CLICK NOISE OR GEAR DISENGAGEMENT IN REVERSE

SUBJECT: CLICK NOISE OR GEAR DISENGAGEMENT IN REVERSE (INSTALL REVISED GEAR SET)

MODELS: 1995-96 CHEVROLET CAVALIER 1995-96 OLDSMOBILE ACHIEVA 1995-96 PONTIAC GRAND AM, SUNFIRE WITH ISUZU 5-SPEED MANUAL TRANSAXLE (RPOS MJ1, MK7)

CONDITION:

SOME OWNERS MAY COMMENT ON A CLICKING NOISE, WITH VEHICLE IN MOTION, IN THE REVERSE GEAR.

YOU MAY ALSO RECEIVE COMMENTS CONCERNING THE ABOVE TRANSAXLES WITH DISENGAGEMENT IN THE REVERSE GEAR.

CAUSE:

THE ISUZU TRANSAXLE USES A TYPICAL SPUR (STRAIGHT CUT) GEAR DESIGN IN ITS REVERSE GEAR SYSTEM. ALL SPUR GEARS HAVE A POTENTIAL OF DISENGAGEMENT WHEN EXCESSIVE LOADS ARE APPLIED OR RELEASED.

THIS EXCESSIVE LOAD CAN OCCUR WHEN THE VEHICLE IS DRIVEN AT A HIGH OR SUDDEN INCREASE OF SPEED IN REVERSE AND THEN THE THROTTLE IS QUICKLY RELEASED. THIS IS **NOT** A RECOMMENDED DRIVING TECHNIQUE.

A TOTAL OR PARTIAL DISENGAGEMENT OF THE REVERSE GEAR MAY RESULT IN EXCESSIVE BACKLASH OF THE GEAR SYSTEM. EXCESSIVE GEAR BACKLASH MAY RESULT IN A CLICK NOISE IN REVERSE.

WHILE THE ABOVE CONDITIONS MAY CAUSE CUSTOMER CONCERNS, IT IS NOT A TRANSAXLE DURABILITY ISSUE.

CORRECTION:

A REVISED GEAR SET IS AVAILABLE TO ADDRESS THE CLICK NOISE OR GEAR DISENGAGEMENT IN REVERSE.

THE REVISED GEARS CONSIST OF A REVERSE IDLER GEAR AND A 1ST/2ND/REVERSE SYNCHRONIZER SLEEVE. THESE GEARS HAVE BEEN REVISED FROM SPUR-CUT TEETH TO A "SLIGHT" HELICAL TEETH CONFIGURATION. HELICAL GEARS TEND TO STAY IN POSITION WHEN LOAD IS APPLIED.

SERVICE PROCEDURE

IMPORTANT: ALL COMPONENTS NOT MENTIONED BELOW SHOULD BE TRANSFERRED TO THE PROPER SHAFT(S) AS REQUIRED PER SECTION 7B3B OF THE APPROPRIATE "TRANSMISSION TRANSAXLE TRANSFER CASE UNIT REPAIR MANUAL". THE 1997 UNIT REPAIR MANUAL IS APPLICABLE FOR BOTH THE 1995 AND 1996 MODEL YEAR ISUZU TRANSAXLE. THE 1997 MANUAL CONTAINS THE LATEST UPDATED INFORMATION.

INSPECT AND CLEAN INTERIOR OF TRANSMISSION FOR ANY METAL SHAVINGS OR DEBRIS.

VERIFY YOU HAVE RECEIVED THE CORRECT INPUT SHAFT (16).

FOR TRANSMISSION RPO "MJ1" (ENGINE RPO "LD2"; VIN CODE D + "LD9"; VIN CODE T) THERE IS **NO** NOTCH CUT ON THE OD OF THE REVERSE GEAR (STRAIGHT TEETH).

FOR TRANSMISSION RPO "MK7" (ENGINE RPO "LN2"; VIN CODE 4). THERE IS AN ONE (1) NOTCH CUT ON THE OD OF THE REVERSE GEAR (STRAIGHT TEETH).

INCORRECT SHAFTS WILL PREVENT ASSEMBLY OF THE TRANSAXLE.

DO **NOT** RE-USE INPUT SHAFT NUT (31) AND OUTPUT SHAFT NUT (60).

1. INSTALL NEW STOPPER PLATE (88) AND PRESS NEW COLLAR (BEARING INNER RACE) (87) ONTO NEW INPUT SHAFT (16)

2. REMOVE EXISTING 1ST/2ND/REVERSE SYNCHRONIZER SLEEVE (37) AND REPLACE WITH REVISED 1ST/2ND/REVERSE SYNCHRONIZER SLEEVE (37).

IMPORTANT: NOTE THE DIRECTION OF SLEEVE BEFORE DISASSEMBLY. REVISED SLEEVE MUST BE REASSEMBLED IN THE SAME DIRECTION.

EACH OPEN PORTION OF THE INSERT SPRING SHOULD FACE THE OPPOSITE DIRECTION FROM EACH OTHER.

3. REMOVE EXISTING REVERSE IDLER GEAR (61) AND REPLACE WITH REVISED REVERSE IDLER GEAR (61).

IMPORTANT: USE **NEW** INPUT SHAFT NUT (31) AND OUTPUT SHAFT NUT (60). THEY MUST BE PROPERLY TIGHTENED TO 128 N.M (94 LB. FT.) AND RETAINED WITH THREAD LOCKING MATERIAL (GM PART NO. 12345493). USE CARE NOT TO ALLOW THE MATERIAL TO FLOW INTO THE SPLINES OF THE 5TH GEAR AND INPUT SHAFT.

STAKING OF THE NUTS AFTER TIGHTENING IS ALSO NECESSARY.

FAILURE TO PROPERLY INSTALL THE NUTS MAY RESULT IN TRANSAXLE SHIFTING CONCERNS.

4. INSTALL REVISED REVERSE DETENT SPRING (50).

PARTS INFORMATION

TRANS ENGINE PART NO. RPO VIN PART NAME QTY

97101058 MJ1 D, T INPUT SHAFT 1 97101061 MK7 4 INPUT SHAFT 1 97101180 ALL ALL PLATE, STOPPER 1 97101714 ALL ALL COLLAR 1 97160667 ALL ALL GEAR, REVERSE IDLER 1 97160666 ALL ALL SLEEVE, 1ST/2ND/REV SYN 1 97088738 ALL ALL SPRING, REV DETENT 1 94124014 ALL ALL NUT, SHAFT(5 PCS PER PACK) 2

WARRANTY INFORMATION FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION NUMBER: K3145 USE PUBLISHED LABOR OPERATION TIME. **ADD** "TO RECONDITION TRANSAXLE COMPLETELY".

FIGURES: 0 ATTACHMENTS: 4

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.

COPYRIGHT 1996 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.