Compression & rebound
Full-bodied coilovers are available with three types of
damping adjustability: manufacturer pre-set, single and double adjustable.
Manufacturer pre-set coilovers are, not surprisingly, pre-set according to what
the manufacturer thinks you need. Coilovers like these are typically valved for
whatever springs they're paired with.
Before looking at coilovers with adjustable damping, it's
important to understand what's being adjusted: compression and rebound.
Compression occurs when the shock's piston moves into its body, compressing the
hydraulic fluid in its chamber below. Rebound happens when it’s pulled away,
again compressing its hydraulic fluid. Generally speaking, compression controls
the motion of the car's un-sprung weight while rebound controls the motion of
its sprung weight. In other words, compression controls how fast weight is
applied toward the tire while rebound controls how fast weight moves away.
Full-bodied
coilovers are available with three types of damping adjustability: manufacturer
pre-set, single and double adjustable.
Shaft speed-the rate at which a shock's valves perform is
also important. Low and medium speeds typically influence handling while higher
speeds contribute to better performance when traveling over bumps. A good shock
is designed with various speeds and situations accounted for.
Single adjustable damping controls both compression and
rebound strokes together while higher-end, double-adjustable, or split level
control, systems manage compression and rebound independently. Depending on the
manufacturer, adjustments can range from eight all the way up to 32 different
user set positions. Single adjustable damping typically affects low-speed
rebound and only slightly affects compression, if at all. Still, these changes
can improve cornering provided the rest of the suspension wasn't found on
Craigslist. Adjustments are made with an externally mounted knob attached to a
shaft that adjusts preload to a spring-loaded needle valve, which controls
internal fluid flow. If you're looking for dramatic changes, be sure to explore
proper tires, shock and spring rates, and anti-roll bar options first. Damping
adjustments are typically best left for fine tuning and specific chassis
balance.
The spring
It's the springs that absorb bumps and control body roll,
not the shocks. They do so by compressing and expanding to absorb individual
wheel motion. It's the springs' job to prevent the chassis from bottoming out,
control the tires when traveling over bumps, and manage body roll when
cornering. They control squat while accelerating and reduce diving while
braking. Springs also establish the car's ride height and center of gravity,
which directly affects handling. Spring rates should be selected carefully. If
they're too soft, the shocks will bottom out. If they're too stiff, any given
tire's contact patch won't be fully utilized when cornering.
Springs also
establish the car's ride height and center of gravity, which directly affects
handling.
Preload
Preload is the amount of pressure applied to the springs
based on how far they're compressed. Generally, a given amount is required to
achieve specific operating characteristics. Adding preload can help mechanical
grip by improving tire contact when turning, but excessive amounts will hurt
performance. The problem with slip-fit coilovers and full-bodied coilovers that
don't feature adjustable lower mounts is that ride height is adjusted dependent
on preload. You can't change one without the other. If your car is mainly
driven on the street or sees the occasional track day, then this is likely an
acceptable tradeoff.
The set up
Installing and properly setting up full-bodied coilovers to
best take advantage of their benefits requires a bit more foresight than a
simple shock and spring installation. Before placing them on the vehicle, each
spring should be slightly and equally preloaded-just enough to keep them from
bouncing around within their assemblies. Next, thread the lower shock mounts
onto their bodies in equal amounts. Refer to your installation instructions,
but you'll typically want to make sure that the shock body threads into its
lower mount at least one full inch. This is your maximum ride height. Install
the coilovers, set the car on the ground, and assess its ride height. Reduce
ride height as necessary using each shock's lower mount. Avoid pre-loading the
springs further to achieve an even lower ride height unless the lower mounts
have completely maxed out.
Coilovers might seem mysterious, but keep in mind that all
shocks try to accomplish the same thing. The major differences can be found in
their design, materials, wear, reliability and rebuilding potential. No matter
how much adjustability a given coilover offers, if they weren't designed
properly from the beginning, no amount of knob turning or spring compressing
will help. In fact, a cruddy set of coilovers can bring out the worst in an
otherwise good suspension. Unless you've studied suspension dynamics, you're
better off choosing a brand you trust and hope somebody there does know a thing
or two about all of this and doesn't have a stuffed animal dangling from a
purple tow hook.
All adjustable
coilovers feature a threaded body design that allows spring height and preload
to be easily adjusted.
Full-bodied coilovers typically feature two-way height
adjustment by means of spring compression and threaded lower bodies that result
in a shorter or longer overall shock body.
Full-bodied
coilovers are made up of several components, including the shock body itself,
the spring, a series of bushings, a bumpstop, upper and lower mounts, jam nuts,
and various nuts, washers and collars that make everything work.
A shock's inner workings are fairly complicated and the
shock compresses and includes a series of passages and valves that control rebounds,
hydraulic fluid is compression and rebound. As the shock compresses and
rebounds, hydraulic fluid is displaced, creating resistance and preventing them
from bottoming out. This full bodied mono-tube coilover features
single-adjustable valving and two-way adjustable ride height by means of its
spring perch and lower mount.
A shock's inner workings are fairly complicated and include
a series of passages and valves that control compression and rebound. As the
shock compresses and rebounds, hydraulic fluid is displaced, creating
resistance and preventing the shock from bottoming out.
