The Turbo 400, or TH400, is a legendary transmission known for its incredible strength and durability. A staple in the muscle car and high-performance world, it’s the go-to choice for handling massive amounts of torque from built engines. Whether you’re building a street machine, a drag car, or restoring a classic, getting the right parts for your TH400 is crucial for reliability and performance.
This guide cuts through the noise to bring you a focused roundup of essential components and kits for your TH400 project. From complete transmissions and rebuild kits to critical seals and accessories, we’ve compiled a list of top-tier products to help you build a transmission that will stand the test of time and power.
Top ATI Turbo 400 Transmission Parts and Kits
- DYMO 69110 LabelWriter 400 Turbo
- Turbo Bee 400 Pack 8oz Paper Cups
- HAHAHA TH350/TH400 Firewall Mounted Dipstick
- Leak Stop Seal Kit for TH400 Transmission
- Polaris RZR Stage 5 Audio Upgrade 400 Watt
- TH400 Stage 1 Deluxe Level 2 Rebuild Kit
- TCI 241000 TH400 StreetFighter Transmission
- JEGS TH400 Performance Transmission
DYMO 69110 LabelWriter 400 Turbo
While not a transmission part, organization is key in any workshop. The DYMO LabelWriter 400 Turbo is a thermal printer that creates professional, smudge-proof labels instantly. It connects directly to your computer via USB, allowing you to print from popular software or its dedicated label application.
This tool is perfect for labeling transmission parts, organizing bins of hardware, or marking electrical connections during an install. Keeping your workspace and parts clearly identified can save significant time and prevent errors during a complex build.
Turbo Bee 400 Pack 8oz Paper Cups
These disposable paper cups are a practical addition for any garage session. Made from food-grade safety paper, they are a reliable choice for coffee, water, or other beverages while you work. The leak-proof coating ensures the cup remains sturdy and won’t become soggy, even after holding liquid for an extended period.
With a pack of 400, you have a ample supply for personal use or for when friends come over to help with the project. Their durability and value make them a simple but effective way to stay hydrated without the risk of damaging your tools or transmission parts with spills.
HAHAHA TH350/TH400 Firewall Mounted Dipstick
This firewall-mounted flex dipstick is a smart solution for vehicles where the factory transmission dipstick tube location is problematic. Engineered for a direct fit with GM TH350 and TH400 transmissions, it serves as a reliable replacement for damaged or missing original equipment. Its flexible design allows for easier routing and installation in tight engine bays.
Constructed from high-quality materials, this dipstick is built to withstand the conditions of high-performance driving. The clear, easy-to-read scale provides accurate fluid level readings, which is essential for maintaining proper transmission operation and preventing damage from low fluid levels.
Leak Stop Seal Kit for TH400 Transmission
A common source of leaks on the TH400 transmission is the speedometer housing. This dedicated leak stop seal kit is designed for a precise fit on TH400, TH375, and TH475 transmissions, ensuring an efficient seal to prevent fluid loss. The kit provides a total solution with a housing O-ring, speedometer shaft seal, and a seal retainer.
By effectively sealing the speedometer cable connection, this kit helps maintain proper transmission fluid levels. This simple fix can prevent more serious issues like overheating and component wear, ultimately extending the life of your transmission and saving you from more costly repairs down the road.
Polaris RZR Stage 5 Audio Upgrade 400 Watt
For those who enjoy their high-performance vehicles beyond the pavement, this audio system brings concert-quality sound to your Polaris RZR. The heart of the system is a powerful 400-watt, 12-inch subwoofer that is designed to acoustically couple with the vehicle’s cockpit for impressive bass response. Its plug-and-play design allows for a seamless installation.
The package is powered by an integrated 400-watt, 4-channel amplifier engineered for the rugged off-road environment. It also includes two 6.5-inch front speakers and two high-output tweeters, all positioned to direct sound precisely at the rider for an optimal audio experience during any adventure.
TH400 Stage 1 Deluxe Level 2 Rebuild Kit
This deluxe rebuild kit is a comprehensive solution for restoring your TH400 transmission to like-new condition or better. It is packed with high-quality components, including Raybestos clutches made in the USA and a premium Transtec gasket kit. The quality of these parts meets the standards demanded by professional transmission installers.
The kit includes everything needed for a thorough rebuild: Stage 1 friction plates, Kolene steel plates, bands, bushings, bearings, seals, and a filter. Using this kit provides assurance that your rebuilt transmission will have the durability and performance to handle increased power and rigorous use.
TCI 241000 TH400 StreetFighter Transmission
The TCI StreetFighter TH400 is a fully assembled, performance-built transmission ready for installation. It is engineered to handle the demands of street performance and mild strip use, offering a significant upgrade over a stock unit. This transmission comes with a built-in bolt-in deep cast aluminum pan for improved fluid capacity and cooling.
It features performance-calibrated valve body for crisp shifts, a heavy-duty sprag assembly for increased strength, and a high-stall speed torque converter matched to the transmission’s specifications. For builders looking for a complete, out-of-the-box solution that saves time and provides reliable performance, the TCI StreetFighter is a top contender.
JEGS TH400 Performance Transmission
JEGS is a trusted name in performance parts, and their TH400 Performance Transmission is built to deliver. This unit is designed for high-horsepower applications, making it suitable for serious street machines and competition vehicles. It comes fully assembled and tested, ready to handle the torque of a powerful engine.
