LOSS OF DRIVE GEARS IN ALL RANGES (INSTALL SRTA TRANS)

SUBJECT: LOSS OF DRIVE GEARS IN ALL RANGES (INSTALL SRTA TRANSMISSION AND CHECK DRIVELINE WORKING ANGLES)

MODELS: 1991-93 CHEVROLET AND GMC TRUCK P3(32) MOTORHOMES WITH 4L80E/4L80-EHD AUTOMATIC TRANSMISSIONS (RPO MT1)

CONDITION:

SOME VEHICLES MAY EXHIBIT A LOSS OF DRIVE GEARS IN ALL RANGES.

CAUSE:

A LOSS OF DRIVE IN ALL RANGES MAY BE CAUSED BY A FRACTURED TRANSMISSION TURBINE SHAFT. A FRACTURE MAY OCCUR AT THE FORWARD CLUTCH FEED HOLE OF THE TURBINE SHAFT DUE TO 1) EXTREME SERVICE APPLICATIONS AND/OR 2) DRIVELINE ANGLE MISALIGNMENT CAUSED BY AFTER-MARKET REAR SUSPENSION COMPONENTS.

CORRECTION:

REMOVE THE TORQUE CONVERTER ASSEMBLY, INSPECT THE TRANSMISSION TURBINE SHAFT FOR FRACTURES. THE TURBINE SHAFT WILL SPIN EASILY IF IT IS FRACTURED. IF THE TURBINE SHAFT IS FRACTURED, INSTALL A SRTA TRANSMISSION ASSEMBLY, CHECK VEHICLE GVW AND REAR SUSPENSION COMPONENTS AND CORRECT DRIVELINE WORKING ANGLES. IF THE TURBINE SHAFT IS NOT FRACTURED, REFER TO SECTION 7A OF THE P MODEL SERVICE MANUAL FOR OTHER CAUSES OF LACK OF DRIVE.

SERVICE PROCEDURE:

IMPORTANT: DRIVELINE WORKING ANGLES MUST BE CORRECTED BY EITHER A CHEVROLET, GMC TRUCK OR MOTORHOME DEALER ON MOTORHOMES THAT EXPERIENCE A TRANSMISSION TURBINE SHAFT FRACTURE. SERVICE REPLACEMENT TRANSMISSION ASSEMBLIES (SRTA'S) INSTALLED TO FIX TURBINE SHAFT FRACTURES ARE NOT NECESSARILY THE RESPONSIBILITY OF GENERAL MOTORS. SEE STEPS 9 AND 11 OF THE FOLLOWING PROCEDURES FOR FURTHER DETAILS. GM CONSOLIDATED FLEET SERVICE OR THE GMC TRUCK DISTRICT SERVICE REPRESENTATIVE WILL REVIEW EACH CASE AND ASSIST IN CONTACTING THE COACH MANUFACTURER FOR PARTICIPATION WITH THE REQUIRED REPAIRS AND ADJUSTMENTS. DRIVELINE ANGLE ADJUSTMENT FOR VEHICLES EQUIPPED WITH NON-GM REAR SUSPENSIONS SHOULD BE THE RESPONSIBILITY OF EITHER THE CUSTOMER OR THE BODY BUILDER.

1. SECURELY BLOCK FRONT AND REAR WHEELS.

2. COMPLETELY REMOVE THE TRANSMISSION FROM THE VEHICLE. REFER TO TRANSMISSION REPLACEMENT IN SECTION 7A OF THE P MODEL SERVICE MANUAL OR THE LIGHT DUTY FORWARD CONTROL AND MOTORHOME CHASSIS SERVICE MANUAL.

3. WITH THE TORQUE CONVERTER ASSEMBLY REMOVED, INSPECT THE TRANSMISSION TURBINE SHAFT FOR FRACTURE(S) (FIGURE 1). THE TURBINE SHAFT WILL SPIN EASILY IF IT IS FRACTURED. THE TURBINE SHAFT WILL NOT MOVE EASILY IF IT IS NOT FRACTURED.

4. IF THE TURBINE SHAFT IS NOT FRACTURED, REFER TO SECTION 7A OF THE P MODEL SERVICE MANUAL OR THE LIGHT DUTY FORWARD CONTROL AND MOTORHOME CHASSIS SERVICE MANUAL FOR POSSIBLE OTHER CAUSES FOR LOSS OF DRIVE IN ALL RANGES. REPAIR AS NEEDED AND CONTINUE WITH STEP 21.

