1987 - 1991 Corvette: Service Bulletin: 4L60 Low & Reverse Clutch New Plate Available

Subject: 4L60 LOW & REVERSE CLUTCH NEW WAVE PLATE IS AVAILABLE
Model and Year: 1987-91 CAPRICE, CAMARO, CORVETTE AND 1987-91 C/K, RN, S/T TRUCKS, G, M VANS AND 1990-91 L VAN WITH 4L60 AUTOMATIC TRANSMISSION
Source: Chevrolet Service Bulletin
Bulletin Number: 91-186-7A - (01/29/1991)

SERVICE INFORMATION: (Figure 2) --------------------------------- Low and Reverse Clutch failure can be caused by case casting flash interfering with clutch plate travel. A new wave plate is now available which will alleviate this condition. This new plate can be used to service any Hydra-matic 4L60 transmission produced after February 9, 1987 (Julian Date 040).

When installing the new wave plate, check for any case flash that may be present in the low and reverse grooves, and use a metal file to remove. See Figure 2 for case location information.

SERVICE PARTS INFORMATION:

Description New Part

------------------------- --------

Plate - Low and Reverse (wave) 8676362

Part is currently available from GMSPO.

DATE OF PRODUCTION CHANGE: (Figure 1) -------------------------------------- Beginning March 28,1990 (Julian Date 087), all HYDRA-MATIC 4L60 transmissions were built using the new low and reverse clutch wave plate.

SERVICE MANUAL REFERENCE:

Refer to the Automatic Transmission Unit Repair Section of the appropriate service manual for low and reverse clutch plate removal and installation information.

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.