The General Motors Turbo 400 has been the most-used transmission in drag racing over the years, because we all know there are more glides out there than anything else. Its brute strength combined with the ability to exist in many different configurations have helped its popularity, but as the transmission has not been produced by GM since 1987, cores are getting harder and harder to find. ATI Performance Products has revitalized the marketplace today with their aftermarket, SFI-Approved, Turbo 400 3-speed transmission case.

“We have been working on this project for the last two years, and it’s been a long-hard road getting the project finished,” explained ATI’s JC Beattie Jr. “Running it on the dyno and having it work is a big deal. I actually didn’t expect it to run on the very first shot. There are always stumbling blocks with a new product like this. It works and we’re excited about it. I’ve got one that will be tested in a car this weekend, and two others out being built right now. We’re going to wait to make sure these work properly in the cars before I machine the next batch of them, but as soon as I get confirmation that it works well in the car, we’ll start churning them out. I want to get it into the car so that we can simulate the shifts and get a good load on it. You just can’t do that on the transmission dyno. Once it runs in the car I’ll get started on the next batch of 50 pieces and we’ll be off and running with production from there. After the transmission was removed from the dyno for its test run, all of the internals were inspected and found to measure as they should.”

The case was designed in-house at ATI, is cast here in the United States, and was machined at ATI Performance Products on their Makino 4-Axis Horizontal CNC machine. The part was originally designed from a factory case that had been modified, epoxied, and tweaked to incorporate all of the latest tricks. Then it was sent off to have a 3-dimensional plastic part “printed” to ensure that all of the modifications and pathways were correct. John Kilgore of Kilgore Racing Transmissions supplied the ATI team with some drawings that were helpful in the process as well.

The list of aftermarket improvements is lengthy, all of which were implemented after careful consideration by the ATI engineers as to what would be most beneficial in an offering like this. “It’s been a big undertaking for the last two years here to do it all in-house. Nobody’s even been able to build one of these for the aftermarket yet, but I’m taking orders today. Racer net on the case is going to be $1,449, and then you can add the bell and tailhousing that you need on from there. The case will accept a Reid bellhousing with a couple of small modifications as well,” Beattie explained.

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ATI T400 SuperCase Improvements:

• Tailhousing area vastly thicker to support 4 WD drive units and high HP cars
• Output shaft bearing installed and retained with snap ring
• Rear of case is larger to accept new sized gear ratios in back of case
• Rear band area thicker and supported for high line pressure applications
• Increased number of intermediate lugs and stand offs on case to drill and tap for center support locks
• Thicker through lug area and drum area for SFI 4.1 and overall case strength
• Accepts ATI Super Bell and other aftermarket bolt on bells with dual bolt patterns
• Labeled in and out Cooler lines and line pressure port
• Decreased depth of VB channels and minimum fluid routing for very quick shifts
• Larger and thicker shift lever support boss for no deflection during shift
• 3 positions for builder to position holder while building unit on bench
• Accepts 99% stock parts
• Machined in only 2 set ups total to assure parallelism on a brand new 4 axis CNC machine
• Cast in the USA and made in house at ATI