4L60E 5-Pinion Front Planetary Carrier 77747B

This is a new front planetary carrier for the GM 4L60E family, sold under Remco part number 77747B. It is the 5-pinion design that GM put in the 4L65E and 4L70E, and it is listed to fit 700R4, 4L60E, 4L65E and 4L70E transmissions from 1982 through 2016. The carrier ships loose with its pinion gears installed; it does not include the ring gear, sun gear, thrust washers or bushings.

The front planet is one of the parts that fails on a 4L60E that has seen heat, towing or extra power. The usual signs are a gear whine that comes and goes with one particular gear, metal glitter in the pan, pinion gears with chipped teeth or excessive end play, or a carrier that has let go completely and left the truck with no drive in some ranges. Most 4L60E units left the factory with a 4-pinion front carrier; the 5-pinion version spreads torque across one more gear, which is why it is the common upgrade during a rebuild of a 4L60E behind a tuned or swapped engine.

On the bench: with the unit torn down, clean the old carrier and mating parts and look at the internal ring gear and sun gear teeth, the thrust surfaces and the output shaft splines. A carrier that failed usually damages its neighbors, so replace any gear with pitted or chipped teeth rather than running it against the new carrier. Check pinion end play on the new part, lube the pinions and thrust washers with ATF or assembly lube, install with new thrust bearings or washers as your kit calls for, and verify overall end play before the case is closed up.