Master overhaul kit for 1997-up GM 4L80E and 4L85E units: gaskets, seals and sealing rings plus friction and steel plates and an 8675545 filter.
Late-model 4L80E and 4L85E transmissions are the four-speeds behind 1997-and-later Silverado and Sierra 2500 and 3500 trucks, Suburban 2500s, and Express and Savana vans, often paired with the 6.0L, 8.1L or a diesel and asked to tow at the limit. When one starts slipping on the 2-3 or 3-4 shift, engages late, or comes out of the pan smelling burnt with friction debris on the magnet, this new master rebuild kit covers the overhaul. It includes the full gasket and seal set (O-rings, lip seals and sealing rings), a friction and steel plate module, and a replacement filter listed against GM filter number 8675545. Shipping weight is 12.1 lb.
From 1997 on, GM sent cooler return oil to the center support to lubricate the middle of the geartrain, and redesigned a group of internal hard parts around that change. The clutch packs still do the same job: forward, direct, intermediate, overdrive and overrun clutches each clamp a set of frictions against steels with line pressure fed through sealing rings. Heat is what kills them. Once a pack burns, the steels usually show heat marks too, which is why this kit replaces frictions and steels together instead of frictions alone. New plates give you a matched stack and a known starting point for setting clearance.
Rule out pressure control and wiring first; a failing pressure control solenoid or a bad harness connection can feel like worn clutches. Our 4L80E Silverado 2500 shift problems guide walks through the order of tests. Transmission Digest also notes the overdrive roller clutch holds in first through third and that its plastic cage can melt when the unit overheats, so if the truck lost fourth or freewheels on decel, plan on inspecting that roller clutch along with the plates. A clear line pressure test with slipping that persists confirms the rebuild.
This kit is listed for GM 4L80E and 4L85E transmissions from 1997 and later. It is not the kit for a 1991-96 unit, which predates the center-lube redesign and uses several different seals. Within the 1997-up range, the internal hard parts changed again: Transmission Digest shows 1999-and-later rear carriers differ from the 1991-98 design, and Sonnax identifies 2004-and-later valve bodies by their late-style pressure control solenoid. Those changes do not affect the soft parts in this kit, but they matter for anything else you replace, so match your transmission ID tag or send us your year and VIN. Browse the rest of the late-model parts on our 4L80E parts page.
Tear down and inspect the pump, drums, planetaries, center support and case bushings, because the kit does not replace hard parts. The center support holds the intermediate sprag; a towing truck is a good candidate for the 34-element intermediate sprag, which replaces the lighter factory sprag. Soak the frictions in ATF, lube the seals and rings with assembly lube, and check clearance pack by pack. If the shifts were already soft before failure, add the 4L80E shift kit while the valve body is out. Install the new filter and pan gasket last, flush the cooler and lines, fill with Dexron VI, and run the adaptive relearn with a scan tool. GM's 2006 Silverado manual puts normal transmission temperature at about 180 to 200 F, so watch the gauge on the first loaded drives.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes. It is listed for both the 4L80E and the 4L85E from 1997 and later.
No. Units built before 1997 use the earlier pump-fed lubrication layout and several different seals. Use one of our 1991-1995 or 1990-96 master kits for an early transmission.
The kit includes a replacement filter listed against GM filter number 8675545, along with the gasket and seal set and the friction and steel plates.
Yes. Run the transmission adaptive relearn after the rebuild so shift pressure is reset for the new clutches instead of the old worn ones.
Bushings, any scored drums, the torque converter, and the overdrive roller clutch if the unit was overheated. A heavy-duty intermediate sprag and a shift kit are common upgrades on towing trucks.
