A/T - Harsh 1-2 Shift
87buick12Bulletin: 87-7440-14
Date: Nov.: '87
Ref. No.: 87-192-7440
Corp. Ref. No.: 777147
SUBJECT: HARSH 1-2 SHIFT
MODELS AFFECTED: 1984-87 CENTURYS, LESABRES, ELECTRAS AND RIVIERAS EQUIPPED WITH THM 440-T4 (ME9) TRANSAXLES
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.
FIGURE 1 - BOTTOM PAN, FILTER, ACCUMULATOR AND GOVERNOR COVER ASSEMBLY:
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) Governor Pipe Retainer (129) Accumulator Cover Spacer Plate (120) Gaskets (119)
FIGURE 2 - CASE PASSAGES - BOTTOM VIEW:
FIGURE 3 - CASE PASSAGES - CHANNEL PLATE SIDE:
Inspect the 2nd clutch passage by measuring the hole depth which should be a minimum of 72 mm (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 8.5 mm (21/64") drill bit at 72 mm (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 (MEO) Automatic Transaxle Unit Repair Section in the appropriate Service Manual.
Harsh 1-2 Shift