5. IF THE TURBINE SHAFT IS CRACKED, INSTALL A SRTA TRANSMISSION ASSEMBLY. REFER TO THE 4L80E/4L80-EHD SRTA MODEL REPLACEMENT INFORMATION IN THE APPROPRIATE GM PARTS CATALOG. ALSO REFER TO TRANSMISSION REPLACEMENT IN SECTION 7A OF THE P MODEL SERVICE MANUAL OR THE LIGHT DUTY FORWARD CONTROL AND MOTORHOME CHASSIS SERVICE MANUAL.

IMPORTANT: ALL RETURNED HYDRA-MATIC 4L80-E TRANSMISSIONS WILL BE DISASSEMBLED AND INSPECTED IN AN EFFORT TO INCREASE PRODUCT INTEGRITY. ATTEMPTING REPAIRS COULD DESTROY ROOT CAUSE ANALYSIS.

COOLER FLUSHING: COOLER FLUSHING AND A FLOW CHECK MUST BE PERFORMED WHENEVER A TRANSMISSION IS REMOVED FOR SERVICE. IT IS IMPERATIVE TO FLUSH THE COOLER PRIOR TO A SRTA INSTALLATION, OR WHEN FLUID CONTAMINATION IS SUSPECTED. USE KENT-MOORE TOOL J35944 AND SOLVENT J35944-20 TO FLUSH THE COOLER. INSTRUCTIONS ARE PUBLISHED IN EACH SERVICE MANUAL ON- VEHICLE SERVICE SECTION.

6. DETERMINE IF THE MOTORHOME HAS EITHER AIR BAGS OR A TAG AXLE INSTALLED AS AFTER-MARKET REAR SUSPENSION COMPONENTS. AIR BAGS ARE INSTALLED BETWEEN THE AXLE AND THE FRAME AND TAG AXLES ARE INSTALLED BEHIND THE DRIVE AXLE.

7. DETERMINE THE MODEL DESIGNATION (THIS MAY BE DETERMINED THROUGH THE SERVICE PARTS IDENTIFICATION LABEL OR THE VEHICLE IDENTIFICATION NUMBER), THE WHEELBASE AND THE WELD TO WELD (FIGURE 2 - DIMENSION T) PROP SHAFT LENGTHS (IN INCHES) OF THE MOTORHOME.

8. WITH THE ABOVE INFORMATION, DETERMINE IF THE VEHICLE MATCHES A DESCRIPTION LISTED IN TABLE A.

9. IF THE MOTORHOME DOES NOT MATCH A DESCRIPTION LISTED IN TABLE A, THE CHASSIS HAS BEEN MODIFIED AND THE DRIVELINE ANGLES MUST BE RECORDED. SOURCES OF INFORMATION FOR CALCULATING THESE ANGLES CAN BE FOUND IN THE P MODEL SERVICE MANUAL OR THE LIGHT DUTY FORWARD CONTROL AND MOTORHOME CHASSIS SERVICE MANUAL. RECORD THE DRIVELINE ANGLE MEASUREMENTS. IF QUESTIONS STILL REMAIN, CONTACT EITHER GM CONSOLIDATED FLEET SERVICE AT 1-800-334-5370 (SELECT OPTION NUMBER 5) OR GMC TRUCK TECHNICAL ASSISTANCE CENTER (1-800-832-6391). ONCE THE ACTUAL ANGLES ARE RECORDED AND FOUND OUT OF SPECIFICATION, CONTACT EITHER GM CONSOLIDATED FLEET SERVICE AT 1-800-334-5370 (SELECT OPTION NUMBER 5) OR YOUR GMC TRUCK DISTRICT SERVICE MANAGER BEFORE PROCEEDING.

10. DETERMINE IF THE VEHICLE HAS EITHER A STANDARD GM LEAF SPRING REAR SUSPENSION WITH OR WITHOUT AIR BAGS, OR, IF THE MOTOR HOME HAS A NON-GM SUSPENSION WITH OR WITHOUT A TAG AXLE. AVAILABLE GM MOTORHOME LEAF SPRING REAR SUSPENSION SYSTEMS ARE ILLUSTRATED IN FIGURE 3.

11. IF THE MOTORHOME HAS A NON-GM REAR SUSPENSION WITH OR WITHOUT A TAG AXLE, RECORD THE DRIVELINE WORKING ANGLES. SOURCES OF INFORMATION FOR CALCULATING THESE ANGLES CAN BE FOUND IN THE P MODEL SERVICE MANUAL OR THE LIGHT DUTY FORWARD CONTROL AND MOTORHOME CHASSIS SERVICE MANUAL. IF QUESTIONS STILL REMAIN, CONTACT EITHER CHEVROLET TECHNICAL ASSISTANCE (1-800-227-3175) OR GMC TRUCK TECHNICAL ASSISTANCE CENTER (1-800-832-6391). ONCE THE ACTUAL ANGLES ARE DETERMINED AND FOUND OUT OF SPECIFICATION, CONTACT EITHER GM CONSOLIDATED FLEET SERVICE AT 1-800-334-5370 (SELECT OPTION NUMBER 5) OR YOUR GMC TRUCK DISTRICT SERVICE MANAGER BEFORE PROCEEDING.

