HARSH 1-2 SHIFT CONDITION CHECK 2ND CLUTCH FEED

1984-87 6000 AND 1987 BONNEVILLE MODELS EQUIPPED WITH THM 440-T4 (ME9)

BULLETIN COVERS:

A harsh 1-2 shift condition on a THM 440-T4 transaxle may be caused by a blocked or partially drilled 2nd clutch feed passage in the case. This condition may be repaired by following the Service Action information in this bulletin.

SERVICE ACTION:

Before removing the transaxle from the vehicle, inspect the 2nd clutch feed passage for blockage or a partially drilled condition. To perform this inspection, remove the following items (refer to Figure 1): transaxle bottom pan (59), filter (58), accumulator cover (121) with governor pipes (124, 125) and governor pipe retainer (129), accumulator cover spacer plate (120) and gaskets (119).

Inspect the 2nd clutch passage by measuring the hole depth which should be a minimum of 72mm (2.835"), as shown in Figures 2 and 3. If the 2nd clutch passage is properly drilled, refer to the THM 440-T4 Diagnosis Section in your service manual for other possible causes of a harsh 1-2 shift condition.

If the 2nd clutch passage is not fully drilled:

1. Remove the transaxle and disassemble components up to and including the channel plate (24).

2. Mark an 8.5mm (21/64") drill bit at 72mm (2.835") from the tip using tape or other acceptable method. From the bottom pan side of the case, finish drilling the 2nd clutch passage to the depth as marked on the drill bit.

NOTICE: AVOID DRILLING TOO DEEP INTO THE 2ND CLUTCH PASSAGE BECAUSE IT WILL DAMAGE THE CASE.

3. Remove metal chips caused by drilling and thoroughly flush the repaired case passages with clean solvent.

4. Reassemble the transaxle.

SERVICE MANUAL REFERENCE:

Refer to the THM 440-T4 (ME9) Automatic Transaxle Unit Repair section in the appropriate 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.