Master overhaul kit for the GM 6L80E with bonded clutch pistons, frictions, full seal set and pan filter for 2006-2017 trucks, SUVs and cars.
If your 6L80E is already on the bench, or you have a 2006-2017 Silverado, Sierra, Suburban, Escalade, Camaro or Corvette that slips, flares or loses gears even after the solenoid side checks good, the clutch pistons are part of the answer. This master kit, manufacturer part number CXT-GN03820, goes further than a standard soft-parts kit by including bonded clutch pistons along with the frictions for the 1-2-3-4, 3-5-Reverse, 4-5-6 and Low/Reverse packs, the pan and valve body gaskets, the full O-ring and sealing ring set, front and rear seals and the pan filter. It also fits the heavier 6L90E. The kit ships in one box at 17.26 lb.
Each 6L80 clutch is applied by a piston that oil pressure pushes against the plate stack. On a bonded piston the rubber sealing lip is molded directly to the piston rather than fitted as a loose seal, so there is no separate lip seal to roll or pinch during assembly. The catch is that the lip ages with the piston. After years of heat cycling it hardens or separates, and the clutch loses apply pressure no matter how good the frictions are. That is why a rebuild that only changes plates can come back slipping. Replacing the pistons while the drums are already apart removes that weak point for the cost of a few extra minutes per pack.
Check line pressure against the scan tool command first, so you know the pump and controls are making pressure and the problem is inside the packs. With the unit apart, air-check each drum before and after assembly; a piston that leaks down or a pack that will not stroke tells you where the apply pressure is going. An input drum air check tester for the 3-5-R and 1-2-3-4 drums makes this repeatable. Our 6L80 common problems guide covers the failure patterns, and the 6L80 Escalade shift problems guide walks through gear-by-gear diagnosis.
Listed for 2006-2017 6L80, 6L80E, 6L90 and 6L90E transmissions in the Chevrolet Silverado 1500 and 2500 HD, Suburban, Camaro and Corvette, GMC Sierra, Cadillac Escalade and STS, and Hummer H2. Internal parts saw revisions over that twelve-year run, so compare each new piston to the one you remove before installing it. Confirm 6L80 versus 6L90 by RPO code (MYC or MYD), and if anything looks different, send us the year and VIN and we will sort it out before you build. See all 6L80 parts for drums, valve bodies and tools.
The kit does not include wave plates, hard parts, a torque converter, the TEHCM or the valve body, so inspect wave plates and drums closely. Sonnax documents that the OE 4-5-6 clutch fails from too few clutches and limited piston-to-plate apply area, and that the backing plate can cone under load, so check that backing plate for flatness. Lubricate each bonded lip with Dexron VI or assembly lube and seat the piston straight; a 6L80E clutch drum removal and installation tool keeps the drum work clean. If the TEHCM pressure switches were part of your symptoms, a 6L80 pressure switch repair kit lets you service them while the module is already out. Set every pack clearance, fill with Dexron VI through the check plug, then reset transmission adapts and run a fast learn so the TCM relearns against new clutches.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
This kit adds bonded clutch pistons to the usual frictions, gaskets, seals and filter. Pistons are the part that most often gets reused in a cheaper rebuild, and a hardened piston lip will cause slipping even with new frictions.
The listing covers bonded pistons, frictions for the 1-2-3-4, 3-5-R, 4-5-6 and Low/Reverse packs, gaskets, seals and the filter. Wave plates and hard parts are not included, so inspect yours and replace any that are cracked or flattened.
It is listed for 2006-2017 6L80, 6L80E, 6L90 and 6L90E units. Confirm your RPO code (MYC or MYD) and compare each piston to the original before installing.
Plan on a converter service or replacement, bushings, a pump inspection and a cooler flush or new cooler. A drum air check tool and a pressure switch repair kit are worth having on hand.
Fill with Dexron VI through the check plug at operating temperature, then reset transmission adapts and complete a fast learn with a scan tool. GM lists the adapt reset as its fix for some harsh 6L80 downshifts, and it matters even more on fresh clutches.
