How Flex Plates Work


A flexplate is designed to work with engines fitted with an automatic transmission unlike the flywheel which is associated with manual transmission vehicles. Though performing the same task of transferring engine power to the transmission and holding the ring gear which the starter uses to crank the engine over the flexplate is vastly lighter in weight than a flywheel which is heavier to hold the clutch assembly. Made of stamped steel the flexplate is balanced and can only be mounted onto the crankshaft one way. Acting like a solid coupler the flexplate is bolted to the crankshaft and to the automatic transmission torque converter.

What goes wrong?

 Due to the stress of the engine delivering power through the torque converter a flexplate can crack causing a clicking noise when the engine is under load or idling. If this condition is left unattended it will break completely severing the engine power from the transmission. When a starter motor malfunctions it can cause abnormal wear on the ring gear which is used to mesh with the starter motor pinion gear. This condition will be accompanied by grinding while the starter is in use.

What's the cost?

Replacing the flex plate means removing the transmission in most cases. This cost will vary depending if you have front wheel, four wheel or rear wheel drive vehicle. Typically charges will be between $700.00 to $1300.00 (US) plus the cost of the flexplate which can cost between $90.00 and $140.00 (US) in most cases.


  • Lighter weight than a flywheel
  • Designed with a ring gear for the starter
  • Attaches to the torque converter
  • Bolts to the crankshaft of the engine
  • Can crack creating a ticking noise

Let's see!

Here is the job of the flexplate sitting between the engine and automatic transmission. In this image you see the transmission being removed exposing the flexplate which is normally covered by the bell housing.
flexplate transmission

The starter motor uses a ring gear mounted to the flexplate designed to turn the engine over for starting.
ring gear


Our certified technicians are ready to answer flex plate questions for free. We hope you saved money and learned from this guide. We are creating a full set of car repair guides. Please subscribe to our 2CarPros YouTube channel and check back often for new videos which are uploaded regularly.

Article published