For 1990-2009 cars

# PINION WASHER WEAR DISASSEMBLY INSPECTION

When disassembling any THM 700-R4 transmission, it is important to inspect the input and reaction carriers for possible pinion washer wear.

When the bottom pan is removed, inspect the bottom pan and oil for brass particles. Signs of pinion washer wear will be noticeable in the oil pan. Small collections of brass particles near the front of the oil pan may indicate worn input carrier pinion washers. Small collections of brass particles near the rear of the oil pan may indicate worn reaction carrier pinion washers.

If these brass particles are found or if the transmission is being disassembled for any reason, inspect the carriers as follows:

1. Visually inspect the roller thrust bearing inside the carrier for wear or damage.

2. Visually inspect the pinions for damage or wear.

3. Check the end play of each pinion as shown in illustration.

If necessary replace the carriers with the following part numbers:

Input Carrier Assembly, Part Number 8647458*

Reaction Carrier Assembly, Part Number 8647052

*Some early 1982 THM 700-R4 transmissions were built with a forward roller clutch. Replacing only the input carrier in these models will result in interference between the carrier and sun gear. On these models you must use service package number 8642947. This package will convert the transmission from the forward roller clutch to the forward sprag clutch. Also, this package contains an instruction sheet on how to make these changes.

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.