Replacing the rear shocks on your Honda Civic will improve the ride as well as tighten up the suspension and improve the handling of the car. The shock absorbers work to dampen the bumps as you pass over them, but they also smooth the suspension travel and keep it from reacting erratically under stress. There are many grades of shock absorbers that can be used to replace the stock shocks, so check with a parts counter associate at the auto-parts store to determine which are best for your needs.
Raise the rear of your Civic off the ground using a jack and support it with a set of jack stands positioned under the axle. Locate the access cover on the top of the wheel well inside the car and pop it loose with a flat screwdriver.
Locate the metal cap inside the access hole and remove it from the top of the shock absorber. Locate the 10mm nut on the top of the shock absorber stud and remove it with a socket and ratchet, then pull the rubber isolator off the mounting stud.
Move under the car and remove the lower shock absorber mounting bolt with a ratchet and socket, then slide the bolt out of the mount. Pull the shock away from the mount and lower the entire shock down and out of the car. Discard the old shock.
Position a new shock absorber into the upper mount, then slide the bottom mounting eye into the lower mount. Insert the mounting bolt through the mount and shock, then tighten it with a socket and ratchet.
Move to the top mount and install the rubber isolator that comes with the shocks, the metal washer, and the 10mm nut, then tighten the nut until the shock is secure. Snap the metal cap over the shock mount and install the cover over the access hole.
Move to the opposite side of the car and repeat the process. Raise the rear of the car off the jack stands with a jack, remove the stands from under the car and lower it to the ground. Remove the jack from under the car.