A/T - Slipping/No Reverse/No Manual 2-1 Gear Downshift

87chevy29
GMC NUMBER: 88-T-54

GROUP: 7A - Automatic Transmission

DATE: November, 1987

CORPORATE
NUMBER: 867108

SUBJECT: SLIPPING OR NO REVERSE/NO MANUAL 2-1 DOWNSHIFT-AFTER TRANSMISSION SERVICE-INFORMATION ON SERVICE PACKAGES WITH INCORRECT VALVE BODY AND CASE GASKETS

MODELS: 1987 LIGHT DUTY MODELS AND 1988 C/K MODELS EQUIPPED WITH THM 700-R4 AUTOMATIC TRANSMISSIONS

BULLETIN COVERS:

A slipping or no reverse or a no manual 2-1 downshift condition which occurs after transmission service. Information regarding service package part number 8657906 (spacer plate gaskets) which may contain incorrect valve body and case gaskets.

SERVICE ACTION:

Service Package Number 8657906, containing both the valve body and case gaskets, may contain a prior design gasket that could cause the following operating concerns if installed onto any 1987 THM 700-R4 transmission:

1. Slipping or no reverse - If installed into a 1987 THM 700-R4 transmission without an Auxiliary Valve Body.

FIGURE 1 - 1987 THM 700-R4 CASE AND VALVE BODY GASKETS:

2. No manual 2-1 downshift - If installed into a 1987 THM 700-R4 transmission with an Auxiliary Valve Body.

If Service Package Number 8657906 (spacer plate gaskets) is used for any 1987 THM 700-R4 transmission, first verify that it has the correct valve body and case gaskets (refer to Figure No. 1). If the holes identified as 1, 2 and 3 are not visible or are not in the correct location, do not use and return the package to GMSPO. Use Service Package Number 8657938 as listed under Service Parts Information.

SERVICE PARTS INFORMATION:

8657938 Package - Spacer Plate Gaskets