Replace as soon as possible if they are worn...... I drove my car late last spring on a sat nite ,coming back from a friends house,..cruising 95 mph ,top down ,elbow on door , along the conc barrier on the feeway...parked it over nite , took it out next morning and drove 300 yds up the street at 5 mph (max) when the upper ball joint on drivers side decided to break off!wheel just fell out at bottom , luckliy at that speed nothing happened... if it had happened 1 mi. earlier , i.e. nite before, I probably would have needed a new elbow, paint and body work....