For 1990-2009 cars

# TRANSMISSION UPDATES SUMMARY 125 TRANSMISSION

THIS BULLETIN PROVIDES THE NECESSARY INFORMATION TO UPDATE ANY OF THESE TRANSMISSIONS WHEN INTERNAL REPAIRS ARE REQUIRED. WHEN MAKING INTERNAL REPAIRS ON ANY 1980-1982 THM 125/125C TRANSMISSION, THE FOLLOWING LATEST DESIGN PARTS SHOULD BE USED WHERE APPLICABLE. PART NUMBER PART NAME 8631987 (1980-81) SOLID TURBINE SHAFT 8631968 (1982) OIL SEAL RINGS

8637640 BAND ANCHOR PLUG (IF DISLOGED)

8643964 THIRD ACCUMULATOR CHECK VALVE AND SPRING

8637836 (1980-1981) OIL WEIR

112496 PRESSURE REGULATOR VALVE

TO HELP YOU PROVIDE THIS SERVICE, WDDGM WILL PACKAGE THE PARTS INDICATED AS A SINGLE ITEM UNDER THE FOLLOWING PART NUMBERS: 1980-1981 MODELS - 8643995 1982 MODELS - 8643996

IN ADDITION TO THE ABOVE ITEMS, THE FOLLOWING SHOULD BE CHECKED: A.CHECK AND DRILL VENT HOLE IN THE CASE COVER IF NOT PRESENT

B.CHECK WEAR IN DIFFERENTIAL CARRIER BORE TO DETERMINE NEED FOR RIGHT DRIVE AXLE EXTERNAL BEARING REPAIR PACKAGE. PACKAGE PART NUMBER IS 8643931. THE AXLE SHAFT SLEEVE SEAL ORIGINALLY AVAILABLE ONLY IN THIS KIT IS NOW AVAILABLE AS A SEPARATE PART UNDER P/N 8643962.

IF INSPECTION OF THE TRANSMISSION AT THE TIME OF DISASSEMBLY REVEALS ANY FORM OF INTERNAL DAMAGE, THE TRANSMISSION COOLER LINES SHOULD BE CLEANED AND FLUSHED USING THE PROCEDURE PROVIDED IN SECTION 7A OF THE 1982 SERVICE MANUAL, PAGE 7A-2.

ALSO ONLY LOCTITE #515, P/N 1052756, SHOULD BE USED AT THE CASE COVER TO CASE GASKET TO PREVENT LEAKS IN THIS AREA. BEFORE USING KENT-MOORE TOOL J-288535 (INTERMEDIATE BAND APPLY PIN GAUGE), IT SHOULD BE CHECKED AND RECALIBRATED.

