TOTAL TORQUE: Basic questions on the Turbo 400 Transmission

Author: Total Performance   Date Posted:16 June 2023 

TOTAL TORQUE: Basic questions on the Turbo 400 Transmission main image TOTAL TORQUE: Basic questions on the Turbo 400 Transmission image

TOTAL TORQUE:  Your Basic Guide to Turbo 400 (TH400) Transmissions in Australia

Welcome to our “How to” blog post called “Total Torque”.

Tags: Turbo 400 Transmissions, TH400, T400,


Welcome to our overview blog post about the Turbo 400 Transmission. Designed to provide you with basic information about Turbo 400 (TH400) transmissions. As the leading shop for top-quality Turbo 400 transmissions for sale in Australia, we're committed to helping you make informed decisions. Join us as we dive into the world of TH400 transmissions, answering your most pressing questions and equipping you with the knowledge you need to find the perfect transmission for your vehicle.

What is a Turbo 400 Transmission?

Exploring the Turbo 400: Discover the fundamentals of the Turbo 400 transmission, its design, and its reputation for durability and strength.

Key features and benefits: Uncover the advantages of the TH400, including its robust construction, high torque capacity, and compatibility with various applications.

How Does a Turbo 400 Transmission Work?

The TH400 is a three-speed automatic transmission that uses hydraulic power and sophisticated mechanical systems to deliver seamless gear shifts and optimize performance. It is renowned for its strength and ability to handle high horsepower and torque applications, making it a popular choice for muscle cars, drag racers, and heavy-duty vehicles.

At the heart of the TH400 is a complex network of components that work together to transfer power from the engine to the wheels. Let's break down the key elements and their functions:

Torque Converter: The torque converter is responsible for transmitting engine power to the transmission. It utilizes fluid coupling to smoothly transfer torque, allowing the engine to idle while the vehicle is stationary.

Planetary Gear Sets: The TH400 incorporates multiple planetary gear sets that interact with each other to create various gear ratios. These gear sets consist of sun gears, planet gears, and ring gears, which engage and disengage to deliver the desired gear ratio.

Hydraulic System: The TH400 relies on hydraulic pressure to control gear selection and shift timing. The transmission pump sends pressurized fluid to various components, including clutches and bands, to engage and disengage the gears.

Clutches and Bands: Clutches and bands play a crucial role in transmitting power and controlling gear engagement. The clutches, operated by hydraulic pressure, connect different components to lock or release specific gear sets. Bands are used to hold or release gears during specific gear changes.

Valve Body: The valve body acts as the control centre of the transmission, directing hydraulic fluid to the appropriate clutches and bands based on throttle input, vehicle speed, and other parameters. It houses various valves and solenoids that regulate fluid flow and pressure.

As you drive, the TH400 continuously monitors engine speed, vehicle speed, throttle input, and other factors to determine the optimal gear for performance and efficiency. The hydraulic system engages and disengages the clutches and bands, enabling seamless gear changes and delivering power to the wheels.

Turbo 400 Transmission Specifications:

Length and dimensions: The Turbo 400 transmission typically measures approximately 24.4 inches in length, allowing for precise fitment in a variety of vehicles.

Gear configuration: The TH400 boasts a three-speed configuration, consisting of three forward gears and one reverse gear. Aftermarket th400 gearboxes can also have a “Reverse” pattern where the 3 forward gears are reversed when using the selector. The reverse pattern sequence looks like this P-R-N-1-2-3.

Performance Capabilities and Capacity:

Handling horsepower: The Turbo 400 transmission is renowned for its ability to handle high horsepower and torque applications, making it suitable for high-performance vehicles and heavy-duty applications. Horsepower ranges generally start at 600hp and go up from there to 2000hp + depending on quality and combination of parts installed.

Weight considerations: Weighing around 135-150 pounds, the Turbo 400 transmission strikes a balance between strength and weight, contributing to overall vehicle performance and weight distribution.

Essential Maintenance:

Transmission fluid requirements: The Turbo 400 transmission requires approximately 12 quarts of transmission fluid to ensure proper operation and lubrication.  Consider aftermarket deep pans and aftermarket dipsticks to make sure you have the correct “levels”

Always refer to the manufacturer's recommendations for the specific fluid type and capacity. It is crucial to regularly check the transmission fluid levels and maintain them within the recommended range for optimal performance and longevity. Additionally, keeping the transmission fluid cool is important, as overheating WILL lead to damage. You must use an external transmission cooler and upgrading the cooling system to help maintain optimal operating temperatures.

Identification & Differences between Turbo 400 and Turbo 350:

Identifying a Turbo 400 transmission: To identify a genuine TH400 transmission, look for visual cues such as the distinctive pan shape and the unique oil filler tube location. Additionally, check the transmission case for "TH400" or "Turbo 400" markings. The TH400 typically has a larger case compared to the TH350. The fluid pan on the TH400 has 13 bolts, while the TH350 has 11 bolts. The TH350 has a TV (Throttle Valve) cable and the TH400 does not. These visual differences can help in accurate identification.

While both the Turbo 400 and Turbo 350 transmissions share similarities in their general design, they have distinct differences:

Torque capacity: The Turbo 400 is known for its higher torque capacity, making it ideal for high-performance and heavy-duty applications. The Turbo 350 has a lower torque capacity in comparison.

Gear ratios: The Turbo 400 features a different gear ratio configuration compared to the Turbo 350, providing different performance characteristics. The gear ratios for the Turbo 400 are as follows:

First gear: 2.48:1

Second gear: 1.48:1

Third gear: 1.00:1

Reverse gear: 2.07:1

The Turbo 350, on the other hand, has the following gear ratios:

First gear: 2.52:1

Second gear: 1.52:1

Third gear: 1.00:1

Reverse gear: 1.93:1


Congratulations! You're now equipped with more knowledge to navigate the world of Turbo 400 (TH400) transmissions. Total Performance stocks and sells top-quality Turbo 400 transmissions in Australia, we're here to provide expert guidance and assist you in finding the perfect TH400 transmission for your high-performance needs. Don't hesitate to reach out to our knowledgeable team for personalized recommendations and support.


Keywords: Turbo 400 transmission, TH400 transmission, Turbo 400 transmission Australia, Turbo 400 transmission specifications, Turbo 400 transmission performance, Turbo 400 transmission maintenance, identifying a Turbo 400 transmission, differences between Turbo transmissions.

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