Last year, with the upgrade from 35" tires to 40" tires and the upgrade of the skid unit from RKO Enterprises, it was determined that the rear axle needed to be upgraded. The Sterling 10¼" axle is a heavy duty unit, but with the extra water and now foam, it had become marginal. It was not only the weight carrying capability, but it was the stopping power of the brakes as well. Even with a rear disc brake conversion, the truck did not even come close to stopping on a dime. So last year, after quite a bit of searching, a firm in Florida called Differential Engineering was discovered and a new custom Dana 80 was ordered in November of '06. The new Dana 80 axle was special ordered to be nearly six inches wider than stock, with dual piston Dana 60 calipers and a custom driveline parking brake mounted at the rear yoke. The new gears are 4.30 as opposed the the 3.55's that were installed in the Sterling. This is one heavy duty axle.
As you can see from the photos, the Dana 80 took a while to build and it was finally delivered in early 07. It was well crated and protected, especially considered it was shipped by Roadway. The axle was incredibly heavy and getting it loaded into the trailer was not an easy assignment. Once the axle was in my possession, I contracted with Liberty Sandblasting to paint it with gloss black superthane paint, as the other axles had been painted previously. They promised it back in a week, three weeks later it was finally ready, only to find that the paint job was less than perfect. It was not worth haggling about knowing the bare spots could be covered when the paint is touched up after the installation.
The driveshaft had to be modified as well because the new Dana 80 required a 1410 u-joint which the current driveline did not have. Before actually swapping the axles, the brake calipers and new yoke assembly had to be cleaned and painted as well as the brake rotors. After spending a considerable amount of time taping off the braking surfaces on the rotors, they were painted blue to inhibit rust. The brake calipers well then painted blue as well, using a quick drying enamel. All of these parts were allowed to dry overnight before being installed on the Dana 80 axle. Once installed, the axle was suspended from the shop crane at the back of the garage and the Mag-Hytec differential cover was installed. The truck was then jacked up, one side at a time. The tires and wheels were removed and then jack stands were placed under the rear leaf springs. This then kept the height of the truck at or near the same height as it was with the tires and wheels installed. Now that the truck was suspended, the rear axle could be removed.
The axle removal process began by removing the Air Lift air springs. This was very simple. the air lines are connected with quick connect style connectors. The air line popped out easily and the two bolts that attach the air springs to the truck frame were removed. Then the u-bolts that connect the bottom mounting plate to the leaf springs were removed and the air springs slid out and were set aside. Next the shock absorbers were detached from the axle and left hanging from the frame. The anti-sway bar was also removed. The driveshaft was disconnected at the yoke and suspended out of the way with a rubber tie down strap. Now it was time to bring in the jack to support the axle so the main u-bolts could be removed. Using a Craftsman ATV jack, the jack was rolled into place and raised up the bottom of the differential. Old towels and shop rags were used to keep the axle from getting scuffed and scratched. A ratcheting cargo tie-down was used to secure the axle to the jack so it could not roll off. Now the four u-bolts and two ORU lift blocks were removed and the Sterling axle was lowered down and rolled away.
Installation of the Dana 80 axle was pretty much the reverse process. Once the old axle was out of the way, the Dana 80 was lowered onto the Craftsman jack and secured. It was then rolled underneath the truck and raised into place. The ORU lift blocks were set on the spring pads and then the axle was raised the rest of the way up the springs. The new u-bolts which were purchased from St. Louis Spring were then slid into place. This was no easy task because three of the four u-bolts were too narrow at the "u". This caused the ends of the bolts to spread out as they were forced up around the Dana 80 axle. Fortunately, they were able to be squeezed together to fit through the new mounting plates which were fabricated at Differential Engineering. Needless to say, mounting the axle to the springs took significantly more time to accomplish than anticipated. Once they were in place, the Dana 80 axle was secure and the ATV jack was lowered and rolled out of the way.
Next, the u-bolts had to be cut down because they were about an inch too long. After they were cut and ground smooth, the nuts and bolts were painted to keep them from rusting and just to make them look nice. Now, the air springs were re-installed because this was the easy part. The next step was to get the parking brake caliper installed so the yoke could be lined up on the Dana 80 axle for the rear driveshaft to be reattached. This was not an easy task. The tolerances very tight and the thickness of the paint did not help things. The Mico brake caliper was finally put in place and bolted together. The anti-sway bar, for which mounting tabs were welded to the axle tube when it was being created, did not allow the factory Ford anti-sway bar to fit. The size of the differential housing is just too big. It may be modified later, but for now, the Dana 80 axle will be without a swaybar.
The next order of business was to reattach the shocks. This was a difficult task because of the high pressure with which these shocks are charged. It took some muscle to compress the shocks and get them in the mounts without letting them expand before getting the mounting bolt installed. After the shocks were taken care of, the driveshaft, after having been modified locally, was reinstalled and the u-joint was connected. The Dana 80 differential was filled with Amsoil's severe gear 75-90 gear oil along with two bottles of Ford Racing friction modifier for the limited slip differential. At this point, the truck was lifted up using a porta-power under the springs so as not to scuff the paint on the new axle. The wheels and tires were reinstalled and the truck once again was sitting on it's own rubber. The last task was bleeding the brakes. With new brake lines formed and installed, the air was bled from the lines and the Dana 80 axle swap was complete.
The truck was pulled out of the garage and parked sideways on an incline for about 20 minutes per side in order to allow the gear oil to flow into the hubs to lubricate the bearings. The only thing left is to connect the parking brake, but because that will require a custom cable and mount, that will be saved for another article. The Dana 80 axle is one beefy beast and the truck's stance is much wider now thanks to the non-standard width. Now, starting, stopping and cornering have been greatly improved. It was a big job, but it was well worth it. The Dana 80 should be the last major project for Project Responder. Now it's time to enjoy the fruits of my labors.