SOLID TURBINE SHAFT OIL SEAL RINGS SOLID OIL SEAL RINGS ARE USED TO MINIMIZE CONVERTER OIL DRAINBACK. EXCESSIVE CONVERTER OIL DRAIN-BACK CAN RESULT IN DELAYED ENGAGEMENT INTO DRIVE OR REVERSE. THEREFORE, ONLY SOLID SEAL RINGS, WHICH ARE INCLUDED IN THE UPDATE KIT, SHOULD BE USED WHEN REASSEMBLING THE TRANSMISSION. INSTRUCTIONS FOR REPLACEMENT OF SCARF CUT OR DAMAGED SOLID OIL SEALS IS AS FOLLOWS: 1.IF THE TURBINE SHAFT WAS ORIGINALLY EQUIPPED WITH SOLID TYPE OIL SEALS, REMOVE THEM BY CAREFULLY CUTTING WITH A KNIFE (FIGURE 1, PAGE 4). SCARF CUT SEALS DO NOT REQUIRE CUTTING. 2.PLACE THE SEAL INSTALLER (J-29569-1) OVER THE TURBINE SHAFT AND LUBRICATE THE INSTALLER WITH PETROLATUM (FIGURE 2, PAGE 4). 3.PLACE THE SOLID OIL SEAL RING OVER THE SEAL INSTALLER AND CAREFULLY, BUT QUICKLY SLIDE THE SEAL DOWN TO THE SEAL RING GROOVE. REMOVE THE SEAL INSTALLER (FIGURE 2, PAGE 4). 4.LUBRICATE THE INSIDE OF THE SIZING TOOL (J-29569-2) WITH PETROLATUM OR EQUIVALENT. PUSH THE SIZING TOOL DOWN OVER THE SEAL AND TURN. REMOVE THE SIZING TOOL AND INSPECT THE SEAL TO BE SURE THAT IT IS PROPERLY SEATED IN THE GROOVE (FIGURE 3, PAGE 4). 5.TO INSTALL THE SEAL ON THE OTHER END OF THE SHAFT, TURN THE SHAFT OVER AND REPEAT THE ABOVE PROCEDURE. * SEE BULLETIN FOR ILLUSTRATIONS * SUBJECT: NEW DESIGN BAND ANCHOR PLUG BEGINNING IN MID-JUNE 1981, ALL 125 AND 125C TRANSAXLES WERE ASSEMBLED WITH A NEW DESIGN BAND ANCHOR PLUG. THE NEW DESIGN BAND ANCHOR PLUG HAS A TAB WHICH HOLDS THE PART IN PLACE. SEE FIGURE 5. SERVICE INFORMATION 1. TRANSAXLES BUILT WITH THE PAST DESIGN BAND ANCHOR PLUG REQUIRED A STAKING OPERATION TO HOLD THE PART IN PLACE. SEE FIGURE 6. THIS STAKING OPERATION IS NOT REQUIRED WITH THE NEW DESIGN BAND ANCHOR PLUG AS IT IS HELD IN PLACE BY THE REVERSE OIL PIPE. SEE FIGURE 7. 2. TO REMOVE OR REPLACE THE DESIGN BAND ANCHOR PLUG, THE REVERSE OIL PIPE MUST BE REMOVED. 3. FOR SERVICE, USE THE NEW DESIGN BAND ANCHOR PLUG PART NUMBER 8637640 WHICH IS INCLUDED IN THE UPDATE KIT. SUBJECT: BURNT INTERMEDIATE BAND AND DIRECT CLUTCH FAILURE TO PREVENT THE POSSIBILITY OF INTERMEDIATE BAND FAILURE, THE NEW STYLE DUAL LAND VALVE AND CONICAL SPRING, SERVICE PART NUMBER 8643964 WHICH IS THE UPDATE KIT, SHOULD BE INSTALLED IN 1980-1981 125 TRANSAXLES IF NOT PRESENT, USING THE FOLLOWING INSTRUCTIONS. 1. REMOVE THE INTERMEDIATE SERVO COVER AND GASKET. 2. REMOVE THE THIRD ACCUMULATOR CHECK VALVE AND SPRING. 3. INSPECT THE THIRD ACCUMULATOR VALVE BORE FOR PRESENCE OF THE VALVE SEAT (FIGURE 8). ALSO, INSPECT FOR WEAR OR DAMAGE TO THE SEAT. 4. PLUG THE FEED AND RELEASE HOLES IN THE BORE USING PETROLATUM (FIGURE 8). 5. REPLACE THE THIRD ACCUMULATOR CHECK VALVE WITH A DUAL LAND CHECK VALVE. CENTER THE VALVE SO IT WILL SEAT PROPERLY. 6. LEAK TEST THE VALVE SEAT BY POURING SOLVENT INTO THE ACCUMULATOR CHECK VALVE BORE. CHECK FOR A LEAK ON THE INSIDE OF THE CASE. (A SMALL AMOUNT OF SEEPAGE IS ACCEPTABLE.) 7. IF THE VALVE LEAKS, TAP THE VALVE WITH A BRASS ROD AND RUBBER MALLET, TO TRY TO RESEAT THE VALVE. 8. AGAIN, LEAK TEST THE VALVE SEAT. 9. IF THE VALVE CONTINUES TO LEAK, IT WILL BE NECESSARY TO REPLACE THE CASE. 10. IF THE VALVE DOESN'T LEAK, REMOVE THE CHECK VALVE AND INSTALL THE NEW CONICAL VALVE SPRING INTO THE VALVE (SMALL END FIRST). REFER TO FIGURE 9. INSTALL THE VALVE INTO THE CASE CORE (FIGURE 8). 