These cars came with a th400 transmission

What is a th400 transmission?

TH400 transmission refers to the automatic shift, three-speed transmission popularly known for its durability and legendary transmission. It is commonly used in large engine applications as it can function more reliably than other transmissions.

It was first introduced to Buick and Cadillac, Chevrolet, and Oldsmobile cars and made its way to heavy trucks after a while. It has become a popular option for transmission in the automotive industry and is present today in many cars.

Due to its strength, it makes a suitable conversion transmitter more efficient in adaptability to cars than those without the TH400.

This technology was primarily used in Buicks and Cadillacs launched between 1965-1967. For a while, it was changed to 3L80 (3-speeds, Longitudinally positioned, 8000 lbs. GVW) when it was introduced to heavier-duty GM trucks.

The transmission is still done in many cars such as Jaguar, Ferrari, Jeeps, Rolls-Royce, GM, Buick, and Cadillac cars. Some features that the th400 transmission carries are the aluminum and iron construction integrated bell housing, its weight (weighs 135 pounds without fluid and the gears.

These characteristics make them popular as they assure durability, which is a big concern for many car owners. Another significant factor that is highly considered is engine compatibility and adaptability.

Car models have carried this transmission technology; thus, it has remained in production, especially for military applications and heavy-duty GM. Below are some of the models that incorporate the th400 transmission.


Th400 is predominantly used in these cars since their engines are compatible with the transmission. They are mostly made of high-quality steel that contributes to their durability.

Buick V6 or V8 versions are popular in this sense and have shared the same pattern with the Pontiac, Cadillac, and Oldsmobile. The cars have been made since 1961 with the V8, a first generation manufactured in 1953.

More vehicle makers have shared their engines’ popularity, thus becoming one of the most shared engines. Dealerships have taken up these models and used them for most of their productions too.

The Buick V8 and V6 version were primarily used, and their engine capabilities are compatible with the th400 technology. The th400 gear transmissions can last up to 60,000 miles so they can be very reliable.

However, regular service and maintenance are essential at any stage for good care of your car. Th400 will also vary according to the models, such as Oldsmobile, Pontiac, and Cadillac.

This technology was mainly used until the late 80s; therefore, some new automatic transmissions may not work effectively with the th400.

The adapters range between $600 and 900, thus affordable. You, however, have to ensure that compatibility is achieved.

AMC/Mopar Jeep

Under American Motors Corporation (AMC), the Jeep brand has also been a well-sought car. Despite using a variety of transmissions, Jeep has had a heavy-duty three-speed automatic transmission used in full-sized jeeps.

These were under the SJs and J series, built in the late 60s. Later, the AMC engine pattern was used, which was different from the SJs, which followed the BOPC (Buick, Oldsmobile, Pontiac, Cadillac).

A Mopar Jeep can cover a mileage of 80,000 to 150,000 miles. With an automatic transmission system, engines are more durable and thus durability of the transmission system.

Transmission is essential, especially with engine compatibility; therefore, you must consider it effectively.

Jeep offers service options to give you convenient approaches toward transmission assembly. While there is a difference between the first th400 and the AMC versions that have the AMC style case, other models are compatible with the AMC 16 and V8 engines.

Details can be obtained for the AMC service center, where conversion can be made possible. Therefore, you can improve your Jeep’s powertrain through other transmissions like the torque converter that is essential in changing gears.

Mopar car transmission systems also offer replacements for select models of Jeep and Chrysler. The average cost of the th400 transmission for Jeeps is $2800 and can only be effective on distinct models.


Th400 has been famously linked to the Chevrolet models, made initially compatible to cover the Chevy 90. These were manufactured in 1965 and grew popular before General Motors (GM) turned to other modes of automatic transmissions, like the Chevrolet’s Powerglide.

Th400 transmission was a practical option as it led to the high performance of Chevrolet Small and Big Block drives up to 1991 when Powerglide entered the market.

Strength and durability were a convenient option taken up, especially by General Motors, in the past before other models were introduced.

Total mileage covered for the th400 models was close to 60,000 with transmissions, which created a standard of durability and efficiency.

Over time, the advancement of transmission technology has contributed to the growth of solid and high-performing cars. The average cost of the Chevrolet th400 aluminum heavy-duty transmission case is around $1,100.

Like the Mopar Jeep, compatibility is critical, so it can only apply to a few models or brands. Other costs incurred can be in servicing the product since building the th400 needs to be done by reliable professionals.

It significantly shifts from modern automatic transmissions but offers good performance and quality.


The th400 technology was also used in Rolls-Royce, which started in the late 60s to 1990. It was made of cast iron, forming the center support for the transmission assembly.

This was fitted to the LHD and Phantom V and VI models, which were equipped with this technology in 1992 when the last GM400 gearbox was made.

Rolls-Royce is among the first cars with the th400 that did their fittings with specifications that led to durability and reliability for extended periods.

The Rolls-Royce productions are consistent, and even in the th400 technology, the gear could cover 55,000 very reliable miles.

The average price of the transmission case is $2,000; replacements and repairs are priced differently depending on where you take your car for service.

Despite its popularity in the past, introducing new automatic transmissions widely helped with efficiency. A common issue with the th400 is that in the case of high rev from the engine, it may quickly shift early and, in the process, lessen efficiency.

This is a result of a malfunctioning kick-down switch responsible for shifting gears and maintaining power usage. Thus this inconvenience during transmission.

Sucking more power from the engine in this process leads to inefficiency, even though it is stronger.

Take away

The TH400 was a reliable transmission even though used in the early years of car manufacture and production. It was convenient and the beginning of the automatic transmission technology, inspiring car makers and other production sectors to focus on converting the engine power to transmission in shifting gears.

Cars such as Jeep, Chevrolet, and Buick are examples of the first cars where the make was dominantly used.

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