILE THE VEHICLE TRACKED ALMOST STRAIGHT AHEAD. SINCE THERE WAS STILL POWER AND BRAKING, THE DRIVER WAS ABLE TO ROLL TO A STOP ON THE RIGHT SHOULDER OF THE ROAD. (IF THE LOSS OF STEERING CONTROL HAD OCCURRED THREE MINUTES LATER, IT WOULD HAVE BEEN AT 65 MPH ... WITH POSSIBLY FATAL CONSEQUENCES.) IN THIS VEHICLE THE ENGINE, TRANSMISSION, FRONT SUSPENSION, AND STEERING RACK ARE MOUNTED ON A SUBFRAME. THE SUBFRAME, IN TURN, IS ATTACHED TO THE PRIMARY STRUCTURAL FRAME OF THE VEHICLE WITH FOUR BOLTS M12X1.25 BOLTS; THE ATTACHMENTS INCLUDE RUBBER BUSHINGS TO PROVIDE SOME SHOCK ISOLATION BETWEEN THE SUBFRAME AND THE REST OF THE VEHICLE. THERE IS A STEEL SLEEVE WHICH INSERTS INTO THE INNER BORE OF THE ISOLATION BUSHINGS, AND THROUGH WHICH THE MOUNTING BOLT IS INSERTED. (SEE ILLUSTRATION FROM GENERAL MOTORS "1991 BUICK REGAL SERVICE MANUAL," P. 10.3.3, FIGURE 1.) THERE APPEARS TO HAVE BEEN NO CORROSION PROTECTION PROVIDED OR APPLIED TO THESE SUBFRAME ATTACH COMPONENTS DURING VEHICLE ASSEMBLY. UPON INSPECTION, THE CAUSE OF THE INCIDENT WAS DETERMINED TO BE FAILURE OF BOTH REAR SUBFRAME ATTACHMENT BOLTS AND/OR ISOLATION BUSHINGS DUE TO SEVERE CORROSION IN SERVICE. IMMEDIATELY FOLLOWING THE BOLT FAILURES, THE FRONT SUSPENSION SPRINGS FORCED THE REAR OF THE SUBFRAME DOWNWARD, RESULTING IN THE STEERING COLUMN SHAFT DISCONNECTING ENTIRELY FROM THE STEERING RACK ASSEMBLY.