5R55E Master Rebuild Kit

Four-wheel-drive Rangers with the 4.0L V6 and the 5R55E five-speed automatic are hard on transmissions. Towing, off-road use and bigger tires all add heat. When a 4x4 starts slipping out of fourth, takes too long to engage reverse, or shows black fluid with band lining on the dipstick, the right fix is a complete overhaul. This 5R55E master rebuild kit is the 4x4 package for 1997-up units. Unlike the 2WD kit, it includes all three bands and the deep 4x4 filter.

What comes in the 4x4 kit

• Overhaul kit with gaskets, seals and O-rings
• Friction kit and steel kit
• Intermediate, overdrive and reverse bands
• Deep 4x4 filter
• Front pump bushing

There is no extension housing bushing in the box, and that is on purpose. On a 4x4 the transfer case bolts to the back of the transmission through an adapter, so the 2WD tailshaft bushing is not used.

How the bands work in a 4x4 5R55E

The 5R55E grew out of the four-speed 4R55E. It keeps three bands and adds a fifth ratio. Ranger Station lists the ratios as 2.47, 1.87, 1.47, 1.00 and 0.75. Because the intermediate and overdrive bands work in more than one gear, they wear faster than the clutch packs. The low/reverse band holds the gearset for reverse and manual low. A 4x4 backing a trailer up a ramp loads that band harder than most 2WD trucks ever will. That is why this kit replaces all three bands and does not leave the reverse band to chance.

Symptoms that point to this kit

• No reverse, or a long delay before reverse engages when the fluid is hot
• Slip or flare on the 2-3 or 3-4 upshift
• Burnt fluid and band or clutch material in the pan
• Ratio codes P0731-P0735 with a slipping feel
• Shudder or slip on the converter clutch with code P0741

How to confirm before buying

A burnt reverse band is not always the band's fault. Sonnax's vacuum test guide for the 4R44E through 5R55E family shows worn inner and outer reverse modulator valves causing delayed reverse, a burnt reverse band and a burned direct clutch. If you rebuild with new bands and reuse a worn valve body, the new bands can burn the same way. Plan on inspecting or replacing the valve body as part of the job. Our 5R55 harsh or delayed shifts walkthrough covers the order of checks.

Fitment

This kit is listed for 1997-up 4x4 5R55E, 4R55E and 4R44E transmissions in Ford and Mazda applications. Ranger Station shows the 5R55E behind the 4.0L in Rangers from 1998 through 2011. The deep filter fits the 4x4 pan. If your truck is two-wheel drive, use the 5R55E 2WD master rebuild kit for 1997-2011, which has the 2WD filter and tailshaft bushing. This kit does not fit the 5R55W or 5R55S in the 2002-up Explorer, Mountaineer or Mustang. Sonnax treats those as a separate family. Read the ID tag on the case, or send us your year and VIN to confirm. Everything else for this family is on the 5R55 parts page.

Install notes

• With the unit apart, check the planetary pinions for end play and pitting. Replace a noisy carrier with a 5R55E planetary instead of reusing it.
• Inspect the 5R55E sun shell splines and the drum bushings. Both are common wear points under 4x4 loads.
• Soak the three bands and all frictions in Mercon V before you assemble.
• Set band servo travel and clutch pack clearances with the new parts in place.
• Clean the transfer case adapter mating surface, and use a new gasket or sealant there per the service procedure.
• Flush the cooler, fill with Mercon V, and check the level hot on the dipstick.

Why is there no extension housing bushing?

This is the 4x4 kit. On a four-wheel-drive truck the transfer case mounts behind the transmission, so the 2WD tailshaft bushing is not used. The kit includes the front pump bushing.

Does this kit include the reverse band?

Yes. It has all three bands: intermediate, overdrive and reverse. The 2WD 1997-2011 kit has only the overdrive and intermediate bands.

Will it fit my 2WD Ranger?

The internal parts fit, but the filter is the deep 4x4 type, and the 2WD extension housing bushing is not included. For a 2WD truck, order the 2WD 5R55E master kit.

Does it fit a 4R44E or 4R55E four-speed?

It is listed for the 4R44E, 4R55E and 5R55E 1997-up in 4x4 form. Confirm your unit on the case tag before ordering. Earlier units can differ.

What fluid should I use?

Mercon V. Pre-soak the bands and frictions in it, flush the cooler after the rebuild, and set the level hot on the dipstick.

• 5R55 Harsh or Delayed Shifts: A Diagnostic Walkthrough