There are other parts to a strut, extra parts that rarely wear out, but are essential for the assembly to work properly
and to be installed. You do not need to purchase these every time a strut is changed, probably 80% of the time they are simply reused.
However, they all have to be removed when changing out a strut, so while you are there, and have it all apart, it's best to replace the parts then as a measure
of preventive maintenance.
Always inspect the ones on the vehicle and determine their condition beforehand, that way you know what to order
when purchasing new struts. Changing them at the same time as the struts can also save you big labor costs, since they are taken off and changed over anyway.
Having to disassemble a strut to replace these parts later is costly.
The parts are usually: An Upper Mount (bushing, or bearing), an Upper Boot, Upper Bumpstop (cushion), Upper Springseat, Upper Isolator,
Coil Spring, Lower Isolator, Lower Springseat (perch), and of course, the strut itself.
An Isolator is usually a cushion, made or rubber or a similar material. It can do two things: It can keep the metal on the spring and the metal on the spring perch from
chafing against each other, causing a noise (99% of the time when people think a strut itself is making, say, a creaking noise, it's actually the Isolator has worn out), and the
other function can be to add a bit of cushion to absorb vibration. (many luxury cars use them for this reason). It can do both functions as well.
On most vehicles the lower spring perch is welded to the strut housing, and never available seperatley. However, on some modern vehicles, the perch
is now a separate part. In those cases you just reuse the original perch (sliding it off the old unit and onto the new one). But if yours is bent, rusted out, damaged, etc, a
new one will usually be offered from one of our shock manufacturers.
Here below is a diagram below to give the basics of where these parts are on a strut.
Obviously every car / truck is different, but the basics would be the same.
Here in this picture below, are just some random springseats / Isolators. They vary in size and how they look, but function all the same way.
Note that while looking up your vehicle in our Online Catalogs (see the tabs at the top of the page), you can click on a part number, and it will show a picture of the exact part.