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How do Transmission Adapter Plates Work

When looking at a new engine, transmission or transfer case for an off-road ride, you may have been told that you also need a transmission adapter plate. But why, exactly, is it important to use this part? And why is it that some transmission adapters are so expensive? Knowing the answers to these and other questions will help you hit the right combination for power and torque when you’re going adventuring.

What Is a Transmission Adapter Plate?

An adapter plate is something that lets you join two parts or components that won’t fit together in their OEM form. This could be because they are different sizes and shapes or have different fittings. You’ll find them in almost any industry, including appliances, home electronics and medical equipment.

In the case of transmission adapter plates, they allow you to connect different transmissions, engines and transfer cases while operating as they were designed to from the get-go. If you want to use a certain combination that isn’t offered by the vehicle manufacturer, the right transmission plate lets you do so without having to completely overhaul the rest of the drivetrain.

Most off-road transmission adapters are flat metal plates with holes for the bolt attachments. Although simple at first glance, they must be incredibly strong to withstand the power and torque these components generate.

Types of Transmission Adapters

There are two basic custom transmission adapter designs. Engine to transmission adapters, or bellhousing adapters, are for when you replace either of these components with an aftermarket part that doesn’t fit. Likewise, transmission to transfer case adapters may be needed to mate these components when making upgrades. In both cases, the plate will align the transmission input shaft with the motor/transfer case shaft.

It’s important to also note that you may need more than just a transmission adapter plate when doing engine swaps. Other required parts to help everything connect properly can often include custom flex plates, flywheels, clutches and torque converters.

Can an Adapter Plate Combine Any Engine and Transmission?

Theoretically, you can match any engine to any transmission — or any transmission to any transfer case — using the right adapter. However, you also need to account for the power ratings of each. If you connect a 405-horsepower LS6 engine to the stock transmission in a Toyota Camry, then your transmission will be overtaxed and fall apart. An adapter plate may also not work if the gearbox shaft has a different number of splines as the engine.

Finally, even if an engine and transmission will work in theory, that doesn’t mean they can realistically be mated. Some combos are too large to fit together or fit underneath your vehicle without interfering with other parts — or they may just require too much effort to be worth your while. Do your research before starting to make sure you’re on the right track. The experts at Advance Adapters are happy to answer your questions Monday-Friday and help you find the correct transmission plates.