6L50 Planetary 2012

This is a used OEM output planetary with its sun gears for the GM 6L50 six-speed automatic, removed from a good transmission in a wrecked 2012 Chevrolet Camaro with the 3.6L V6. The donor unit had 54,000 miles on it, and the assembly comes loaded as shown in the photo. If your V6 Camaro or Cadillac CTS has a 6L50 that whines with road speed, lost a gear after a bang, or you found chewed pinions and glitter in the pan on teardown, this is the rear geartrain piece you are shopping for.

What the output planetary does in a 6L50

The 6L45 and 6L50 use a Lepelletier layout: one conventional planetary up front feeding a composite Ravigneaux gearset at the back. The front set supplies a reduced input speed, and the rear set combines that with turbine speed to make all six forward ratios and reverse. The output planetary is the part of that rear set that turns the output shaft, so every ratio the transmission makes, from the 4.065 first gear to the 0.674 sixth and the 3.200 reverse, passes through these pinions and sun gears on its way to the driveshaft.

That is why a failure here rarely stays polite. The clutches (1-2-3-4, 3-5-Reverse, 4-5-6, 2-6 and low/reverse) only decide which members of the gearsets are driven or held. If a pinion bearing or pin wears through, the noise and the debris show up in every range, and a stripped sun gear spline or pinion can leave you with no drive at all even though the clutch packs are fine.

Symptoms of a worn 6L50 output planetary

• A whine or growl that rises and falls with road speed, not engine speed, and is often worse on the coast
• Loss of a specific gear, or a clunk followed by no movement in Drive or Reverse
• Steel flakes or needle bearing pieces on the pan magnet and in the filter
• Blued pinions, loose pinion gears or excessive end play on the carrier during a rebuild
• Gear ratio errors and a limp-mode default gear when the computer sees input and output speeds that do not match

How to confirm the planetary is the problem

A 6L50 with no movement or a slip is more often hydraulic than mechanical. Sonnax and Gears Magazine both document valve body and solenoid faults, such as a worn check ball in the 1-2-3-4 clutch circuit or a line pressure solenoid stuck in exhaust, that make a healthy geartrain feel dead. Pull the codes and run a line pressure test first, using our 6L45/6L50 limp mode diagnosis guide. A planetary problem points the other way: correct pressure, noise that tracks vehicle speed, and metal in the pan. Once the unit is apart, spin each pinion by hand, check for rough or notchy bearings, and measure pinion end play as covered in our thrust washer and end play guide.

Fitment

This assembly came out of a 2012 Camaro 3.6L V6 with the 6L50 (GM RPO MYB). The 6L50 was also used in the Cadillac CTS, STS and SRX and in other GM rear-drive applications, but internal parts were revised over the production run and the 6L45 used in BMW and smaller GM cars is a different unit. Compare the tooth counts, spline count and overall height of this assembly with the one you removed before you install it. If you are not sure, send us your year and VIN and we will check it for you. The full lineup of parts for this family is on our 6L45/6L50 transmission page, and if you are working on a BMW 6L45 instead, look at the 6L45 planetary for 2007-2013.

Install notes

• Wash the assembly and blow out every lube hole in the carrier and the sun gear shafts. On the larger 6L80 and 6L90, Sonnax documents debris packing the output planetary lube dam and starving the pinions, so a clean oil path matters here too.
• Replace the thrust bearings and thrust washers on both sides of the planetary rather than reusing the ones from the failed set, and check the bushings that ride on the output shaft.
• A planetary failure throws metal through the whole unit. Clean or replace the cooler and lines, install a new filter, and plan on fresh seals and frictions from a 6L45/6L50 overhaul kit.
• Inspect the drum that sat next to the failed set. If its bushings or splines are damaged, the matching 2012 6L50 1-2-3-4 and 3-5-R clutch drum came out of the same Camaro.
• Refill with Dexron VI only, check the level hot as described in our 6L50 fluid type and capacity guide, then clear the adapts and complete a shift relearn.

Will this output planetary fit my 2010-2015 Camaro V6?

It came out of a 2012 Camaro 3.6L V6 with the 6L50, so other V6 Camaros with the 6L50 are the closest match. Compare the tooth and spline counts with your old part, or send us your year and VIN to confirm before you order.

Does it fit the 6L45 in a BMW 328i or 128i?

No, plan on the BMW 6L45 needing its own parts. The 6L45 is a lighter-duty unit and its internals differ from the 6L50. See our 6L45 planetary listings for those cars.

What comes with this part?

The output planetary with its sun gears, loaded as shown in the photo. It came from a running transmission with 54,000 miles. Thrust bearings, washers, seals and clutches are not included.

How do I know my planetary is bad and not the valve body?

Planetary failures make a whine or growl that follows road speed and leave steel debris in the pan, while line pressure stays normal. A 6L50 that will not move but stays quiet usually has a valve body, solenoid or check ball problem, so pressure-test it first.

What fluid do I use after installing it?

Dexron VI. Flush or replace the cooler and lines after a planetary failure, install a new filter, check the level hot, and run a transmission adapt relearn when the job is done.

• 6L45 Limp Mode: Causes and How to Diagnose It
• 6L50 Fluid Type, Capacity and Service Interval
• Transmission Endplay and Thrust Washer Wear: Why It Matters
• 8 Signs Your Transmission Is Going Bad