A/T - THM 200/200C Erratic Shift Patterns
87chevy10GMC NUMBER: 87-T-55
GROUP: 7A - Automatic Transmission
DATE: May, 1987
CORPORATE
NUMBER: 777107R
SUBJECT: ERRATIC SHIFT PATTERNS DAMAGED/ROLLED GOVERNOR SEALS
MODELS: 1976-1980 LIGHT DUTY MODELS WITH THM 200 AND 1978-1987 LIGHT DUTY MODELS WITH THM 200C AUTOMATIC TRANSMISSIONS
Some 1976 through 1987 vehicles equipped with transmissions as described above may have erratic shift patterns (such as late or no upshifts) due to an O-ring seal on the governor cover assembly causing incorrect governor pressure.
NOTICE: The erratic shift pattern may be more noticeable after the transmission reaches normal operating temperature.
FIGURE 1 - GOVERNOR COVER ASSEMBLY:
SERVICE ACTION: (Refer To Figure No. 1)
Remove the governor cover (on vehicle service) and inspect the internal governor cover seal (37). If damaged or rolled, replace the entire governor assembly (36). The seal is not available separately.
IMPORTANT: Internal governor cover seals must be well lubricated with petroleum jelly to prevent damage during installation.
SERVICE PARTS INFORMATION:
P/N 8628933, governor assembly (200 and 200C)
- includes seals (35) and (37) as shown in Figure No. 1.
SERVICE MANUAL REFERENCE:
Refer to the appropriate vehicle service manual, Section 200C for proper installation procedures.