Factory shocks on pickup trucks are usually a compromise among a number of disparate factors. The price the original equipment manufacturer pays is one factor, as is passenger comfort and how well they hold up when people use the truck.
The 2015 GMC half-ton used for this upgrade story was as top of the line as you could get in 2015 without opting for the Denali package. As fancy as it was, the shocks felt underdamped, especially in rebound. It would handle small bumps OK, but larger bumps really unsettled the truck.
Another rub was that it came with P rated tires. The P stands for passenger car, which isn’t very truck like, nor is it ideally suited for towing, which is one of the reasons people buy trucks in the first place. Duh.
The owner upgraded the wheels and tires to E load range LT, which underscored how bad the factory shocks were, so it was clear the suspension cried out for an upgrade, too.
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We went with Bilstein 6112s for the front, which come with springs, and can be adjusted to four different height settings. For the rear, we went with Bilstein 5160s, a monotube shock with a piggyback reservoir, and we upgraded the clamps that hold the reservoirs. We also added a three-quarter-inch lifting block to the rear axle to raise the rear for towing.
It’s about a thousand-dollar upgrade, but the result was worth it. Towing a trailer is no longer a white-knuckle affair. Large bumps and undulations no longer unsettle the truck, and the ride is well damped with or without a trailer attached. It’s now buttery smooth with a trailer in tow.
A couple of tips on the installation. The fronts are coilovers, and the new shocks need the factory top hat, which means you need a spring compressor to do the job. Do not rent one and attempt to do the job yourself. That’s how people lose fingers and eyes. We took them to one of our favorite local shops, Superior Brake and Alignment in Santa Barbara, Calif., which specializes in alignments and suspension work. We had them swap out the front top hats — and everyone still had fingers when we were finished.
The rears would have taken about 20 minutes, but because we were adding three-quarter-inch lifting blocks, we had to jack up the truck by frame, remove the rear axle from the leaf springs, which was a heavy, clumsy exercise. Luckily, there are locating dowels and holes on the leaf spring, axle and the lifting block, so when everything goes back together, it’s in the right place. We did the blocks first, then installed the new shocks, but you have to remove the lower shock mounts to install the lifting blocks.
This would make for a great winter project to upgrade a truck. Come race season, all the wrench time should go toward the racecar. Here’s how the project unfolds.