Your GMC Sierra is not only great for hauling all kinds of loads but also for carting around your family. Whether you use it to go to the grocery store, or take it off-roading and camping, you need to keep your suspension system in good repair. After 60,000 miles under normal driving conditions, replace your shocks and struts. This process works best for a Sierra 1500 and only covers replacing the shocks, because GMC doesn't equip the Sierra trucks with struts.
Lift the front end of the Sierra with a floor jack, and support it by the frame with jack stands. Locate the shocks in the undercarriage. They look like two tubes that slide in and out of each other with a slender stem at the top. Pop the hood and orient yourself to the suspension system from the top.
Remove the nut from the top of the shock with a ratchet, and slide the upper insulator off the stem. Follow the shock absorber to where it meets the control arm behind the wheel hub, and remove the mounting nuts. Pull the shock out from the bottom. Repeat on the other side of the Sierra.
Mount the shock absorber from the bottom of the car by sliding the stem of the new shock through the mounting hole in the upper spring pocket connected to the frame. Align the shock with the mounting holes in the control arm. If you need to, support the control arm with a jack stand to properly align the holes. Bolt the shock to the lower control arm and, with the dial on the torque wrench set to 18 ft-lb, tighten the bolt until you feel the wrench slip.
Slide the upper insulator onto the stem on the upper side of the bracket, and hand-tighten the upper nut. Repeat Steps 3 and 4 on the other side of the Sierra.
Lower the front end of the Sierra, and use a wrench to hold the top of the shock just below the stem while you torque the upper nut to 15 ft-lb. Close the hood.
Raise the rear end of the Sierra with a floor jack, and support it by the frame with jack stands. Locate the shocks directly behind the rear wheels.
Use a ratchet and a wrench to remove the upper mounting nut and bolt from the bracket in the frame. Remove the lower mounting nut and bolt from the control arm, and pull out the shock. Repeat on the other side of the rear of the Sierra.
Position the new shock absorber between the control arm and the mounting bracket. Install the lower nut and bolt and the upper nut and bolt and torque them both to 70 ft-lb. Repeat this step on the other side of the Sierra
Lower the rear end of the truck.
