4R100 Transmission Master Rebuild Kit w/ Raybestos Frictions

When a 4R100 in a Super Duty, Excursion or E-Series van starts slipping under load, loses fourth gear, or leaves a puddle under the bellhousing and the tailshaft at the same time, the fix is a teardown and a full set of soft parts. This kit packs that job into one order: a complete 4R100 overhaul gasket and seal set paired with a Raybestos friction clutch module (RCP96-091), sold under manufacturer part number W36004EGW. It fits the 1998-and-up 4R100 in F-250, F-350, F-450 and F-550 Super Duty trucks, the Excursion and E-Series vans, in 2WD and 4WD form.

What this kit renews in a 4R100

The 4R100 is the 1998 successor to the E4OD: the same four-speed gearset and case layout, with a revised pump, a stamped-steel coast clutch drum and a PTO option. Shift quality depends on two things this kit replaces. The first is sealing: the overhaul set covers the case and pump gaskets, metal-clad lip seals, Teflon and cast-iron sealing rings, and the O-rings and square-cut seals in the drums, servos and valve body. The second is friction: the Raybestos module supplies new friction plates for the clutch packs, including the 24-tooth reverse and 32-tooth overdrive frictions that take the worst of a loaded diesel or V10 truck.

Know what is not in the box. Steel separator plates are sold separately. Steels that are flat, clean and not heat-blued can go back in; blued or warped steels should be replaced, or the new frictions will not last.

Symptoms this overhaul addresses

• Slip or flare on upshifts that gets worse when the fluid is hot or the truck is towing
• No fourth gear with burnt fluid and clutch material in the pan; Transmission Digest traced one 4R100 with that complaint to the overdrive piston return spring ring coming out of its groove
• Delayed or harsh engagement into drive or reverse from worn piston seals
• External leaks at the front pump seal, case and extension
• Fluid that smells burnt after heavy towing, the unit's known stress point

How to confirm before you buy

Rule out the inexpensive faults first. Read codes, check the solenoid pack resistance and the condition of the case connector, and put a gauge on line pressure. A corroded connector or a broken lock tab can set codes that look like a failed unit. Our E4OD and 4R100 problems guide and shift solenoid guide cover those tests. If pressure is good and the unit still slips, the clutches are the problem and an overhaul is the honest fix.

Fitment

This kit is for the 4R100, 1998 and later. It is not for a pre-1998 E4OD, and some 1998 trucks still had the E4OD, so confirm the unit: a 4R100 case has a PTO opening and a stamped-steel coast clutch drum. One more check matters on this unit. Ford built PTO and non-PTO coast clutch drums, and the PTO drum holds three frictions where the non-PTO drum holds two, so count the plates in your drum before you order. Our 4R100 vs E4OD guide shows both drums. You can find every E4OD and 4R100 part we carry on the E4OD/4R100 parts page, or send us your year and VIN to confirm before ordering.

Install notes

• Inspect the pump, drums and bushings before reassembly. A 4R100 bushing driver kit makes bushing replacement accurate instead of a hammer-and-socket job.
• Check the coast clutch drum bearing or bushing and the drum teeth; a worn drum should be replaced with a 1998 4R100 clutch drum.
• Install a locking spiral ring behind the overdrive piston return spring in place of the open-end ring.
• Soak the frictions in MERCON V before assembly, set pack clearances to spec, and air-check every drum.
• Flush the cooler and lines and replace or service the torque converter.

More updates worth doing while it is apart are in the E4OD and 4R100 wear points guide.

Does this 4R100 kit include steel plates?

No. It includes the full overhaul gasket and seal set plus a Raybestos friction module. Steel plates are sold separately. Reuse steels only if they are flat, clean and not heat-blued.

Which trucks does this kit fit?

The 1998-and-up Ford 4R100 in F-250, F-350, F-450 and F-550 Super Duty trucks, the Excursion and E-Series vans, 2WD and 4WD. It does not fit the earlier E4OD.

Does it matter if my 4R100 has a PTO?

Yes, for the coast clutch pack. The PTO coast clutch drum holds three frictions and the non-PTO drum holds two, so count the plates in your drum and confirm the kit covers it before you start.

What fluid should I use after the rebuild?

MERCON V automatic transmission fluid. Soak the new frictions in it before assembly, flush the cooler, and check the level hot after the first drive.

What should I buy along with this kit?

Plan on a torque converter service or replacement, steel plates if yours are blued, a locking overdrive piston retaining ring, and any hard part that fails inspection such as bushings or the coast clutch drum.

What is the manufacturer part number?

The complete kit is W36004EGW, and the Raybestos friction module inside it is RCP96-091.

• 4R100 vs E4OD: Differences, Interchange & Which Is Stronger
• E4OD Rebuild Guide: Known Wear Points and Upgrades
• E4OD Common Problems and Fixes
• E4OD Shift Solenoid Symptoms and Replacement