Link Bushing

• The suspension system features numerous bushings between its different parts and the vehicle frame. Those that are found particularly on the linkages are called link bushings.
• Link bushings are designed to allow some movement between the linkages and the parts they are connected to. They are also meant to absorb and dampen vibration and noise as a type of anti-vibration mounting.
• Depending on the system style, link bushings may be found in components including link rods or sway bar links, end links, link pins, trailing links, Panhard rods, lateral links, and top links.
• The material of the bushing greatly determines its durability and performance. Some materials that are used to make link bushings are rubber and polyurethane.
• Having worn or damaged link bushings might not only make driving uncomfortable and difficult but could also make it dangerous. It is then best to change them as soon as possible.

For a vehicle to move, its wheels need to have constant contact with the road or ground. Without this contact, the wheels and tires would not be able to translate the power from the engine into motion. What helps keep the wheels on the road is the suspension system. It is a network of parts that provides certain degrees of freedom to the wheels so they could follow the contours of the ground.

In addition to helping the wheels stay in contact with the road, the suspension system also supports various internal components and parts in the undercarriage. It is also designed to make the ride more comfortable by minimizing the road noise and vibration that is transmitted into the cabin. Providing the necessary flexibility and noise and vibration suppression in the suspension system are bushings, a type of anti-vibration mounting.

The suspension system features numerous bushings between its different parts and the vehicle frame. Those that are found particularly on the linkages are called link bushings. Just like any other flexible mounting in the suspension system, link bushings are designed to allow some movement between the linkages and the parts they are connected to. They are also meant to absorb and dampen vibration and noise as a type of anti-vibration mounting.

There are several linkages in the suspension system. Depending on their location, their purpose is to control the surge, yaw, pitch, and sway of a vehicle. With the linkages working together with the other suspension components that manage the heave and roll, the system is able to control the six degrees of freedom of a vehicle.
 
Link bushings typically look like thick cylindrical washers and are usually inserted in the connection points of the linkages. They serve as a pivot for links that don’t feature ball joints at the attachment points. In this manner, the link bushings become the interfaces that prevent metal-on-metal contact and minimize friction between the components.

As mentioned, there are multiple linkages in a suspension system. The type and configuration of the system determine the number and kinds of links it has. Some types of suspension systems are MacPherson struts, multi-link, and torsion bar. Depending on the system style, link bushings may be found in these components:

• Link rods or stabilizer, sway bar, anti-roll bar, or drop links
• End link
• Link pin
• Trailing link
• Panhard rod
• Lateral link
• Top link

The material of the bushing greatly determines its durability and performance. Since the movements of the suspension system and body, such as sway and roll, affect steering, handling, ride, and general drivability, the link bushings should be made to meet the vehicle's performance requirements. Additionally, as the suspension system endures great and opposing forces such as vehicle load and road impact, the bushings like the sway bar link bushings should also be able to handle the forces. Some materials that are used to make link bushings are:

Rubber

Highly elastic and flexible, rubber makes for supple bushings that can provide considerable cushioning to the rigid suspension parts that they hold. Bushings made from this material, such as rubber sway bar link bushings, isolate and absorb vibrations and noises well. Automakers often use rubber link bushings as they meet the standards for noise, vibration, and harshness (NVH) reduction.

Polyurethane

Bushings made of polyurethane are rigid compared to those made of rubber as the material is turned into hard plastic. Since they are rigid, polyurethane bushings tend to conduct more vibration and noise through the suspension system and into the cabin. On the other hand, the stiffness of this type of bushing, like polyurethane sway bar link bushings, allows for firmer handling as the movement of the suspension parts are more limited.

Some of the other materials used for bushings include metals like aluminum. While these could be highly rigid, they could be designed and shaped to still provide some movement in the suspension system while also making handling very stiff. Because of their characteristics, metal bushings are often only used in high-performance applications.

Link bushings could also be made of a combination of materials. When link bushings feature components that are made out of different materials, the quality and performance of the bushing could be augmented.

Like all car components, link bushings could wear-out over time. They could become warped, degraded, or damaged due to the forces they experience. They could also become weaker with age. Because of their location, worn link bushings could affect the performance of the suspension system. A few of the signs of bad link bushings include:

Unusual Sounds

Since link bushings are situated at the attachment points and serve to cushion the suspension linkages, they would fail at preventing metal-to-metal contact when they become worn or warped. Degraded link bushings could also cause looseness at the connection points. The bumping and rubbing of the linkages could then result in clicking, clunking, knocking, and rattling noises.

Poor Handling

Having bad link bushings could affect a vehicle’s movement and handling. Worn, warped, degraded, or damaged link bushings would not be able to securely hold the linkages. The excess movement between the linkages could cause handling to be sloppy, twitchy, and unstable.

Having worn or damaged link bushings might not only make driving uncomfortable and difficult but could also make it dangerous. It is then best to change them as soon as possible.

The primary consideration in looking for link bushing replacements are your vehicle's year, make, and model. Carmakers usually employ different types, designs, and configurations of suspension systems. As such, the linkages and their bushings might not be the same across different makes of vehicles and even two models from the same automaker. These details could also determine the type of sway bar link bushing replacement that you would need. Whether you choose rubber or polyurethane link bushings, replacement parts need to be compatible with your vehicle to ensure that they would fit.

Another thing to consider in getting end link bushing replacements would be the kind of performance that you prefer. If you are satisfied with the feel and handling of a factory suspension system, then it is best to go for replacement link bushings that are made of the same material as the stock part. On the other hand, if you would like your vehicle to have firmer handling, opting for link bushing replacements that are made from a more rigid material like polyurethane might be the way to go. Typically, original equipment manufacturers (OEMs) use rubber to make bushings. Meanwhile, polyurethane bushings are usually available as aftermarket replacements and can be bought at auto parts stores like CarParts.com.