5R55W Master Rebuild Kit 2000-2010, new other (see details) and ready to install. Fits the 5R55W. Ships fast from the USA.
A Ford Explorer or Mercury Mountaineer with a 5R55W that flares on the 2-3, loses fifth on the highway, or engages forward several seconds late when warm has usually worn out more than one part by the time the symptoms show. This 5R55W master rebuild kit, listed for 2000-2010, is for the overhaul that follows: the transmission comes out, gets torn down, and every clutch pack and seal is renewed together. It is sold in new-other condition, which means new rebuild parts that are not in the original factory packaging.
The W is the Explorer and Mountaineer version of the 5R55. Sonnax identifies it by its 24-tooth overdrive sun gear, where the 5R55S uses a 38-tooth sun. That difference lives in the hard parts, not the soft parts, but it is a reminder that W and S units are not freely swappable. Inside, the W combines three bands with multi-plate clutches and one-way clutches. The overdrive band carries second and fifth, which is why those gears are often the first to go. A master kit lets the rebuilder replace the wear items and every seal and gasket in one job, so the reassembled unit is not left with one old clutch pack waiting to fail. Inventory the kit against your teardown before you start, and order separately any drum, pump or solenoid body that turns out to be damaged.
Start with the pan. If the fluid is clean, rule out solenoids, wiring and the valve body using the pressure checks in our 5R55 harsh or delayed shift walkthrough. GEARS Magazine documented a 2006 Explorer with severe delayed forward where solenoid and sensor readings were normal and the forward clutch was the only damage, so normal electrical tests do not rule out a worn clutch. If you find band lining, measure the servo pin bores before buying anything, as explained in our servo pin bore wear guide. A worn bore will burn new bands no matter how good the kit is. Our 5R55W Explorer common problems page lists the other failures that show up at the same mileage.
The listing names 5R55W units for 2000-2010. Sonnax places the W in 2002-2003 Explorers and Mountaineers, with the S following in some 2004-2005 trucks, so the vehicle model year alone does not tell you which unit you have. Read the ID tag on the case, compare against our 5R55S vs 5R55W differences guide, and remember that later units use an updated solenoid pack, so the base plate and filter must match. If you are unsure, send us your year and VIN and we will match it. The full range of W and S parts is on the 5R55 collection page.
| Fits | 5R55W 2000-2010 |
| Part type | Master Rebuild Kit |
| Condition | New Other (See Details) |
| 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.
It depends on whether the truck has a W or an S. Sonnax notes the S replaced the W in some 2004-2005 models. Check the tag on the transmission case or send us your VIN and we will confirm before you order.
The two share a lot of design, but hard parts like the overdrive sun gear differ, as do some solenoid pieces. Order the kit for the unit stamped on your tag.
Often, yes. GEARS Magazine traced a 2006 Explorer with this complaint to a worn forward clutch even though solenoid and sensor readings were normal. Rule out low fluid and the valve body first.
Mercon V. Behind the 4.0 or 4.6L a dry unit takes roughly 12.4 to 12.7 quarts, filled and checked hot at the T30 plug on the case.
Worn bushings, a scored pump, an original solenoid block and, if the servo bores are oval, a bore sleeve repair. A shift kit is a common add-on for an Explorer that tows.