11. INSTALL THE SERVO GASKET AND COVER. (DO NOT USE OLD GASKET). SUBJECT: OIL WEIR THE OIL WEIR WHICH FIRST WENT INTO PRODUCTION IN SEPTEMBER, 1981, SHOULD BE INSTALLED IN ALL 125 AND 125C TRANSAXLES IF NOT PRESENT. THE OIL WEIR IS LOCATED IN THE REAR CASE - OIL PAN AREA AND WILL REVISE THE LUBRICATION FLOW AROUND THE DIFFERENTIAL ASSEMBLY. REFER TO FIGURE 10. THE OIL WEIR, PART NUMBER 8637836, IS HELD IN PLACE BY A RETAINING CLIP, PART NUMBER 8637837, BOTH PARTS ARE PROVIDED IN UPDATE KIT. SUBJECT: SOLID PRESSURE REGULATOR VALVE RETAINING PIN IF THE PRESSURE REGULATOR VALVE RETAINING PIN IS WORN OR MISSING, A CONDITION OF NO DRIVE, HARSH SHIFTS, OR HIGH LINE PRESSURE COULD OCCUR. IF PIN IS NOT THE NEW SOLID DESIGN, INSTALL PART NUMBER 112496 PROVIDED IN THE UPDATE KIT, USING THE FOLLOWING DIRECTIONS. 1. POSITION THE CONTROL VALVE AND OIL PUMP ASSEMBLY WITH THE MACHINED PORTION FACE DOWN. BE CERTAIN THE MACHINED FACE IS PROTECTED TO PREVENT NICKS, BURRS, SCRATCHES, ETC. COMPLETELY DISASSEMBLE PRESSURE REGULATOR VALVE TRAIN AS SHOWN IN FIGURE 11. 2. USE A 3/8 DRIFT PUNCH AND HAMMER TO STAKE (CLOSE) THE PRESSURE REGULATOR VALVE RETAINING PIN HOLE. SEE INSERT FIGURE 12. STAKE THE PIN HOLE ONLY ENOUGH TO HOLD THE NEW RETAINING PIN IN PLACE AFTER ASSEMBLY. 3. REASSEMBLE THE PRESSURE REGULATOR AND REVERSE BOOST VALVE TRAIN ASSEMBLY (SEE FIGURE 11). 4. RETAIN THE VALVE TRAIN WITH A NEW STEEL RETAINING PIN, P/N 112496. THE NEW PIN MUST BE INSERTED FROM AND FLUSH WITH THE MACHINED FACE OF THE CONTROL VALVE AND OIL PUMP ASSEMBLY. SUBJECT: OIL OUT THE VENT DIAGNOSIS. THE FOLLOWING INSTRUCTIONS SHOULD BE USED TO DRILL A VENT HOLE IN THE CASE COVER (IF NOT PRESENT) TO PREVENT THE POSSIBILITY OF AN "OIL OUT THE VENT" CONDITION. 1. DISASSEMBLE THE TRANSAXLE TO THE CASE COVER. 2. REMOVE THE CASE COVER AND INSPECT THE AREAS ADJACENT TO THE MANUAL VALVE FOR FLATNESS TO CASE AND EXTERNAL POROSITY. 3. WASH CASE COVER COMPLETELY WITH SOLVENT TO REMOVE ALL TRANSAXLE OIL, AND THEN DRY BEFORE PROCEEDING WITH THE FOLLOWING DRILLING OPERATION. 4. DRILL A 6.00 MM (1/4 INCH) HOLE THROUGH THE BREATHER AREA OF THE COVER AS INDICATED IN FIGURE 13. LATE 1980 PRODUCTION HAS THIS PASSAGE AND DOES NOT REQUIRE DRILLING. USE A SMALL DRILL OR PUNCH TO START HOLE. 5. REPLACE BOTH SPACER PLATE GASKETS WITH NEW SPACER PLATE GASKETS. 6. REASSEMBLY TRANSAXLE. SUBJECT: INTERMEDIATE BAND APPLY PIN GAGE CALIBRATION CHECK AND ADJUSTMENT PROCEDURE THE FOLLOWING CALIBRATION CHECK AND ADJUSTMENT PROCEDURE SHOULD BE MADE PRIOR TO USING KENT-MOORE TOOL J-28535 INTERMEDIATE BAND APPLY PIN GAGE. TO CHECK CALIBRATION: 1. HOLD J-28535 GAGE DOWN TIGHTLY AGAINST J-28535-50 CHECKING BLOCK. FIGURE 14. ROTATE SHOULDER PIN TO ASSURE IT IS SEATED ON FLAT SURFACE. 2. WHITE LINE MUST BE ACROSS CENTER OF SIGHT HOLE. TO ADJUST CALIBRATION: 1. CALIBRATION PIN IS SECURED WITH LOCTITE. 2. TURN PIN WITH A SMALL PIPE WRENCH OR VISE-GRIP PLIERS. APPLYING HEAT TO LOCTITE WILL EASE TURNING EFFORT. 