A/T - Premature Wear of Direct Clutch

90chevy26
GMC NUMBER: 90-7A-105

GROUP: 7A Automatic Transmission
DATE: October, 1990

CORPORATE
NUMBER: 077134

SUBJECT: DIRECT CLUTCH DISTRESS

MODELS: 1985-90 C/K, R/V, P TRUCKS AND G-VAN WITH 3L80 AND 3L80-HD AUTOMATIC TRANSMISSIONS

BULLETIN COVERS Some HYDRA-MATIC 3L80/3L80-HD models experienced Direct Clutch distress. This distress was caused by an oil leak in the clutch apply circuit at the Center Support joint between the Case and the Center Support. A new Center Support (654), Case Assembly (10), Piston (650) and Bolt (79) eliminated this root cause for Direct Clutch distress.

Figure 1:

DATE OF PRODUCTION CHANGE (See Figure 1) Beginning March 1, 1990 (Julian Date 060) all 1990 HYDRA-MATIC 3L80/3L80-HD transmissions were built with the new Center Support (654), Case Assembly (10), Intermediate Piston (650) and Bolt (79).

Figure 2:

SERVICE PROCEDURE (See Figure 2)

Important

Use new bolt (79) only with new support (654) and new piston (650). Use new piston (650) only with new support (654). Use new support assembly (654) in previous case (10) only with previous bolt (79). Use new case (10) only with new support (654), new piston (650) and new bolt (79). Do not reuse old Center Support (654).
Torque bolt (79) to 32 lbs. ft. (43 N-m) and assure the bolt head (79) is seated to the bottom of the case (10).

Important

DO NOT USE NEW BOLT (79) WITH PREVIOUS CASE (10).

Figure 3 - 1990 3L80 Model Year Case View:

SERVICE PARTS INFORMATION (See Figure 3)
Parts are currently available through GMSPO.

SERVICE MANUAL REFERENCE Refer to the Unit Repair section of the appropriate Service Manual for the proper Pump Bushing and Seal replacement procedures.