The why and how is not important. The point is, you just busted your axleshaft U-joint and you’ve got to replace it. If you’re out on the trail, there are a couple of things you can bring along that’ll make the task much easier. If you’re in your garage, so much the better. To show you a couple of tips, we grabbed a set of roached full-size Dana 44 shafts from a beater and a brand-new set of G2 chromoly alloy axleshafts that are slated to go into a high-horsepower YJ project. Normally the PN 98-2031-002 shaft setup for Dana 30 axles come completely assembled, but we special-ordered an unassembled kit so we could run down some U-joint installation highlights.
Stock axleshafts use C-clips...
Stock axleshafts use C-clips to retain the U-joint caps. Older ones are almost always seized on with rust and filth. A flathead screwdriver and a few gentle whacks with a hammer will free them up. Pry out the C-clips from both sides.
We bought this 3-in-1 Ball...
We bought this 3-in-1 Ball Joint/U-Joint service kit (PN 38335) from Harbor Freight Tools years ago. It’s a real time-saver in the garage when installing U-joints. If you’re at home, once you’ve removed the C-clips chuck the clamp up in your vise and use an impact wrench or hand tools to drive the U-joint cups out of the shaft bores.
If you’re out on the trail,...
If you’re out on the trail, use a socket large enough for the U-joint cap to pass through on the bottom and another socket slightly smaller than the U-joint cap to drive out the joints. In lieu of beating on a good socket, we cut a section of heavy-wall DOM and keep it in our trail tool bin for this purpose.
Drive the U-joint cap almost...
Drive the U-joint cap almost all the way out of the shaft, but make sure the inner cap doesn’t come out of its bore, like this one has. Instead of trying to drive the outer cap all the way out, it’s better to grab it with a pair of pliers once it’s nearly free and twist it out, making sure the inner cap stays in its bore so it can more easily be driven out and the trunions freed from the shaft ears.
Despite their good construction...
Despite their good construction with 4340 chromoly steel, rolled splines, and larger 30-spline shafts, notice how the G2 Axle & Gear shafts come with genuine Spicer 760X U-joints. When used with full-circle clips, the Spicer joints will offer long-life and surprising strength. Unless you’re upgrading to fancy and expensive aftermarket joints, grab the Spicers if you have the option.
If you’re running full-circle...
If you’re running full-circle clips, make sure you install the snap rings before assembling the U-joint. There’s nothing worse than driving in the U-joint cap and then realizing your snap ring is laying there next to you. Be careful not to damage the seal.
Being careful not to let any...
Being careful not to let any of the needle bearings fall out and get trapped between the cap and trunion, gently drive the first cap into its bore. It helps if you hold the trunion up into the cap during this operation so that the needle bearings don’t fall out. If you have a second pair of hands, this is much easier. Resist driving the caps directly with the hammer once you get them started.
Once the cap is driven through,...
Once the cap is driven through, install the C-clip or snap ring into place and then carefully drive on the second cap. Gently pull the trunion up and partially out of the cap you just installed as you insert the second cap. This will help keep the needle bearings from falling out of the second cap until it’s centered in its bore.
With the second cap driven...
With the second cap driven down far enough to expose the C-clip recess, install the C-clip or snap ring in the second cap. Once both inner and outer shafts are assembled onto the new U-joint, check that the joint moves freely and without binding. A few gentle-but-firm raps on the shaft ears will free up the joint movement if it’s tight.