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HANDLING
traits
This section deals with vehicle dynamics. After exploring this
section, we hope you'll have a better understanding of what your
car is doing underneath you - especially when you're really pushing
it - and how to anticipate and deal with those situations where
grip quickly turns into slip.
There are two main ways a car will behave when the tyres start
to lose grip: it will either understeer,
or oversteer. Different cars are set
up to counteract these two situations in different ways, but all
cars can eventually succumb to both.
Under- and oversteer are both affected by
weight transfer and grip. We'll also discuss
these important factors, and how you as a driver can use them
to your advantage.
For understeer, read on or click here.
Move on to oversteer.
Move on to weight transfer.
Move on to grip.
understeer
Understeer is what happens when the front
end of the car loses its grip before the rear end. The
result is a feeling that the car refuses to change direction in
response to your steering inputs, and doesn't follow your intended
path. Some drivers describe this as 'washing wide', 'pushing'
or 'ploughing straight on'.
Virtually all cars made today - even many high-performance sports
cars - are engineered to initially behave this way under extreme
cornering conditions, because it's generally easier to correct
(especially on public roads).
The main contributing factor to understeer is
heading into a corner with too much speed. When this happens,
the easiest way to counteract the understeer is to react as you
probably would instinctively: ease off of the
throttle, and let your speed fall until the front tyres
regain grip. If you've carried way too much speed into the corner,
then simply lifting off isn't going to be enough; you may have
to also begin to straighten the wheels until
the front tyres find grip, then carefully brake to scrub off more
speed. Once your speed falls sufficiently, you can then
smoothly feed some steering lock back in to get you around safely.
It might even be necessary to slow to a very low speed, to ensure
that you don't return to understeer, and to regain your mental
composure.
When easing off the throttle, do it with care!
This can't be stressed enough. On some cars (especially
older, front-drive models) understeer can quickly turn to oversteer
- and a total loss of control - if you lift too suddenly or too
much. So, be smooth when you lift, and pay attention to how the
front and rear react to your inputs (see oversteer for
more info on this scenario).
Understeer can sometimes occur when accelerating
hard out of a corner. To prevent this, reduce the amount
of throttle; be smooth, steady, and patient. Look at where you
need to end up once the road straightens out, and you'll be able
to judge throttle inputs instinctively.
Understeer is generally a very undesirable thing to have during
committed driving, because it can rob you of speed, and the car
just feels frustratingly lazy and dull. There are a few ways you
can prevent under-steer in the first place:
- don't go into corners too fast - make sure
the tyres have enough grip to change the direction of the car
- be smooth with your steering inputs - turning
the wheel too quickly will overwhelm the front tyres; they won't
bite into the road, because they're changing direction too quickly
- be patient with the throttle if you start
to wash wide mid-corner, you're probably feeding in too much
throttle
^ Back to handling traits menu
oversteer
Oversteer is what happens when the rear end
of the car loses its grip before the front end. The result
is a sensation of the rear trying to rotate around and swap places
with the front. With oversteer, the rear end of your car is trying
to hurtle straight on, while the front is continuing to change
direction.
Oversteer is a far more dangerous situation to have on a public
road than under-steer, because it can happen
very quickly, and requires fast reflexes and foresight
to successfully recover (it's quite difficult to provoke oversteer
in most road cars, since they're deliberately designed to behave
this way). Oversteer (especially on a public road) should be
approached with the utmost respect.
Oversteer generally can occur under these situations:
- violently quick side-to-side swerving (ever
wonder how some cars end up facing backward on the motorway?)
- suddenly or completely lifting off the
throttle during hard cornering
- too much power applied to the rear wheels
during cornering (rear- and four-wheel-drive cars only)
Sometimes, it can be a combination of these factors that cause
oversteer or an outright spin, and some cars will react more strongly
to these situations than others. Many modern traction and stability
control systems can almost completely prevent oversteer from becoming
a spin.
When used in a controlled manner, oversteer can be a helpful
cornering aid, because it helps steer a car
more tightly around a corner. Fully exploring the oversteer
properties of your car is probably something best left to a closed
course or a large, empty, vacant lot. If you do find yourself
in a situation where oversteer becomes unwanted, here are a few
ways to prevent or eliminate it.
- Applying opposite lock (briefly
turn the wheel in the opposite direction to the tail slide).
This is usually instinctive, but the moment you feel the rear
tyres begin to regain grip, start to unwind the steering to
once again point in the direction you want to travel, or you'll
end up spinning the other way! Look to where you want to end
up, and not at where/what you're trying to avoid spinning in
to, or you'll probably end up there.
- Don't come off the throttle too quickly
or too much while cornering. This is known as lift-off
oversteer, or lift-throttle oversteer. By lifting too much,
the weight of the car is thrown to the front tyres. As the front
then suddenly gains more grip, the rear - just as suddenly -
loses it, which can trigger a spin.
- Applying more throttle can also be used
to 'settle the tail' if it begins to break loose. By
doing this, weight is shifted to the rear of the car, momentarily
giving the rear tyres more grip. Beware though, as you're also
increasing your speed, and you could risk running wide. This
last technique might be more useable for those with more experience,
or those who can practise it in an area with lots of run-off
space.
