Back in the Apr. '07 issue, we chronicled the buildup of a completely new chassis for our '67 Chevy C10 sport truck by Orange County Auto Shop. The goal was to build a chassis that would lower the body closer to the ground without having to cut up the floor of the cab with a traditional body drop. To accomplish this goal, we built the chassis out of 2x4x0.120-inch rectangular steel tubing that was approximately 2 inches shorter in height than the stock chassis, which made lowering the body downward very easy. We also swapped out the stock 12-bolt solid rear axle, in favor of an independent rear suspension that featured a differential taken from an '03 Ford Expedition. The IRS kept the driveline from moving up and down with the movement of the suspension, and that also enabled us to further lower the body down on the chassis without having to modify the transmission tunnel within the cab. The chassis worked out beautifully, and now we are ready to finish up the front and rear suspensions.
Our control arms, like all of the bulkheads and crossmembers in our chassis, were built from 4130 chrome-moly tubing. All of our pivot points in the suspension swing on FK Bearings 1-inch spherical bearings and 3/4-inch rod ends. These bearings feature a Teflon liner to wipe the bearing clean as it rotates, and the entire assembly is much stronger than a standard bushing. We chose Slam Specialties airbags to actuate the suspension and provide ride height adjustment for a couple of good reasons. For one, they are reliable and have a great track record of not failing. Secondly, these airbags offer extremely good travel without the 'bag's outer diameter expanding greatly as air pressure increases. This means that the 'bags will fit well into tight spaces, which is what we are faced with when trying to package the 'bags, shocks, and rear axles all within the confines of the rear control arms. To control the movement of the suspension and keep the ride in check, we went with Fox Shox 2.0 reservoir dampers. These shocks are also fully rebuildable, and we'll be able to re-valve them, should the ride quality need improvement once the truck hits the road.
Our air source for the suspension comes from a pair of Air Zenith OB1 100-percent duty cycle compressors. These 12-volt air compressors offer quick fill times, are fully rebuildable, and have an oilless design, which means that maintenance is minimal. The compressors will fill two 3.3-gallon reserve air storage tanks, which we built ourselves. To control the flow of air between the storage tanks and the airbags, we chose AccuAir's VU4 electric valve and manifold combo. This very small system features eight individual valves built into a 5x3-inch aluminum manifold that will independently control airflow to all four corners of the suspension. Not only is the unit small, but it features 3/8-inch ports, so the air will flow fast and the suspension will move quickly, and it also comes with a pre-wired connector to adapt to any switchbox you like. Those are the basic parts we'll be installing in this story. Let's take a look at how it all came together.
'67 C10: 'Bag It, Drop It
1. Our control arms began life as 1-1/2 od by 0.120-inch wall chrome-moly tubing and 3/16-inch cold-rolled steel plate. After figuring out how wide the rear arms needed to be to accommodate both the shock and the airbag, we bent the tubing and attached the bearing housings that we bought from McKenzie's Performance Products in Fullerton, California. The arms were gusseted and TIG-welded together. The arm pictured here is one of the rear lower control arms. | 
2. To gain clearance for a longer stroke damper, we crafted a pocket in each arm that allowed us to drop the lower mounts for the dampers below the upper plate. This added 1-1/2 inches of stroke versus simply mounting the damper to the gusset plate. | 
3a. To install the spherical bearings into the arms, we first greased the housings and inspected the bearings to make sure there weren't any burrs present on the races. The bearings were then pressed into the housings, using a vise and a piece of tubing that contacted the outer bearing race and not the bearing itself |
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3b. Once the bearings were all the way into the housings, snap rings were installed to make sure they stayed there. | 
4a. The gusset plates we welded onto the rear LCAs will serve as the lower mounting points for our Slam Specialties airbags. Our upper mounts began life as a pair of standard 'bag plates that we bought from Master Image Customs. |
4b. These 1/4-inch plates have the bolt pattern and cutout for the air fittings already present for most any airbag, and they serve as an excellent starting point for designing your own mounts. | 
5. We attached the rear upper 'bag mounts to a crossmember we had previously built into our rear suspension bulkhead. Although not visible in this photo, there are three gusset plates behind and around the upper 'bag mounts to securely fasten them to the chassis. On the left-hand side of the photo, you can see we've begun mocking up our shock mounts, and the rear axleshafts are already installed into the differential. | 
6. Fox Racing shocks work well in many applications because you can re-valve the shocks at home. The remote reservoirs are overkill in this application because they are designed to keep the shock oil cool when running through rough terrain for extended periods of time. We won't be doing any of that, but still, the reservoirs will look cool strapped to our chassis, and the excellent function of these dampers make them worthwhile. |