A/T - Slipping Or No Third Gear After Overhaul

TSB: 86-58 (Nov).

SUBJECT Servo Release Seal

PROBLEM:
No third gear, or slipping third gear, after overhaul

TRANSMISSIONS AFFECTED:
Many domestic automatics that release an intermediate (second gear) band and apply a clutch for third gear.

EXAMPLES: THM 200, 200C, 2004R, C-4, C-6, FMX, 325, 325-4L

POSSIBLE CAUSE:
Leaking servo release seal. It may be broken, cut or worn.




When any of the transmissions listed above, and many others, shift from second gear into third gear, the band is released hydraulically, using third gear clutch oil. The second gear apply oil is not drained off. It remains on the apply side of the servo piston. In most instances, the servo release area is somewhat larger than the apply area. The space between apply and release is vented into the sump. Release oil leaking past the seal is exhausted into the sump.

CURE: Replace the servo release seal.