TH400

Stepping up in strength and capability, the Turbo 400, or TH400, is renowned for its resilience under pressure. This three-speed automatic transmission has been the backbone of many high-performance and heavy-duty applications since its inception. Its ability to manage significant horsepower and torque makes it a preferred choice for drag racing and off-road ventures.

There are numerous variations in design, configurations, and customizations available for the TH400 transmission, allowing for tailored builds to meet specific performance needs. With so many variations and custom options available, finding the right TH400 transmission for sale is easier than ever for enthusiasts and builders alike.

Benefits of the TH400 Transmission

If you’re considering the TH400 transmission for your project, there are several advantages that set it apart from other automatics. Its proven history in both factory applications and high-performance builds makes it a trusted choice for enthusiasts who demand strength and dependability.

Legendary Durability – The TH400 transmission was engineered to handle serious torque and horsepower. Built with a durable OEM case, direct drum, and forward drum, the TH400 is engineered to handle significant horsepower and torque, making it a top-rated choice for drag racing, off-road builds, and custom performance vehicles. With a cast-iron center support, robust geartrain, and heavy-duty components, it was built to take abuse in everything from drag cars to heavy-duty trucks.

Proven Performance – For decades, the TH400 has been the go-to transmission for racers and builders. Its consistent performance and ability to transfer power efficiently have made it a staple in drag racing, muscle cars, off-road vehicles, and commercial applications. When reliability and strength are non-negotiable, the TH400 delivers.

Simplicity & Reliability – Unlike later transmissions that rely on complex electronics, the TH400 is fully mechanical. This simplicity translates into fewer failure points and easier maintenance. Builders appreciate its straightforward design, which makes repairs and upgrades more accessible compared to modern electronic units.

Adaptability for Builds – Whether you’re restoring a classic, building a street/strip car, or outfitting an off-road rig, the TH400 transmission adapts well to a wide range of setups. With broad aftermarket support, it’s easy to find parts, upgrades, and rebuild kits. Its compatibility with numerous GM engines also makes it a natural fit for swaps and performance projects.

Frequently Asked Questions About the TH400 Transmission

Is a TH400 a 3 speed or 4 speed?

The TH400 transmission is a three-speed automatic transmission. It does not feature an overdrive gear like later transmissions, such as the 4L80E. Instead, it delivers strong, efficient power transfer across its three forward gears, making it highly effective for high-performance, towing, and racing applications where strength matters more than fuel economy.

Is the TH400 a good transmission?

Yes! Many enthusiasts consider the TH400 to be one of the best automatic transmissions ever built. Its legendary strength, proven track record in both factory and racing environments, and mechanical reliability make it a trusted choice even decades after its introduction. Whether you need a durable option for a muscle car, a heavy-duty truck, or a drag strip build, the TH400 continues to hold its own.

What’s better, TH350 or TH400?

The TH350 and TH400 each have their advantages, but the TH400 is generally stronger and more durable. It was designed for higher horsepower and torque applications, making it the better option for heavy-duty or racing use. The TH350, being lighter and more compact, is often preferred in lower-horsepower builds where weight and efficiency are priorities. If your project demands maximum strength, the TH400 is typically the better choice.

How much HP will a TH400 handle?

In stock trim, the TH400 is capable of reliably handling around 450–500 horsepower and substantial torque, depending on the application and condition of the transmission. That is of course, based on stock trims: some custom builds are rated for over 1000 hp.

Choosing the Right TH400 Transmission For Your Build

Because the TH400 has been around for decades, it’s not hard to find a TH400 transmission for sale from aftermarket builders, specialty shops, or online marketplaces. The key is knowing how to choose the right one for your project. Investing in a high-quality, properly rated TH400 transmission can save you money and time by reducing the need for future repairs or replacements.

Availability of Rebuilt and Custom TH400 Transmissions

Enthusiasts can choose from factory-style rebuilds that restore the transmission to its original specifications or custom-built versions tailored for racing, towing, or high-horsepower street use.

If you opt to go with a custom-built TH400 transmission, you can request features like upgraded shift kits, custom gear ratios, or heavy-duty internals to match your application’s demands. Key components such as steels and torque converters can be selected based on your desired performance characteristics.

Why Buying from a Trusted Builder Matters

While it may be tempting to buy a used unit or an inexpensive rebuild, not all TH400 transmissions are created equal. A poorly assembled or worn transmission can quickly lead to failure under load. Protecting your investment is crucial, so always choose a reputable supplier who can guarantee the authenticity of the transmission and its components.

Choosing a transmission from a trusted builder ensures that quality components, proper assembly techniques, and real-world testing are part of the process. This is especially important if you plan to push the transmission with high horsepower or heavy towing demands.

Buy a Custom-Built TH400 Transmission from Gearstar

When it comes to getting the most out of your build, trust matters, and Gearstar is a leader in crafting high-performance TH400 transmissions designed to meet the demands of muscle car restorations, drag racing setups, off-road rigs, and heavy-duty trucks. Each unit is assembled by a single master technician, ensuring meticulous attention to detail and unmatched craftsmanship.

Every Gearstar transmission is built-to-order, not mass-produced. Once assembled, each unit is thoroughly dyno-tested under real-world load conditions to guarantee flawless operation before it leaves the shop. This extra step ensures that your transmission performs exactly as intended the moment it’s installed.

Backed by quality assurance and customer satisfaction, Gearstar transmissions are designed to deliver years of trouble-free performance. Plus, our shipping and pricing options are transparent, allowing you to know exactly how much it will cost to get your custom-built TH400 transmission from our shop to your garage. If you’re searching for the highest quality TH400 transmission for sale, Gearstar can deliver a custom-built unit designed specifically for your project.