Full overhaul kit for a GM 4L80E or 4L85E: frictions, steels, seals, gaskets, band and a new filter to rebuild a slipping heavy-duty 4-speed.
A 6.0L Silverado or Sierra 2500 HD, Suburban or Yukon XL 2500, or Express or Savana 3500 that has towed for years will eventually wear out its 4L80E or 4L85E clutches. When it starts slipping under load or the fluid comes out black, this master rebuild kit covers the overhaul in one box: clutch frictions, steel plates, seals, gaskets, a band and a new oil filter. It is listed for 4L80E and 4L85E units from 1997 on, under manufacturer part number COP-AP-TMS-TOR01101, and weighs 12.1 lb.
Both transmissions share the same case family, valve body and gear ratios; GM added the 4L85E as a heavy-duty variant with five-pinion planetary sets where the 4L80E uses four-pinion carriers. The clutch packs, seals and band are what wear in normal hard use, and this kit replaces all of them so the rebuilt unit holds line pressure and applies each clutch firmly again. Because it includes the band and filter, you are not left waiting on a separate order once the unit is torn down. The kit is aimed at the 1997-and-later center-lube design, which Transmission Digest describes as GM moving the cooler return line from the pump to the center support.
On 2000-and-up units, rule out the converter before blaming the clutches: Transmission Digest documents torque converter clutch cracking on these trucks that sets a hard-to-diagnose slip code. Check codes, solenoids and the internal harness, then run a line pressure test. Our Silverado 2500 4L80E problems guide and Express van 4L80E guide walk through the failures specific to these vehicles. If pressure is good and the unit still slips, or the pan is full of debris, an overhaul is the fix.
This kit is listed for GM 4L80E and 4L85E transmissions, 1997 and later, in the Silverado 2500 HD, Sierra 2500 HD, Suburban 2500, Yukon XL 2500, Express 3500 and Savana 3500 with the 6.0L V8. The 4L80E is RPO MT1 and the 4L85E is RPO MN8, which you can confirm on the glovebox or door-jamb option label. Inside the 1997-up range GM still made changes, such as the 1999 move to thicker planetary pinions and the 2004 revised solenoids and harness, so verify the transmission model and year before ordering and send us your VIN if in doubt. Year-specific kits and parts are on our 4L80E parts page.
Inspect the hard parts before anything new goes in. Check the pump for scoring and bushing wear, and replace it with the 1997 4L80E pump if the gears or body are worn. Measure every bushing and drum, check the overdrive roller clutch and intermediate sprag, and inspect the drum the band rides on; a burnt band usually means the drum surface needs attention too. Vacuum test the valve body, as Sonnax recommends for this family, to find worn bores before they undo the rebuild. On a 2004-and-later truck, the 2004-up master solenoid kit renews the solenoids and harness while the pan is off. Soak the frictions in ATF, set clutch clearances, air-check each circuit, flush the cooler and lines, install a new converter, and fill with Dexron VI, then recheck the level at operating temperature.
| Fits | GM 4L80E, 4L85E (also listed 4L80, 4L85), 1997 and later |
| Vehicles | Silverado 2500 HD, Sierra 2500 HD, Suburban 2500, Yukon XL 2500, Express 3500, Savana 3500 with 6.0L V8 |
| Includes | Clutch frictions, steel plates, seals, gaskets, band, oil filter |
| Manufacturer part number | COP-AP-TMS-TOR01101 |
| Kit weight | 12.1 lb |
| Note | Verify transmission model and year before ordering |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes, it is listed for both, 1997 and later. The two share the clutch and seal layout; the 4L85E's main difference is its five-pinion planetary sets, which are hard parts not included in a rebuild kit.
Check the RPO codes on the option label in the glovebox or door jamb. MT1 is the 4L80E and MN8 is the 4L85E.
Clutch frictions, steel plates, seals, gaskets, a band and an oil filter. Bushings, the pump, drums, sprags and the torque converter are not included and should be inspected and replaced as needed.
Yes. A used converter carries debris from the old failure back into the new unit, and 2000-and-up 4L80E converters have a documented clutch cracking problem that can set slip codes.
Dexron VI. It is GM's current specification for these transmissions and is back-serviceable for older Dexron III units.
It is listed for 1997 and later. Earlier units are a different lube design, so use a kit listed for those years.
