A/T - Harsh Engagement or Double Bump From P or N to R
88buick18Bulletin 89-7440-1
Date Nov. '88
Ref. No. 89-030-7440
Corp. Ref. No. 717106R
SUBJECT: HARSH ENGAGEMENT OR DOUBLE BUMP FROM PARK OR NEUTRAL TO REVERSE.
MODELS AFFECTED: ALL 1984-89 VEHICLES EQUIPPED WITH THM 440-T4 (ME9) TRANSAXLES
This bulletin supersedes 87-7440-13 (Corp. Ref. 717106R) which should now be discarded. The bulletin has been revised to add 1988-1989 model years, W Car line, and updated part numbers for the reverse band assembly and 84-86 2nd clutch housing drum and bushing assembly.
BULLETIN COVERS
A harsh engagement or double "bump" from park or neutral to reverse in a THM 440-T4 transaxle may be caused by one of the following items: "oxidized" fluid (the fluid may visually appear to be OK), or the reverse band assembly and 2nd clutch housing drum and bushing assembly.
SERVICE ACTION
Check engine idle speed and engine/transaxle mounts. If okay, drain and replace the transaxle fluid then road test vehicle for the above condition. If the condition still exists, replace the reverse band assembly and 2nd clutch housing drum and bushing assembly with the appropriate parts listed below in "Service Parts Information".
FIGURE 1 - THM 440-T4/THM F-7 TRANSAXLE IDENTIFICATION INFORMATION:
SERVICE PARTS INFORMATION (Figure 1)
Model Year Part No Description
1984-1989 8668012 Reverse Band Assembly
1987-1989 8661912 2nd Clutch Housing Drum & Bushing Assy.
1984-1986 8662936 2nd Clutch Housing Drum & Bushing Assy.
Parts are currently available from GMSPO.
SERVICE MANUAL REFERENCE
Refer to the THM 440-T4 Automatic Transaxle Unit Repair section in the appropriate model year service manual for repair procedures.