NEW PARKING BRAKE MECHANISM (BRAKE DRUM AT REAR OF TRANS.)

TRANSMISSION APPLICATIONS: SUBJECT: 1989 THM 475/HYDRA-MATIC NEW 'P' CHASSIS MOTOR HOME MODEL 3L80-HD WITH 14.5K - 16.5K GVM

TRANSMISSION MODELS: VEHICLE APPLICATIONS: 9HJA 1989 'P' TRUCKS

Bulletin Covers:

A new 1989 HJA model for 7.4L carb, (P Truck) motor home chassis, 14.5 - 16.5k GVWR (Gross Vehicle Weight Rating), was released. The information contained in this bulletin lists the parts that are new, and deleted, along with correct assembly, disassembly procedures that are not contained in the Unit Repair Section. The deleted parking mechanism parts are replaced by a brake drum which is located at the rear end of the transmission.

DATE OF PRODUCTION CHANGE: (Figure 1) ------------------------------------- November 1, 1988 (Julian Date 305) production began building the 475/3L80-HD HJA model.

NEW PART:

New Converter Assembly - 8650904 (Brazed Converter Pump)

DELETED PARTS: (Figure 2) -------------------------- Pawl - Parking Lock - 8633060 Shaft - Parking Lock Pawl - 8624976 Retainer - Parking Pawl Shaft - 148148 Spring - Parking Pawl Return - 8623041 Bracket - Parking Lock - 8624112 Bolt - Hex HD (5/16-18 X .62) - 179814 or 179816 Actuator Asm - Parking Lock - 8624091

SERVICE ACTION:

When servicing 1989 THM 475/HYDRA-MATIC 3L80-HD HJA model, it is important to follow the procedures in this bulletin during disassembly and assembly of the Detent Lever and Manual Shaft.

Transmission Disassembly:

Detent Lever and Manual Shaft

Remove or Disconnect (Figure 2)

1. Nut (703) and Pin (704).

2. Detent Lever (707).

3. Plug (709).

4. Shaft (705) and Seal (706).

Transmission Assembly:

Detent Lever and Manual Shaft

Inspect

Detent Lever (707) for: - Damage or cracks Manual shaft for damage

Install or connect (Figure 2)

1. Plug (709).

2. Detent Lever (707).

3. Manual Shaft (705) and Seal (706).

4. Nut (703) on Shaft (705).

4. Pin (704).

SERVICE MANUAL REFERENCE:

Please record this information in any 1989 THM 400/475 Unit Repair Section of the Service Manual.

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.