4R100 Planetary 1998, remanufactured and ready to install. Fits the 4R100. Ships fast from the USA.
1998 is the year the Ford 4R100 arrived, and it is also the year that causes the most confusion at the parts counter. If you own a 1998 heavy-duty F-Series or E-Series van and the transmission has started to whine, slip out of a gear or shed metal, this remanufactured planetary is listed specifically for the 1998 4R100. The photo shows the assembly with its long splined shaft passing through the ring gear and carrier, so you can compare it directly with the part you remove. A reman part has already been inspected and set up, which takes the guesswork out of a used gearset.
The 4R100 has the same three-gearset layout and ratios as the E4OD it replaced: 2.71, 1.54, 1.00 and 0.71 forward, and 2.18 in Reverse. The overdrive planetary sits at the front, and the forward and reverse planetaries share a common sun gear in the rear half. Shafts connect the sets, and that is why a planetary for this unit can be supplied with its shaft, as shown. The ATRA chart shows the forward clutch applied in every forward gear and the overdrive members switching between a 1:1 lock and 4th. If a shaft spline strips or a pinion bearing fails, drive through that path stops, even when the clutches are healthy.
Wear on these parts usually comes from heat and lack of lube. Sonnax notes that the OE plastic front lube/drainback valve in E4OD and 4R100 units can melt at high fluid temperature, restricting front lube oil and causing overdrive planetary failure. First-year trucks are now old enough that heat, towing and tired cooler lines have usually taken a toll.
A truck that will not move can also have a pump, filter or pressure problem, and a 1998 4R100 with an electrical fault will fall back to failsafe. Check fluid level and condition, scan for codes, and confirm line pressure before condemning hard parts. The Sonnax vacuum test locations are covered in our E4OD valve body testing guide. Debris on the magnet is the best clue: friction dust indicates clutches, while needles and steel point at a planetary or shaft. On the bench, check spline wear on the shaft and hub, then spin every pinion and feel for roughness or end play. The E4OD and 4R100 problems guide explains the overheated overdrive failure.
This listing is for the 1998 4R100. Be careful with that year. Sonnax groups 1995-1998 E4OD units with 1998-later 4R100 units for some parts, which shows that some 1998 trucks and vans still left the factory with an E4OD while others received the new 4R100. Check the case: a 4R100 case has a PTO port and an E4OD case does not. The listing does not state the Ford part number or the gearset position, so compare shaft length, spline counts, pinion count and ring gear teeth with your old assembly. Send us your VIN if you are unsure. Our 4R100 vs E4OD guide covers the identification points, and the E4OD and 4R100 collection lists the matching parts.
| Fits | 4R100 1998 |
| Part type | Planetary |
| Condition | Remanufactured |
| 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.
1998 was the changeover year, so either is possible. A 4R100 case has a PTO port and an E4OD case does not. Your VIN and the transmission tag are the most reliable way to confirm it.
The gearsets in this unit are linked by shafts, and the assembly in the photo includes its shaft. Compare shaft length and spline counts with your old part before installing.
It can be stripped splines on a shaft or hub, but check fluid level, the filter, line pressure and codes first. Steel debris on the magnet points more strongly to a hard-part failure.
MERCON V ATF. Set the final level on the dipstick at normal operating temperature with the engine idling in Park.
Thrust washers and bearings, the filter, a full seal kit, and any drum or hub with worn splines. If the old part failed from heat, also deal with the front lube/drainback valve and cooler flow.
