A/T - Slipping/Loss of Drive Range
GMC NUMBER: 86-T-140 7A - AutomaticSECTION: Transmission
DATE: March, 1987
SUBJECT: SLIPPING AND/OR LOSS OF DRIVE RANGE
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.
Figure No. 1 - TRANSMISSION IDENTIFICATION:
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.
Figure No. 2Forward Clutch Sprag Assembly:
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 (660) must be removed and not replaced on units built before July 17, 1986 (Figure No. 2).
SERVICE PARTS INFORMATION
P/N 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.
Figure No. 2Forward Clutch Sprag Assembly:
Figure No. 2
Forward Clutch Sprag Assembly