^ Back to handling traits menu
weight transfer
Weight transfer, put simply, is a term used to describe
how a car's balance shifts in relation to changes in speed or
direction. Having a decent understanding of weight transfer,
how it affects your car's handling, and how you can make it work
for you will help make your driving smoother, and increase your
car control skill.
We're all familiar with weight transfer:
- under acceleration, a car squats over its rear tyres - the
car's weight is 'thrown back', and the rear becomes heavier.
- under braking, a car dives forward over its front tyres -
the car's weight is 'thrown forward', and the front becomes
heavier
- whilst cornering, a car leans toward one side - the car's
weight is pitched to one side, and that side becomes heavier
The goal of a good driver is to keep these changes in weight
transfer smooth, and to eliminate unnecessary weight transfer
all together. Or in other words, to keep the
car balanced. But weight transfer is by no means a bad
thing; the key is knowing how to use it to your advantage.
Weight transfer affects how each of your car's
four tyres grip the road. The tyre with the most weight
pressing it down onto the road has the most grip. If you can keep
weight transfer smooth and consistent during braking, accelerating,
or cornering, you can maximise stability and grip. To make weight
transfer smooth, simply keep your brake, throttle, and steering
inputs as smooth as you can.
When your inputs neat and decisive, and the weight transfer is
smooth, your car's reactions to changes in speed or direction
will become more predictable and easier to manage. This stable,
predictable condition is known as 'taking
a set'; once the weight of the car has been fully
transferred, it pushes the tyres firmly onto the road to provide
optimum grip, and the car is properly balanced and stable.
Jerky or erratic inputs upset the balance
of the car and causes instability, because the tyres can't
grip long or efficenty enough to take the car along your intended
path. Once you understand how - and feel when - your car takes
a set you will begin to work with these forces. As a result, you'll
find yourself fighting less with the car during
hard driving.
Here are some examples of how weight transfer can affect handling
during hard driving:
- Smoothly but quickly squeezing the brake pedal - instead of
suddenly mashing it - will give the car time to shift its weight
forwards progressively. A sudden loss of weight (and therefore
grip) over the rear tyres due to sudden braking can
cause your car's tail-end to become very unstable, and
make it very difficult to properly negotiate an upcoming corner
- Easing off the brake pedal - instead of suddenly releasing
- while going into a corner will ease the transition between
extreme braking and extreme cornering. Suddenly releasing will
shift the some of the car's weight rearwards, which
causes the front tyres to lose turn-in grip, and leads
to frustrating understeer.
- In mid-corner, lifting off the throttle too quickly will pitch
the car's weight forward, resulting in a
loss of rear-end grip (oversteer) and very likely, a
spin.
Weight transfer is dynamic and fluid, which means
it's happening all the time, and in different directions
and amounts; from front to back, side to side, and even (especially)
corner to corner. It happens every time you brake, accelerate,
turn or perform perform any combination of those. If you're able
to understand how to use weight transfer to your advantage, you'll
be smoother, safer, and a lot faster.
Note: your human passengers also undergo weight transfer.
If their brains don't have enough time to get used to a change
in direction, then car sickness will set in. Keep the poor souls
in mind too.
^ Back to handling traits menu
grip
Grip is actually the friction between the road surface
and the contact patches of your tyres. If you take an
A4/Letter-sized sheet of paper and divide it into four equal rectangles,
you'd be looking at the gripping surface available to your typical
family hatch. The fact that these tiny surfaces keep a 1300-kilogram
high-speed vehicle on the road is quite amazing.
A sound principle to consider is learning to manage your
available grip. The total amount of grip a tyre
has must be shared by three familiar forces:
- Acceleration
- Braking
- Cornering
Tyre grip is like human concentration. If we devote our brain
to one task only, we can perform it with maximum efficiency. If
we introduce another task, then our concentration and efficiency
for the first task falls. The more mental ability we devote to
one task, the less we can give to the other. There's only so much
we're able to juggle at one time.
Tyres are much the same. Braking can only be performed at 100
per cent efficiency if it's the only task we ask the tyres to
perform. The same is true of acceleration or cornering. The moment
we try to introduce another task to tyres which are already gripping
at 100 per cent efficiency, they become overwhelmed by the double-duty,
and all grip is lost.
When driving on public roads, it's crucial to understand
how much grip is available at any given time, and how
much you should devote to one task. Keep a reserve of
grip available for unexpected situations, like a corner
which tightens unexpectedly, a misjudged entry speed, or a deer
that strays onto the road mid-bend.
On the track, it's safer to brake, accelerate, or corner
at the very limit. But there are instances where you
have to brake and turn in to a corner, or accelerate whilst coming
through or out of one. In both cases, knowing how to manage all
your available grip, to achieve the desired result, will make
you safer on the road and faster on the track.
^ Back to handling traits menu
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Note: since understanding all aspects of on-the-limit behaviour
can get a lot more complicated than this, you can visit Raadius'
Resources section to find more in-depth
information.
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