5R55E Sun Shell

If a Ford Ranger, Mazda B-Series or Explorer with the 5R55E has lost reverse and third gear at the same time, or the rebuilder found a sun shell with rounded splines or a cracked weld at teardown, this is the part you are shopping for. This listing is a used, inspected original Ford sun gear and shell assembly for the 5R55E, the no-sensor-hole version. The same design traces back to the A4LD and is shared with the 5R44E, and it is listed for 1997-and-later units. It is cross-referenced in the parts trade as interchange 56622CK, which helps when you are comparing it to the part in your hands.

What the sun shell does in a 5R55E

The 5R55E is an electronic five-speed built on the A4LD layout: a front overdrive section ahead of a Simpson-style gear train, where one long sun gear is shared by the front and rear planetary sets. The sun shell is the bell-shaped steel piece that wraps around the forward clutch area and ties the reverse/high clutch drum to that sun gear. When the reverse/high clutch applies, it drives the sun gear through the shell, which is how the unit gets reverse and its direct ratios. When the intermediate band clamps the reverse/high drum, the shell holds the sun gear still, which is what produces second-gear reaction. In other words, the shell carries load in more gears than most people expect, and when its lugs or splines wear, several ranges go at once.

Symptoms of a worn or broken 5R55E sun shell

• No reverse and no third at the same time, while first and second still pull, because both ranges depend on the shell
• A clunk, then loss of drive, after the shell weld or the sun gear spline lets go under load
• Second gear that slips or flares even with a fresh band, because the band can no longer hold the sun gear through worn lugs
• Metal flake in the pan and a shiny, stepped wear pattern on the shell lugs where they engage the drum
• Gear-ratio codes such as P0732 or P0733 on vehicles whose computer monitors those ratios

How to confirm before you buy

Delayed or missing reverse on this family is not always hard-part failure. Transmission Digest has documented 4R44E and 5R55E units with delayed reverse caused by a checkball that starves the direct clutch feed, and Sonnax ties many 5R55-family shift complaints to fluid and valve body wear. Check fluid level and condition, pull codes, and read our 5R55 harsh or delayed shift walkthrough first. If reverse and third are both gone, or the pan is full of steel, the shell moves to the top of the list.

Fitment

This shell is listed for the A4LD, 5R44E and 5R55E, 1997 and later, in the no-sensor-hole style. Ford changed parts around the input and forward drum area when later units picked up a turbine speed sensor, so a shell with sensor windows and one without are not automatically the same. Lay your old shell next to the photos: match the sensor-hole style, the lug count and the sun gear spline before you order. If you are not sure, send us your year and VIN and we will check it. You can see every part for this family on the 5R55 transmission page, and the five-speed 4-cylinder version is covered by the 5R44E sun shell listing.

Install notes

• Check sun gear end play and the thrust washers on both sides of the shell; replace any washer that is scored or dished
• Inspect the sun gear bushings and the matching splines on the planet carriers; a new shell on worn carriers will not last
• Look at the lugs on the reverse/high drum, since they wear against the shell and should be a clean fit
• Fill with Mercon V and set the level with the engine running at operating temperature

Most shell failures show up during a full teardown, so this is a good time to install a 5R55E rebuild kit and check the 5R55E planetary that runs on this sun gear.

Will this sun shell fit my 1997-2011 Ford Ranger 4.0L with the 5R55E?

It is listed for 1997-and-later 5R55E units in the no-sensor-hole style. Compare the sensor-hole style, lug count and sun gear spline to your old shell, or send us the year and VIN and we will confirm it before it ships.

Does it come with the sun gear?

Yes. This is the sun gear and shell as an assembly, not a bare shell, so you are not pressing a gear into a new shell on the bench.

Why did I lose reverse and third at the same time?

In this gear train both reverse and the direct ratios run through the reverse/high clutch, the sun shell and the sun gear. A stripped spline or broken shell takes out both. A failed reverse/high clutch or a feed problem can do the same, so check those before you buy.

Is the A4LD shell the same as the 5R55E shell?

This listing is shared by the A4LD, 5R44E and 5R55E from 1997 up. Earlier A4LD units and later units built with a turbine speed sensor can differ, so match your part rather than going by name alone.

What should I replace along with the sun shell?

Thrust washers, sun gear bushings and the clutch packs in a rebuild kit. Inspect both planet carriers and the reverse/high drum lugs, and replace anything worn.

What fluid does the 5R55E use?

Mercon V automatic transmission fluid. Check the level hot with the engine running after installation.

• 5R55 Harsh or Delayed Shifts: A Diagnostic Walkthrough