HARSH NEUT TO DRIVE NEUT TO REV SHIFT ENGAGEMENT

MODELS: 1987 LIGHT DUTY MODELS WITH THM 400 AUTOMATIC TRANSMISSIONS AND 1988 C/K MODELS WITH THM 400 AUTOMATIC TRANSMISSIONS

TRANSMISSION MODELS:

FDA, FFA, FJA, FMA FNA, FPA, FQA FTA, FUA, FWA, FYA, FZA, LAA, LBA LCA, LDA, LFA, LHA, LJA, LKA, LMA LRA, LSA, LTA, LUA, LWA, LZA

BULLETIN COVERS:

Certain 1987 and 1988 light duty models with THM 400 transmissions (refer to list above) have new forward and direct clutch assemblies with a "dished" steel clutch plate. This new design clutch plate improves forward and reverse engagement shift feel by cushioning piston apply.

DATE OF CHANGE: (Figure No. 1) -------------- July 22, 1986 (Julian Date 203) for listed 1987 THM 400 transmission models.

SERVICE ACTION: (Figures No. 2 and No. 3) --------------- When servicing the forward and/or direct clutch, inspect the "dished" clutch plate (#612, Figure No. 2 and #624, Figure No. 3) for scoring, cracks, or flatness.

Also, when servicing the direct clutch assembly, note position of the two 2.32mm (.0915"), and three 1.97mm (.7775"), flat steel plates (Figure No. 3, Item 622). To properly assemble the direct clutch pack, follow the dished steel plate with: a .0915" steel plate, fiber plate, the second .0915" steel plate, and complete by alternating fiber and .0775" steel plates.

SERVICE PARTS INFORMATION:

Part Number Description ----------- ----------- 8625196 .054" Dished Clutch Plate

8623849 .0775" Flat Clutch Plate

8625197 .0915" Flat Clutch Plate

SERVICE NOTE:

The new forward and direct clutch assemblies cannot be used for past model service as other 1987-88 calibration changes contribute to the improved engagement shift feel.

SERVICE MANUAL REFERENCE:

Refer to the Forward and Direct Clutch Assembly sections of the 1987 THM 400 Unit Repair 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.