Flexplates

Is there an automatic transmission between the engine and the wheels in your project? Then it's the flexplate that transfers power from the crankshaft to the torque converter. We stock flexplates in both standard and billet versions for e.g. Ford, Dodge and BMW, and several of them fit diesel engines.

What does a flexplate do?

The flexplate bolts to the crankshaft and connects the engine to the torque converter in an automatic transmission. It sits in the same place as the flywheel on a manual gearbox, but is typically thinner and lighter, because the torque converter itself provides the necessary mass. The plate also carries the starter ring gear. Increased torque, higher boost pressure or hard use can cause cracks around the bolt holes in a stock plate, which is why many choose a stronger version for their project. If your car has a manual gearbox, you should look at flywheels and clutch kits instead.

How to choose a flexplate

• Engine and transmission: The plate must match both the engine and the transmission type, e.g. 5R110, 6R140 or 68-RFE, and often the model year as well. Always check the part number against your car.
• Material: Billet versions are machined from solid material and are usually stiffer than a pressed stock plate. Whether that's necessary depends on torque and use.
• Certification: Some products are SFI certified, which may be required in certain motorsport classes.
• Ring gear and bolt pattern: The tooth count must match the starter, and the bolt pattern must match the torque converter.

When installing, you should typically use new bolts, threadlocker and the specified tightening torque. Also make sure the torque converter is correctly engaged with the transmission pump before the engine and transmission are pulled together. In this category you'll find e.g. ATS Diesel with billet flexplates, BD Diesel and Pure Drivetrain Solutions, which offers a flexplate for BMW B48/B58/S58.

Frequently asked questions

What is the difference between a billet flexplate and a standard flexplate?

A standard flexplate is typically pressed from sheet steel. A billet version is machined from solid material and is usually stiffer. What makes sense depends on torque, use and transmission.

When do I need an SFI-certified flexplate?

Some motorsport classes require SFI-certified parts in the drivetrain, e.g. when the car runs faster than a certain limit. Check the rules for your class, and make sure the certification applies to the specific part number.

How do I detect a cracked flexplate?

Typical signs are a clicking or knocking noise from the bell housing, especially at idle or during gear changes, as well as vibrations. Cracks often form around the bolt holes. Stop driving and have the plate inspected.