SLIP OR LOSS OF DRIVE NEW SPRAG RACE AND HUB ASSY.

MODELS: 1982-86 LIGHT DUTY MODELS WITH THM 700-R4 AUTOMATIC TRANSMISSIONS (MD8)

THIS BULLETIN CANCELS AND SUPERCEDES TRUCK SERVICE BULLETIN 86-B-100 DATED JULY,1986, ALL COPIES OF WHICH SHOULD BE DESTROYED.

A slipping or loss of drive range condition on a 1982 through 1986 THM 700-R4 transmission may be caused by slipping of the forward clutch sprag assembly. This condition can result in belling or flaring of the reverse input housing and reaction sun shell. A new sprag, race, and hub assembly is used in production and is available for service.

DATE OF CHANGE (Figure No. 1) -------------- July 17, 1986, Julian date 198, a new sprag, race, and hub assembly was incorporated into all (including SRTA) 1987 THM 700-R4 transmission models.

SERVICE ACTION

When using the new sprag, race, and hub assembly, the sprag assembly wear plate (640) and the input carrier to race thrust washer (66M must be removed and not replaced on units built before July 17, 1986 (Figure No. 2).

SERVICE PARTS INFORMATION

PAN 8663774 - sprag, race, and hub assembly.

SERVICE MANUAL REFERENCE:

Refer to the 1986 Unit Repair Manual (X-8637) section 700-R4, Figure No. 58, for transmission internal parts.

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.