3. ADJUST PIN TO CENTER WHITE LINE IN SIGHT HOLE. 4. RESEAL PIN WITH LOCTITE NO. 290 OR EQUIVALENT. NOTICE: ONCE GAGE IS RECALIBRATED, DO NOT INTERMIX SHOULDER PINS WITH OTHER GAGE BODIES. STAMP OR MARK SHOULDER PIN AND GAGE BODY TO DENOTE THEY ARE MATCHED. SUBJECT: TRANSAXLE IDENTIFICATION FIGURE 15 PROVIDES 125/125C TRANSAXLE IDENTIFICATION INFORMATION. SUBJECT: GENERAL SERVICE PROCEDURE INFORMATION 125/125C TRANSAXLE TORQUE CONVERTER EVALUATION THE CONVERTER SHOULD ONLY BE REPLACED IF ONE OF THE FOLLOWING CONDITIONS EXIST: 1. EITHER THE FRONT OIL PUMP COVER ARE BADLY SCORED, WHICH RESULTS IN CAST IRON GRINDINGS ENTERING THE CONVERTER AND OIL CIRCUIT. CHECK FOR METALLIC PARTICLES IN THE CONVERTER BY USE OF A MAGNETIC PROBE. 2. INTERNAL CONVERTER FAILURE, SUCH AS THE STATOR OVERRUN CLUTCH NOT LOCKING, THRUST BEARING FAILURE, ETC. SUCH FAILURES ARE ALSO NORMALLY ASSOCIATED WITH "ALUMINIZED" OIL IN THE CONVERTER. 3. END PLAY IN THE CONVERTER EXCEEDS 1.2 MM (0.050"). THIS MEASUREMENT CANNOT BE ESTIMATED, BUT MUST BE MADE WITH TOOL J-29830 OR J-29060. 4. LEAKING EXTERNALLY, SUCH AS THE HUB WELD AREA. A CONVERTER THAT HAS BEEN IN SERVICE AND, WHICH DID NOT LEAK, VERY LIKELY NEVER WILL. 5. A SCORED, OR OTHERWISE DAMAGED HUB, WHICH COULD CAUSE A FRONT SEAL FAILURE OR FRONT PUMP BUSHING FAILURE. 6. A BROKEN, DAMAGED, OR EVEN POSSIBLY A BAD FITTING CONVERTER PILOT, WHICH COULD CASUE THE CONVERTER TO EITHER NOT FIT INTO THE CRANKSHAFT BORE PROPERLY, OR NOT BE CORRECTLY ALIGNED WITH THE CRANKSHAFT. 7. THE OIL COOLER LEAKED, WHICH ALLOWED ENGINE COOLANT CONTAINING ANTIFREEZE TO ENTER THE TRANSAXLE. IT WILL NOT BE NECESSARY TO REPLACE CONVERTER IF CONTAMINATED ONLY BY WATER. SEE CONVERTER FLUSHING PROCEDURE IN THE CHASSIS SERVICE MANUAL. OBSERVE THE "REVISION TO CONVERTER FLUSHING PROCEDURE" IN THE 1982 JANUARY SERVICE GUILD, PAGE 28. NOTICE: ANTIFREEZE WILL ATTACH THE "VITON" O-RING SEAL ON THE SELECTIVE SPACER AND THE GLUE USED TO BOND THE CLUTCH MATERIAL TO THE PRESSURE PLATE, WHICH MAY CAUSE TRANSAXLE DAMAGE. THE CONVERTER SHOULD NOT BE REPLACED FOR ONE OF THE FOLLOWING CONDITIONS: 1. THE OIL HAS AN ODOR, IS DISCOLORED, AND THERE IS NO EVIDENCE OF METAL PARTICLES. THERE IS NO INDICATION THAT THERE IS INTERNAL DAMAGE, NOR ANY PUMP DAMAGE. POUR OUT AS MUCH OIL AS POSSIBLE FROM THE CONVERTER AND REPLACE THE OIL FILTER IN THE PAN. 2. DAMAGED THREADS IN ONE OR MORE OF THE THREE CONVERTER BOLT HOLES IS NOT A REASON FOR CONVERTER REPLACEMENT. CORRECT SUCH CONDITIONS WITH THE USE OF A HELI-COIL OR ITS EQUIVALENT. SUBJECT: OIL COOLER FLUSHING IF METALLIC PARTICLES OR COOLANT HAVE BEEN CARRIED WITH THE FLUID THROUGHOUT THE TRANSAXLE, THE FLUID COOLER AND LINES MUST BE FLUSHED. FOLLOW THE FLUSHING PROCEDURE IN THE APPROPRIATE CHASSIS SERVICE MANUAL. SUBJECT: END PLAY CLEARANCE - 125C ONLY END PLAY SETTINGS THAT ARE NOT WITHIN SPECIFICATION MAY CAUSE TRANSAXLE DAMAGE. THE FOLLOWING IS A LIST OF END PLAY CLEARANCES FOR 125C TRANSAXLES FROM THE APPLICABLE CHASSIS SERVICE MANUAL. INPUT SHAFT TO CASE COVER - 0.10 TO 0.84 MM (.004" TO 0.33") REACTION SUN GEAR TO INPUT DRUM - 0.33 TO 0.13 MM (.013" TO .005") REVERSE CLUTCH HOUSING TO LO RACE - 0.08 TO 1.17 MM (.003" TO .046") FINAL DRIVE TO CASE - 0.12 TO 0.82 MM (.005" TO .032") (LATE 81 THRU 83) FORWARD CLUTCH SNAP RING TO BACKING PLATE CLEARANCE - 1.0 TO 1.5 MM (.04" TO .07") SELECT PROPER INTERMEDIATE BAND APPLY PIN

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.