When you try something that hasn't been done before you can run into some issues; as with any project vehicle, our Ultimate Avalanche was swinging from fun to frustrating. When we last checked in, our 2003 Chevy Avalanche was stripped and on the rack at Off Road Unlimited, plus we had just picked up two brand-new axles from Dynatrac. The plan was simple enough: Put the axles under the truck, use suspension components from our friends at Tuff Country, and add an Atlas transfer case for good measure. The problems arose when we wanted to incorporate our special rear axle with rear steer, and make the computer-controlled transmission communicate with the geardriven transfer case. In the end almost everything worked, and we only had to throw a few things across the shop in frustration. You would think that being big-time magazine guys, we would have all the cool stuff and not have any problem building a rig, but that is only slightly true. We do have all the cool stuff, it's just tricky to put it all together on an unusual platform. Follow along as we get our Ultimate Ulcer--er, Avalanche--closer to being a trail-taming freak machine. The guys at Off Road Unlimited were excited to see us every morning, though it was probably more because of the Krispy Kreme donuts than because of the bright and shiny attitude. Mauricio Natera was happy to install some brackets from which to hang our Tuff Country springs on the front of our Av. Off Road Unlimited has done many solid axle swaps in the past, but never on an Avalanche.The guys at Off Road Unlimited were excited to see us every morning, though it was probabl Next we stuck our Dynatrac Pro-Rock 60 under the front of the truck. We decided on 6-inch lift springs, though we may go to 4-inch springs eventually if the truck sits too tall. We like our vehicles low, but with as much ground clearance as possible. The front will also be getting two Tuff Country SX8000 performance shocks on each side.Next we stuck our Dynatrac Pro-Rock 60 under the front of the truck. We decided on 6-inch In the rear of the truck we had a few rules we wanted to stick with. No lift blocks because we don't like axlewrap, and narrow springs because we had a special rear-steer axle made and we didn't want the tires to hit the springs. Our solution was to move the springs under the frame instead of out on the sides. This should meet all our needs by allowing us to run a lower lift spring and possibly give better articulation since the axle will now have more leverage on the springs, though towing may be a bit scary. We started by building front spring hangers for the frame from some 1/4-inch plate.In the rear of the truck we had a few rules we wanted to stick with. No lift blocks becaus For the rear shackles we had a few obstacles. First we needed to box the frame and then cut a hole and sleeve it. For this as well as most of the other welding we used Miller Electric MIG welders.For the rear shackles we had a few obstacles. First we needed to box the frame and then cu Then we did some mocking up to see where the springs would extend to on full stuff and at ride height, and finally we made some shackles and bolted everything up.Then we did some mocking up to see where the springs would extend to on full stuff and at Initially we planned on going spring-under. Though this seems archaic to some folks, we felt the loss of ground clearance would be offset by also losing almost all the axlewrap. We even went so far as to get this awesome spring-under U-bolt plate kit from Dynatrac. The biggest problem we ran into was that the 6-inch lift springs we had were still just too short for the truck. Finally we changed directions and went spring-over in the rear with Tuff Country 3-inch lift springs. This ended up working out perfectly and left just enough room for the rear-steer components, which we will touch on next month.Initially we planned on going spring-under. Though this seems archaic to some folks, we fe Because our rear axle has steering knuckles, we needed a way to lock it out for highway driving. For this we asked Karl Knoll to do some extreme machining for us. Knoll works at Off Road Unlimited and loves to make things with the lathe and chromoly.Because our rear axle has steering knuckles, we needed a way to lock it out for highway dr We also contacted Aurora Bearing for a set of its 3/4-inch rod ends. We recommend these lockout bars running from the steering knuckles to some custom tabs welded to the axletube for any street-driven rig with rear steer. Though it's a slight hassle to remove them before hitting the trail, it is good insurance.We also contacted Aurora Bearing for a set of its 3/4-inch rod ends. We recommend these lo We could've kept the NV246 and converted it to bolt-on yokes, but we didn't want the front driveshaft spinning all the time. A 4.3 Atlas transfer case from Advance Adapters would solve all of our problems and give us a better low range.We could've kept the NV246 and converted it to bolt-on yokes, but we didn't want the front The final adapter setup we used included an adapter on the back of the automatic and a 1 1/4-inch spacer. We clocked the Atlas to get a near flat belly under the truck, and only had to notch the crossmember slightly. A tranny mount from Energy Suspension fit perfectly on the adapter, but we had to slightly modify the crossmember. High Angle Driveline outfitted our gearbox with a rear-driveshaft parking brake since none of our axles had parameters for one. We like to be difficult, thus we ended up modifying his mounting bracket so we could reach the stock e-brake cable, but it locks up great and should hold the truck on any hill if need be.The final adapter setup we used included an adapter on the back of the automatic and a 1 1 To shift the transfer case we cut a hole in the tunnel right beside the driver's right leg. A little heat from the torch allowed us to bend the levers slightly, and we were quickly shifting with ease. The fit was so easy we almost thought GM might have once been considering an Atlas as a standard feature. Yes, we'll keep dreaming.To shift the transfer case we cut a hole in the tunnel right beside the driver's right leg With the axles in place, we moved to the driveshafts. Again we contacted High Angle and quickly had two shafts at our door. The rear shaft has a 1410 joint at the axle and the 1-ton 1350 CV at the Atlas, and installed like a dream. The front shaft was supposed to have a 1410 CV to deal with the steep angles and another 1410 joint at the axle. When lack of sleep and lack of lunch are combined with not enough space for the awesome 1410 CV, frustration kicked in. The problem was that the CV was just too big and burly and was not going to clear the automatic transmission. We finally settled down and decided on a special smaller U-joint, that High Angle wanted us to test, which would handle the angle. We have every confidence that it will hold up, but even so we packed a spare.With the axles in place, we moved to the driveshafts. Again we contacted High Angle and qu The final mission for this month was to get a signal from the transfer case to the computer, to convince everything to work in harmony. Since the stock transfer case had a speed sensor, we needed something that would duplicate the signal to the computer, but it had to be run off the Atlas. The still-unsolved solution came from Abbott Enterprises in the form of a Signal Generator and an Electronic Ratio Adapter (ERA).The final mission for this month was to get a signal from the transfer case to the compute The Signal Generator plugs into the speedometer gear on the Atlas, and then produces an electrical signal. This signal, which runs through the ERA to the computer, originates from the generator mounted under the driver's seat by Eric Garding of ORU. Theoretically, after some test runs you dial in the perfect setting in the ERA and the speedometer works. This let the truck run and drive and had the tranny shifting. However, there were still some "check engine" lights on, and we felt there were some issues with the way the tranny was shifting. We'll explore those issues and others next month.The Signal Generator plugs into the speedometer gear on the Atlas, and then produces an el SOURCES Advance Adapters 4320 Aerotech Center Way P.O. Box 247 Paso Robles CA 93446 805-238-7000 Aurora Bearing Co. 6-30/-859-2030 email@example.com Energy Suspension 1131 Via Callejon San Clemente CA 92673 Abbott Enterprises High Angle Driveline Off Road Unlimited www.offroadunlimited.com Miller Electric 8-004-AMI-LLER www.millerwelds.com Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!