GENERATORS W/VACUUM PUMP AND HYDRAULIC BRAKES

DIESEL-POWERED MEDIUM DUTY VEHICLES WITH HYDRAULIC BRAKES INCORPORATE A VACUUM PUMP WHICH IS DRIVEN FROM AN EXTENSION ON THE GENERATOR ROTOR SHAFT. THIS IS ACCOMPLISHED BY MACHINING (REDUCING) THE REAR ROTOR SHAFT BEARING SURFACE AND PRESSING ON THE EXTENSION. (THE EXTENSION THEN BECOMES THE REAR BEARING SURFACE). A DIMENSIONAL CHANGE TO THE SHAFT AND EXTENSION WAS PHASED INTO PRODUCTION DURING APRIL, 1981. THE ROTOR SHAFT DIAMETER (O.D) HAS BEEN INCREASED WITH A CORRESPONDING CHANGE IN THE INSIDE (I.D.) OF THE PRESSED-ON EXTENSION. SERVICE PARTS ORDERED AFTER 4-1-81 ARE OF THE NEW TYPE. THE NEW ROTOR SHAFT AND EXTENSION ASSEMBLY IS INTERCHANGEABLE WITH THE FORMER DESIGN. PART NUMBER INFORMATION ROTOR ASMS. 1984911 NEW ROTORS (INCLUDING EXTENSION) EXHIBIT DATE CODES OF 1D01 (APRIL 1,1981) OR LATER STAMPED ON THE END OF THE POLE PIECE. GENERATOR ASMS. 1100094 - 65 AMP. GENERATOR ASMS. 1100095 - 80 AMP. GENERATOR ASMS. 1100096 - 100 AMP. NEW GENERATOR ASSEMBLIES EXHIBIT DATE CODES OF 1D01 (APRIL 1,1981) OR LATER STAMPED ON THE DRIVE END UNDER THE PART NUMBER. DATE CODE EXPLANATION 1 = YEAR 1981 D = MONTH APRIL 01 = 1ST DAY OF MONTH YEAR 1 = 1981 YEAR 0 = 1980 MONTH A = JAN B = FEB C = MARCH D = APRIL E = MAY F = JUNE G = JULY H = AUG J = SEPT K = OCT L = NOV M = DEC

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.