DELAYED PARK/NEUTRAL TO DRIVE SHIFT ENGAGEMENT

Models Affected: 1981-89 THM 200-4R, SAFARI WAGON

BULLETIN COVERS:

Service and parts information for a new forward clutch housing and shaft assembly. The new assembly has a larger forward clutch feed orifice in the forward clutch shaft. The new forward clutch housing and shaft assembly may address a delayed drive engagement concern (refer to "Service Action"). There are no changes to the forward clutch die cast piston and clutch pack that were introduced with the neutral to drive (feed-bleed) garage shift package (refer to bulletin 87-7-27.

DATE OF PRODUCTION CHANGE: (Figure 1) --------------------------------------

August 24, 1988, Julian Date 237, the new forward clutch housing assembly was introduced on all 1989 THm 200-4R models.

SERVICE ACTION:

The THM 200-4R "garage shift package" (refer to Figures 2 and 3) softens the Park/Neutral to Drive shift engagement feel by cushioning the apply of the forward clutch piston. The cushioned apply increases shift time, this does not indicate a transmission durability concern.

When diagnosing a delaye drive engagement concern, verify the apply time using a stopwatch and use the following guidelines to decide if service action is necessary:

1.5 - 2.0 second apply time Normal apply time. housing assembly may not provide a decrease in apply time.

2.0 - 3.0 second apply time The new housing assembly may decrease apply time by approximately .5 - 1.0 second.

3.0 or more second apply time Inspect for other causes* of delayed Drive engagement. If no other causes are found, the new housing assembly decrease apply time.

*Conditions which contribute to delayed Drive engagement:

- Improper Fluid Level - Cut Or Overlapping Teflon Seal Rings On Forward Clutch Shaft. - Cracked Or Broken Forward Clutch Piston - Cut Or Rolled Forward Clutch Piston Seals - Porosity In The Center Support

If forward clutch housing replacement is necessary, use the chart under "Service Parts Information" for the appropriate service part number based on model year, build date and transmission model.

SERVICE PARTS INFORMATION:

Part No. Description Year - Models --------- ----------- 8639969 New Forward Clutch 1986 (built after Julian Date Housing Assembly 115) 6AAF, AB, AP, CA, HF, KC, KJ

1987 7HFF, 7KCF, 6KJF, 7HDF

1988 8CTF, 8KTF

1989 ALL

8639969 should be used to service the above models/years built with the "Garage Shift" package. All other models use part number 8639942 until current GMSPO stock is depleted.

8639970 New Neutral to Drive 1981 - 1982 All Models Shift Package - 1983 - All (Except 3OZ Model) 1984 - 4AA, 4AP, 4BQ, 4BY, Contains: New Forward 4HE, 40G, 40J, 40M Clutch Housing Complete, 1985 - 5AA, 5AO, 5AP, 5BQ, Front Internal Gear, and 5HE, 50G, 50J, 50M Thrust Washer. 1986 - 6BRF (or the following models built before Julian Date 115) 6AAF, 6ABF, 6APF, 6CAF, 6HFF, 6KCF, 6KJF 1987 - 7BRF

8639970 must be used when updating the above models/years to a Garage Shift package; should that option be desired. All other models being updated to a Garage Shift package, use part number 8639943 until current GMSPO stock is depleted.

Parts (8639969/8639970) are currently available from GMSPO. Only verifiable emergency VIP orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be cancelled as incorrectly ordered while the 400 control is in place.

Parts (8639942/8639943) are currently available from GMSPO.

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.