REAR AXLE PINION BEARING NOISE

SOME EARLY BUILT 'F' SERIES MAY ENCOUNTER A PINION BEARING NOISE AS A RESULT OF CARRIER DISTORTION AT THE FRONT PINION BEARING OUTER RACE AS DESCRIBED IN BULLETIN 4-106 DATED JUNE 30/82. TO CORRECT THIS CONDITION A CARRIER DESIGN CHANGE WAS INITIATED AND WENT INTO VEHICLE PRODUCTION DURING THE MONTH OF JUNE, 1982 (SEE FIGURE 1). THE NEW DESIGN CARRIER ALSO REQUIRES THE PINION BEARING PRELOAD AND THE TORQUE ARM TO CARRIER ATTACHING BOLTS TO BE TORQUED AT THE MINIMUM SPECIFICATIONS; HOWEVER, THE NEW CARRIER IS MUCH LESS LIKELY TO DISTORT IF AN OVER TORQUE CONDITION DOES OCCUR. A SERVICE BOLT PACKAGE (PART NUMBER 10028612), FOR ATTACHING THE TORQUE ARM TO THE REAR AXLE CARRIER, HAS BEEN RELEASED TO CORRECT THIS CONDITION ON VEHICLES BUILT WITH FIRST DESIGN CARRIER. THE PACKAGE CONTAINS TWO STANDARD BOLTS, ONE STANDARD NUT, AND ONE SPECIFICALLY MACHINED NUT. WHEN INSTALLED PROPERLY, THE NEW BOLTS WILL PREVENT AN OVER TORQUE CONDITION AT THE FRONT PINION BEARING LOCATION, THUS ALLOWING REUSE OF THE CARRIER WHENEVER PINION BEARING REPLACEMENT IS REQUIRED. THE FOLLOWING INFORMATION IS PROVIDED FOR IDENTIFICATION OF FIRST DESIGN VERSUS SECOND DESIGN CARRIERS. ASSEMBLY PLANTS WERE INSTRUCTED ON MAY 17, 1982 TO IMPLEMENT USAGE OF AXLE ASSEMBLIES WITH THE SECOND DESIGN CARRIER CASTING; HOWEVER, AXLE ASSEMBLIES WERE NOT IDENTIFIED WITH NEW AXLE CODES UNTIL JUNE 4, 1982. AXLE ASSEMBLIES IDENTIFIED WITH THE NEW CODE WILL USE A DIFFERENT NUMERICAL CHARACTER (THREE INSTEAD OF TWO) IN THE FIRST POSITION OF THE CODE AS IT APPEARS ON THE AXLE ASSEMBLY AS SHOWN BELOW: SECOND DESIGN AXLE ASSEMBLY CODE: 3JX AXLE CODE C MFG 155 JULIAN DATE 1 SHIFT SECOND DESIGN AXLE ASSEMBLIES WITHOUT THE NEW IDENTIFICATION CODE CAN BE IDENTIFIED WHEN THE TORQUE ARM IS REMOVED BY NOTING THE REDUCED CLEARANCE BETWEEN THE CARRIER CASTING AND LOWER FRONT TORQUE ARM BUSHING AS ILLUSTRATED IN FIGURE 1. SECOND DESIGN CARRIERS CANNOT BE FITTED WITH THE BOLT KIT. CLEAN VEHICLE IDENTIFICATION BREAKPOINTS INDICATING TOTAL USE OF SECOND DESIGN CARRIERS AS FOLLOWS: NORWOOD CN516372 VAN NUYS CL545325 THE FOLLOWING SERVICE PROCEDURE MUST BE USED WHEN INSTALLING THE BOLT KIT ON FIRST DESIGN CARRIERS. 1.REMOVE TORQUE ARM TO CARRIER FORWARD THROUGH BOLT AND NUT AND RETAIN WASHERS. 2.LOOSEN TORQUE ARM TO CARRIER REAR THROUGH BOLT NUT. 3.REMOVE AND INSTALL FRONT AND REAR PINION BEARINGS AS OUTLINED IN SECTION 4 OF THE 1982 'F' SERIES SERVICE MANUAL AND SET PINION BEARING PRE-LOAD TO 2.7N.M (24 IN. LBS.). 4.THOROUGHLY CLEAN CARRIER WHERE NEW NUTS FROM SERVICE PACKAGE (PART NUMBER 10028612) WILL CONTACT CASE. 5.INSTALL ONE OF THE EXISTING WASHERS FROM THE ORIGINAL FORWARD THROUGH BOLT ON THE M14 X 2 X 40MM BOLT. 6.LOOSELY INSTALL THE M14 X 2 X 40MM BOLT AND M14 X 2 NUT IN THE UPPER TORQUE ARM TO AXLE CARRIER BOLT HOLE (SEE FIGURE 2). 7.COAT THREADS OF M14 X 2 X 80MM BOLT WITH LOCTITE 271 (PART NUMBER 992959). 8.POSITION THE SPECIFICALLY MACHINED NUT ON THE CARRIER WITH THE MACHINED SURFACE TOWARD THE HOUSING AS SHOWN IN FIGURE 3. 9.INSTALL THE REMAINING WASHER FROM THE ORIGINAL FORWARD THROUGH BOLT ON THE M14 X 2 X 80MM BOLT AND INSTALL BOLT AS SHOWN IN FIGURE 2. TORQUE BOTH FORWARD BOLTS TO 150 N.M. (110 FT. LBS.). 10.TORQUE REAR THROUGH BOLT 115 N.M (85 FT. LBS.). 11.INSTALL PROPSHAFT AND COMPLETE REAR AXLE ASSEMBLY INSTALLATION. USE MOST APPLICABLE LABOUR OPERATION FROM CANADIAN LABOUR TIME GUIDE AND CLAIM .2 HR.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.