Shocks & Struts
How do I know if my vehicle really needs new shock absorbers?
You need new shocks (and/or struts) if your original shocks (or struts)
are worn out, damaged or leaking. Leaking is easy enough to see (just look
for oil or wetness on the outside of the shock or strut) as is damage
(broken mount, badly dented housing, etc.). But wear is often more of a
subjective thing to judge. There are also instances where the original
equipment shocks may not be worn, damaged or leaking, but may not be
adequate for the job they're being asked to do. In such cases, upgrading
the suspension with stronger, stiffer or some type of special shock (or
strut) may be recommended to improve handling, for trailer towing, hauling
overloads or other special uses.
Shocks and struts do not require replacing at specific mileage intervals
like filters or spark plugs, but they do wear out and eventually have to
be replaced. How long a set of original equipment shocks will last is
anybody's guess. Some original equipment shocks may be getting weak after
only 30,000 or 40,000 miles. Struts usually last upwards of 50,000 or
But when exactly a shock or strut needs to be replaced is hard to say.
Because the damping characteristics of shocks and struts deteriorate
gradually over time, the decline in ride control often passes unnoticed.
So by the time you think you need new shocks or struts, it's usually way
past the point when they should have been replaced.
One way to evaluate your need for new shocks or struts is to consider how
your vehicle has been handling and riding lately. Does it bounce
excessively when driving on rough roads or after hitting a bump?
A strut is basically a shock
absorber mounted inside a coil spring. Struts perform two
jobs: They provide a dampening function like shock absorbers,
and they provide structural support for the vehicle
suspension. That means struts deliver a bit more than shock
absorbers, which don't support vehicle weight -- they only
control the speed at which weight is transferred in a car, not
the weight itself.
Because shocks and struts have so much to do with the handling
of a car, they can be considered critical safety features.
Worn shocks and struts can allow excessive vehicle-weight
transfer from side to side and front to back. This reduces the
tire's ability to grip the road, as well as handling and
Does the nose dip when braking? Does the body roll or sway excessively when cornering or driving in crosswinds? Does
the suspension bottom out when backing out of the driveway or when hauling extra passengers or weight?
A "bounce test" is still a valid means of checking the dampening ability
of shocks and struts. If the suspension continues to gyrate more than one
or two times after rocking and releasing the bumper or body, your shocks
or struts are showing their age and need to be replaced.
Why Replace Them?
Weak shocks and struts won't necessarily create a driving hazards if
you continue to drive on them, but there are studies that show worn
shocks increase the distance it takes to stop a vehicle on a rough
surface. Increased body sway due to weak shocks or struts can also
increase the risk of skidding on wet or slick surfaces.
shocks and struts also increase suspension wear (though marginally)
but can have an effect on tire wear.
The reason why most people decide to have worn shocks or struts
replaced, however, is to improve overall ride quality. If you're
sick of bouncing and rocking on rough roads, a new set of shocks or
struts will firm up your suspension and restore proper ride control.
If you're interested in performance handling, you can upgrade to
premium "gas" charged shocks or struts. These are charged with high
pressure nitrogen gas to help minimize foaming in the hydraulic
fluid inside the shock. This lessens "fade" on rough roads and helps
the vehicle maintain better ride control when cornering.
There are also "heavy-duty" replacement shocks and struts that have
larger diameter pistons than stock. These too, provide increases
resistance for greater control -- but may be a little too harsh for
everyday driving. So some shocks have special valving or adjustable
valving that allows the amount of resistance to vary.
Another option to consider if you tow a trailer or haul extra cargo
are overload or air-assist shocks. Overload shocks have a coil
spring around them to increase the load carrying capacity of the
suspension (these also tend to ride stiffer than standard
replacement shocks). Air-assist shocks have an adjustable air
bladder that acts like a spring to carry extra weight. With this
type of shock, air can be added on an "as needed" basis when hauling
Shocks and struts are generally replaced in pairs -- though this
isn't absolutely necessary if only one shock or strut is leaking or
has suffered damage at a low mileage.
require a fair amount of suspension disassembly as What's more, the
wheels must usually be realigned after replacing a strut. For this
reason, you're probably better off letting a professional replace