4R100 Overhaul Kit 1998, new and ready to install. Fits the 4R100. Ships fast from the USA.
1998 was the first model year Ford put the 4R100 name on its heavy-duty four-speed automatic, the unit that replaced the E4OD behind the 7.3L Power Stroke, the 5.4L and the 6.8L V10 in big pickups and E-Series vans. Twenty-plus years on, a first-year 4R100 that drips at the pump, hesitates before Drive on a cold start, or flares on the 2-3 shift with a load behind it usually needs a full reseal. This listing is a new overhaul kit for the 1998 4R100, pictured sealed in Toledo Trans-Kit packaging.
An overhaul kit is the soft-parts base of a rebuild: the case and valve body gaskets, lip seals, molded piston seals, O-rings and sealing rings. In the 4R100, pump pressure regulated by the EPC solenoid travels through the stator support, the drum sealing rings and the case passages to six clutch packs and two bands. Every one of those joints relies on a seal from this kit. When the rubber hardens with heat and age, oil bleeds off before it reaches a piston, so clutches apply slowly and slip under torque. Frictions and steels are a separate purchase if the packs are burnt.
A weak electrical signal can mimic worn seals. Pull codes first, measure line pressure with a gauge, and check the EPC circuit as described in our EPC solenoid symptoms guide. If pressure is low with good electrical readings, or the unit only slips when hot, internal leakage is the likely cause and the kit is the right starting point. Our E4OD and 4R100 problems guide lists the hard-part failures to look for while it is apart.
This kit is listed for 1998 4R100 units. 1998 is the year Ford standardized on a common F81P pump casting and released the first stamped-steel coast clutch drums, so a 1998 unit is not a carbon copy of a 1997 E4OD or a 2001 4R100. Transmission Digest reports two 1998 drums: a non-PTO drum with two frictions and a PTO drum with three frictions riding on a ball bearing. Diesel and many gas trucks use PWM converter clutch control, while a few gas trucks used on-off lockup. Seals in the kit are shared across these versions, but confirm your build from the ID tag or send us your year and VIN. The full E4OD and 4R100 parts collection has the matching hard parts, and our 4R100 vs E4OD guide explains each change.
| Fits | 4R100 1998 |
| Part type | Overhaul Kit |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is listed as an overhaul kit, which is the gasket and seal set. It is pictured sealed, so check the contents against your teardown. If the clutch packs are burnt, add frictions and steels or a clutch module.
1998 is the changeover year and many catalogs still call these units E4OD. Read the ID tag on the case or send us your year and VIN and we will confirm it before it ships.
These units originally used MERCON. That fluid is no longer made, and MERCON V is the current service fluid. Fill to the hot mark on the dipstick.
Only if the gears, pocket and bushing are clean and within spec. A scored pump loses volume at idle and a resealed unit will slip again, so inspect it carefully.
Yes for hard parts. PTO units use a different coast clutch drum with three frictions on a bearing. The seal set is shared, but match the drum and its thrust parts to what came out.
