5R55S Planetary, remanufactured and ready to install. Fits the 5R55S. Ships fast from the USA.
If your 2002-and-later Ford Explorer or Mercury Mountaineer has a whine that rises with road speed, a flare into or out of fifth, or bronze and steel glitter in the pan, the overdrive planetary at the front of the gear train is one of the first places a rebuilder looks. This listing is a remanufactured overdrive planet kit for the 5R55W and 5R55S, built around the 24-tooth overdrive sun gear. It is not just a bare carrier: the kit is assembled from cleaned and inspected original Ford hard parts and includes the overdrive planet carrier, the overdrive ring gear and its snap ring to the center shaft, the 24-tooth sun gear with its washer and snap ring to the overdrive drum, the bearing with races between sun gear and carrier, the bearing between carrier and center shaft, the overdrive direct clutch pressure plate (.200 in.) with its snap ring, a piston kit and the coast clutch drum.
The 5R55 family uses a simple planetary ahead of the main gearset to give an extra ratio. The coast clutch drum, the overdrive sun gear and the carrier work together: lock them and the gearset turns as one, hold or release members and the output of the overdrive set changes. Because the sun gear meshes with every pinion on every revolution, wear here shows up as noise long before it shows up as a lost gear. The carrier in this kit uses hollow pinion pins and is matched to the double reluctor ring design, so it is meant for units built that way.
The tooth count matters. Sonnax describes the W as the 24-tooth overdrive sun gear version and the S as the 38-tooth version. Even though both are sold as 5R55S/W parts, the gear sets are not interchangeable piece by piece. This kit is the 24-tooth set; if your unit has a 38-tooth sun gear, look at the 5R55W planetary for 2002 and other listings on the model page instead and confirm the tooth count before ordering.
That last point is the one to take seriously. ATSG technical writer Wayne Colonna notes it is common to see a 5R55N, S or W come in with the overdrive planetary destroyed by lack of lubrication. The center lube for the overdrive planetary and the coast clutch drum is fed from the front pump through the cooler bypass/thermal valve. If that valve or the pump flow control valve is sticking, a new planet kit will starve the same way the old one did.
Pull the pan first. Fine gray paste is normal; flakes of steel or bronze are not. Scan for codes and look at whether a ratio code points to one gear, then follow our 5R55S noise diagnosis guide to separate gear whine from pump, converter or driveline noise. If the complaint is a slip rather than a noise, the servo pin bore wear guide covers the far more common cause of 5R55W/S slipping, which no planetary will fix.
Listed for the 5R55W and 5R55S with the 24-tooth overdrive sun gear. Sonnax dates the W to 2002-2003 Explorer and Mountaineer before the S took over in 2004-2005 models, with the S also in 2003-and-later Lincoln LS and Thunderbird. Hard parts changed across those years, so count the teeth on your old sun gear, compare the carrier pin style and reluctor, or send us your year and VIN before ordering. The 5R55N (1999-2002 Jaguar S-Type, Lincoln LS and Thunderbird) shares only a few parts with the W/S and is not covered. Browse everything for this family on the 5R55 parts page.
| Fits | 5R55S |
| 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.
No. This kit is built around the 24-tooth overdrive sun gear. Sonnax identifies the 24-tooth set with the W and the 38-tooth set with the S, and the gears are not mixed. Count the teeth on your old sun gear before ordering.
The overdrive carrier, overdrive ring gear and snap ring, 24-tooth sun gear with washer and snap ring, the sun gear and carrier bearings, the overdrive direct pressure plate (.200 in.) with snap ring, a piston kit and the coast clutch drum. Seals, frictions and filter are not included.
The most common cause in 5R55N/S/W units is lack of lubrication. Center lube to the overdrive set comes from the pump through the cooler bypass/thermal valve, so a sticking valve or worn pump flow control valve can starve it. Fix that circuit or the new parts will fail the same way.
Mercon V. Sonnax notes early Mercon V factory fill before May 2005 was linked to solenoid trouble, so flush out old fluid completely when the unit is back together.
Yes. Ford units built after 2002 use adaptive shift strategy, so clear adaptives with a scan tool and road test to let the PCM relearn shift pressure.
