DELAYED 2/3 SHIFT/LOSS OF 3RD THM 440-T4 3RD CLUTCH SEAL

MODELS/YEARS: 1984 THROUGH EARLY 1987 MODELS WITH 440-T4 TRANSAXLE

This bulletin contains updated Julian Date breakpoints and supersedes 86-T-63A which should be discarded.

Along and/or delayed 2-3 shift on a THM 440-T4 transaxle may be caused by a leaking 3rd clutch inner seal (Figure 1, Item 635A). A new, thicker seal is used in production and available for service replacement. The new seal can be recognized by a small group of hash marks on the inside diameter of the seal.

Date of Production Change:

Between September 1, 1986 (Julian Date 244) and February 12, 1987 (Julian Date 043), a new 3rd clutch inner seal was phased into production. This change is also on all service replacement transmission assembly (SRTA) models effective November 15, 1986 (Julian Date 319). See Figure 2.

Service Action if this condition is encountered:

o Remove transaxle, disassemble, inspect, and replace with parts in the following service package:

Package Number Description -------------- ----------- 8646991 -Housing and shaft assembly, input -Seal, 3rd clutch inner -3rd roller clutch assembly

o To service 1987 models with the new seal design, use seal kit only (input and 3rd clutch, part number 8644919) which contains the new thicker seal.

o The new thicker seal in the kit, part number 8644919, may also be used to service models built prior to the above Julian Dates provided a long or delayed 2-3 shift condition has not occurred and the third clutch inner seal is not found to be damaged upon unit disassembly.

Service Manual Reference:

Refer to the THM 440-T4 (ME9) automatic transaxle section of contents for 3rd clutch service information.

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.