Shop 6L80 Parts →
The 6L80 is GM's rear-drive six-speed automatic. It debuted for 2006 and went on to cover Silverado, Sierra, Tahoe, Yukon, Escalade, Camaro, Corvette and plenty of LS swaps. The 6L90 is its heavier-duty sibling, found in HD pickups, Express and Savana vans and other heavier applications. Most sealing hardware is shared, which is why kits are usually sold as 6L80E/6L90E.
Inside are five clutches: 1-2-3-4, 3-5-reverse, 4-5-6, 2-6, and low/reverse, plus a low one-way clutch. Every one of those is fed through seals and sealing rings, and a leak anywhere in that circuit shows up as a flare, a slip, or a shift code long before you see a drip on the driveway.
What Is in a 6L80 Overhaul Kit
A proper overhaul kit is the reseal side of a rebuild. The 6L80E/6L90E overhaul seal and gasket kit we carry is a good example of a complete set:
- Input (front pump) and output shaft seals
- Oil pan gasket
- Paper gaskets for the pump and valve body plate area
- Internal O-ring set for the pump, case and clutch housings
- Sealing rings for the shafts that feed the rotating clutches
- External seals for the manual shaft and other case penetrations
What It Does Not Include
- Friction plates and steels. Those come in a master kit like the 6L80 master rebuild kit.
- Pistons. Many 6L80 pistons have bonded (molded-on) seals. If the lip is torn, hard or cut, the piston is the replacement part.
- The filter. Buy it separately, for example the ATP B-239 6L80 filter and gasket kit.
Overhaul Kit or Master Kit?
| Your Situation | Buy | Why |
|---|---|---|
| Leaking but shifts clean, fluid is red | Overhaul kit + filter | The clutches are fine. You are fixing seals. |
| Slips, flares, or fluid is dark with debris | Master kit + pistons as needed | Heat damaged the frictions; steels may be blued or warped. |
| Pump noise or pump bushing wear | Overhaul kit + pump | A worn pump will chew new seals. See the reman 6L80 pump. |
| Shift codes with a clean, full unit | Diagnose first | Control solenoid valve body faults do not get fixed by a gasket kit. |
Our 6L80 rebuild kit guide covers the master-kit side in more detail.
Install Notes That Prevent Comebacks
- Size the input shaft sealing rings. The rotating clutch feed rings on the 6L80 input shaft are the Teflon style that stretch during install. Use an input shaft seal ring expander and resizer so they go on without being cut and shrink back before the housing slides over them.
- Lube every O-ring and lip with Dexron VI or assembly lube. A dry O-ring on the pump or case will roll and cross-leak.
- Pull the old filter seal. On GM units the filter neck seal often stays in the bore when the old filter comes out. A new filter pushed in over the old seal will not seat and the pump can suck air.
- Drive the front seal square with a driver that bears on the outer edge. A cocked seal leaks at the bell housing and gets misdiagnosed as a rear main.
- Air-check each clutch before the control valve body goes back on. Listen for a firm apply and no hiss.
- Flush or replace the cooler after any failure that made debris. Debris trapped in the cooler will wash back into a fresh unit.
- Fill with Dexron VI and set the level using GM's procedure at the correct fluid temperature. Our 6L80 fluid capacity and fill procedure lays it out.
Finding the Leak Before You Buy
Not every 6L80 leak needs a teardown. Pan gasket and cooler line leaks are outside jobs. Front pump seal and internal leaks are not. Clean the area, run the truck, and trace the wet spot upward to its highest point. Our 6L80 fluid leak guide covers the usual spots, and the 6L80 filter and pan kit guide covers the pan side.
Common Mistakes
- Reusing a hard bonded piston because the gasket kit looked complete.
- Forcing stretched sealing rings into a housing. They shave, and the clutch they feed slips.
- Assuming any GM six-speed is a 6L80. Check the case tag. Front-drive six-speeds use completely different kits.
- Skipping the TEHCM caution. On the 6L80 the control module is built into the control solenoid valve body. A reseal does not require programming, but replacing that assembly does. Do not swap it as a "while I'm in there" part without a way to program it.
6L80 and 6L90 Parts Ship Same-Day
Overhaul kits, master kits, pumps, filters and sealing ring tools for GM's six-speed. Free shipping on every order. More hard parts are available from our sister shop CoreTransmissionParts.com.
Shop 6L80 Parts →FAQ
Does a 6L80 overhaul kit fit the 6L90?
Most are cataloged for both 6L80E and 6L90E because the sealing hardware is largely shared. Check the kit's listed applications and confirm your case tag before ordering.
Does the 6L80 overhaul kit include pistons or clutches?
No. An overhaul kit is seals, gaskets, O-rings and sealing rings. Frictions and steels come in a master kit, and bonded pistons are usually sold separately.
Do I need a special tool for the 6L80 input shaft sealing rings?
It is strongly recommended. The Teflon-style rings stretch when installed and must be resized before the housing goes over them, or they get cut. An expander and resizer set makes that a few-minute job.
Do I have to program anything after resealing a 6L80?
Not for a reseal. Programming is needed if the control solenoid valve body with the integrated TCM is replaced. After any rebuild, clear codes and let the transmission relearn its shifts, or run a relearn with a capable scan tool.
What fluid does the 6L80 use?
Dexron VI. Fill and check the level using GM's procedure at the specified fluid temperature, since the 6L80 does not have a traditional owner dipstick on most trucks.