Hang Huge Axles Under Anything - Jp Magazine

Pete Trasborg Brand Manager, Jp

Looking back at it now, it seems inconceivable that we began this swap three years ago. You first saw it in “Jeep Full Size Axle Swap,” (May ’09). We told you then that we were swapping a Dana 60, Dana 70, and NP205 for a Dana 60, Dana 70, and NP205. We also worked the math and figured out how to run HMMWV tires and wheels under our M-715. The plan was to just do it at home, but we finally realized a driveway with a big incline, crawling on our backs, and huge parts didn’t mix. So, we took the truck and parts to Higher Ground 4x4 and Fabrication to get some help and we got the front axle put in it for the feature “Mix and Match 1-Ton Axles,” (Apr. ’12).

big Beef off Road Evolution Photo 37410320

Swapping axles is never an easy undertaking, and this particular swap was more difficult than most due to our rag-tag parts selection. We took the project to Off Road Evolution in Fullerton, California,for the final chapter of the swap. The crew there helped us put our drawn-out, three-year project to bed in about three days, and we picked up a few more pointers on axle swaps along the way.

PhotosView Slideshow One of the first things Off Road Evolution noticed when we dragged the truck into the shop was that the front steering linkage wasn’t right. The truck originally had high-steer arms on it, so we went with Dynatrac’s high-steer arms and steering linkage. What we didn’t notice was that once the truck was back on the ground, the drag link actually ran uphill from the pitman arm. A quick call to Dynatrac and we were able to get steering arms that swapped the tie rod end mount from over-the-arm to under-the-arm. Dynatrac also had the tie-rod end with the correct taper for our application. Some of our parts had been sitting around for a while but, after a good cleaning, Off Road Evolution was able to correctly set up the 4.56 gears. Notice the use of a case spreader—no hack-job gear installs in this shop. For one-stop-shopping, we got our gears, master install kit, and even the wheel bearings and seals from Randy’s Ring and Pinion. The original plan was to rebuild our NP205 so we picked up a full rebuild kit from Northwest Fab. We were also switching from a passenger-side drop T-case to a driver-side drop but we wanted to keep the shift levers in the factory location. So, we went with Northwest Fab’s bolt-on cable shifter kit for the NP205. Due to the location of our T-case and the location of our shifters, we needed to get longer cables. Fortunately, Northwest Fabrication stocks many various lengths, so that wasn’t a problem. Of course, we had to make some modifications to make them work with our shifters, but we’ve now got a driver-side drop T-case working with our factory shifters. The plan to rebuild the NP205 was chugging along smoothly. Until we realized the junkyard-fresh new-to-us driver-drop T-case was actually a Dana 24. After tearing through all the local junkyards in hopes of finding a divorced NP205 and coming up with nothing, we called Northwest Fab to see if we could return the rebuild kit and we were just going to use the Dana 24. Once they heard our story, they told us they happened to have this freshly rebuilt, divorced-mount NP205 in stock for $999. The tubular mount was based off the factory T-case crossmembers and built by Higher Ground 4x4 and Fabrication. Once we got under the Jeep, it was pretty clear where the T-case needed to go: the location was determined by the jackshaft of our Spicer 3053A transmission. Our old T-case was flat between the framerails and we’ve been wondering about a slight vibration. Off Road Evolution put the new mount in at an angle to match the angle the engine and transmission and keep the jackshaft straight. Lo and behold, our weird no-longer-a-mystery vibration has disappeared. The way the old T-case mount sat in the frame, there was no way for us to run the exhaust between the framerails and we ended up with rock-grabbing, leg-burning side pipes. The old mount also left no way to build a high-clearance skidplate. This time around it was possible not only to get the entire mount above the level of frame, but to angle it so that we could eventually run the exhaust inside the framerails and ditch the side pipes. We could have clocked the T-case down and not cut the floor, but the flat belly was more important to us than the floor of the cab. So, we just cut the floor of the cab until it was no longer in the way of the T-case. Our seat mounts just clear it and a simple sheetmetal box will close the gaping hole in the floor. The factory U-bolt plates were too small to accept the U-bolts for the larger-tubed axles so we had to make new ones. When we started this, we had no way to bend 1⁄4-inch-thick plate to make new ones, so we went with much thicker steel plate. All this time, we figured that the bent portion of the factory plate (arrow) was just for strength, but it turns out that isn’t all. According to Off Road Evolution, the smooth radius of the plate is also important so there is no stress point on the spring. The way our new plates are sitting on the spring, with no radius, will eventually lead the spring to break at that point. The plates had to come back off and get radiuses ground into them before we took the truck wheeling. From the factory, the M-715 has a drum parking brake on the rear output of the T-case. When we swapped in the previous NP205, we just threw the parking brake away. This time, we decided we’d like a little more safety than just leaving the truck in gear so we contacted TSM manufacturing for the company’s disc brake parking brake kit. The company didn’t offer an NP205-specific kit, but they did have a kit that had the correct size cap and bolt spacing for our 1410 yokes. We were just going to figure out a mount for our application and the company was going to entertain building and offering it. However, the disc didn’t work with our new JE Reel driveshaft. We are working with both companies to see if there might be driveshaft end/disc configuration that will work, so stay tuned. We went with dual-piston Ford F-250 calipers and custom heavy-duty caliper mounts. However, the ID of the mount was too small for the OD of our axletube. We just wanted to Jersey-rig it and torch the hole bigger with an oxy-acetylene, but we were vetoed by Off Road Evolution. Their reasoning is that if you torch-cut the bracket, it might not sit square on the tube, or the spacing from the rotor might be wrong and possibly result in vibration. In the end, it usually pays to do it right the first time. Our rear Dana was out of an ’87 Chevy and used a keyway and snap ring (A) to lock the axle hub nut down. We’ve seen issues with these and we were missing some parts anyway. Our old Dana 70 used hex nuts (B) and was a common way to hold hubs on 20 years ago. The problem with them is that they require a thin-walled socket to install and don’t leave much space between the nut and hub to work in. The parts on the right (C) are the current parts that Dynatrac uses and is our favorite setup for retaining hubs.