4R70W Input Drum 2003

A 2003 Ford with the 4R70W that suddenly will not move in Drive, or slips and flares through the first three gears while Reverse still pulls, has a good chance of a failed forward clutch drum. This listing is a used 2003 4R70W input drum, shown on its long input shaft, for rebuilders and owners who need a straight replacement for that model year without paying for a new aftermarket drum.

What the input drum does in a 2003 4R70W

The input drum is the forward clutch drum, and the shaft it rides on carries power in from the torque converter. Inside the drum is the forward clutch piston and plate pack. When the forward clutch applies, the drum drives the forward sun gear and the planetary does the rest. The forward clutch is applied in first, second and third, so this drum takes the brunt of every take-off and every load you pull. Sonnax lists forward drum breakage as a chronic failure across the AOD, AODE and 4R70W series, with no Forward, slipping gears and ratio codes as the results.

Symptoms on a 2003

• No Drive, or a long delay before the truck or car moves, with Reverse still working
• Slipping in first through third, worst on a hill, when towing or after a long drive
• Gear ratio codes P0731, P0732 or P0733
• Dark, burnt fluid and metal in the pan
• Third and fourth gear slip that is actually a direct clutch problem; see the note below

How to confirm it before you buy

A 2003 4R70W has a valve body from the post-2001 run. Work Truck Online reported that Ford dropped a reinforcement plate on valve bodies built after 2001, right where the forward and direct clutch circuits meet, and that the lost clamping led to third and fourth gear slip and direct clutch burnout. So before you blame the forward drum, sort out which gears slip. Slip in first through third points at the forward clutch; slip in third and fourth points at the direct clutch and valve body. Our 4R70W 3-4 clutch failure guide covers the direct side, and the Expedition shift problems guide covers pressure and solenoid checks. Low line pressure will burn any forward pack, so test it first.

Fitment: 2003 only, and why

2003 is the last year before Ford's 2004 changes. ATRA documents that 2004 brought a new ring gear and output speed sensor that do not interchange with earlier parts, and that 2004-on forward drums have three apply holes where earlier drums have one. ATRA calls the apply-hole change cosmetic, but a 2003 rebuild should stay with 2003-era parts around it. Common 2003 4R70W applications include the F-150, Expedition, Navigator, Mustang and the Crown Victoria, Grand Marquis and Town Car, but confirm with the trans tag on your case. Compare the shaft length, spline count and drum height with the photo, or send us your year and VIN. For a 2004 or later unit use the 2004 4R75W input drum, and browse the full 4R70W collection for the rest of the rebuild.

Install notes for a used drum

• This is a used part. Before it goes in, clean it, check the bushing for scoring, look at the shaft splines and sealing ring grooves, and air-check the piston with the pack installed.
• Run new frictions, steels, piston seals and sealing rings. The 1997-2003 4R70W master rebuild kit covers a 2003 unit.
• Set forward clutch clearance with a feeler gauge and the right selective snap ring.
• Check the pump and stator support ring lands; a worn 1995-2003 4R70W pump will starve the new pack.
• Flush the cooler and refill with MERCON V.

Does this 2003 drum come with the input shaft?

The listing photo shows the drum on its input shaft. If you need to confirm exactly what ships, send us a message before ordering.

Will a 2003 drum work in my 2004 F-150?

Ford changed the ring gear, output speed sensor and other geartrain parts for 2004, and the forward drum went from one apply hole to three. Use a 2004-up drum for a 2004 or later unit and keep the geartrain from the same era.

My 2003 slips in third and fourth. Is it the input drum?

Probably not first. Third and fourth gear slip usually points to the direct clutch and the post-2001 valve body problem. Forward drum failures show up as slip or no engagement in first through third.

It is used. What should I check before installing?

Inspect the bushing, splines and sealing ring grooves, install a new clutch pack and seals, air-check the piston, and set the clutch clearance before final assembly.

What fluid does a 2003 4R70W use?

MERCON V. Flush the cooler and lines when you replace a failed forward drum so debris does not come back into the new parts.

• 4R70W 3-4 Clutch Failure: Symptoms and Fix
• 4R70W Expedition Shift Problems: Diagnosis and Fix
• 4R70W F150 Common Problems and Fixes
• 4R70W Crown Victoria Common Problems and Fixes