DuPont™ Vespel®SP-21D Thrust Washers


Application Description

Thinner, lighter Vespel® SP-21D thrust washers replace all-metal needle bearings in a new 7-speed automatic transmission for rear-drive vehicles

Good mileage, compact design and fun to drive!

Occupying almost the same space as a 5-speed automatic transmission, JATCO Products’ new 7-speed transmission creates an exciting driving experience for luxury-class, rear-drive vehicles. The automatic transmission’s superior response time delivers both exciting acceleration and a quiet, leisurely experience depending on the driver’s desire – while still improving fuel efficiency.

Benefits Gained:

Reduced size, weight and number of parts

Vespel® SP-21D thrust washers are thinner and lighter than comparable metal thrust needle bearings, helping to reduce the automatic transmission’s overall size and weight. In addition, Vespel® SP-21D thrust washers can rotate directly against the aluminum housing, allowing a reduction in the number of parts and an easier assembly process.

Materials Selected and Why

Superior resistance to heat and wear. Capability of direct contact with aluminum components

Vespel® thrust washers have demonstrated many years of superb reliability in transmission applications due to:

  • The lack of melting point means the washer will not melt
  • A high limiting PV value (an indicator of resistance to wear) which is superior to other engineering resins
  • Low-wear rates when used directly against lubricated aluminum components, even in the presence of contamination or foreign matter in the oil
  • Custom-designed oil grooves on the washer surface allow precise control of oil flow, further enhancing resistance to wear
  • The ability to easily form an oil film on its surface which creates a very low coefficient of friction


Click here to view a PDF of the case study.