4R70W Sun Shell 2004

If your 2004 Crown Victoria, Grand Marquis, Town Car, V6 Mustang, 4.6L E-Series van, 4.6L Expedition or F-150 Heritage suddenly lost second gear and overdrive, will not back up, or rattles from the middle of the transmission, the sun shell is one of the first hard parts to suspect. This is a new OEM 4R70W sun shell listed for the 2004 model year, the first year Ford built the stronger late-design shell.

What the sun shell does in a 4R70W

The 4R70W makes all four forward gears and Reverse from one compound gearset with two sun gears. The shell is the stamped steel drum with the reverse sun gear formed on its top. Its tabs lock into the reverse clutch drum, so whatever happens to that drum happens to the reverse sun gear. In Reverse the reverse clutch drives it. In second the intermediate clutch and its one-way diode hold it still, and in overdrive the overdrive band holds it. That is a lot of reaction torque concentrated where the gear meets the stamping, which is why cracked shells are a known 4R70W failure on high-mileage, towing and police-duty units.

What changed for 2004

ATRA's 4R70W/4R75E interchange notes describe the 2004-up shell as stronger: either a two-piece riveted or a later one-piece design, with thicker metal along the chamfer at the base of the gear to resist cracking. The height from the bottom of the sun gear to the bearing surface was cut by .030 in. to make room for a thicker two-piece bearing. Because of that, ATRA says the shell, bearing and forward sun gear have to be changed together when going to the late parts, or end play will be wrong. Ford serviced that set as kit 4L3Z-7D234-AA.

Symptoms of a failed 4R70W sun shell

• Engine flares and no second or overdrive, while first and third still work
• No Reverse, or Reverse that slips, with a normal Drive engagement
• Clunk or rattle from mid-case that changes with load
• Steel slivers on the pan magnet, sometimes pieces of the stamping itself
• Gear ratio error codes after a gear goes missing, with no electrical fault found

How to confirm it before you order

Lost second and fourth can also come from a burned intermediate clutch, a failed overdrive servo or a pressure problem, so do the cheap checks first. Scan for codes, look at the fluid and pan, and check line pressure. The Crown Victoria shift problems guide covers the overdrive servo and pressure regulator faults that mimic a mechanical failure on the Panther cars, and the Expedition common problems guide covers the trucks. If the friction material looks healthy but the magnet is full of steel, plan on a teardown. A broken shell is easy to see: a split around the gear base or torn drive tabs.

Fitment

Listed for 2004 4R70W units. In 2004 Ford ran four versions of this transmission, and per the Ford AOD reference the 4R70W stayed in the Panther cars, the 3.9L Mustang, the 4.6L E-Series and Expedition, and the F-150 Heritage, while the 4.6L new-body F-150 got the 4R70E and the 5.4L 3-valve got the 4R75E. Those electronic units have a turbine speed sensor that reads the forward drum through the shell, and ATRA warns they need a non-magnetic shell or they shift harshly or not at all. Read your transmission tag, compare the shell to the photo, and send us your year and VIN if anything is unclear. For an earlier unit see the 1993 4R70W sun shell, and browse the full 4R70W collection.

Install notes

• Fit a new thrust bearing under the gear and keep the late shell, bearing and forward sun gear together as a set.
• Inspect the reverse clutch drum tabs and the planet carrier; a failed shell often damages both. The 2004 4R70W planetary is listed if the carrier is chewed up.
• Check end play at the input shaft and correct it with the selective washer.
• Clean the case, flush or replace the cooler and fit new frictions and seals. The 2004-2014 master rebuild kit covers the soft parts.
• Refill with MERCON V and set the level hot in Park.

Will this 2004 sun shell fit my 2001 Crown Victoria?

It can, but not on its own. The 2004-up shell is .030 in. shorter at the bearing surface and uses a thicker bearing, so ATRA says the shell, bearing and forward sun gear must be changed as a set. If you only want the shell, order the earlier design for your year.

My 2004 F-150 has a 4R70E. Can I use this shell?

Only if it is the non-magnetic version. The 4R70E reads the forward drum through the shell with a turbine speed sensor, and a magnetic shell causes harsh or no shifts and speed sensor codes. Check your tag and send us your VIN before ordering.

What does a broken sun shell feel like while driving?

Usually the transmission pulls normally in first, then flares when it tries to shift into second, may grab third, and has no overdrive. Reverse is often weak or gone because the same shell carries the reverse sun gear.

What else should I replace with the shell?

The thrust bearing under the sun gear, the filter, and any frictions contaminated with steel. Inspect the planet carrier, forward sun gear and drum tabs, and flush the cooler.

What fluid does a 2004 4R70W take?

MERCON V. Ford's own MERCON V guidance warns against using it where MERCON LV, SP or Type F is specified, but a 2004 4R70W calls for MERCON V.

• 4R70W Crown Victoria Shift Problems: Diagnosis and Fix
• 4R70W Expedition Common Problems and Fixes
• 4R70W Crown Victoria Common Problems and Fixes
• 4R70W F150 Common Problems and Fixes