Timing Belts Timing Belts have been used on camshaft and injection pumps on automotive engines for around 30 years. Dayco® manufactures timing belts for OEM’s utilizing the latest technologies in design and materials. The basic function of a timing belt is to transmit synchronous movement from one driven shaft to another . This is achieved by “meshing”between the tooth of the belt and the tooth of the pulley. A timing belt has a complex structure and is made up of three elements. A rubber compound (usually highly saturated nitrile) that makes up the toothed part and the back of the belt. Nylon (sometimes a double layer) is extremely flexible and used to cover the teeth. High modular fiber glass cords, which are resistant to tensile stress and will not deform give the belt its outstanding stability. All Dayco timing belts meet or exceed OEM specifications.