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DEFINITIONS -
Bump = When a spring is made to compress.
This is also broken down into -
Low Speed Bump = Slow compression on the spring such as acceleration,
cornering and braking.
and
High Speed Bump = Fast compression of the spring such as kerbs or potholes.
Rebound = When a spring is made to expand.
EXPLANATION
When a car is travelling along the road in a stable condition at a steady
speed in a straight line the suspension and springs will be in a state
of equilibrium although the springs will have some load already on them
due to the weight of the car on each corner.
Things that affect the dampers and springs are acceleration, cornering
and braking, but also kerbs and pot holes, or anything that creates a
movement effect on the wheels or the car chassis.
ACCELERATION
When a car accelerates the front will tend to lift and the rear will tend
to drop. Partly due to the Centre Of Gravity(COG) being affected by it's
inertia and trying to stay where it is when the wheels are trying to push
it forward. Ever seen a motorcycle do a wheely, this is where the power
of the bike combined with inertia of the COG overcomes the weight on the
front wheel. Even on a lower power bike the rider can just give a tug
on the handlebars as he accelerates and this will be enough to pull the
COG back over the rear wheel as the bike moves forward. This is an extreme
example and not generally seen on a car because of the relatively low
power to weight ratio. Unless - it has massive power to weight ratio such
as on a dragster.
The effects are low speed rebound on the front and low speed bump on
the rear.
CORNERING
When a car enters a corner, the COG will want to move towards the outside
of the corner and will cause the car to try to roll over and if the car
had a sufficiently high COG with a narrow track it probably would. Thankfully
sports and high performance cars are designed to have a low COG and apart
from in extreme circumstances the COG remains inside the wheelbase and
track. So the car will simply roll within that area causing the outside
suspension to compress and the inside suspension to expand.
So in a corner the outside suspension is subject to low speed bump and
the inside suspension is subject to rebound.
BRAKING
When a car brakes, the front will tend to dive towards the road and the
rear will tend to lift as the COG is trying to carry on moving forward
over the front wheels which of course are trying to slow down. Because
of this another effect is that the COG (or weight) moves closer to the
front axle and so the front tyres take more of the braking force, in
extreme circumstances this could be up to 80% or even 90% of the braking
effeciency. This is one of the reasons that the rear wheels will lock
so much easier than the front, as the braking force between the pad and
disc becomes greater than the frictional force between the tyre and the
road and this can end up in a skid.
How is this related to KW suspension kits.
ON THE ROAD
Where you have adjustable bump and rebound on a suspension kit it means
that you can alter the amount of damping for each type of driving situation,
for instance if the car is being driven mainly on the public road it
can be set up for a softer ride so that acceleration, cornering and braking
are slightly more comfortable not only for the driver but also for the
car and this will give the suspension and fittings of the car a longer
life.
ON THE TRACK
When on a track the suspension can be set up to be a bit harder as the
track is usually a lot smoother than a public road so the emphasis is
on resistance to movement of the suspension and this will help to control
the chassis in pitch and roll situations. Which means that the car is
kept under better control especially when cornering and braking.
The KW suspension has a high speed bump
setting which is set at the factory, what this means is that although
the low speed bump can be set fairly hard, the high speed bump will allow
some movement in the damper should the wheel encounter something that
would otherwise jar the suspension, such as a kerb on a track or a pothole
on the public road.
So with KW suspension it isn't so much
a compromise as having the best of both worlds.
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