1992 Corvette: Service Bulletin: Harsh 1-2 Upshift

Subject: HARSH 1-2 UPSHIFT INSTALL SERVICE PACKAGE
Model and Year: 1992 CAPRICE, CAMARO AND CORVETTE 1992 C/K, G, L/M, S/T TRUCKS
Source: Chevrolet Service Bulletin
Bulletin Number: 92-318-7A - (09/15/1992)

TRANSMISSION APPLICATIONS: SUBJECT: 1992 HYDRA-MATIC 4L60 Harsh 1-2 Upshift ;Install Service Package

TRANSMISSION MODELS: VEHICLE APPLICATIONS: 2AAM, 2ACM, 2ADM, 2AKM, 2BAM, B, F, Y Cars 2BBM, 2BCM, 2BHM, 2BRM, 2BWM, C/K, S/T TRUCKS 2CAM, 2CBM, 2CCM, 2CFM, 2CHM, G, L, M Vans 2CJM, 2CPM, 2FTM, 2FUM, 2FZM, 2HBM, 2HDM, 2HLM, 2KHM, 2KJM, 2KMM, 2LHM, 2MDM, 2MJM, 2MSM, 2SHM, 2TAM, 2TBM, 2TLM, 2TWM, 2WAM, 2WBM, 2WCM, 2YAM, 2YCM

CONDITION (Figure 1):

Some vehicles equipped with a 1992 HYDRA-MATIC 4L60 transmission built between Julian Date 061 (March 1, 1992) and Julian Date 171 (June 19, 1992) may experience a harsh 1-2 upshift. NOTE: Once the transmission is brought to operating temperature, the condition may not be able to be reproduced until a "cold soak" (overnight) is performed.

CAUSE:

The above condition may be caused due to a tapered 1-2 accumulator sleeve. The tapered bore may cause the 1-2 accumulator valve to stick in the bottom of the bore.

CORRECTION (Figure 2):

To improve the 1-2 shift, install the service package listed in this bulletin. A 1-2 accumulator valve and 1-2 accumulator valve sleeve (which, normally, is not serviceable) is included in the package.

SERVICE PARTS INFORMATION: Package Number Transmission Models 8687992 2AAM, 2ACM, 2BAM, 2BBM, 2BCM, 2BHM, 2BRM, 2BWM, 2CAM, 2CBM, 2CCM, 2CFM, 2CHM, 2CJM, 2FTM, 2FUM, 2HBM, 2HLM, 2KHM, 2KJM, 2KMM, 2LHM, 2MJM, 2SHM, 2TLM, 2TWM, 2WAM, 2WBM, 2WCM

8688900 2ADM, 2AKM, 2CPM, 2FZM, 2HDM, 2MDM, 2MSM, 2TAM, 2TBM, 2YAM, 2YCM

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

Labor Operation Number T7601 (Valve Body, R&R).

Labor Time: C/K, G, L/M, S/T Trucks 1.8 hrs.

Labor Time: Caprice 1.7 hrs. Camaro 1.4 hrs. Corvette 1.3 hrs. Corvette with folding top add 0.6 hrs.

SERVICE MANUAL REFERENCE:

Refer to the HYDRA-MATIC 4L60 Unit Repair Section of the appropriate service manual for repair 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.