It includes numerous upgrades over a stock transmission, such as a performance valve body for improved shift quality, upgraded clutches and bands for increased holding capacity, and a precision-machined case. Choosing a JEGS transmission provides a robust and reliable foundation for any high-performance project where durability is non-negotiable.
Buying Guide: How to Choose the Best ATI Turbo 400 Transmission
When I’m building a serious performance vehicle, the transmission is one of the first things I consider. You can have all the horsepower in the world, but if your transmission can’t handle it, you’re going nowhere fast. The TH400 is a legendary platform, and ATI Performance Products takes it to a whole new level with their built units. But with a few options available, picking the right one is key. This buying guide will walk you through what to look for in an 8 Best ATI Turbo 400 Transmission Review and Selection Guide.
First, you need to be honest about your power goals. Are you building a stout street machine, a weekend drag strip warrior, or a dedicated race car? ATI categorizes their transmissions based on torque capacity for this exact reason. Their Street Fighter line is perfect for most high-performance street applications, while the Super Street Fighter can handle more power and occasional strip use. If you’re running a serious nitrous or boost setup, you’ll be looking at the Pro Street Fighter or the race-only units. Matching the transmission to your engine’s output is the most critical step; too little capacity and you’ll be shopping for a new one soon.
Next, think about the converter. This is a huge part of the transmission’s personality and performance. ATI offers their own renowned torque converters, and the stall speed you choose will dramatically affect how the car drives. A lower stall is better for a street car that sees a lot of cruising, while a higher stall is necessary to get a high-horsepower engine into its power band off the line. Don’t just guess on this; talk to a tech expert at ATI or your builder. They can recommend a stall speed based on your cam, rear-end gears, and tire size.
You should also consider the internal components and options. Are you planning to run a manual valve body for complete control, or do you prefer the convenience of a full-auto? What about the gear ratios? While the TH400 has a great set of stock ratios, ATI can tailor these for specific applications, like a deeper first gear for better launches. Also, look at the case. For extreme power levels, an aluminum case is lighter and can be stronger, but it’s also more expensive. For most builds, the nodular iron case is more than sufficient. Finally, think about the output shaft and yoke. Make sure you get the correct length and spline count for your driveline.
My final piece of advice is to think about the future. It’s often smarter to buy a transmission rated for a bit more power than you’re making right now. This gives you room to grow without having to rebuild or replace your transmission after your next engine upgrade. A well-chosen ATI TH400 is an investment that will last through many iterations of your project.
Frequently Asked Questions
What makes an ATI TH400 better than a stock unit I have built locally?
The main difference comes down to consistency, component quality, and engineering. ATI uses their own specially designed components, like their Super Sprag assembly and hardened intermediate shafts, which are significantly stronger than even the best aftermarket stock-style parts. Every transmission is dyno-tested before it leaves their facility, so you know it works. While a good local builder can make a strong transmission, ATI’s process is standardized and backed by extensive racing R&D, which gives me a lot of confidence in the product.
Can I use an ATI TH400 in my street-driven car?
Absolutely. This is a common misconception. Their Street Fighter and Super Street Fighter lines are specifically engineered for street and strip use. They are fully automatic, shift smoothly under normal driving, and are built to handle the heat and stop-and-go traffic of street driving. You can absolutely have a brutal, 1000+ horsepower transmission that behaves perfectly on the street. The key is selecting the right model and pairing it with an appropriate torque converter stall speed.
Do I need to run an external transmission cooler?
Yes, and this is non-negotiable in my book. Heat is the number one killer of automatic transmissions. Even for a mild street car, an external cooler is cheap insurance. For any performance application, the stock radiator cooler is not enough. ATI will often recommend or include a specific cooler with their transmissions. Proper cooling will dramatically extend the life of your fluid, clutches, and seals, making it one of the best investments you can make for your drivetrain.
What kind of horsepower can the different ATI TH400 models handle?
ATI rates their transmissions by torque, but we often think in horsepower. Their Street Fighter models are typically rated for up to around 700-800 horsepower in a street/strip car. The Super Street Fighter can handle up to about 1000 hp. For anything beyond that, you’re looking at the Pro Street Fighter and their race-specific models, which can handle well over 1500 hp and massive torque from boosted or nitrous engines. It’s always best to consult their latest catalog or website for the most current torque ratings.
How do I decide between a full manual valve body and a full automatic?
This comes down to how you use the car and your personal preference. A full manual valve body requires you to shift every gear manually; there is no “Drive” setting. It provides instant, positive shifts and is ideal for a dedicated race car or a street car where you want total control. A full automatic valve body will shift on its own, just like a stock transmission, but with much firmer, performance-oriented shifts. For a car that sees a lot of street miles or is driven by others, the full auto is the much more user-friendly choice. When reviewing an 8 Best ATI Turbo 400 Transmission Review and Selection Guide, this is a key comfort and usability decision.
What maintenance is required for an ATI TH400?
These are built to be robust, but they aren’t zero-maintenance. You should regularly check the fluid level and condition. After initial break-in, I always recommend changing the fluid and filter. Depending on how hard you run it, subsequent fluid changes should be performed more frequently than a stock transmission—perhaps every 10,000-15,000 miles for a street car or after a certain number of passes at the track. It’s also a good idea to periodically check the tightness of the transmission mount, crossmember, and driveshaft bolts.