SERVICE BRAKES, HYDRAULIC:FOUNDATION COMPONENTS:DRUM
Oct 27, 1991
130 units potentially affected
The defect: THESE VEHICLES HAVE FRONT AXLES WITH BRAKE CAM OPERATION OPPOSITE TO THE ROTATION OF THE BRAKE DRUM (CAM OPPOSITE), AND THERE IS A TENDENCY FOR BRAKES TO CHATTER UNDER LOW AIR PRESSURE, RESULTING IN VIBRATIONS. THE VIBRATIONS INDUCE STRESSES IN THE TIE ROD END BEYOND ITS ENDURANCE LIMIT, AND RESULT IN CRACKS IN THE THREADED PORTION OF THE STUD WHERE THE TUBE ENDS.
The risk: CRACKS IN THE TIE ROD CAN RESULT IN SEPARATION OF THETIE ROD AND LOSS OF VEHICLE CONTROL WITHOUT PRIOR WARNING.
The remedy: REPLACE THE CAM OPPOSITE BRAKE ACTUATION WITH CAM SAME BRAKE OPERATION, BY INTERCHANGING THE LEFT AND RIGHT CAM ASSEMBLIES TO AVOID BRAKE CHATTERING; AND REPLACE TIE RODS.
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