II.Distressed Two Plate 4TH Clutch Assembly Service

Figure 2 - Single And Two Plate 4TH Clutch Assemblies:

INFORMATION FOR THM 440-T4 AND 3800 ENGINE TRANSAXLE MODELS

BULLETIN SECTION COVERS: (Refer To Figure 2)

Service information for a distressed two plate 4th clutch assembly. Some 1990 transaxle models for the 1990 Bonneville models equipped with a HYDRA-MATIC 4T60 (*THM 440-T4) and 3800 engine may have a new style 4th clutch plate assembly. If service is required for a distressed 4th clutch assembly, follow the procedure listed under "Service Procedure".

The following models were scheduled to be produced with a two plate 4th clutch assembly for the start of production of the 1990 model year: OBAH, OBDH, OBFH, OBHH, OBJH, OBPH, OBWH and OPAH. These models will now have the previous single plate 4th clutch assembly.

IMPORTANT: Do not update a single plate 4th clutch assembly transaxle model to the two plate style; the 4th clutch apply feel will be affected.

The 1990 Service Manual should be updated to show that some models are produced with the two plate 4th clutch assembly.

DATE OF PRODUCTION CHANGE:

Models OBAH, OBDH, OBFH, OBHH, OBJH, OBPH and OBWH built after July 31, 1989 (Julian Date 212) will have the single plate 4th clutch assembly instead of the two plate 4th clutch assembly.

SERVICE PROCEDURE:

If service is required for a distressed two plate 4th clutch assembly, install the service package listed under "Service Parts Information" that will contain the previous single plate 4th clutch assembly, 4th clutch apply plate and calibration conversion components.

IMPORTANT: The valve body assemblies for the two plate 4th clutch will not be available for the following models: OBAH, OBDH, OBFH, OBHH, OBJH, OBPH and OBWH. If a valve body assembly is required, order the valve body assembly from the GMSPO catalog (single plate calibration) and also order the single plate 4th clutch package listed under "SERVICE PARTS INFORMATION". Install all parts from the package.

POSSIBLE MISBUILDS IF PARTS ARE MIXED:

1. If a technician converted a single plate to a two plate 4th clutch assembly without changing the valve body assembly, this would create a harsh 4th clutch apply.

2. If a technician converted a two plate to a single plate 4th clutch assembly without installing the calibration conversion components (1-2 accumulator bushing/valve) from the single plate 4th clutch package, this would create a very soft 4th clutch apply feel.

SERVICE PARTS INFORMATION:

Part Number Description Year Model Usage

8668980 Package - Single Plate 4th Clutch 1990 OBAH OBDH OBFH
- Plate Assembly, 4th Clutch
- Plate, 4th Clutch Apply
- Plate, 4th Cl. Reaction (two in pkg.)
- Bushing/Valve 1-2 Accumulator
- Instruction Sheet

8668981 Package - Single Plate 4th Clutch 1990 OBHH OBPH OBWH
- Plate Assembly, 4th Clutch OBJH
- Plate, 4th Clutch Apply
- Plate, 4th Cl. Reaction (two in pkg.)
- Bushing/Valve 1-2 Accumulator
- Instruction Sheet

Parts are expected to be available for part numbers 8668980 and 8668981 on 01-02-90. Until then, normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be canceled as incorrectly ordered while the 400 control is in place.

SERVICE NOTES:

The transaxle model OPAH was not built with a two plate 4th clutch assembly, so there is no single plate 4th clutch conversion service package.
SERVICE MANUAL REFERENCE:

Refer to the appropriate 1990 Service Information Manual for service procedures.