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1998 GMC Suburban Axles - Bolt-in Brawn

Posted in How To: Transmission Drivetrain on May 1, 2007
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Have you fit your rig with bigger tires? Do you use your rig off-highway? Have you increased your rig's horsepower or torque?

If you answered yes to any of these questions (and we're sure you did), it would be prudent to consider upgrading your rig's axleshafts. You see, the axleshafts in your rig's axles were designed to function inside of certain parameters. When you fit bigger, grippier meats and attack a rough trail or start shoving more power to the axles, you will most likely exceed those parameters. So what will happen? Well, an axleshaft can snap; the splines can twist; or if we're talking front axles, the axle joints can be the weak link and self-destruct.

So what's the big deal? You can just drive slow and limp back to town, right? Uh, no, not always. Depending on the axle, the breakage may cause collateral damage (damage to other critical components) and/or the breakage can cause the vehicle to be immovable. Naturally, this is a major inconvenience and it could be life-threatening if you're 20 miles from help in the middle of nowhere.

Here you can see the Randy's Ring & Pinion front and rear axles, Super Joints, bearing kits, and other components that we installed. We also installed a pair of 35-spline lockout hubs to go with the new 35-spline outers.

The solution is to install a pair of upgraded axleshafts and U-joints before the stockers puke. Sure, this takes planning and money, but in the long run you'll save yourself the hassle and embarrassment (at the very least) of an incapacitated rig.

We want to give you the lowdown on what it takes to upgrade the axleshafts on two popular axles-the Dana 60 front and the GM 14-bolt rear. In this case, both axles are under a 454ci-powered '98 GMC Suburban 3/4-ton that rolls on 35-inch tires. The rig is a workhorse that is routinely used both on- and off-highway. We contacted two companies we trust: Randy's Ring & Pinion for the parts, and Custom Differentials for the installation. From Randy's we procured its Yukon alloy axleshafts for the 14-bolt, a Yukon Dana 60 4340 35-spline axle kit, a pair of Yukon 4340 chromoly Super Joints, and a pair of Dana 60 wheel-bearing kits. Ordering from Randy's is as easy as picking up the phone, thanks to the toll-free number and knowledgeable sales team. The team of technicians at Custom Differentials in Bloomsdale, Missouri, installed all of the components while we took photos. The axle gurus at Custom Diff can handle any axle build from mild to off-the-hook wild. This install was another day at the office for them.

Follow along as we show you how it all goes together and how the stock components pale in comparison to Yukon's beefy aftermarket components.

PhotosView Slideshow

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.

PhotosView Slideshow

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.

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


Custom Differentials
Bloomsdale, MO 63627
Randy's Ring & Pinion
Everett, WA 98204

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