A hub between car wheels and suspension
Ball joint is a sphere bearing that connects control arm to steering knuckle. It connects to casing of control arm and bearing bolt of wheel side. Its operating principle is similar to ball socket of human hip joint. Ball joint acts as a hub between car wheels and suspension. Ball joint installed on lower control arm categorizes into press-fit, bolt, rivet, and arm unit. Ball joint installed on wheels has upper fastening type and pinch bolt fastening type.
Design: Housing material for ball joint includes steel type and plastic type of ball socket. Steel type collocates with M to M ball stud and steel bearing, and uses grease nipple to lubricate continuously. On the other hand, plastic uses mirror polished ball stud and plastic bearing (lupital POM). It seals special compound grease when in production, and does not include grease nipple.
Reminder: Some competitors use low label steel or incorrect heat treatment. This can lower the price, but also lower parts use life by 30%.