Shock absorbers last between 30,000 and 45,000 miles, depending upon your car's weight, as well as the severity of the pothole population in your area. Proper replacement can help preserve your car's suspension. Bad shocks wreak short-term havoc on ride and handling, and long-term havoc on alignment and the entire suspension system. Look for fluid leaks at each shock absorber. Shocks which show evidence of a leak must be changed. Does your car bounce up and down excessively after hitting a bump in the road? If so, the shocks should be changed.

Replacing conventional shock absorbers involves simply unbolting the old shocks and installing new ones. Most shocks are bolted to the frame by an upper straight pin, held in place by a single nut. You'll have to use a pair of pliers to hold the shaft while you turn the bolt with a box wrench. You may find the two sheetmetal bolts on the bottom frozen with rust. If a wrench won't work, torch or chisel them off, or use a nut splitter.

To reduce weight and conserve space in crowded engine compartments, many manufacturers have moved to MacPherson strut suspensions. Here the strut/damper unit is surrounded by the spring and acts as a suspension support member. Professionals use powerful spring compressors to prevent the springs from suddenly uncoiling. Without these tools and a lot of experience with MacPherson struts, it's best to leave this job to your service mechanic. If you decide to replace the struts yourself, be sure you also have the correct service manual.