An introduction to the most misunderstood part of
your vehicle: the suspension
things in life just sound too complicated to wrap our brains around. Quantum
physics, Federal Reserve monetary policy and brain surgery are all fields that
leave students and adults alike scratching their heads in bewilderment. All too
often, the inner workings of an automobile's suspension gets lumped alongside
these enigmatic subjects. Even seasoned gear heads, who can blueprint an engine
without so much as breaking a sweat, get weak in the knees around torsion bars
Of course, many people are quite happy not knowing why it is that their
vehicle can go over a speed bump without bottoming out. Sure, ignorance can be
bliss, but knowledge is power. That's why AutoAnything is here to arm you with
more suspension information than you can shake a dip stick at. First things
first, we need to understand how your suspension system ties into your vehicle
and how it works. Then, we'll investigate the good stuff: how to tweak and tune
your suspension for improved handling, daring looks and extreme performance.
we imagine an automobile, the first thing that pops into our minds is the body.
After that, we probably think about the cockpit, the engine compartment and
maybe even the chrome wheels. Hardly anyone would visualize a
yoke eliminator, a
differential or a leaf spring. Why? The answer might be best summed up with
an old cliché: out of sight, out of mind. There is a whole other dimension to
our vehicles that mostly goes unnoticed because it is hidden away under a glitzy
exterior. What's the name of this strange realm, you ask? It's called a chassis.
One of the toughest words to come out of France since
laissez-faire, "chassis" literally means "frame," but it refers to more than
just your vehicle's platform. The chassis is basically everything on your
automobile from the ground up to the bottom of its body. An automotive chassis
is made up of 4 components:
- Vehicle Frame: Like the DNA swimming around in our cells,
the frame of any vehicle is its building block. It is the base on which every
other critical part of the vehicle is anchored, including the engine,
transmission, and even the body.
- Wheels and Tires: The all important link between the road
and the automobile, wheels and tires make forward momentum possible. After
energy and torque are created, it's up to the wheels and tires to create the
traction needed to roll around.
- Steering Works: Energy without control is a recipe for
disaster, especially when you're barreling down a windy mountain road at
breakneck speeds. Everyone knows what a steering wheel is, but there's more to
it than meets the eye. Deep down in the bowels of your chassis is an intricate
weave of connecting arms and linkage that guides your wheels and keeps you in
- Suspension Systems: The part of your chassis that
directly affects how your vehicle feels, the suspension is in charge of
responding to road conditions. A suspension is the middleman between the road
and you. The road dishes up rugged conditions, and your suspension transforms
the bumps and dips into cloudlike smoothness (or stiff-as-a-board rigidity to
suit the tastes of off-roaders).
suspension system basically has 1 very important job. It is in charge of
controlling the ride of your vehicle. Now, ride means a lot of things to a lot
of people. To a couple of preteens loitering around the front of their local
strip mall, A ride is simply the parent who shows up to drive them home. Or, to
an employee at Disneyland, a ride is the mechanical teacups that the kids love
to twirl around in. However, to an auto enthusiast, ride is a vehicle's ability
to create a comfortable feel while in motion. On freshly poured concrete and
washboard paths alike, your suspension reacts to the situation and keeps your
vehicle from rattling around like a Mexican jumping bean.
There are 2 tools that your suspension uses to smooth out your ride: springs
and dampeners. Let's take a closer look at how these marvels of automotive
are your suspension system's first line of defense. As you drive over any
surface, you will inevitably encounter bumps and dips. These variations in the
surface of a street (or backcountry trail) send vertical energy through your
wheels. Humps send your tires skyward, and holes draw them down. The spring's
job is to absorb this energy and bring your wheels back to a state of
equilibrium, which is when they are all at their standard height.
There are 3 basic type of springs used on modern automobiles: coil springs,
leaf springs and torsion bars.
