78 How do I know whether my shocks are worn out?
Description
This article is from the VW Technical FAQ, by with numerous contributions by Jan Vandenbrande others.
78 How do I know whether my shocks are worn out?
A: Shocks either lose their damping capability or freeze up. The result is
that your car may not handle well (or safely). When you bounce the front of
the car, a good set of shocks will stop the motion in less than one cycle:
Bounce the car couple times, let go, and it should go up and a small amount
down and then STOP.
Just look at your old mechanics/physics books for damped and undamped
impulse response of a spring and damper combination.
Test for seizing: you press down, and it stays down. Note that Sport Shocks
may be so stiff that it will barely move when you press down.
Note also that this failure mode occurs mostly on A1 cars which put too
much side loads on shocks.
I [Jan] went thru several virtually indestructible Bilstein sport shocks
due to this failure. Hold on that receipt for life time warrantee!!!!
Also suspect your shock if you hear an excessive amount of swishing.<NOISE>
That's cavitation (local boiling of oil) which usually accelerates wear.
"Gas" shocks contain a chamber of pressurized gas that keeps the oil under
pressure and prevents cavitation, increasing damping capabilities and
reducing wear.
For the front "shocks" you have two choices for replacement: You can either
buy an entirely new strut (which is the whole assembly, usually sold in
combination with springs) or replace the shock insert in your existing
strut (cheaper, more work). Most of the time you replace the insert.
The rear shocks are replaced as a whole, and fairly easy to do yourself.
Note that the fronts tend to wear out long before the rears.
Note, if you replace the front shocks you may want to consider replacing
the upper strut bearings.
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