DIRECT CLUTCH DISTRESS CAUSE & CORRECTION OUTLINED

TRANSMISSION APPLICATIONS: SUBJECT: 3L80/3L80-HD DIRECT CLUTCH DISTRESS

TRANSMISSION MODELS: VEHICLE APPLICATIONS: 1985-90 C,K,P,R,V TRUCKS G-VAN W/3L80/3L80-HD

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 Centre Support joint between the Case and the Centre Support. A new Centre support (654), Case Assembly (10), Piston (650) and Bolt (79) eliminated this root cause for Direct Clutch distress.

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

SERVICE PROCEDURE: (Refer to 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 no reuse old Centre Support (654).

Torque bolt (79) to 43 N.m (32 ft.lbs.) 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).

SERVICE PARTS INFORMATION: Refer to Figure 3 New Service Description Package Models -------------------------------- ------- --------- Pkg - Case Assembly (Light Truck) 8629990 see Fig. 3 Pkg - Case Assembly (Heavy Truck) 8629991 see Fig. 3 Pkg - Support, Race, Plug, Piston & Bolts 8629994 All

Parts are currently available from CANSPO.

SERVICE MANUAL REFERENCE:

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

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.