Overhaul gaskets, seals, friction plates and steels for a full bench rebuild of the Ford 4R70W, 4R75E and 4R75W four-speed automatic.
A 1998-2003 Ford F-150 or F-250 that slips in overdrive, has burned the forward clutch, or no longer pulls cleanly through the gears usually ends up on the bench with glazed frictions, heat-blued steels and gaskets that have gone hard. This master package combines three parts of that job in one box: the gasket and seal overhaul kit, the friction plate set and the matching steel plate set. It fits the 4R70W and its 4R75E and 4R75W variants. The manufacturer part number is Zun-4R70W, and the package ships at 7.5 lb in a 12 x 6 x 6 in box.
The 4R70W is the wide-ratio electronic successor to Ford's AODE. Each gear depends on clutch packs that are squeezed by oil pressure acting on a piston. The overhaul kit renews the gaskets, rubber seals, molded pistons, sealing rings and thrust washers that hold that pressure and set the drum clearances. The friction and steel sets renew the packs themselves. Buying them together matters because clutch pack clearance is set by the full stack: new frictions run against worn steels leave you chasing clearance, and the heat from that mismatch is what burns a fresh rebuild. Hard parts, the pump, the valve body and the torque converter are not included.
Before buying a full kit, rule out the problems a rebuild will not cure. Transmission Digest describes pressure regulator bore wear that bleeds EPC pressure away so line pressure never rises, which makes a healthy unit slip. Sonnax publishes a vacuum test guide for this family that isolates worn valve body bores on the bench. Pull the pan, check the fluid hot, scan for codes and test line pressure. Our 4R70W F-150 common problems guide covers the usual failures, and the Explorer shift problems guide explains how the same unit behaves in the lighter SUV.
The kit is listed for F-150 and F-250 trucks with the 4R70W, roughly 1998 through 2003. Ford ran several friction counts and drum changes across this family, and the F-250 Super Duty used a different transmission, so check the ID tag on your case before you order. Count the plates in each pack as you strip it and compare them to the kit. This kit is not for 2004 and later units: ATRA documents a 2004 change to the ring gear and output speed sensor that does not interchange, plus a non-magnetic sun shell for 2004 and up, so a 2004 truck needs the 4R70W master rebuild kit for 2004. If you are unsure, send us your year and VIN. More parts are on the 4R70W collection page.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It combines the gasket and seal overhaul kit, a friction plate set and a steel plate set, along with molded pistons, sealing rings and thrust washers. The pump, valve body, torque converter and other hard parts are not included.
No. Ford changed the ring gear, output speed sensor and sun shell for 2004, and those parts do not interchange. Use a 2004-specific kit.
No. Super Duty trucks used a heavier transmission. This kit is for F-150 and F-250 trucks that have the 4R70W, so check the tag on your case.
Worn clutches, a worn pressure regulator bore that drops line pressure, or a solenoid problem can all cause it. Pull the pan and test line pressure before you commit to a rebuild.
These 1998-2003 trucks use MERCON V. Do not substitute MERCON LV or Type F. Set the final level hot on the dipstick.
