Editing Constant-velocity joint (section)

=== Birfield joints ===
The Birfield joint is a type of constant-velocity joint based on the Rzeppa joint but confined the travel of the six balls using elliptical tracks. They have improved efficiency and are widely used in modern cars for the outboard driveshaft joints.<ref>{{cite web |url=https://www.beyonddiscovery.org/vehicle-technology/625-birfield-joint-based-on-the-rzeppa-principle.html |title = 625 Birfield joint based on the Rzeppa Principle - Vehicle Technology}}</ref>  The Birfield joint was developed by [[Birfield Industries]] and came into widespread use with the development of front-wheel drive cars such as the [[Mini]].<ref name="Nunney2007">{{cite book|author=Malcolm James Nunney|title=Light and Heavy Vehicle Technology|url=https://books.google.com/books?id=xLxySLNAe3YC|year=2007|publisher=Routledge|isbn=978-0-7506-8037-0}}</ref>