flexplate
{{Short description|Metal disk connecting car parts}}
A flexplate or flex plate is a metal disk that connects the output from an engine to the input of a torque converter in a car equipped with an automatic transmission.{{Cite journal |last1=Zhang |first1=Da Ke |last2=Wang |first2=Chong |last3=Yang |first3=Yi Chao |last4=He |first4=Han |date=January 2013 |title=The Layout Optimization for Axial Stiffness of a Flexplate Disk with Weight and Inertial Moment Constraints |url=https://www.researchgate.net/publication/272001167 |journal=ResearchGate}} It takes the place of the flywheel found in a conventional manual transmission setup.
Design
The name refers to the ability of the disk to flex along its main axis to account for gear changes and/or small misalignments as rotational speeds change.{{Cite web |date=2022-09-26 |title=Flex plate – What Does It Do? |url=https://www.gmride.com.my/blog/flex-plate-what-does-it-do/ |access-date=2023-10-23 |website=Guard My Ride |language=en-US}} Flexplates are generally much thinner and lighter than flywheels not only because of the required flexibility, but also due to the smoother coupling action of the torque converter{{Cite book |url=https://books.google.com/books?id=Lc54AAAAQBAJ&pg=PA62 |title=South African Automotive Light Vehicle Level 4 |date=2013-06-15 |publisher=Jones & Bartlett Learning |isbn=978-1-4496-9788-4 |language=en |access-date=2024-11-08 |via=Google Books}} and the elimination of the clutch surface.{{Cite web |title=How an Engine Flex Plate Works |url=https://www.2carpros.com/articles/how-flexplates-work |access-date=2023-10-23 |website=2carpros.com |date=2022-03-11 |language=en}}
Like a flywheel, a flexplate normally handles coupling to the starter motor via gear teeth cut along its outer edge. These teeth give the flexplate a gear-like appearance in spite of this being a secondary function.{{Citation needed|date=May 2024}}
Flexplates come in many forms, but are usually either stamped steel (for road cars), a machined two-piece billet (for race cars), or a machined one-piece billet (for high-performance drag racers).{{Cite web |last=Patterson |first=Jeremy |date=2015-11-23 |title=Flexplate Technology And Choosing The Flexplate For You |url=https://www.dragzine.com/tech-stories/drivetrain/bulletproof-flexplates-and-choosing-the-flexplate-for-you/ |access-date=2023-10-23 |website=Dragzine |language=en-US}}