4L80E Master Rebuild Kit with Frictions, Steels and Filter

A master rebuild kit for the GM 4L80E and 4L85E, 1997 and later, the heavy-duty four-speed behind 3/4-ton and 1-ton Silverado, Sierra, Suburban, Express and Savana trucks and vans. The kit covers the full seal side of an overhaul (gaskets, O-rings, lip seals and sealing rings) and adds a friction and steel plate module plus a replacement filter, listed against GM filter number 8675545.

This is the kit for a 4L80E that has been worked hard: towing, plowing or high mileage, with slipping on the 2-3 or 3-4 shift, delayed engagement, or burnt, dark fluid with friction material in the pan. When the packs have burned, the steels are usually heat-marked as well, so replacing frictions and steels together keeps each pack matched and gives you a clean baseline for clearance.

On the bench: tear the unit down and inspect the hard parts the kit does not replace, including the pump, drums, planetaries, the center support and the case bushings. Soak the new frictions in ATF before assembly, install the seals and sealing rings with assembly lube, and check clearance on each clutch pack as you stack it. Install the new filter and pan gasket last.

After the rebuild, flush the cooler and lines before you fill, and run the adaptive relearn with a scan tool. Confirm your unit is a 1997-or-later 4L80E before ordering; earlier units differ in several seals.