Expands and re-sizes the input and turbine shaft Teflon seal rings on a GM 6L80 or 6L90E so they slide over the shaft without cutting or crimping, then sizes them back down for a clean, leak-free fit during a rebuild.
If you are rebuilding a 6L80 or 6L90E out of a Silverado, Sierra, Tahoe, Yukon, Escalade, Camaro or Corvette and the complaint was a slow or slipping engagement, especially into Reverse when the truck is cold, the seal rings that feed the clutches are high on the suspect list. Replacing them is cheap. Installing them without damage is the hard part. This tool is a matched expander and sizing collar for the scarf-cut Teflon rings on the shaft side of the 6L80 and 6L90E, so the new rings go on round, sit flat in their grooves, and close back down before the shaft goes into its bore.
In the 6L80 family, fluid for the rotating clutches travels through drilled passages in the stator support and shafts, and solid Teflon rings in machined grooves keep each feed circuit separate where a stationary part meets a turning one. Gears Magazine notes that the rings on the back of the stator support seal the feed oil for the 3-5-R and 1-2-3-4 clutches. A ring that is rolled, nicked at the scarf joint, or stretched oversize leaks that oil into the next circuit or back to sump. The expander cone opens a new ring just enough to walk over the shaft lands without catching an edge. Once it drops into the groove, the sizing collar slides over and compresses it back to its working diameter, so it enters the mating bore without being shaved or pinched.
A ring leak is a hydraulic fault, so rule out the cheaper causes first: correct Dexron VI level, a clean filter and seal, and a line pressure test against commanded pressure. Our 6L80 common problems and fixes guide walks through the failures that look alike, and the 6L80 pump failure symptoms guide covers the stator support and pump side, where these rings live. If the unit is already apart, air-check each circuit; a hiss at a ring land tells you more than any scan tool.
The tool is listed for the GM 6L80 and 6L90E input and turbine shaft Teflon rings, which covers the 2006-2020 trucks, SUVs and performance cars that used these units, plus crate and swap builds. It is not a universal sizer. GM updated the stator support rings on early units, and Gears Magazine reports that the later rings will not fit the earlier pump without machining, so check which ring style your support and shaft use before you start. If you are unsure, send us the year and VIN and we will help you match it. Everything else for the unit is on our 6L80 transmission parts page.
Clean the grooves and lands and check that the ring edges are not burred. Lubricate the new ring and the cone with Dexron VI or assembly lube, push the ring up the expander with even pressure, and let it drop into its groove with the scarf joint closed. Slide the sizing collar on and leave it for a few minutes so the Teflon relaxes to size, then remove it and assemble right away. Do not reuse old rings; a fresh 6L80E/6L90E overhaul seal and gasket kit includes them. If the stator support itself is cracked or worn, a replacement 6L80 pump is the better repair. After the unit goes back in, fill with Dexron VI, check the level at operating temperature, and reset adapts.
| Fits | GM 6L80 and 6L90E automatic transmissions |
| Application | Input / turbine shaft Teflon seal rings |
| Function | Expands rings for install, then re-sizes to spec |
| Material | Steel, corrosion-resistant finish |
| Use | Transmission rebuild and seal ring replacement |
| Ships from | USA |
The scarf-cut Teflon sealing rings on the input and turbine shaft side of a 6L80 or 6L90E. These seal the clutch feed circuits where a turning shaft meets a stationary bore.
Teflon rings take a set when stretched. A ring pushed on by hand often ends up oversize, nicked at the joint or rolled in the groove, and it leaks clutch apply oil the first time it sees pressure.
It sizes the shaft rings on both, but GM changed the stator support ring design and the late rings do not fit early pumps without machining. Confirm which rings your parts use before assembly.
Most often a slow or slipping Reverse or Drive engagement that is worse cold, plus flare on upshifts and clutches that burn up early after a rebuild.
Lubricate rings with Dexron VI or a clean assembly lube, and fill the transmission with Dexron VI when it goes back in.