12. IF THE MOTORHOME HAS A GM LEAF SPRING REAR SUSPENSION WITH OR WITHOUT AIR BAGS MOUNTED BETWEEN THE FRAME AND AXLE HOUSING, MODIFY DRIVELINE ANGLES FOLLOWING STEPS 13 THROUGH 20.

13. USING THE VEHICLE IDENTIFICATION NUMBER OR THE SERVICE PARTS IDENTIFICATION LABEL, DETERMINE THE GVW OPTION AND THE REAR SPRING OPTION OF THE MOTORHOME.

14. FOR MOTORHOMES WITHOUT AIR BAGS, USE THE ABOVE INFORMATION AND TABLE B TO DETERMINE THE SHIMS NEEDED, IF ANY, BETWEEN THE FRONT AND REAR CENTER BEARING SUPPORT(S) AND CROSSMEMBER(S).

15. FOR MOTORHOMES WITH AIR BAGS, USE THE ABOVE INFORMATION AND TABLE C TO DETERMINE THE SHIMS NEEDED, IF ANY, BETWEEN THE FRONT AND REAR CENTER BEARING SUPPORT(S) AND CROSSMEMBER(S).

16. IF SHIMS ARE NEEDED, FOLLOW STEPS 17 THROUGH 20. IF SHIMS ARE NOT NEEDED, CONTINUE WITH STEP 21.

17. REMOVE THE PROPELLER SHAFTS AND CENTER BEARING SUPPORT(S) FOLLOWING PROPELLER SHAFT REPLACEMENT IN SECTION 4A OF THE P MODEL SERVICE MANUAL OR THE LIGHT DUTY FORWARD CONTROL AND MOTORHOME CHASSIS SERVICE MANUAL.

18. REMOVE HANGER ASSEMBLY(S) FROM THE CROSSMEMBER(S) BY DRILLING THE FOUR RIVETS OUT FROM BETWEEN THE HANGER(S) AND CROSSMEMBER(S).

19. INSTALL REQUIRED SHIM(S) BETWEEN THE PROP SHAFT HANGER ASSEMBLY(S) AND THE CROSSMEMBER(S) (FIGURE 4) USING FOUR BOLTS (SEE PARTS LIST), FOUR NUTS (GM P/N 6262213) AND, IF REQUIRED, FOUR WASHERS (GM P/N 2436163). TORQUE NUTS TO 23.5 N.M (17.4 LBS. FT). WASHERS ARE ONLY REQUIRED WITH BOLT GM P/N 9418995 USED WITH 1.00, 1.25 AND 1.5 INCH SHIMS. ALL OTHER BOLTS LISTED ARE FLANGE HEAD BOLTS AND DO NOT REQUIRE A WASHER.

IMPORTANT: A COMBINATION OF SHIMS MAY BE REQUIRED TO REACH THE APPROPRIATE SHIM THICKNESS. WASHERS ARE ONLY REQUIRED WITH STANDARD BOLTS (GM P/N 9418995).

20. REINSTALL THE PROPELLER SHAFTS AND CENTER BEARING SUPPORT(S) FOLLOWING PROPELLER SHAFT REPLACEMENT IN SECTION 4A OF THE P MODEL SERVICE MANUAL OR THE LIGHT DUTY FORWARD CONTROL AND MOTORHOME CHASSIS SERVICE MANUAL.

21. TEST DRIVE VEHICLE.

SERVICE PARTS INFORMATION:

P/N DESCRIPTION

15984590 1/4 INCH SHIM 15984591 1/2 INCH SHIM 15984592 1 INCH SHIM 6262213 NUT 2436163 WASHER 9441662 BOLT USED WITH 0.25 AND 0.5 INCH SHIMS 9441547 BOLT USED WITH 0.75 INCH SHIMS 9418995 BOLT USED WITH 1.00, 1.25 AND 1.5 INCH SHIMS

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OP DESCRIPTION LABOR TIME

K7000 TRANS. ASSEMBLY, REPLACE USE PUBLISHED LABOR OPERATION TIME T7676 DRIVELINE ANGLE CORRECTION 1.0 HRS

FIGURES: 5 ATTACHMENTS: 3 TABLES

CAPTIONS: FIGURE 1 - FRACTURED TURBINE SHAFT FIGURE 2 - WELD TO WELD PROPSHAFT LENGTH FIGURE 3 - GM MOTORHOME LEAF SPRING REAR SUSPENSIONS FIGURE 4 - SHIM INSTALLATION

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 1994 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.