Universal joint: A mechanical device that transmits torque and/or rotary motion between two shafts, while permitting angular variances.
If you 'wheel your rig on a regular basis, chances are you've blown a universal joint. It's not hard to do, after all. Throw gobs of torque at your driveline, or mount up a set of 35-inch tires to those wimpy stock axles, and you're sure to hear the familiar "pop" that means it's time to get out the tools. It's nearly a rite of passage into the 4x4 world. Over the past few years, however, the aftermarket has been working diligently in an effort to eliminate this rite of passage through the production of high-strength and -performance U-joints. Does this mean you'll never blow a U-joint again? Not necessarily. But it does translate into a lot more assurance in your vehicle while on the trail. If you think it'll break, it probably will. So equipping your rig with the stoutest U-joint available is certainly an excellent means of keeping your 4x4 up and running through every obstacle in its path.
U-joint HistoryWith roots dating back to the 1500s, when a gentleman by the name of Jerome Cardan first discovered its basic principle, the U-joint as we know it came to fruition in 1903. While still a college student, Clarence Spicer was granted a patent for his first universal joint. Shortly thereafter, Spicer began manufacturing the new joint, and along with Charles Dana, he formed the Spicer Manufacturing Corporation. The universal joint quickly became the industry standard and is still employed today for innumerable automotive and manufacturing applications.
CTM Racing Products
Competition-proven to be one of the strongest axle U-joints on the market, CTM U-joints are available for Dana 44 and Dana 60 applications. The company also recently introduced a 1310-series driveshaft U-joint and a 1350-series unit is in the prototype stage. All the CTM U-joints are CNC-machined from 300M chrome-moly and are heat- and cryogenically treated to be virtually unbreakable. The U-joints are completely rebuildable and feature greasable bearing caps fit with bronze sleeve bushings. Built with a thicker body and a larger pin diameter, all CTM U-joints are offered with a lifetime warranty against breakage. When installing CTM U-joints, the company recommends using high-quality chrome-moly axleshafts.
Longfield Super Axles
Designed as an affordable high-strength U-joint upgrade, Longfield Super Joints have shown to be 30 to 40 percent stronger than stock. In creating its Super Joints, the company begins the process with Spicer 760X U-joints and applies a series of heat and cryogenic treatments. The bearing caps are treated to prevent cracking and are offered with grease fittings to maintain proper lubrication. Also, the needle bearings are replaced with high-impact brass bushings. Longfield Super Joints are available for Dana 44 and Dana 60 axle applications and include full-circle snap rings for installation.
The Brute Force U-joint from Neapco is a higher-strength upgrade from the company's standard design. Brute Force U-joints are available for driveshaft and front axle applications and feature a solid-forged crossbody for a higher load-carrying capacity. The U-joint caps are fitted with high quality, steel needle bearings and are precision-ground to provide a smooth rolling surface. Grease reservoirs at each trunnion end are pre-packed with high-temperature, water-resisting, synthetic lithium grease, and red Nitrile rubber seals are used to maintain the internal lubrication and reduce friction between the sealing surfaces.
One of the more unique U-joint offerings comes from Ox, maker of the manually activated Ox Locker. Currently available for Dana 30, Dana 44, and Dana 60 applications, the Ox U-joint is said to be twice as strong as conventional U-joints. The assembly consists of an 8620-steel ball that accepts four 8620-steel trunnion pins. The pins stretch to the center of the ball through aerospace bronze-alloy bushings and are secured by two retainer rings hidden beneath center access covers on both sides of the U-joint. Ox informed us that the ball shape of the U-joint cross effectively eliminates flex in the U-joint body. As a result, related stress upon this component is transferred to the axleshaft instead. The company intends to offer other versions of the Ox U-joint, including one using needle bearings that will be offered for driveshaft and everyday-use applications. Ox U-joints are available through 4 Wheel Parts Wholesalers.
The granddaddy of them all, Spicer U-joints still remain one of the most widely used U-joints on the market. The Spicer Life Series Cardan U-joint is the company's latest and greatest design, and is said to offer advanced features for longer life and superior performance. The U-joint cross is cold-formed for increased strength and partially drilled through to maintain strength and retain the premium lithium-based grease that's applied at the factory. A thermo-plastic seal guard and triple-lip seal prevent contamination from outside elements and help secure the bearing onto the trunnions. Flat-ended needle bearings are used within the bearing caps, which are installed along with composite thrust washers designed to reduce end galling and lower U-joint operating temperatures. Spicer offers a number of different grades of cardan-style U-joints available for various applications.
TCI Automotive's Performance U-joints are specially designed to meet the demands of off-road applications. Featuring a solid-body design and a forged construction, TCI U-joints are prepacked with synthetic-lithium grease and use Teflon-coated outer seals to reduce seal failure and the entry of contaminates. The bearing surfaces are ground and finished to offer precision operation and to ensure an accurate fit within the yoke. TCI Automotive U-joints are available for 1310- and 1350-series applications.
Tom Wood's Custom Driveshafts
Well known for its custom driveshafts, Tom Wood's has stepped it up a notch. The company now offers its Gold Seal U-joints, which are warranted against breakage for the life of the U-joint. The Gold Seal U-joints are manufactured using the highest-quality standards and have exceeded manufacturers' load, life, and strength requirements. U-joints are available for 1310-, 1330-, and 1350-series applications and feature a grease fitting in the body of the cross.
That's the Breaks
It's going to happen; you're going to break. Sooner or later, that U-joint will inevitably fail and you'll be trail side with tools laid out in the dirt. Luckily, however, it's fairly easy to dictate how often you'll experience such an occurrence. One of the most common causes of U-joint failure is lack of maintenance. By properly inspecting your driveline on a regular basis for irregular wear, improper geometry, or damage, you can effectively extend the life of your U-joints and related components. The following photos detail some of the common problems that lead to U-joint failure. If you've experienced similar results with the U-joints in your 4x4, consider having your driveline inspected by a professional to ensure that you're not on your way to creating any catastrophic damage.