Automatic Transmission Flexplates

An automatic transmission flexplate is similar to the flywheel that is used with a manual transmission. Like the flywheel, a flexplate is mounted on the end of the engine’s crankshaft and rotates whenever the engine is running. It has a ring gear on its circumference that engages with the starter drive to turn the crankshaft when the ignition key is turned to start. The torque converter bolts to the flexplate just as the clutch mounts to the flywheel, and both assemblies transmit engine power to the transmission. The most common reasons for flexplate replacement are cracks and damage to the ring gear teeth. But no matter what kind of flexplate problem you’re having you can restore optimal function with one of our OE quality replacement and performance flexplates.

Unlike the thick and heavy flywheel, a flexplate is thin and light. The flywheel stores rotational energy to smooth the engine’s power output. Its inertia smooths out the intermittent power pulses created by combustion in the cylinders, effectively providing continuous power output. The mass of the torque converter serves the same purpose so the flexplate doesn’t need to be thick and heavy. The flexplate also doesn’t require the strength and density of a flywheel because it doesn’t have to provide the friction surface for a clutch disc as the flywheel does. But the main reason a flexplate is thin and light, and why it is so-named, is so it can flex back-and-forth in response to torque converter fluid pressure and crankshaft fore-and-aft movement as rpm varies.

A typical flexplate is constructed from a stamped steel disc to which a ring gear is welded. There may be holes strategically drilled in the disc and/or a small weight may be welded to the disc for balancing purposes. Of course, there are machined holes for the flexplate-to-crankshaft bolts and torque converter mounting bolts, and there may be larger holes for weight saving. For an engine to start the reciprocating assembly must rotate to draw in and compress the air/fuel mixture, which is then ignited by the spark plugs, enabling the engine to run on its own. When the ignition key is turned to START, the starter solenoid energizes the starter motor and engages the starter drive gear with the flexplate ring gear. An overrunning clutch disengages the drive from the ring gear when the engine starts.

A flexplate can crack because of engine-to-transmission misalignment or an engine or torque converter that is out of balance. If cracks are present, they will usually be in the area of the crankshaft or torque converter bolt holes. A knocking noise coming from the rear of the engine may indicate a cracked flexplate. Knocking can also be caused by loose or missing torque converter mounting bolts or a warped flexplate. If you hear grinding noise when you start your vehicle, the flexplate ring gear may have worn, chipped or broken teeth. Ring gear damage can be caused by long term use that involves frequent start-ups, a starter that is not mounted properly, such as one that is improperly shimmed, and on older vehicles, engaging the starter while the engine is running.

No matter what you’re working on or what kind of flexplate problems you’re experiencing, we have the replacement flexplate needed to restore proper vehicle operation. We offer flexplates that are manufactured according to original equipment specifications, so when repairs are completed you can count on the performance your vehicle was designed to deliver. In addition to flexplates, here you’ll also find flexplate reinforcements and flexplate mounting bolts. We also have each and every part needed to complement your vehicle's rev-happy engine, performance automatic transmission flexplates among them!