Basics of Shocks and Struts
by Pat Goss
We get lots of questions about the differences between shock absorbers and struts. What is the difference?
A shock absorber on an automobile does one thing and one thing only, keeps the car from bouncing. Struts are considerably different. Struts are a structural part of the suspension system and are mounted to the chassis of the vehicle on the top, and they come down through. They give us a place to mount the coil spring, and the spring is what maintains the height of the vehicle, so we have a plate in here for the spring. It also replaces the upper control arm and it connects directly to the knuckle on the car, which in many cases gives us a minor ability to adjust alignment.
Okay, so there is a big difference here, what’s the advantage? Well, shock absorbers usually give you better handling, while struts give you a lower initial cost for the vehicle.
Now if you want to check these, and they should be checked on a regular basis, you’re going to do two things; number one you’re going to bounce the vehicle up and down, and you do that over each wheel. Consider the normal state of rest and then you get it bouncing so that it bounces above and below the normal state of rest. You’re going to let go of it in the down position and it should come right back to the center and stop. If it continues to oscillate, the shock or strut on that corner of the vehicle is bad, and you always replace them in pairs, two fronts or two rears.
Second thing you do is you raise the vehicle up and you look for any signs of oil leaking out of that shock or strut. If oil is leaking out it’s bad and again you replace the pair of them, the fronts or the rears.
But if you want to replace them yourself, the shock is not much of a problem. Just follow the directions that come with the shock absorber. But the strut, remember that spring? That thing could be very dangerous. Don’t just go un-bolting parts of the strut because you could be in for a nasty surprise when that spring takes off. To do a strut you have to have spring compressors such as we have mounted on this spring right here. This will compress the spring and give us the ability to handle it. You have to be careful with it because it’s still dangerous, but you should be able to change the struts yourself.
If you have a question or comment, write to me.
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