1982 - 1991 Corvette: Service Bulletin: Transmission Stuck in First Gear

Subject: TRANSMISSION STUCK IN FIRST GEAR
Model and Year:
1982-91 CAPRICE, CAMARO AND CORVETTE
1982-91 C/K, G, S/T’
1985-91 M VAN
1987-91 RN AND 1990-91 L VAN WITH 4L60 AUTOMATIC TRANSMISSION
Source: Chevrolet Service Bulletin
Bulletin Number: 91-371-7A - (06/28/1991)

Bulletin Covers:

Some HYDRA-MATIC 4L60/700-R4 transmissions may experience a "no upshift" or "stuck in first gear" condition. This may be caused by the input carrier to output shaft retaining ring coming unseated, or retaining ring omitted during assembly. This can allow the output shaft to move slightly, and cause wear on the governor gear (the governor gear ON THE GOVERNOR, not the governor drive gear on the output shaft). The governor gear wear may be described as an "apple cored" condition. If the governor gear is worn, the transmission cannot upshift out of first gear.

Service Information:

Remove the governor and inspect the governor gear. If it is "apple cored", disassemble the transmission and look for the presence of the input carrier to output shaft retaining ring.

o If the retaining ring is missing, replace it, but make sure the original retaining ring is not broken and stuck inside the transmission.

o If the retaining ring has become unseated, replace the retaining ring with a new one since the original has probably been over-expanded.

When installing a new retaining ring, be careful not to over-expand the retaining ring.

Service Parts Information:

The input carrier to output shaft retaining ring is available in several packages through GMSPO. It is included in the snap ring package, overhaul repair components package, and overhaul seals and gasket package.

Service Manual References:

Reference the Automatic Transmission Unit Repair Section of the appropriate service manual for retaining ring 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.