5R55E Input Drum

If your Ranger, Mazda B4000, Explorer or Mountaineer with the 5R55E five-speed slips in second and fifth, loses engine braking, or came apart on the bench with a glazed front drum and burnt plates, this is the part you are looking for. It is the 5R55E overdrive drum, the front drum that the input shaft drives, which is why many shops simply call it the input drum. This one is a rebuilt assembly loaded with good clutches and steels, with worn pieces replaced, so it goes in as a working unit rather than a bare shell you still have to build up.

What the input drum does in a 5R55E

The 5R55E is not related to the later 5R55W and 5R55S. Sonnax traces it to the 4R44E of 1995, which became the 4R55E with heavier parts for the 4.0L in 1996 and then a five-speed for 1997, when Ford started applying the front servo to get an overdriven first and fifth. That front servo works the overdrive band, and the overdrive band wraps around the outside of this drum. Inside the drum sits the coast clutch pack. Sonnax notes that in the 5R units the coast clutch valve both vents overdrive servo release oil and brings on the coast clutch, and lists no 2nd, no 5th, no coast clutch apply and no engine braking as the symptoms when that control is lost. In other words, this one drum carries the band surface and the clutch pack that those gears depend on.

Symptoms of a worn 5R55E overdrive drum

• Slip or flare going into 2nd, or 5th that slips or will not hold under light throttle
• No engine braking when coasting in a manual low range
• A dark, glazed or blued band surface on the drum, or a band that has worn through its lining
• Friction material and steel debris in the pan along with a burnt fluid smell
• Slip that returns soon after a rebuild where the old drum was reused

How to confirm the drum is the problem

Not every 2nd and 5th slip is the drum. Sonnax points out that EPC circuit wear in the 4R44E and 5R55E valve body causes broken bands and servo piston seal blowout, and that leakage at the coast clutch valve alone can cost you gears and engine braking. Check fluid level and condition first, scan for codes, and watch line pressure if you can. If the band surface on the drum is scored or the coast clutch plates are burnt, the drum needs replacing, but fix the hydraulic cause at the same time or the new drum will go the same way. Our 5R55 harsh or delayed shift walkthrough covers the order of checks, and the 5R55 identification guide will confirm you have an E and not a W or S before you order.

Fitment

This drum is for the 5R55E only. It is not interchangeable with the 5R55W, 5R55S or 5R55N, which use a different geartrain. The 5R55E went into Ford Ranger and Mazda B-series trucks and into V6 Explorer and Mountaineer models, and the family ran through several revisions over the years. Compare the old drum side by side with this one: the band surface diameter, the spline count, the lug pattern for the clutch plates and the bushing. If you are unsure, send us your year and VIN before ordering. Every 5R55E part we carry is on the 5R55 transmission parts page.

Install notes

• Inspect the bushing and the sealing ring surfaces on the shaft the drum rides on; a grooved ring land will leak coast clutch apply oil no matter how good the drum is.
• Air check the coast clutch piston with the drum assembled before it goes into the case, and confirm the pack clearance.
• Fit a new overdrive band. A band that has run on a glazed drum will not seat properly on a fresh surface. The 5R55E overhaul kit covers the gaskets and seals for the job.
• If the old band burnt, look hard at the valve body. The Sonnax Zip Kit for the 4R44E and 5R55E valve body addresses the bore wear Sonnax ties to these failures.
• Refill with Mercon V, check the level hot, and road test 2nd and 5th under light and moderate throttle before you call it done.

Is the 5R55E input drum the same thing as the overdrive drum?

Yes. On the 5R55E the front drum is driven by the input shaft, holds the coast clutch pack, and has the overdrive band wrapped around it, so it is sold under both names. This is that front overdrive drum, rebuilt and loaded with clutches and steels.

Will this fit a 5R55W or 5R55S Explorer?

No. The 5R55W and 5R55S are a different design from the 5R55E and their drums do not interchange. If your Explorer is a 2002 or later model, use our identification guide or send us your VIN and we will point you to the right part.

What else should I replace with the drum?

Replace the overdrive band, the sealing rings the drum runs on and the gaskets and seals in an overhaul kit. If the old band burnt, inspect or repair the valve body EPC and coast clutch valve bores so the new drum is not starved of pressure.

What symptoms point to this drum rather than the valve body?

A scored or glazed band surface, burnt coast clutch plates or a lining that has worn off the band point to the drum. Slip in 2nd and 5th with clean hard parts usually points back to valve body leakage or low EPC pressure.

What fluid does the 5R55E take after the repair?

Mercon V automatic transmission fluid. Check the level with the transmission at operating temperature.

• 5R55 Harsh or Delayed Shifts: A Diagnostic Walkthrough
• 5R55 Identification Guide: 5R55S vs W, N and E
• 5R55 Noise Diagnosis: Whine and Clunk