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Suspension Modification &
Advice |
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Will
lowering my car make it handle better?
Are their any adverse
effects of fitting lowering springs?
How can I over come
wheel scrub?
Are
there different types of spring?
Are there any bad
points to installing up rated shock absorbers?
What can I do to help
prevent chassis damage?
What are polyurethane
suspension bushes?
Are there any other
types of shocks/springs that I could fit?
Do bigger rims help
the handling of the car?
Are there any problems
with larger wheels?
Suspension has been around longer than cars, it was first
used in horse drawn carriages to make the ride more comfortable
for the people travelling inside. This early suspension
was a design called ‘leaf spring’ suspension.
This type of suspension is still in use today, mostly
on large lorries but also on some cars. As cars started
to appear on the roads new forms of suspension were developed
to improve ride quality. Over time the design has changed
a lot and the uses for suspension have also changed.
On a race car the suspension is designed to flex or move
just enough to keep the wheels of the car on the track
to improve both grip and traction. Conversely the suspension
on an off road vehicle is designed to move as much as
possible to attempt to keep the wheels of the vehicle
on the ground and to stop it from toppling over.
These two systems are extremes of suspension in terms
of movement, but both have the same goal. To keep the
wheels on the ground, to achieve greater control.
A road going car is very hard to set up. It has to be
able to hold the car on the road at high speeds and round
corners while still providing a comfortable ride for the
passengers over things such as “pot-holes”.
By far the most popular and dynamic suspension system
is the shock absorber and spring set up. This can provide
a mix of both the firm control of a race car and the supple
movement of an off road vehicle.
Car manufactures spend a large amount of time designing
and testing the suspension of their cars before they allow
it to be used on the road. So why, if so much effort has
been put into the design, would anyone want to modify
their car’s suspension?
This is a good question and one that I hope this page
will answer. The thing you have to realise about the stock
suspension is that it is a compromise between road holding
and comfort. In order to make the car comfortable they
have had to sacrifice road holding and stiffness. So to
gain a sportier handling car you must change some parts
of your suspension.
When thinking of modifying your suspension the first thing
you must ask yourself before anything else is, what do
I want my suspension to do?
If your answer is something like ‘I want a street
legal go-kart’ then here are the things you must
consider before you go any further. |
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Will lowering my car make
it handle better? |
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Yes.
Lower you car can make handle better due to the lower
centre of gravity and increased stiffness of the new springs.
This will make it harder for you car to roll round corners
thus keeping the inside wheels on the ground better, resulting
in faster or safer cornering. It will also make your car
look better as it will look more aggressive on the road.
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Are their any adverse effects
of fitting lowering springs? |
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Yes.
Lowering your car will not necessarily give you better
handling! You may find that your shocks are too soft for
the new ride height or that they are past their prime.
In either case the suspension will bottom out over bumps
and round corners. This can be dangerous and even cause
permanent damage to the structure of your car, it can
also make the ride very bumpy and uncomfortable. In some
cases it can make the wheels leave the ground while cornering
and this could end in disaster. Along with this the wheels
may be too big for the reduced amount of space under the
arches. This could result in tyre scrub and possibly wear
both your tyres down and rub against bodywork. It may
even cause you to have a puncture at high speed!!!
As a rough guide, if you only lower your car down to 30mm
you should have no problems.
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How can I over come wheel
scrub? |
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Are there different types
of spring? |
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Yes.
There are many springs on the market to help give your
car a better ride but the main different types are normal
coil and progressively wound coil.
The coil is a spring that is wound round at a set diameter
and with set spaces between each wind on the spring. This
is the most common type to be found on stock suspension
set ups. The other main type of lowering spring is the
progressively wound spring. This differs from the normal
spring by having different spacing between some of its
winds and not keeping the same diameter of coil along
its length. This spring will give a stiffer ride than
the normally wound spring.
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Are there any bad points to
installing up rated shock absorbers? |
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Yes.
If the shocks are too hard, your car too old or in bad
repair then the rigid nature of the shocks will place
too much strain on the chassis of the car and could cause
dangerous week points. Even on new or good condition cars,
stiff shocks can put too much stress on the chassis or
body of the car and cause permanent, dangerous damage.
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What can I do to help prevent
chassis damage? |
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Fitting
strut braces to the top points of the suspension can reduce
the stress put on the car by keeping the suspension turrets
in their correct places. The brace can do this because
it is very stiff and resistant to compressive and tensile
stresses. The brace not only reduces the stress put on
the chassis of the car but also helps to keep the suspension
geometry in the correct shape while cornering, acceleration
and braking. This improves handling and reduces tyre ware.
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What are polyurethane suspension
bushes? |
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On
every car there is a set of rubber bushes that hold together
moving parts of the suspension. They are there to stop
metal on metal contact and to absorb some of the impact
stress from the movement of the suspension.
Polyurethane is a hard plastic compound that can take
much higher stresses than rubber. It lasts a lot longer
than rubber and can reduce the play in suspension parts.
This in turn makes the steering more direct and accurate
along with making the ride of the car stiffer. These are
an ideal up grade if you have already replaced your shocks
and springs.
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Are there any other types
of shocks/springs that I could fit? |
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Do bigger rims help the handling
of the car? |
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Are there any problems with
larger wheels? |
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Yes.
As the wheel size (in inches) increases the available
space under the arch becomes less. This can cause problems
with tyre contact to suspension components or bodywork.
In either case it can be very dangerous. As the wheel
increases in size its circumference also increases. This
will mean that your speedometer will read a slower speed.
Not only is this a problem for sticking to speed limits
but it is also illegal. The solution to this problem is
to fit a lower profile tyre to the larger rim with the
overall result reducing the circumference to match the
old wheels existing size. Remember, the wider the tyre
the harder it is going to be to turn the wheel at lower
speeds. If you don’t have power steering then it
may not be as easy to drive at lower speeds, not to mention
parking.
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