Any sign of oil on the outside of shock absorber bodies indicates that the seals have started to leak, necessitating replacement of the units as assemblies. Internal failure of the shock absorber is harder to detect, but symptoms such as rear axle patter or tramp on uneven road surfaces may provide clues. To check for failure, remove the shock absorber from the vehicle, hold it vertically, and operate it through its full stroke eight to ten times; a lack of resistance in either direction suggests the need for replacement. For front shock absorber replacement, raise the front end of the vehicle, use an open-ended wrench to prevent the upper end from turning, and remove the upper stem retaining nut, retainer, and rubber grommet. Next, remove the two bolts retaining the lower shock absorber pivot to the control arm and pull the assembly out from the bottom. When installing, fit the lower retainer and rubber grommet over the upper stem, install the shock absorber in the fully extended position through the lower control arm and spring, and then fit the upper rubber grommet, retainer, and attaching nut after the upper stem has passed through the upper control arm frame bracket. Hold the upper stem with an open-ended wrench and torque-tighten the retaining nut, then install and torque tighten the bolts at the shock absorber lower pivot before lowering the vehicle. For rear shock absorber replacement, raise the rear end of the vehicle and support the rear axle, then remove the lower shock absorber retaining nut, retainer, and rubber grommet, followed by the two upper attaching bolts to remove the shock absorber. During installation, push the lower retainer and rubber grommet into position, extend the shock absorber to the proper length, place it into position, and install the two upper attaching bolts. Finally, push the remaining retainer and grommet into position and install the lower attaching nut, torque all fasteners, and lower the vehicle.
Posted by GMPartsGiant Specialist 
