Rockwell 2.5-Ton Axles

For decades the 2.5 ton (2-1/2 ton) Rockwell axle has been the go-to axle for guys looking to run over 44-inch tall tires and a staple for rigs competing in the Top Truck Challenge. The tall third member, square axle tubes, and big six-lug pattern make them easy to spot. Inside of the nearly 300-pound third member is a 2.44:1 upper gear ratio which drives a 2.75:1 lower gear ratio. This four-gear reduction differential delivers a final drive ratio of 6.72:1.

Look for steering axles that are equipped with the more serviceable U-joint-style axle shafts. The giant drum brakes will be useless for most applications, so don’t sweat it if one is missing parts. If possible, try and rotate the yoke on the third member. What you are checking for is if it is tight or has a lot of play. This will give you a hint of what kind of shape the internals may be in. Without drum brakes these axles weigh around 700 pounds, so plan accordingly.

How Much More Do They Weigh?

Is there a huge difference between a Dana 44, Dana 60, and a 2-1/2 ton Rockwell? A complete Dana 44 frontend (defined as one with steering components and disc brakes) weighs approximately 240 pounds, a complete Dana 60 frontend weighs approximately 505 pounds, and a complete 2-1/2 ton Rockwell front steer axle weighs approximately 640 pounds. Obviously, if your rig were equipped with Dana 44s the weight increase in installing Rockwells would be substantial. However, if your truck is currently sitting on Dana 60s, the difference in weight to upgrade to a pair of Rockwells would be less than 270 pounds. The rear 2-1/2 ton Rockwells are a bit lighter in weight than the fronts because of the lack of steering components, which is minor if your rig tips the scales at more than 2 tons.

Axle Positioning

These axles can be configured in lots of different ways. In stock form, the fronts were bolted to the springs with the tie-rod facing behind the axle and the driveshaft flange on the passenger side. The rears also have the driveshaft flange offset to the passenger side. You can spin the axles 180 degrees on the springs or, because the center sections come with a driveshaft flange attached to both sides of the pinion shaft, you can rotate the center section 180 degrees on the housing by re-drilling a few holes. This will allow you to accommodate virtually any driveshaft offset or clearance issue you may encounter.

A few other things you may need to consider when locating these axles in your rig and deciding on the orientation of the driveshaft flanges is that the center section is massive and sticks 9-1/2 inches above the top of the axle tube. Interference with oil pans, crossmembers or suspension links is a definite possibility unless you get creative with your swapping and flopping.

Centersection

Double reduction-style – The upper ring-and-pinion gearset drives an intermediate gear that, in turn, drives the big, gnarly bull gear. The differential or locker is housed inside the carrier sandwiching the bull gear. As mentioned above, you can rotate the center section 180 degrees on the housing by re-drilling a few holes.

Improved Driveshaft Clearance

One key factor that makes the Rockwell axle desirable for extreme off-roading is the top-loading third member design. Well beyond that of a high-pinion Dana axle, the Rockwell features an input shaft that is mounted a full 9-1/2 inches above the center line of the axle housing allowing for super-flat driveshaft angles.

However, the extremely tall third member can make fitting these massive hunks of metal under a rig a real challenge.

Tires & Suspension

These axles have 6.72 gears, so unless you’re going to be running at least 42 or 44 inch tires and an overdrive, you can kiss highway-driving goodbye. Big tires, pliant leaf springs and even moderate power levels don’t work well with these axles. There’s so much gearing, weight and leverage involved that massive axlewrap is hard to avoid. Consider building a three or four link suspension off their square axle tubes instead.

Rockwell 2.5 Ton Axle Specifications

The above listed specifications are correct to the best of our knowledge, however, we cannot guarantee their accuracy.

Rockwell 2.5 Ton Replacement Part Numbers

 

The above listed part numbers are correct to the best of our knowledge, however, we cannot guarantee their accuracy.

Popular Rockwell Axle Upgrade Parts: 

ARB Air Locker (RD145)

Eaton Detroit Locker (225S15)

Yukon Grizzly Locker (YGLR2.5-16)

RCV 16 Spline Axle Shafts (CVJRCK-16)

RCV 16 Spline Flanges (RCK-SLUG-16T)

RCV 47 Spline Axle Shafts (CVJRCK-47)

RCV 47 Spline Flanges (RCK-SLUG-16T)

RCV 47 Spline Spool (RCK-SPL-47)

Mile Marker Lock-Out Hubs (11167-01)

Billet Inner Axle Seal Upgrade

Manual:

Rockwell 2-1/2 (2.5) Ton Technical Manual

Photos:

Click the photos to enlarge.