Flywheel - Flexplate

Step by step instruction on how an automotive flywheel and flex plate works. This article pertains to all vehicles.

Step 1 - At the rear of every engine is a flywheel flex plate mounting flange in which these units are bolted to. Vehicles equipped with an automatic transmission are typically fitted with a flex plate which is thinner and lighter weight than its counter part, the flywheel which is usually designed for standard transmission vehicles.

Flywheel-Flex Plate Mounting Flange (Block Cutaway)

Step 2 - The flywheel is made of a sturdier design to accommodate the clutch assembly which is used in manual transmission applications.

Flywheel w/Clutch

Step 3 - Hybrid vehicles with automatic transmissions are fitted with a flywheel which is designed to couple the transmission to the crankshaft.

Hybrid Flywheel

Step 4 - The starter is used to turn the flex plate or flywheel to start the engine via the ignition key.

Starter Motor

Helpful Information

A flex plate or flywheel is designed with a ring gear on the outer edge which is used by the starter. These units also have the ability to help balance the engine while in operation. A flex plate can fail by forming a crack in the main web of the unit which is accompanied by a chipping or ticking that changes with RPM and engine load.

Standard transmission vehicles utilizes the extra spinning weight a flywheel to help smooth shifting characteristics. A flywheel provides the friction surface for the clutch assembly, this surface along with the clutch pressure plate creates the engagement platform of the clutch.


Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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