GMC 20955430 Rear Shock Absorber Assembly

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To remove the shock absorber, raise the rear of the vehicle and support it securely on jackstands. Disconnect the electrical connector and the airline from the shock absorber. Support the rear axle with a floor jack. Remove the shock absorber fasteners and then remove it. Installation is the reverse of removal.

Park the vehicle on level ground, turn the engine off and set the parking brake. Check the tire pressures. Push down at one corner of the vehicle, then release it while noting the movement of the body. It should stop moving and come to rest in a level position within one or two bounces. If the vehicle continues to move up and down or if it fails to return to its original position, a worn or weak shock absorber is probably the reason. Repeat the above check at each of the three remaining corners of the vehicle. Raise the vehicle and support it securely on jackstands. Check the shock absorbers for evidence of fluid leakage. A light film of fluid is no cause for concern. Make sure that any fluid noted is from the shocks and not from some other source. If leakage is noted, replace the shocks as a set. Check the shocks to be sure that they are securely mounted and undamaged. Check the upper mounts for damage and wear. If damage or wear is noted, replace the shocks as a set (front or rear). Visually inspect the steering and suspension components (front and rear) for damage and distortion. Look for damaged seals, boots and bushings, and leaks of any kind. Examine the bushings where the control arms meet the chassis. Clean the lower end of the steering knuckle. Have an assistant grasp the lower edge of the tire and move the wheel in and out while you look for movement at the steering knuckle-to-control arm balljoint. If there is any movement the suspension balljoint(s) must be replaced. Grasp each front tire at the front and rear edges, push in at the front, pull out at the rear, and feel for play in the steering system components. If any free play is noted, check the idler arm and the tie-rod ends for looseness. The CV Boot is very important because it prevents dirt, water and foreign material from entering and damaging the constant velocity (CV) joints. Oil and grease can cause the boot material to deteriorate prematurely, so it's a good idea to wash the boots with soap and water because it constantly pivots back and forth following the steering action of the front hub, the outer CV Boot wears out sooner and should be inspected regularly. Inspect the boots for tears and cracks as well as loose clamps. If there is any evidence of cracks or leaking lubricant, they must be replaced.

Raise the vehicle and support it securely on jackstands. Inspect the shock absorbers for evidence of fluid leakage. A light film of fluid is generally not a concern. Ensure that any fluid noted is from the shocks and not from another source.

Start by loosening the front wheel lug nuts, raising the vehicle, and removing the wheel. Support the outer end of the lower control arm with a floor jack and detach the tie-rod end from the steering knuckle. Remove the upper mounting nuts and the two bolts that attach the lower end of the shock absorber to the lower control arm. Pull the shock out from below.

After supporting the rear axle, the shock absorber upper and lower mounting fasteners should be removed.

Follow the same steps as removing the coil-over shock absorber model, but use a backup wrench on the stem to remove the upper mounting nut and related hardware. Remove the lower mounting nut and bolt, noting the direction in which the bolt points.

After supporting the rear axle, the shock absorber upper and lower mounting fasteners should be removed.

Raise the vehicle and support it securely on jackstands. Inspect the shock absorbers for evidence of fluid leakage. A light film of fluid is generally not a concern. Ensure that any fluid noted is from the shocks and not from another source.

Have an assistant grasp the lower edge of the tire and move the wheel in and out while you look for movement at the steering knuckle-to-control arm balljoint. If there is any movement, the suspension balljoint(s) must be replaced.

To install, reverse the removal steps and ensure the lower mounting bolt is pointing in the same direction as before.

To install, reverse the removal steps and ensure the lower mounting bolt is pointing in the same direction as before.

The first step is to raise the rear of the vehicle and support it securely on jackstands placed underneath the frame rails.

If leakage is noted, it's advisable to replace the shocks as a set.

Start by loosening the front wheel lug nuts, raising the vehicle, and removing the wheel. Support the outer end of the lower control arm with a floor jack and detach the tie-rod end from the steering knuckle. Remove the upper mounting nuts and the two bolts that attach the lower end of the shock absorber to the lower control arm. Pull the shock out from below.

If leakage is noted, it's advisable to replace the shocks as a set.

The shock absorber can be installed by reversing the removal steps and tightening the fasteners to the torque specifications.

The rear axle should be supported with a floor jack placed under the axle tube closest to the shock absorber being removed.

To install, reverse the removal steps and tighten the mounting fasteners to the torque specifications. If equipped with a suspension control system, reconnect the electrical connector to the top of the shock absorber.