- Coil Springs:
- Like an industrial-grade Slinky, a coil spring is basically a heavy-duty
strip of metal that has been wound around to form a spiral or
Coil springs are ideal for absorbing up-down energy, but their design does not
deal well with side-to-side motion. As such, coils springs are typically found
on all 4 wheels of most cars, and on the front suspensions of some trucks and
- Leaf Springs:
- Picture Robin Hood's trusty bow mounted to the underbelly of an
automobile–that's basically what a leaf spring looks like. More specifically,
a leaf spring is a stack of steel strips, called leaves. All the leaves are
curved, and their arc flexes up and down when it goes over uneven paths. Leaf
springs have a proven track record that spans all the way back to the medieval
times, when they were used to support the axles of horse-drawn carriages and
olde-time paddy wagons. Today, leaf springs are primarily used on rear-wheel
drive automobiles, 4-wheel drive rigs, heavy-duty trucks, vans and SUVs. They
do not deliver the same ride quality as coil springs, but leaf springs are
more robust and handle weight better.
- Torsion Bars:
- Instead of flexing or compressing, a torsion bar absorbs energy by
twisting. One end of the torsion bar is fixed firmly to a vehicle's frame, and
the other side links to the vehicle's control arm. When the auto runs across a
rough patch of road, the up-down energy flows into the torsion bar, which then
twists. Because only the one side is mounted firm, the torsion bar will only
rotate so far before it spins back in the opposite direction. Torsion bars are
primarily used on front-end suspensions, and are found on all types of
Newton's 3rd Law of Motion states, for every action there is an equal and
opposite reaction. When a suspension spring takes in upward energy, it has to
release it as a downward force. However, that downward momentum then causes the
spring to bounce back upward. This back and forth resonance, or
to engineers, would go on for miles if not for another key suspension component:
dampeners (aka shock absorbers).
Just as Penn would have a dull Vegas act without Teller, a spring would not
improve your ride unless teamed up with a shock. It's the shock's job to make
the energy from your springs soft and as bounce-free as possible. Imagine
dropping a basketball off the roof of your house. If it falls onto concrete, it
will bounce back up and dribble down the driveway. On the other hand, if it
falls onto a pile of pillows or leaves, then it will just stop and wait for you.
In a nutshell, that's what a shock does.
Different vehicles are deigned and built to do different things. A sporty
little roadster and a behemoth dually pickup would not roll around on the same
chassis, and they certainly would not use the same suspension type. As you would
expect, there are a number of suspensions rolling around all over, from the
traffic nightmares of Los Angeles to the wide-open routes of the Gobi Desert.
There are 2 basic types of suspension systems: dependent and independent.
Let's take a closer look at the unique characteristics of each system.
On a dependent suspension system, the wheels on the left and right side of
the vehicle are connected and work together. Generally, the dependent suspension
uses a solid axle that spans across the entire width of your frame. Because both
wheels are linked to this single beam, they respond to road conditions as a
pair. If the
of one wheel bends outward, then the other wheel follows suit.
uneven terrain, dependent suspension systems function a lot like a seesaw. When
one side dips into a pothole or rises over a rock, the other side goes in the
opposite direction, either up or down. Needless to say, this bucking energy can
be about as comfortable as riding a mechanical bull. However, with modern shock
absorbers and springs, dependent suspension systems can be quite comfortable
off-road and on.
Because of their ruggedness, dependent suspensions are often used on
heavy-duty trucks, SUVs and rear-wheel drive cars. They also find there way onto
some front-wheel drive autos. But, most new cars have some form of independent
rear suspension system for greater ride comfort. Besides, most people wouldn't
drive Saturn, BMW or Hyundai sedans on dirt roads except in the rare event that
they find themselves in the starring role as fleeing bandit in an episode of
COPS: On Location in Las Vegas.
the name implies, an independent suspension system does not use a single axle to
connect both sides of the vehicle. Instead, the wheels on an independent
suspension system react separately to road conditions. Bumps and basins on the
passenger's side do not cause the driver's side wheels to rise or fall.
Independent suspension systems are rapidly becoming the standard for
automobiles, and some SUVs and trucks too are using this engineering. They
provide superior ride quality but are more expensive and time-consuming to
manufacturer than dependent suspension systems.