8L90 Planetary 2015, remanufactured and ready to install. Fits the 8L90. Ships fast from the USA.
This is a remanufactured reaction planet carrier for the GM 8L90 eight-speed automatic, listed for 2015 and later units. It is the steel four-pinion carrier with 89 outer splines, interchange number 334584B-P. Rebuilders reach for it when an 8L90 from a Silverado or Sierra 1500, Tahoe, Yukon, Escalade, Camaro or Corvette comes apart with pitted or blued pinions, worn pinion bearings or chewed splines, usually after the owner noticed a whine that rose with road speed or found glittery steel in the pan.
The 8L90 stacks four planetary gear sets into a compact nest: direct and overdrive, input, reaction and output. Transmission Digest's teardown of the unit describes the reaction set as a dual sun gear, a ring gear and this planet carrier. The ring gear is splined to the aluminum 1-2-3-4-5-Reverse clutch hub, so when that clutch holds, the reaction ring is grounded to the case. The carrier itself is splined to the output ring gear and rides on a thrust bearing retained by a metal baffle, with a spiral retaining ring holding the set together. Because the carrier is tied to the output gear set, it is turning whenever the truck moves, and a damaged pinion or bearing makes noise in more than one gear.
Whine on an 8L90 is not always the gear train. A torque converter or pump noise follows engine speed, and an axle or wheel bearing noise follows road speed even in neutral coast. Drop the pan and look at the magnet first: friction lining points at clutches, bright steel points at gears and bearings. Our 8L90 common problems guide covers the shudder and converter complaints that get confused with gear noise, and the 8L90 pump failure guide explains how to rule out the pump.
This carrier is listed for 2015-up 8L90 transmissions. Before you order, count the pinions and the outer splines on your old carrier: this one is a four-pinion steel design with 89 outer splines, and those two details need to match. The 8L45 is a lighter-duty member of the family and uses its own internal parts, so do not assume interchange. If your carrier is too damaged to count, send us your year and VIN and we will help match it. All of our parts for this unit are on the 8L90 parts page, including the matching 8L90 sun shell.
| Fits | 8L90 2015 |
| Part type | Planetary |
| Condition | Remanufactured |
| Brand | GM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is the reaction planet carrier, the third of the four gear sets. Its ring gear is held by the 1-2-3-4-5-Reverse clutch and the carrier drives the output ring gear.
Count the pinions and outer splines on your old part. This carrier is a four-pinion steel design with 89 outer splines, listed for 2015-up 8L90 units. Send us your VIN if you cannot confirm it.
Do not assume it will. The 8L45 is the lighter-duty member of the family. This part is listed for the 8L90.
Replace the thrust bearings on both sides of the set, inspect the sun and ring gear teeth, and flush the cooler. If metal reached the clutch packs, rebuild them at the same time.
GM specifies DEXRON HP for the 8L90. Check the level hot using the factory procedure, then complete the fast learn with a scan tool.
