Conditions of a burned forward and/or direct clutch may be caused by a loose center support bolt. A new center support bolt has gone into production to help increase torque retention.
Beginning December 14, 1987 (Julian Date 348) all THM 400/475 transmissions were built with the new bolt.
When ordering an updated support package from GMSPO the new bolt will be included. The bolt must be installed whenever replacement of the center support is required.
If the bolt is not in the center support package, then purchase the new bolt separately. Refer to Service Parts Information.
Part No. Part Description -------- ---------------- *8629916 THM 400/475 Package-Center Support and Race Assembly *8625990 THM 400 Package-Center Support and Race Assembly 8670757 Bolt-Case to Center Support
*Refer to the service parts list for correct model applications.
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.