1993 Corvette: Service Bulletin: Transmission "Whine" Noise, Loss of Motion in all Gears, or Missing Clutch Disc Rivets

Subject: TRANSMISSION "WHINE" NOISE, LOSS OF MOTION IN ALL GEARS, OR MISSING CLUTCH DISC RIVETS (REPLACE TRANSMISSION CLUTCH HOUSING)
Model and Year: 1993 CHEVROLET CORVETTE WITH SIX-SPEED MANUAL TRANSMISSION AND 5.7L (LT1) ENGINE (VIN CODE P)
Source: Chevrolet Service Bulletin
Bulletin Number: 37-71-40

CONDITION:

SOME OWNERS MAY COMMENT ABOUT A TRANSMISSION "WHINE" NOISE IN NEUTRAL AND IN ALL GEARS WHEN THE CLUTCH IS ENGAGED (FOOT OFF CLUTCH PEDAL).

THE ABOVE OWNER MAY ALSO EXPERIENCE A LOSS OF MOTION IN ALL GEARS.

PRELIMINARY DEALERSHIP INSPECTION MAY REVEAL LOOSE OR MISSING RIVETS IN THE CLUTCH DRIVEN DISC.

Cause:

IF THE VEHICLE IS BUILT BETWEEN THE VIN BREAKPOINTS OF 110966 THROUGH 113902 AND THE CLUTCH HOUSING HAS A CASTING DATE OF EITHER "JANUARY, FEBRUARY, OR MARCH 1993", THE CLUTCH HOUSING MAY BE THE CAUSE OF THE CONCERNS. THE CLUTCH HOUSING MAY HAVE A MISLOCATED TRANSMISSION TO CLUTCH HOUSING PILOT BORE. SEE FIGURE.

THIS MISLOCATED PILOT BORE MAY SIDELOAD THE TRANSMISSION’S INPUT SHAFT, THEREBY PRODUCING THE "WHINE" NOISE.

THE ABOVE CONDITION MAY ALSO SHEAR THE RIVETS OF THE CLUTCH DRIVEN DISC CAUSING THE CLUTCH DRIVEN DISC FRICTION FACING TO BE DISENGAGED FROM THE SPLINED HUB.

CORRECTION:

VERIFY THE VEHICLE FALLS INTO THE ABOVE BREAKPOINT.

VERIFY THE "WHINE" NOISE OCCURS ONLY WITH THE CLUTCH ENGAGED.

VERIFY THE SUSPECT CLUTCH HOUSING HAS A CASTING DATE OF EITHER "JANUARY, FEBRUARY, OR MARCH 1993". NOTE: SUSPECT HOUSINGS WILL HAVE NO MORE THAN THREE (3) "DOTS" IN THE CAST DATE. SEE FIGURE.

AFTER ABOVE VERIFICATION, REPLACE CLUTCH HOUSING, P/N 10126448. PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

NOTE: IF THE VEHICLE REQUIRES A REPLACEMENT OF THE CLUTCH DRIVEN DISC DUE TO SHEARED RIVETS, THE CLUTCH HOUSING ** MUST ** ALSO BE REPLACED.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION: K0800 REPLACE CLUTCH DRIVEN DISC (INC. CLUTCH HOUSING)

USE PUBLISHED LABOR OPERATION TIME

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.