Making CV Joints Live

If you've lifted your IFS vehicle, there are a few things you're probably already living with that you wish you weren't. One may be vibration coming from the front drive axle assembly. Perhaps you live in fear of applying too much power off-road when you have the wheels turned at all. You might have already blown up your share of CV joints, or heard enough stories about other people doing it that you don't want to experience it yourself.

First, let us say for the record that CV joints aren't bad, they're just misunderstood. They are actually stronger than comparable U-joints because there is more contact area to distribute the torque load across. They also move throughout their entire range of operation without any binding. Take a straight-axle 4x4, turn full lock and drive. That crow-hop you feel is the steering U-joint binding and releasing as the axleshafts rotate.

So why do CVs fail? All joints fail when used beyond their original design. How many times have you been on the trail behind someone in a Jeep, changing the front-axle U-joint in his Dana 30 or behind a K5 Blazer knocking new U-joints in his Dana 44? One difference is that a CV joint is more entertaining when it lets go - with more broken parts, and generally more than a "snap." Another difference is that a broken U-joint doesn't always destroy an axleshaft. Although it almost always deforms the ears that the U-joint fits in (making it easier to fail the next time) you can usually replace the U-joint. A CV joint failure usually destroys the half shaft that it is attached to, so there are more expensive parts to replace every time there is a failure. The primary reason CV joints fail in lifted 4x4s is that they are expected to transfer torque while operating at greater angles than they are capable of. This is especially true with really tall or long-travel suspension systems, and is exaggerated when tires taller than 37 inches are used and there is some big horsepower involved.

The advantages of a CV joint design outweigh the disadvantages, though, so it was just a matter of time until someone made an assembly worthy of serious abuse. We started spotting orange caps on some massive CV joints under off-road racing and competition rock-crawl buggies with IFS. A little investigation led us to RCV Performance in Loves Park, Illinois. The company has been around for 60 years, making a variety of drivetrain components. At one point, the bread and butter of the company was making U-joints for all sorts of applications. As the team watched off-roading change over the last 10 years, they thought there was a need for a much improved CV joint.

The first thing they did was study what broke in the CV joint, and under what conditions. Even though CV joints are used in quite a variety of applications, two things became apparent. The failures were typically in applications with suspension lifts or in suspension systems with longer travel than stock, and all of the components in the CV joint were fairly weak. So they set off to build a better joint.

RCV joints are made from billet steel, and they do all of their own machining to deliver extremely precise manufacturing. They also found that contaminants, let into the CV joint by failed boots, contributed to failure. RCV Performance designed their Pro 4 CV joint as a round bell and developed a polyurethane cap as a seal. This is much more resistant to rips and punctures, and seals well as it slides on the outside of the bell.

In some applications, such as the infamous GM 1500, 2500, 3500 IFS, they discovered that using a plunging CV joint at the center section just didn't give enough travel as the suspension moved from full compression to full droop. So RCV combined a number of components to produce an assembly that accommodates the travel, range of angles necessary and strength to live on a lifted 4x4 with big tires.

The company offers CV joint solutions for a variety of models, including Hummers, Mercedes G-Wagon and others, in addition to custom CV joints and related components for anything you can dream up. They also manufacture high-strength axleshafts, drive flanges and related components.