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Suspension Joint Types: Which Ends Where

Bushings And Rod Ends
Jp Staff | Writer
Posted May 1, 2011

Urethane, Rubber, Rod Ends, And More

With so many suspension companies and options available, picking the right suspension lift kit for your Jeep can be a daunting task. Most lifts consist of a few common and somewhat similar parts such as new coil springs, shocks, and control arms. But what's on the end of those control arms often is the deciding factor that leads you to either recommend your lift kit to others, or to hate and replace it. And if you're building your own custom suspension components, your options become almost limitless. Ultimately every type of suspension joint has its place, but it may not be on your Jeep. Here are the editors' preferences when it comes to urethane, rubber, rod ends, and more.

Cappa's Endings
Rubber has been used as a bushing for nearly a century and it's still used today by every automotive manufacturer. Why? Because it's inexpensive, maintenance-free, relatively easy to replace, and it works. Rubber bushings absorb shock and road noise better than any other joint available. And when properly designed and applied, they can have a very long life. However, improperly applied and low-quality rubber bushings will have shorter lives than mud tires on a top fuel dragster. It's really all about the bushing's dimensions, design, and compound. It's hard to beat factory-Jeep, as Jeep probably spends hundreds of thousands of dollars and many man-hours designing a rubber bushing for a specific application. In most cases, these rubber bushings will outlive any of the other aftermarket options. Companies such as JKS know this. That's one reason the company uses the same original-equipment Jeep bushings in its adjustable control arms, and has done so since 1997. High-quality rubber control arm bushings are the best choice for 99 percent of lifted, street-driven Jeeps. Don't be fooled by cheap imposters-most aftermarket rubber bushings do not match OE quality.

Urethane bushings are typically stiffer and less flexible than rubber. Since they are oil resistant they can last longer than rubber in some applications. However, urethane bushings generally require frequent lubrication to keep them from making a squeaky racket. In high-movement applications, such as on a suspension control arm or track bar, the bushings will eventually wear, regardless of how often you lubricate them. They aren't sealed from the elements all that well and grease attracts dirt. The dirt and grease mixture acts like an abrasive compound on the bolts, bushings, and sleeves. This wear eventually causes unwanted slop in the connection. Urethane is good for leaf spring bushings, but it wouldn't be my first choice for a control arm or track bar end.

There are many different qualities of rod ends and the cheap ones have no place on your vehicle, but let's get one thing straight. Not all rod ends are called Heim joints. Heim is a company that builds rod ends. You wouldn't say, "I'll have a McDonalds," every time you order a hamburger, right? So with that out of the way, rod ends are for racing. Period. They are best applied in a clean environment where they are inspected or replaced every few hundred miles. If you run them through the mud and grime regularly and keep them in daily service for many thousands of miles, you'll be rewarded with loose, squeaky, and clunking control arms.

Rod ends are also rigid. Oh sure, they provide plenty of flex from side to side with the proper misalignment washers, but there is no give in a rod end. It's essentially a metal-to-metal connection. This can lead to suspension and frame brackets cracking and even tearing free. Adding a flexible bushing (rubber or urethane) to one end of a control arm can alleviate some of these stresses but it does little to increase the overall life of a rod end in a Jeep application.

Many people will disagree and maybe I'd feel differently if I lived in a wet state, but the one place where rod ends make sense to me is in the steering. That is as long as high-quality rod ends are used and they are mounted correctly. The only exception would be if the Jeep was driven daily. And like Hazel, I always use right-hand rod ends so I only need to carry one spare.

Rod ends make disassembly of the steering linkages much easier, especially for trail repairs. Sitting in a puddle while banging on the steering knuckle or pitman arm to get a ball joint to pop free isn't my idea of a good time. And it can't be good for the durability of any of the components involved. There really is no easy way to remove a ball joint. A pickle forks always destroys the dust boots.

Rebuildable joints such as the Super Flex joints from Rubicon Express and Johnny Joints from Currie Enterprises provide a good alternative to rod ends in suspension applications that see a lot of water and mud. They are not as harsh and rigid as rod ends, are just as flexible, but are slightly more rigid than solid rubber or urethane bushings. If you have a wet and muddy high-movement application that seems to eat even the high-quality stock Jeep rubber bushings, these greasable and rebuildable joints may be the answer. But you'll have to grease them regularly (every 3,000 miles or so), and in some cases keep them properly adjusted, or they will wear out quickly and make noise.


Currie Enterprises
JKS Manufacturing
Alliance, NE 69301
Rubicon Express
Rancho Cordova, CA 95742
Murray, UT 84107
Parts Mike
FK Bearing
Southington, CT 06489
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