8F35 Overhaul Kit 2018-2021

Searching for a reseal kit because the 8F35 in your Ford Escape, Edge, Bronco Sport, Maverick or Lincoln Corsair takes a second to grab Drive on a cold morning, flares between gears once it is hot, or is leaving drops under the bell housing? This new Precision 8F35 overhaul kit carries the gasket set, the sealing rings and the rubber seals for a full teardown. It is listed for the 2018-2021 units and it does not include pistons. That makes it the right box for a builder whose pistons inspect clean and who only wants to pay for the soft parts.

What the overhaul kit does in an 8F35

The 8F35 is a transverse eight-speed. Every ratio change is a hand-off between hydraulic clutches and brakes, and each one is applied by a piston that only moves if fluid stays trapped behind it. Gaskets seal the case halves, the valve body and the pump to their mating surfaces. Lip seals and O-rings hold pressure on the pistons, and the Teflon and cast sealing rings carry that pressure across the spinning shafts and drum hubs. Ford fills the unit with Mercon ULV, an ultra-low viscosity fluid, so even a small leak path bleeds off apply pressure quickly. When the seals harden with heat and age, clutch fill times stretch, the adaptive strategy keeps adding pressure to compensate, and eventually the shift turns into a slip or a bang.

Why the no-piston version

The 8F35's pistons use bonded rubber, molded directly to the steel. If the bonding is intact, the lips are soft and there are no tears or nicks, a builder can reuse them and this kit covers everything else. If a piston shows a lifted or cracked lip, buy the pistons separately or step up to our 8F35 overhaul kit with pistons so the job is not held up halfway through assembly.

Symptoms that call for a reseal

• Late engagement into Drive or Reverse after the car has sat, which shortens once it warms up
• Engine flare on upshifts with hot fluid, especially on a highway on-ramp
• Shifts getting firmer over time as the controls raise pressure to cover a leak
• Wet seams at the pan, side cover or case halves
• Slip-ratio or gear-ratio codes that return after a fluid service and adaptive reset

How to confirm before you buy

Ford has issued several bulletins on the 8F35 that are fixed without a rebuild, including software updates for shift quality, so rule those out first. The big hardware failure is the output planet carrier: on units built on or before December 20, 2021, worn carrier needle bearings send debris through the transmission and cause slipping and harsh engagement. A reseal will not fix that. Pull the pan and look for needle pieces or heavy metal in the filter before you order. Our 8F35 bulletin guide explains each Ford fix and the build dates it covers.

Fitment

The kit is listed for 8F35 transmissions dated 2018-2021, which matches the early production that is most likely to be torn down now for the carrier bearing failure. Ford's 8F family entered production for the 2019 model year in US vehicles, so a vehicle titled as a 2018 needs its transmission tag checked before you order. The 8F24, 8F35, 8F40 and 8F57 share a design but not every part, so read the tag, compare the gaskets to your originals at teardown, or send us your year and VIN to check. More parts for this unit are in the 8F35 collection.

Install notes

• This kit has no frictions, steels or filter. If the clutches are burnt, add the 8F35 kit with frictions, steels and filter.
• Bushings are not included. Aftermarket 8F35 bushing kits exist for 2018-on units, and converter impeller and turbine hub bushings are sold separately, so check every bushing for wear while the drums are out.
• Lubricate lip seals and O-rings with clean Mercon ULV, resize the Teflon rings before installing drums, and air-check each clutch circuit before closing the case.
• Replace the output carrier on affected builds and inspect the input drum sealing surfaces for grooves the new rings would ride on.
• Install the converter with the unit standing vertical so the pump drive chain stays in place, refill with Mercon ULV only, then reset adaptives and drive the relearn.

What is the difference between this kit and the 8F35 overhaul kit with pistons?

This version has the gasket set, sealing rings and seals but no pistons. Choose it when your bonded pistons inspect clean; choose the piston version if any rubber lip is torn, hard or lifting from the steel.

Does it include clutch frictions, steels or a filter?

No. It is the sealing side of the rebuild only. Add a friction and steel kit with a filter if the clutch packs are burnt or glazed.

Will it fix the 8F35 output carrier bearing failure?

No. On units built on or before December 20, 2021, Ford's TSB 22-2281 replaces the output planet carrier. Use this kit to reseal the unit while the new carrier goes in.

My vehicle is a 2018. Does it have an 8F35?

Probably not. The 8F family started production for the 2019 model year in US vehicles. Read the transmission tag or send us your year and VIN before ordering.

What fluid goes back in after the rebuild?

Mercon ULV, as Ford specifies for the 8F35. Do not use Mercon LV or a universal fluid, and reset adaptives with a scan tool after the refill.

• Ford 8F35 Transmission Problems: What the Four Ford Bulletins Actually Say