8L90 Overhaul Kit 2015-2017, new and ready to install. Fits the 8L90. Ships fast from the USA.
This is a genuine GM overhaul kit, part number 24055367, for early 8L90 eight-speed transmissions built from 2015 through 2017. It is a gasket and seal kit: the case and cover gaskets, piston seals, sealing rings and O-rings needed to reseal the unit during a rebuild. It does not contain friction or steel plates. Buyers usually land here with a first-generation 8L90 in a 2015-2017 Silverado or Sierra 1500, Yukon, Escalade or a 2016-2017 Cadillac CT6 that is leaking, losing pressure as it warms up, or slipping after high mileage. GM has superseded and interchanged this kit under several numbers, including 24275661, 24280097, 24283476, 24271918 and 24299803.
Every clutch in the 8L90 is applied by a piston, and every piston depends on its seals to hold the pressure the valve body sends it. The rotating drums are fed through Teflon sealing rings on the shafts and stator support. When those rings and seals harden or wear, apply pressure leaks away, packs engage slowly and slip under load, and the module keeps adapting until it runs out of range. Resealing every circuit at once returns the hydraulic system to factory tightness, which is why this kit is the base of any 8L90 rebuild.
The 2015-2017 years matter here. GEARS Magazine reports that GM redesigned the 2-3-4-6-8 (C4) clutch piston in 2018 and changed the seal groove depth and width, so early and late D-rings are different sizes. An early unit needs early seals, and this kit is the early-design part.
Early 8L units had a known delayed engagement and drop-out-of-gear-at-a-stop complaint that is not a seal failure. GEARS Magazine traces it to air trapped in the stator cover passages and notes GM updated the 8L90 stator support (24277234) and cover (24277964) with an extra check ball. If a C5 clutch relearn will not cure a delayed engagement, check that update before resealing. Our 8L90 pump failure guide covers no-move and priming problems, and the valve body testing guide covers line pressure checks.
Listed for 2015-2017 8L90 (RPO M5U) transmissions in the Cadillac Escalade 6.2L, 2016-2017 Cadillac CT6 3.0L, Chevrolet Silverado 1500 and GMC Sierra 1500 with the 5.3L or 6.2L, and GMC Yukon 6.2L. Production changes do not always line up with model years, so check the C4 piston against the kit seals, or send us your year and VIN. For a unit built 2018 or later, see the 2015-2022 overhaul kit and confirm its seals instead. Every other 8L90 part is on the 8L90 collection page.
| Fits | 8L90 2015-2017 |
| Part type | Overhaul Kit |
| Condition | New |
| Brand | GM |
| Reference | 24055367 |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. It is a gasket and seal kit only. Frictions, steels and the filter are separate, and worn plates should be replaced during the same rebuild.
It is listed for 2015-2017. GM changed the C4 piston seal dimensions in 2018, so a later unit needs late-design seals. Send us your VIN if you are not sure which you have.
No. The 8L45 is a smaller transmission and uses its own overhaul kit.
Possibly not. GM updated the stator support and cover on early units to purge trapped air from the C5 circuit; check for that update first.
DEXRON HP only. After the rebuild, set the level hot at the check plug and run Service Fast Learn with a scan tool.
