NEW SHORT LIP PISTON SEAL DESIGN- W/700R4

Model and Year: 1989 MODELS WITH 700-R4/4L60 TRANSMISSION

TO: ALL CHEVROLET DEALERS

This bulletin covers new clutch piston seal design (Figure 1). The following clutch piston seals have been redesigned to include a shorter lip profile for ease of assembly:

Clutch Piston Outer Seal Clutch Piston Inner Seal ------------------------ ------------------------ * 3-4 * 3-4 * Forward Forward * Overrun Overrun * Reverse Input Reverse Input

Clutch pistons have not changed.

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.

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.