Often do I here someone asking, “when should shock absorbers be changed” and “what brand should be used if they need to be replaced.” My answer to the first question is following the service dealers periodic maintenance schedule would be a good guide. However, there would be some instances where the shocks would fail way before the recommended time stated it would need replacing. Another question to consider is how abused or used your car is? Is it in stock form? If we use mileage or distance traveled by a particular car, the same question applies; how was the car used? Was it driven hard? What were the road conditions traveled by the car? Even if we got two identical cars traveling the same route, but two different drivers with different driving styles using them, then one car would wear out differently from the other.
Just to give you an idea, I weigh about 260 pounds. if I were to drive a Toyota Vios along with another guy weighing 180 pounds driving a similar Vios on a given daily route for one year, the driver’s side on my car would show a slight difference in fender to tire clearance as compared to the other guy who is 80 pounds lighter. Not to mention the slightly higher gas consumption.
A shock absorber is basically a damper. As the spring of a car is compressed (coil spring) or load is applied as it goes over a bump, the spring would then try and return to its normal height. This is how the spring will absorb the energy from the bump and dissipate it. If the force is too strong, the spring will oscillate to much. Making it a bumpy ride. The shock absorber helps dampen the force applied to the spring. This also helps the springs when you apply the brakes, so the car doesn’t nosedive too much. Or when you take a corner, it helps dampen the amount of body roll.
Now back to the when part. Some mechanics recommend shock absorbers should be changed at the same time you change your tires. Roughly 45,000 to 50,000 kilometers. Again, that is if you don’t abuse your car. But why change them even if they’re not broken? For the simple reason called preventive maintenance. The tread wear pattern on your tires can say a lot on the condition of your under chassis. If your steering components are worn, then that means your suspension components are also worn out. The suspension is supposed to absorb the bumps on the road. Besides, you wont be able to do a proper wheel alignment with worn out shock absorbers.
Now if indeed you need to replace the shock absorbers, what brand should you use? To be safe, use the original factory specified shock absorber. Why? The damping rate is just right for your car (in stock set up). This damping rate gives a bit of leeway just in case you decide to upgrade to a more aggressive tread design or larger rim size. These changes can affect car ride and handling. If you car is a higher-end model with larger rims, ask the parts department of the dealer if there are differences between your model and higher-end model suspension wise.
If you want to try the other after-market brands, I would suggest that you go to an authorized distributor or dealer to make sure that you are getting the right part for your car. Why? The part you are planning to replace also ensures that your car is planted on the road properly. The wrong part or a fake part can alter the handling and grip of your car. Safety can be compromised. KYB, Koni, Ome, Tokico and the big name manufactures have very good products. It’s just a matter of research in finding out what will suit your needs.