5R55W Planetary, remanufactured and ready to install. Fits the 5R55W. Ships fast from the USA.
The front of a 5R55W gear train has a known weak spot. On 2002-and-later Ford Explorer and Mercury Mountaineer trucks with the 4.0L or 4.6L, a growl that follows road speed, a flare around the overdrive shifts, or a pan full of needle rollers usually leads straight to the overdrive planetary. This listing is a remanufactured overdrive planetary for the 5R55W, shown in the photo with the speed sensor tone ring around the carrier. It is the part you need when the front planet bearing has let go or the pinions have been run dry.
The overdrive planetary is the first gearset behind the pump. Depending on which clutch or band is applied, it either turns as one locked unit or changes the ratio of everything that follows it, which is how the 5R55W builds its gear range from a compact set of parts. The W version of this gearset is unique. In a Transmission Digest TASC Force article, Sonnax specialist Ed Lee explains that the W uses its own front planet and sun gear, that the front-planet bearing in the W was especially prone to failure, and that the design was not carried into the 5R55S. The failure starts small: the center of the bearing cage on the sun-gear side gets stamped out, and if the truck keeps driving, it ends in a catastrophic gear-train failure.
Lubrication is the other half of the story. ATSG technical writer Wayne Colonna reports that 5R55N, S and W units often arrive with the overdrive planetary destroyed by lack of lube. A replacement carrier will not survive if the lube supply that killed the first one is still restricted.
Pull the pan and look at what is on the magnet before you condemn anything. Fine gray paste is normal wear; bearing rollers and cage fragments are not. Scan for codes, then use our 5R55W noise diagnosis guide to tell a gear-train growl from pump, converter or driveline noise. If the complaint is a slip with no noise, check the far more common servo bore and valve body causes in our 5R55 harsh and delayed shift walkthrough first, since a new planetary will not fix a hydraulic leak.
The listing covers the 5R55W in the 2002-and-later Ford Explorer and Mercury Mountaineer with the 4.0L or 4.6L, and it also names the 2003-2006 Lincoln Aviator 4.6L and the 2005-2010 Mustang 4.0L and 4.6L. Be careful with that wider list. Sonnax identifies the W by its 24-tooth overdrive sun gear and the S by a 38-tooth sun gear, and the later cars and trucks on that list run the 5R55S, where the W front planet was not carried over. Count the teeth on your old overdrive sun gear, compare the carrier and tone ring with the photo, or send us your year and VIN so we can confirm before it ships. Browse every 5R55 part on the 5R55 parts page.
| Fits | 5R55W |
| Part type | Planetary |
| Condition | Remanufactured |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes, this is the overdrive (front) planetary. Transmission Digest documents the W's front-planet bearing as especially prone to failure, with the cage on the sun-gear side stamping out before the bearing breaks up.
Those vehicles are on the listing, but they generally run the 5R55S, which uses a different overdrive sun gear (38 teeth versus 24 on the W). Count the teeth on your old sun gear or send us your year and VIN before ordering.
The two common causes are the W-specific front-planet bearing failure and a lack of lubrication to the overdrive set. Fix the lube supply during the rebuild or the new carrier can fail the same way.
All thrust washers and bearings around the gearset, the filter and pan gasket, and usually the frictions and seals in an overhaul kit, especially if bearing debris went through the unit. Flush the cooler and lines as well.
Mercon V. The case has no dipstick, so the level is set at the T30 Torx plug with the fluid at the correct temperature.
