1988 - 1993 Corvette: Service Bulletin: Click/Whine in 3rd/4th Gear

Subject: CLICK/WHINE IN 3RD/4TH GEAR INST. NEW CLUTCH FIBER PLATES
Model and Year:
1988-93 CAPRICE, CAMARO AND CORVETTE
1988-93 C/K, RN, S/T, M AND G TRUCKS
1990-93 L VAN

Source: Chevrolet Service Bulletin
Bulletin Number: 93-228-7A

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 92-157-7A, DATED APRIL 1992. THE 1993 MODEL YEAR HAS BEEN ADDED, AS WELL AS A NOTE IN THE CORRECTION SECTION. ALSO THE SERVICE PARTS INFORMATION HAS BEEN CHANGED. ALL COPIES OF 92-157-7A SHOULD BE DISCARDED.

CONDITION:

Some 1988-93 vehicles with HYDRA-MATIC 4L60 or 4L60-E transmissions built before November 19, 1992 (Julian Date 324) may exhibit a clicking or whining noise in third and fourth gear. A customer may also describe it as a ticking or rattle noise.

CAUSE:

The clicking noise is caused by transmission fluid passing over the friction plates of the low and reverse clutch. The fluid causes them to vibrate when the low and reverse clutch is not applied (third and fourth gear).

CORRECTION:

Install five new fiber plates in the low and reverse clutch. The new plates have a non-groove configuration.

NOTE: All HYDRA-MATIC 4L60 and 4L60-E transmissions built on or after November 19,1992 (Julian Date 324) have been assembled with the new low and reverse clutch fiber plates.

SERVICE PARTS INFORMATION:

DESCRIPTION PART NO. TRANSMISSION
----------- -------- ------------
Plate Asm., - Low and Reverse Clutch 8684089 4L60-E & 4L60
Package - Overhaul Repair Complete 8685948 4L60-E
Package - Overhaul Repair Complete 8689951 4L60

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.

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