NEW DESIGN FORWARD CLUTCH SMOOTHER PK./NEUT. TO DRIVE. Buick Electra/Park Avenue 1981

For 1990-2009 cars

# NEW DESIGN FORWARD CLUTCH SMOOTHER PK./NEUT. TO DRIVE

#### MODELS AFFECTED: ALL 1981-1987 THM 200-4R (NW9) EQUIPPED VEHICLES (EXCEPT FOR 1986-87 BRF, 1984-85 BQ, AND 1983 BR MODELS)

#### BULLETIN COVERS

A 1981 through 1987 vehicle equipped with a THM 200-4R transmission may have a harsh PARK/NEUTRAL to DRIVE engagement feel. A new design "feed/bleed" system for the forward clutch gives more cushioning during forward clutch apply. This system can be used in most THM 200-4R applications to reduce a harsh DRIVE engagement feel.

DATE OF PRODUCTION CHANGE: (Figures 1 and 2) ------------------------- April 25, 1986 (Julian date 115), these changes were introduced for all THM 200-4R models (except model BRF):

Forward Clutch Assernbly, minus check ball in housing (618) Forward Clutch Piston Asseinbly (622) Additional waved plate (666) Front internal gear (633)

#### SERVICE ACTION

If a vehicle equipped with a THM 200-4R transmission, built prior to April 25, 1986 (Julian date 115), has a harsh Park/Neutral to Drive engagement, install the Service Package listed in Service Parts Information.

#### Models built after April 25, 1986 (Julian date 115), can be serviced with separate parts.

#### NOTICE: This system CANNOT be used on 1986-1987 BRF, 1984-1985 BQ, and 1983 BR models.

#### IMPORTANT: When servicing the forward clutch, select the correct backing plate (627). Backing plate selection affects piston travel, shift feel and clutch durability.

Backing plate selection: (Clutch fully assembled) Apply an evenly distributed load in the direction indicated in Figure 3 to remove slack from the clutch assembly. Use 20 lbs. (9 kg) of pressure against the backing plate--excessive pressure will cause an inaccurate measurement. With the clutch assembly compressed, use a feeler gage to measure the distance between the backing plate and snap ring. Correct backing plate travel is 0.7mm-1.5mm (0.028"-0.059"). Refer to Figure 4 for backing plate identification information.

#### SERVICE PARTS INFORMATION

PART NUMBER DESCRIPTION ----------- ------------ 8639943 Neutral Drive Shift Package (Contains Forward Clutch Assembly, Complete; Front Internal Gear and Thrust Washer)

Parts available separately: 8657257 Forward Clutch Assembly, Complete 8639947 Front Internal Gear and Thrust Washer (Can be used on ALL model years.)

#### SERVICE NOTES

Earlier design front INTERNAL GEARS (Service Package Number 8630909) CANNOT be used with THM 200-4R models built after April 25, 1986 (Julian date 115).

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.