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What’s Inside a Socket-Style Chassis Part?

Socket-Style Suspension Parts

While MOOG® steering and suspension parts come in many different styles, a common design used in many chassis parts is the socket style. Also known as rotational chassis parts, this design derives its name from its similarity to ball and socket of the hip joint of the human body. The socket-style design is used on parts that rotate such as:


Parts of a Socket-Style Chassis Part

Metal housing

The metal housing features the socket that prevents the ball stud from being pulled out. The strength of the housing ensures long fatigue life. MOOG housings are made of fine-grain alloy steel material to better handle high loads. Where applicable, the housing on MOOG parts may feature knurling, which is small ridges along the housing exterior to help with improving the seating depending on the need of the application.

Ball stud

The ball stud is a connection that allows rotational movement within the housing. Depending on its location, the ball stud can be subject to severe axial and radial forces. To resist these forces and prevent the stud from being pulled from the housing, an adequate pullout strength is required. The materials used will have a direct impact on the pullout strength. For maximum strength, MOOG studs are heat treated for durability to ensure that the stud will bend but not break in the event of a collision. It also helps prevent catastrophic failure.


The socket is filled with grease to provide lubrication, keep debris and water out, and maintain noise-free operation. Some MOOG ball joints feature a greaseable design that allow lubrication to flush out contaminants to extend the life of the joints. A non-serviceable socket design can’t flush contaminants from the assembly which can cause corrosion and wear.


Designed to ensure smooth rotation, bearings enable grease to flow through it directly to the surface of the stud. It also helps transmit force into the wall of the housing and cover plate. Bearings inside the housing can be comprised of sintered powdered metal like MOOG’s gusher bearing, polymer or reinforced plastic with carbon fiber.

Dust boot

The dust boot is a rubber boot opening in the joint to keep debris out and grease in. Many original equipment ball joints are designed as sealed units. If the protective boot fails, water and road debris can cause wear and premature failure. A dust boot can be exposed, or it can be integrated inside the part. MOOG has steering and suspension parts in both styles. An advantage of an integrated dust boot is that it can stand up to environmental extremes while allowing contaminants to be flushed.

Socket Preload (washer)

Acting as a spring, the washer preload reduces excessive clearance in the socket and maintains preload forces between the cover plate and the bearing. There are different types including Belleville washer and rubber washer.

Closure method

Known as the cover plate, this part closes socket components to minimize socket looseness. A spun closed cover plate is the traditional closure method while some MOOG parts use its patented pressed-in cover plate.

Learn more about premium steering and suspension parts, find your car part, or find where to buy your auto part today.

The content in this article is for informational purposes only. You should consult with a certified technician or mechanic if you have questions relating to any of the topics covered herein. Tenneco will not be liable for any loss or damage caused by your reliance on any content.

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