HARSH - 1-2 UPSHIFTS (SERVICE PROCEDURE). Buick Regal 1994

SUBJECT: HARSH 1-2 UPSHIFTS (SERVICE PROCEDURE)

MODELS: 1993-1995 BUICK REGAL 1993-1995 CHEVROLET LUMINA 1995 CHEVROLET MONTE CARLO 1993-1995 OLDSMOBILE CUTLASS SUPREME 1993-1995 PONTIAC GRAND PRIX WITH 3.1L ENGINE (VIN M - RPO L82) AND HYDRA-MATIC 4T60-E TRANSAXLE (RPO M13)

CONDITION:

SOME OWNERS MAY NOTICE A HARSH 1-2 UPSHIFT CONDITION. THE HARSH UPSHIFT CONDITION WILL USUALLY BE NOTICEABLE DURING A LIGHT TO MEDIUM THROTTLE UPSHIFT.

CAUSE: (FIGURES 1 AND 2) THE HARSH 1-2 UPSHIFT MAY BE CAUSED BY ONE OF THE FOLLOWING:

- A BINDING 1-2 ACCUMULATOR PISTON IN THE ACCUMULATOR HOUSING. - A MISSING OR LOOSE ACCUMULATOR BUSHING RETAINER. - A METAL SHAVING (BURR) OR DEBRIS IN THE 1-2 ACCUMULATOR SECONDARY VALVE TRAIN IN THE CONTROL VALVE BODY.

IMPORTANT: 3BHW, 4AFW AND 5AFW MODELS HAVE A 1-2 ACCUMULATOR PRIMARY VALVE TRAIN AND 1-2 ACCUMULATOR PISTON/SPRING LINE UP THAT IS DIFFERENT FROM MOST 4T60-E MODELS. DO NOT ASSUME THAT THESE MODELS HAVE A HARSH SHIFT CONDITION DUE TO MISASSEMBLY. FIGURES 1 AND 2 CORRECTLY SHOW THE 1-2 ACCUMULATOR COMPONENTS FOR THESE MODELS. THE 1993 AND 1994 SERVICE MANUAL SECTION 7A-5B IS INCORRECT. THE 1995 SERVICE MANUAL SECTION 7A-5B DOES CORRECTLY SHOW THE 1-2 ACCUMULATOR COMPONENTS.

CORRECTION: (FIGURES 1 AND 2) TO REPAIR THIS CONDITION, PERFORM THE FOLLOWING PROCEDURE:

1. REMOVE AND DISASSEMBLE THE 1-2 AND 2-3 ACCUMULATOR HOUSING ASSEMBLY AND INSPECT FOR THE 1-2 ACCUMULATOR PISTON BEING STUCK OR BINDING IN THE BOTTOM OF THE ACCUMULATOR BORE.

- IF THE ACCUMULATOR PISTON IS STUCK IN THE BORE, REPLACE THE ACCUMULATOR HOUSING. REFER TO SERVICE PARTS INFORMATION. - REFER TO THE APPROPRIATE SERVICE MANUAL FOR SPECIFIC REPAIR PROCEDURES.

2. IF THE 1-2 ACCUMULATOR WAS NOT STUCK IN THE ACCUMULATOR HOUSING, REMOVE THE CONTROL VALVE BODY AND INSPECT FOR A MISSING RETAINER ON THE 1-2 ACCUMULATOR PRIMARY OR SECONDARY VALVE BUSHING ASSEMBLIES.

* REPLACE ANY MISSING RETAINERS. REFER TO SERVICE PARTS INFORMATION. * REFER TO THE APPROPRIATE SERVICE MANUAL FOR SPECIFIC REPAIR PROCEDURES.

3. IF THE 1-2 ACCUMULATOR PRIMARY OR SECONDARY VALVE BUSHING ASSEMBLIES WERE NOT MISSING A RETAINER, DISASSEMBLE THE 1-2 ACCUMULATOR PRIMARY AND SECONDARY VALVE AND BUSHING ASSEMBLIES AND INSPECT FOR A BINDING OR STUCK VALVE DUE TO SEDIMENT OR BURRS.

* CLEAN THE CONTROL VALVE BODY IF BURRS OR DEBRIS ARE FOUND. * IF THE VALVE OR BUSHING ARE DAMAGED BEYOND REPAIR, REPLACE THE CONTROL VALVE BODY ASSEMBLY. REFER TO SERVICE PARTS INFORMATION. * REFER TO THE APPROPRIATE SERVICE MANUAL FOR SPECIFIC CLEANING AND CONTROL VALVE BODY REPAIR PROCEDURES.

SERVICE PARTS INFORMATION: (FIGURES 1 AND 2) PART NUMBER DESCRIPTION ---------------------------------------------------------------------- 8677163 HOUSING - ACCUMULATOR (ITEM 140) 8681510 RETAINER - ACCUMULATOR BUSHING, 3/PACKAGE (ITEM 385) 24200845 BODY ASSEMBLY - CONTROL VALVE, 3BHW, 4AFW, 5AFW (ITEM 301)

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY REQUIRING ONLY STEP 1 OF THE SERVICE PROCEDURE TO BE PERFORMED, USE:

LABOR OPERATION LABOR TIME K6507 USE THE PUBLISHED LABOR OPERATION TIME.

FOR VEHICLES REPAIRED UNDER WARRANTY REQUIRING STEPS 1 AND 2 OR ALL THREE STEPS OF THE SERVICE PROCEDURE TO BE PERFORMED, USE:

LABOR OPERATION LABOR TIME K6570 USE THE PUBLISHED LABOR OPERATION TIME PLUS AN ADD TIME OF 1.0 HOUR.

FIGURES: 2 ATTACHMENTS: 0

LEGEND FOR FIGURES 1 AND 2

ITEM DESCRIPTION

3 CASE, TRANSAXLE 104 COVER, 2-1 MANUAL SERVO BODY 105 SEAL, SQUARE CUT (2-1 SERVO) 132 COVER, ACCUMULATOR 133 GASKET, ACCUMULATOR COVER 134 PLATE, ACCUMULATOR SPACER 135 PIN, 1-2 AND 2-3 ACCUMULATOR 136 PISTON, 1-2 AND 2-3 ACCUMULATOR (1-2 PISTON IS UNIQUE) 137 RING, OIL SEAL ACCUMULATOR PISTON 138A SPRING, 2-3 ACCUMULATOR (INNER) 138B SPRING, 2-3 ACCUMULATOR (OUTER) 139B SPRING, 1-2 ACCUMULATOR (INNER) 139C SPRING, 1-2 ACCUMULATOR (OUTER) 140 HOUSING, ACCUMULATOR 301 BODY ASSEMBLY, CONTROL VALVE 338 RETAINER, 1-2 ACCUMULATOR PLUG 339 PLUG, 1-2 ACCUMULATOR PLUG (PRIMARY) 340 SPRING, 1-2 ACCUMULATOR VALVE (PRIMARY) 341 VALVE, 1-2 ACCUMULATOR (PRIMARY) 342 BUSHING, 1-2 ACCUMULATOR VALVE (PRIMARY) 346 PLUG, 1-2 ACCUMULATOR (SECONDARY) 347 VALVE, 1-2 ACCUMULATOR (SECONDARY) 348 SPRING, 1-2 ACCUMULATOR VALVE (SECONDARY) 349 BUSHING, 1-2 ACCUMULATOR VALVE (SECONDARY) 385 RETAINER, ACCUMULATOR VALVE BUSHING ASSEMBLY

Object Number: 84867 Size: FS

Object Number: 84866 Size: FS

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.