A/T - THM200C Erratic Shift Patterns
87chevy06Number: 87-60
Section: 7A
Date: JAN., 1987
Subject: ERRATIC SHIFT PATTERNS, DAMAGED OR ROLLED GOVERNOR SEALS
Model and Year: 1976-80 VEHICLES WITH THM 200 1978-87 VEHICLES WITH THM 200C
Figure 1 - THM 200C Transmission I.D. Nameplate:
TO: ALL CHEVROLET DEALERS
A 1978 through 1987 vehicle equipped with a THM 200 or THM 200C transmission (Refer to Figure 1) 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. NOTE: The erratic shift pattern may be more noticeable after transmission reaches normal operating temperature.
Figure 2 - Governor Cover Assembly:
Remove the cover (on car service) and inspect (Refer to Figure 2) the internal governor cover seal (37). If damaged or rolled, replace the entire governor cover assembly (36). The seal is not available separately.
Important: Internal governor cover seals must be well lubricated with petrolatum (petroleum jelly) to prevent damage or rolling during installation.
Parts Information:
THM 200/200C Governor Cover Assembly (with seals 35 and 37) P/N 8628933
Refer to the Automatic Transmission Unit repair section of the 1987 THM 200C Service Manual for proper installation procedures.