A/T - New Short Lip Piston Seal Design
89chevy23GMC NUMBER: 89-T-81
GROUP: 7A - Automatic Transmlssion
DATE: July, 1989
CORPORATE
NUMBER: 977121
SUBJECT: NEW SHORT LIP PISTON SEAL DESIGN - FORWARD, 3-4, OVERRUN AND REVERSE INPUT CLUTCHES
MODELS: 1989 C/K
Figure 1:
BULLETIN COVERS: (Figure 1)
New clutch piston seal design. The following clutch piston seals have been redesigned to include a shorter lip profile for ease of assembly:
Clutch Piston Clutch Piston
Outer Seal Inner Seal
* 3-4 * 3-4
* Forward Forward
* Overrun Overrun
* Reverse Input Reverse Input
Clutch pistons have not changed.
Figure 2 - THM 700-R4/HYDRA-MATIC 4L60 Transmission Identification Information:
DATE OF PRODUCTION CHANGE: (Figure 2)
Beginning February 28, 1989 (Julian Date 059), all 1989 Hydra-Matic 4L60 transmissions have been built using seals with the new short lip design on pistons designated above with an asterisk. The remaining three seals (Forward, Overrun and Reverse Input inner seals) will change to the short lip design at a future date.
SERVICE PARTS INFORMATION:
Short lip seals are interchangeable with the current seals. The new design will replace the current seal in service packages as stock is depleted. All eight seals are available in the overhaul kit, or they may be obtained in two separate packages:
Part No. Package Contents
8642919 3-4 Clutch Piston Inner and Outer Seals
Forward Clutch Piston Inner and Outer Seals Overrun Clutch Piston Inner and Outer Seals
8657922 Reverse Input Clutch Piston Inner and
Outer Seals
Parts are currently available from GMSPO.