Newsflash

A sway bar connects the frame on the truck to the rear end with a torsion spring called a sway bar (or more properly, an anti-sway bar). When there is a difference in suspension travel between the sides of the rear end, the sway bar twists, applying additional force to the rear end. This added spring force only happens when there is a difference in suspension travel, so in straight-line driving it is not applied. This method allows a good ride while having increased spring pressure in corners, improving cornering and decreasing body-roll.

Installation:

P-S-T sells polyurethane bushings with graphite made into the material, and I chose to pay for the upgrade. The rear bar, with poly bushings, is $159. P-S-T does not charge shipping in the U.S., which may be a deciding factor when choosing a new rear bar.

The rear bar installation is easier if you have some help, but isn't required. The first step is installing the D-shaped bushings on the bar. This may take some effort with a flat-tip screwdriver but isn't too bad. Use the screwdriver to flex the split in the bushing open enough to force it over the bar, and push the bushing into place. Their location on the bar isn't critical, as long as there is one D-shaped bushing on either side of the bar close to (but not on) the U-shaped part of the bar.

Set the bar on the rear end, arms facing forward (truck) or rear (Blazer) and the dip in the bar facing up, on top of the axle. Let the bar ends rest on the spring for now. Assemble the U-bolts as follows: U-bolt goes over the bottom of the axle, threads up; locking device (C-shaped piece of steel) on top of the axle with the open side facing the axle, then the plate, then the sway bar with the flat part of the bushing resting on the plate. Thread the nuts on the U-bolts but don't tighten them up yet. Install the other U-bolt in the same manner. The U-bolt assemblies don't have to be in any particular place on the axle, and don't have to be even with each other. Just put them as close to the drums as possible without interfering with anything. Now remove the nuts (one at a time) from the U-bolts and install the U-shaped brackets that retain the D-shaped bushings. I did this by removing a nut, slipping the bracket over it, and loosely threading the nut back on. I then removed the other nut, put the bracket in its proper position, and installed the other nut. This way the whole assembly didn't fall off while I was assembling it. Tighten the nuts just enough so that it won't fall apart (it must be loose to allow some final adjustment). The brake lines may get in the way of the U-bolts. GENTLY bend them out of the way so that they don't rub the U-bolts. The U-bolts should be between the axle and the brake lines. Don't kink the line -- it doesn't have to move much and there is enough line for it to be moved away without damage. Gentle persuasion with a large flat-tip screwdriver will work.

Next, assemble the end-links on the odd-shaped brackets. The assembly goes: bolt, cup washer (facing down), bushing (flat side to washer), bracket (dip down, mounting holes up), bushing (flat side down), cup washer (cup facing up), spacer, cup washer (cup facing down), bushing (flat side to washer), bar end, bushing (flat side down), cup washer (cup facing up), and nut. On mine, the end link spacers were a little short, so I added an additional washer under the nut to take up some of the threads; this won't affect the alignment of anything.

Now that the brackets, end-links, and bar are loosely connected, swing the bracket up to the frame (long side to the rear on trucks), and mark the frame for bolt holes. The truck MUST be resting on its wheels on its own weight when you do this. Now, drill four 3/8" holes, being careful of brake lines and the rear-end vent hose. I center-punched each hole, then drilled a 3/16" pilot hole, then a 3/8" hole for each bolt. It was easiest to remove the wheels to gain access to the frame where I had to drill the holes.

Tighten the end-links so that there is no slack in them, and the bushings are SLIGHTLY preloaded (15 ft-lbs. Max). They are retained by nylon lock-nuts, so they aren't coming loose. Overtightening here only ruins the bushings. Install the U-bolts in the frame, and swing the brackets up to meet them. This may take some maneuvering of the bar, which is why the axle bolts aren't yet tight. Tighten up the frame bolts evenly so that the bracket is pulled up flush with the frame; tightening up one nut completely first will put the U-bolt in a bind.

Finally, tighten up the axle U-bolts. 15 ft-lbs. Max here. Make sure the bar is retained and that a few threads are showing through the nut, but don't make them really tight as this serves no useful purpose. Overtightening these bolts only hurts performance.

Now bounce the truck some to make sure you don't have clearance problems (i.e. exhaust, spare tire). That's it! You're done.