This is a informative read:
https://www.hotrod.com/how-to/0609sr...ear-main-seals
Summing up the information:
* Until the 1980s rope seals were made from a woven asbestos material.
* Best quality modern rope seals are made from a graphite impregnated synthetic material.
* Rope seals need to be formed or rolled into the machined groove.
* Rope seals are more forgiving , they require less precision and allow for less than perfect surface finishes.