4L80E Front and Rear Planet Set with Sun Gear, 1999-Up

This is the full gear train section for a 4L80E, not a single planet. You get the front planet, the rear planet, the sun gear, the sun gear shaft, the rear ring gear with its output shaft, and the thrust washers and bearings that go between them. Manufacturer part number is 34583CK. It is built for 1999-up cases and will retrofit back to 1991-1998 units.

The reason a set like this exists is that 4L80E planet failures are almost never isolated. When a pinion needle bearing lets go in the rear planet, the debris goes straight through the sun gear and the front planet on the same fluid path, and the thrust washers behind them get chewed. Techs who replace only the one carrier that looked bad tend to see the trans come back. Buying the section as a matched set is how you close that out in one teardown.

On the bench, the typical symptom that lands you here is a whine or growl that changes with gear rather than road speed, metal flake or bronze in the pan, or a unit that lost drive entirely after a pinion walked out. Once the case is split, pull the output shaft and rear ring, inspect the pinion end play on both carriers, and check the sun gear shaft splines for twist. If the pinions have any measurable rock or the shaft splines are rounded, the whole section gets replaced.

Parts are inspected and rebuilt before shipping. Reuse your existing case, pump, and drums; this covers the rotating gear set only. Set your end play with the selective washer during reassembly the same way you would with new OE parts.