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Suspension Joints Exposed and Explained

1302 4wd 04 Suspension Joints Exposed And Explained Heim Joints
Kevin Blumer | Writer
Posted February 1, 2013

Rotate, Articulate

Details make the difference, a cliché that rings especially true in the case of suspension joints. There are a variety of suspension joints on the market, and one type does not fit all applications with the same aplomb.

This isn't a shootout. It’s a look at what’s available and the features and benefits of each type of suspension joint. While you’re testing your mettle on the trail, they’re rotating and articulating under your rig.

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Most stock vehicles come with rubber bushings from the factory, such as the upper and lower rear links from our 2004 4Runner. Rubber bushings have their downsides, but they’re desirable on a stock rig seen at the dealer lot. Why? Rubber bushings run silently, and they help insulate the vehicle body from road noise and vibration. Rubber bushings do not rotate or articulate, per se. The rubber is vulcanized and therefore permanently attached to the inner eyelet and outer sleeve of the suspension member. As such, the rubber distorts and twists rather than actually rotating or articulating. This quality also means rubber bushings resist movement and can actually limit suspension travel. Another downside is that much of the time you can’t just replace the bushing when it wears out. Instead, you’ll likely have to replace the entire suspension part.

Rod ends (aka Heim joints) are extremely popular in aftermarket and custom suspensions. They’re available in many sizes and are suitable in many suspension locations. For suspension applications, high-quality rod ends that incorporate a Teflon liner between the ball and the socket should be considered essential. The high-quality, Teflon-lined rod ends last longer, run smoother, and transmit less noise.

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Rod ends allow generous amounts of articulation between the threaded shank and the ball, provided you install a pair of high-misalignment spacers into the bore.

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One of the reasons rod ends are so popular in high-performance applications is that they’re so versatile and can be used in steering applications. In this case, a rod end was used to splice a non-matching tie rod and draglink together during a steering-box swap. Bolt-on parts wouldn’t work here, so some custom fabrication and a carefully placed rod end did the trick.

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If you want ultimate suspension geometry control through the complete suspension cycle, you’ll want rod ends (or spherical bearings, but we’ll get to that in a moment) along for the ride. This Early Bronco bristles with rod ends at every suspension pivot. The shocks are mounted to the links below the pivot plane’s centerline so the rear links don’t flop side-to-side.

The spherical bearing is often called a “uniball,” but the two words describe the same thing. Spherical bearings use the same ball-and-socket construction that rod ends do. The difference is that the spherical bearing is housed in a cup rather than in a housing with a threaded shank. The spherical bearing’s cup is welded to the suspension member.

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There are times when gobs of articulation can be too much of a good thing. One way to limit articulation is to use the “wobble stopper” from Kartek Off-Road. The Wobble Stopper is simply a spherical bearing equipped with a pair of Delrin inserts that prevents the bearing from articulating past a certain point. The spherical bearing itself is otherwise the same. The Wobble Stopper comes as a kit that you weld into your suspension part and is most commonly used at the frame end of lower rear suspension links on desert trucks.

Sources

Currie Enterprises
714-528-6957
www.currieenterprises.com
Dave's Customs Unlimited
Fruita, CO 81521
970-216-8179
www.davescustomsunlimited.com
Rubicon Express
Rancho Cordova, CA 95742
877-367-7824
www.rubiconexpress.com
Total Chaos Fabrication
Corona, CA 92880
951-737-9682
www.chaosfab.com
MetalCloak
Rancho Cordova, CA 95742
916-631-8071
www.metalcloak.com
Autofab
Santee, CA 92071
619-562-1740
www.autofab.com
Synergy Manufacturing
San Luis Obispo, CA 93401
805-242-0397
www.synergymfg.com
Kartek Off Road
www.kartek.com
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