It is rumored that polygraphite suspension bushings tend to “squeak”–do they also tend to be annoying when driving over tar strips–i.e. teeth breaking?
Yup they squeak more then the rubber bushings…But they last a lot longer.
The Polyurethane bushings were horrible. I’ve had good luck with the Polygraphite bushings not needing any additional lubrication over many years of use. Simply changing bushings is not going to lead to teeth jarring suspension. However, you are getting a trade off. Less deflection means it won’t be quite as cushy as with rubber. But it solves a whole host of issues if you’re looking for better performance.