A/T - Slipping or Loss of Drive Range
Number 86-7-47 Date 1/87Subject: SLIPPING AND/OR LOSS OF DRIVE RANGE
1982-86 MODELS EQUIPPED WITH THM 700-R4 TRANSMISSION
Figure 1 - TRANSMISSION I.D. NAMEPLATE:
Slipping or loss of drive range condition on a 1982-86 THM 700-R4 transmission may be caused by latching 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 1)
July 17, 1986, Julian date 198, a new sprag, race, and hub assembly was introduced for all 1987 THM 700-R4 transmission models. This change is also in 1987 Service Replacement Transmission Assembly (SRTA) models effective July 17, 1986, Julian date 198..
Figure 2 - Forward 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 (refer to Figure 2).
Service Parts Information
8663773 Sprag, Race, and Hub Assembly 5.0L Firebird Models
8663774 Sprag, Race, and Hub Assembly All other models
Service Manual Reference
Refer to transmission internal parts, Figure 58, 1987 THM 700-R4 unit repair section.