1949 Chevrolet - Back Surgery

Coming together, our axle also employs 11-inch drum brakes, 28-spline shafts, and a 3.55:1 gear ratio. This should be ideal for cruising, especially with the Gearstar 200-4R overdrive trans we're using, and with plenty of stopping power. While we're not going to make this a step-by-step axle buildup, it doesn't hurt to pass on tips, such as greasing the shaft before passing it through the seal. Our shafts had been drilled for a Chevy 5-on-4-3/4 stud pattern.

As explained, I'd long ago C-notched the frame and installed a couple of transverse thick-walled 2x1-inch crossmembers in anticipation of fitting airbags. CPP fabbed a couple of top mounts with tabs to locate the ShockWaves I'll now be using, as well as adding gusset plates down to the chassis 'rails. Note also, progressive bumpstops are now in place in the C-notches.

While Currie welded, straightened, and assembled the axle, CPP had sent out the crossmember, trailing arms, Panhard rod, and assorted bracketry to be powdercoated. Note this kit uses the same trailing arms offered in CPP's truck kits, which is why it features spring/airbag mounts on the top surface. Production kits for cars with stock floorpans (in other words, not C-notched!) may well make use of these, though ours employs brackets located on the axle U-bolts to mount the ShockWaves.

CPP's Craig Chaffers held the new crossmember while it was clamped in position. Note the large holes through which the exhaust system will eventually pass, keeping everything up above the lower edge of the chassis 'rails, which is important on a low car.

The end seals were installed once the housing was deemed straight. Not only does our axle have 3-inch tubes, but it also features Torino large-bearing housing ends.

With the crossmember clamped to the 'rails, the trailing arms were hung from it before being attached to the axle using U-bolts, in the same way Chevy truck axles are mounted. A bracket for the Panhard rod and another that serves as the lower mount for the ShockWaves were also located before the U-bolt was passed through all three components.

On the other side, spacer plates were added above and below the trailing arm to ensure the lower ShockWave mounts were the same height on both sides of the car.

With the U-bolts tightened and the trailing arms bolted to the crossmember, diagonal measurements were taken to ensure the assembly was square in the chassis before any mounting holes were drilled.

With everything square to within 1/16-inch, Craig started drilling the 3/8-inch mounting holes for the crossmember. If your stock fuel line is still attached to the chassis, take care here not to drill through it. The crossmember will bolt in place with all stock fuel and brake lines still in position.

The Panhard rod bracket was next clamped in position on the driver-side chassis 'rail and mounting holes drilled. Note it clears the stock fuel tank and fuel line.

The ShockWaves were the last components to go in. We opted for the 9000-series versions with a 5-inch stroke, as their collapsed length of 11.56 inches was perfect for our application. The offset pumpkin makes their top mounts look very close together in this view, and indeed I may look into fitting an antiroll bar at a later date, if body roll proves to be an issue.

Here's the complete assembly viewed from the front. I had already replaced the driveshaft tunnel with a higher one that cleared the closed driveline at full drop, yet the driveshaft is going to hit the tunnel (the yoke hits on full drop) with the 8-inch axle, so the progressive bumpstops in the C-notches should prevent this.

I'm pleased with the stance on full drop, especially since I never wanted it to "lay frame." This should provide a nice, low ride height when raised a couple of inches.