Caprice Wagon RWD V8-305 5.0L (1991)
Accumulator: All Technical Service Bulletins
A/T - 4L60 Harsh 1-2 Upshift
Number:
91-125-7A
Section:
7A
Date:
November 1990
Corporate Bulletin No.: 077147
Subject:
HARSH 1-2 UPSHIFT
Model and Year:
1991 CAPRICE WITH 5.0L ENGINE
AND 4L60 TRANSMISSION
TO:
ALL CHEVROLET DEALERS
BULLETIN COVERS:
Some 1991 Chevrolet Caprice vehicles equipped with HYDRA-MATIC 4L60 transmissions and 5.0 liter engines may have a harsh 1-2 upshift. A
calibration change has been made to soften the 1-2 shift.
SERVICE INFORMATION:
To soften the 1-2 shift, install the service package listed in this bulletin. A 1-2 accumulator valve spring (which is not normally serviceable) is included
in the package for those technicians who are familiar with control valve disassembly and reassembly. If you do not wish to service the control valve
assembly, you may order a complete replacement control valve assembly from the GMSPO catalog.
DATE OF PRODUCTION CHANGE:
Beginning May 7, 1990 (Julian Date 127) all 1BBM models were built using the revised calibration.
SERVICE PARTS INFORMATION:
Description
Part #
SERVICE PACKAGE - HARSH 1-2
8673944
(reverse boost valve and sleeve,
1-2 accumulator valve spring,
1-2 accumulator piston spring,
spacer plate)
Parts are currently available from GMSPO.
SERVICE MANUAL REFERENCE:
Refer to the HYDRA-MATIC 4L60 Unit Repair Section of the appropriate Service Manual for repair information.
