4L80E/4L85E Master Rebuild Kit with Raybestos Frictions

This is the parts side of a full 4L80E or 4L85E teardown. It covers 1997 through 2011 applications, which is the wide-ratio heavy-duty GM four-speed behind big-block trucks, 2500/3500 Silverado and Sierra, Suburban, Express vans, H1s and swapped LSX builds. You get the overhaul kit (gaskets, seals, O-rings, lip seals, Teflon sealing rings, check balls and the small parts that always go missing), a Raybestos friction module, a matching steel module, a new-design smooth-lined rear band (part 38014BW), and the filter.

The 4L80E fails in predictable places. Direct and forward clutch frictions cook when the converter clutch hangs on, the intermediate sprag lets go, and the rear band glazes so you get a flare on the 1-2 shift. This kit replaces all of that wear material in one box, plus every soft part in the case, so you are not chasing a leaking pump seal or a hard 3-4 accumulator O-ring after the unit is back under the truck.

Order of work on the bench: strip the unit, air-check the drums, measure clutch clearance with the new Raybestos frictions and the supplied steels before you commit, then set your snap ring selection from that stack height. The rear band goes in with the anchor pin seated and the servo pin checked for length. Soak the frictions in clean ATF for at least a half hour before assembly. Fresh Teflon sealing rings on the turbine and stator shafts want a resizer before the pump goes on.

Note this is a rebuild kit, not a complete unit. It does not include a torque converter, pump, hard parts, sprag, or bushings. If your intermediate sprag or 4th-clutch hub is damaged, order those separately.