7. Installing the Super Joints into the axles is a pretty straightforward affair. Yukon provides detailed instructions with full color photos to help you along because installation is slightly different than a standard U-joint. For instance, if a small amount of dirt enters the bearings of a standard U-joint, it can find a place between the rollers and they'll actually function OK for a long time. The Super Joint, however, has only 0.002 inch of clearance between the bearing surfaces, so there is no room for contaminants. The technicians at Custom Differentials are well versed in installing the Super Joints, so installation was undramatic. One note: Because of the large amount of material on the yokes, we had to grind a small amount of material from both the inner and outer yokes so the U-joint would slip into the yokes.
8. The hole in the knuckle was only slightly larger than the beefy new Yukon axle yokes, so we had to tap the axle assembly with a hammer to get it through the knuckle. | 
9. Here you can see the driver-side Super Joint and axleshafts installed in the vehicle. As you can see, the grease Zerks are easily accessible for greasing. The Super Joint kit comes complete with a small grease gun and grease. Yukon recommends that under normal use greasing the U-joints four times a year should be sufficient. Vehicles that see heavier than normal use may need to be lubed more often. | 
10. Here's a view of the fully assembled front driver-side hub assembly as the last lockout-hub bolt is tightened. |
11. Swapping the new axles into the 14-bolt rear axle is relatively quick and painless. After removing the eight axle-flange bolts on each side, the axles can be removed from the housing. | 
12. Like the front axles, the new rear axles are made from a strong alloy that far exceeds the strength of the stock axles. They don't neck down quite as much at the spindle as the stock units, so that's also a strength-enhancer. | 
13. The 14-bolt axleshafts must be cut to fit. Here, the long side shaft is marked for resizing. After it's marked, it's taken to a chop saw to be cut to the proper length. |
14. After it's cut to length, the new axle is simply slid back into the 14-bolt axlehousing, sealed up with silicone, and the axle-flange bolts reinstalled. | | |
The Price of Strength
Not including labor, the parts we installed tallied around $2,000. We think that's a very acceptable price for the high level of strength we added to our axles. In addition, we could've decreased that figure by about $400 by using the less-expensive alloy axle joints instead of the Super Joints. That's a lot of bang for the buck.
Back From the Ashes
Custom Differentials is a full-service shop in Bloomsdale, Missouri, that specializes in everything from basic axle and diff repair to complete custom builds of axles and chassis. It's worth noting that the company is open for business after suffering a devastating fire that destroyed a large portion of its shop. "We have a new 4,080-square-foot fabrication shop equipped with a Mega Bender, CNC plasma table, and everything else needed to build custom chassis," says owner Jeremy Naeger.
Also worth mentioning are the on-grounds four-wheel-drive events which take place several times a year. For more information, visit the Web site at www.custom-differential.com.