FTI Performance TH400 Level 4 Transmissions TH400-4S

Where FTI's complete kit version ships with a torque converter and cooler attached, the TH400-4S is the bare TH400 Level 4 transmission: no torque converter, cooler, or fluid comes with it, so it is sold as the gearbox alone for builders who already have those pieces on hand. That makes it the choice for a shop restocking a working driveline rather than starting from nothing.

What is built into the case

A 2.43 first gear turns on a hardened-steel input shaft riding thirty splines in the TH350/400 style, with a billet steel clutch hub set inside a black, OEM-style aluminum case and deep pan. Reaction times sharpen thanks to the trans-brake fitted into its full manual valve body; steels and clutches rated for heavy use, a 34-element sprag, and a high-flow pump back up a race-prepped case and billet forward clutch hub, and it carries the SFI 4.1/30.1 rating used across this lineup.

What you still need to add

A dipstick, fluid, flexplate, and wiring harness join the torque converter and cooler as items left for the builder to source, since the unit is sold individually rather than bundled.

Q: What is this transmission suited to? FTI points this 900-horsepower-rated build toward bracket racing, high-powered street cars, and mud trucks.

Q: Is this remanufactured or new? It is listed as remanufactured, built up from FTI's Level 4 upgrades rather than sold new.