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Springs, shocks and anti roll bars
all give you a lot of different options in
adjusting a race car's handling
but before you start adjusting
it really helps to understand the specific function of each.
let's start with springs.
The spring's main job is to hold the car off the ground so
it's the load-bearing device carrying the load of the car
keeping it from scraping the ground
Spring rate is a measure of how stiff the spring are,
how much load it takes to deflect them a certain distance
usually in pounds per inch or newtons per millimeter
there's a lot of factors that determine the spring rate
but the primary one is that you need springs stiff enough to hold the car
off the ground under the aerodynamic loads that it sees
Ideally you want to run the softest springs because softer springs
typically get you more grip out of the tires
but if you run them so soft that you buried in the ground
every straightaway than that's obviously not good enough
so you set them just stiff enough for your aerodynamic platform
Depending on the speed range of the track
you will go with stiffer springs at a higher speed track
because there's more aerodynamic forces on the car
and certainly go softer,
much softer springs if you go to a street course
where the speeds are quite low
and there's not a lot of aerodynamic forces
Shock absorbers or dampers as the British refer to them
are another key component in adjusting a car's handling
and that's because they do a lot more than just absorb shocks
The shock absorber has
several roles, but the main role is too
control the release of energy that's in the spring
due to the weight of the car on it
Think of the springs holding up the car, you go over a big bump
now all that energy stored in the springs
wants to release really fast
so the damper or shock absorbers job is to
control that energy release so that the car
doesn't have a big response to the bump
and is controlled and well damped over the bump
if you didn't have shock absorbers the car would literally jump off the road
and be very difficult to drive
A car with worn out shock absorbers will continue to oscillate over a bump
there's a little bit of decay because
the bushings have a small amount of damping
but that is uncontrolled motion
and that means that your
ride heights are changing the loads in the tire changing
and all that decreases the amount of grip
So shock absorbers a really important
to control the mass of the car, the movement of the car
and in that way they can give you
much more group out of the whole platform
Really, shock absorbers are the key
to getting the last bit of grip out of the tire
The suspension controls the tire position
and the damper controls the position of the whole car
and the loads into the tire.
So really, shock absorbers are
the most important piece to get the most grip from car
You used to just bolt on a set of shocks;
set them, and forget them
Today's modern shocks are almost infinitely adjustable and
are perhaps the key to dialing in handling
Well the shock absorbers have a lot of adjustments in
the way you build them, set them up, and the way you adjust them
but primarily there's the bump or compression side which is
when the wheel is moving up closer to the body
and then the rebound side or the extension of the damper
when the wheel is moving away from the body
to break it down in a simple way the rebound side of the damper
is controlling the energy release out of the spring.
So it's controlling the majority of the mass and
the bump side of the shock absorber is
controlling the movement of the tire
and the movement of the tire coming up into the suspension
It's a little more complicated than that but
first-order we think about the rebound is controlling the mass of the car and
the bump controlling the energy in the tire.
But there's one other element in fine tuning your suspension
and that's the bump rubber.
Bump rubbers are an invention that allows us to
run softer springs and lower ride heights
without crashing into the ground.
Because as you get down near the ground
the bumper rubber can come in and basically add spring rate back in
right at the end of the travel before you hit the ground
they exist to protect the dampers, protect the cars from
crashing metal to metal if the suspension runs out of travel
but they also allow us to get a variable rate spring into the
system and allows us to lower the ride height without stiffening
the springs because the bump rubber catches the car
just before it hits the ground
Finally there's the anti-roll bar,
the main tool in adjusting the final balance of the car, front to rear
Well, the anti-roll bar does just like it says
it goes against the roll of the car, it reduces roll.
And if you can reduce the roll of a car,
you can maintain the camber angles of the tires
to the ground in a better range to give you more grip around the lap
So the main function of a roll bar is to reduce chassis roll
giving you more grip out of the tires
Anti-roll bars are typically torsion springs across the car
and you can adjust the length of the arm that
drives the anti-roll bar to adjust it's stiffness
there's other ways but that's the primary way
and stiffening the anti-roll bar
can change the balance of the car quite quickly
In other words, if you stiffen the front anti-roll bar
you get more understeer and if you stiffen
the rear anti-roll bar you get more overseer and
you can use the anti-roll bars as
a quick way to tune the balance of the car
if the car's understeering the first thing is
let's soften the front anti-roll bar
to try and get more grip in the front to reduce understeer
conversely, you could stiffen the rear anti-roll bar
removing grip from the rear
but now you're just hurting the end that's working well.
So usually you try and fix the area that has a problem first.
Fixing a handling problem,
like understeer or oversteer
can be a lot like a cat chasing it's tail
because every time you change one thing
it changes something else
With each understeer, oversteer condition
there's multiple ways to fix it
anti-roll bars usually being the first way, the quickest way
but then you can also adjust your springs and dampers
and rake, that's where the problem gets quite complicated
and you need to have some experience to choose wisely.
SAFEisFAST.com
There is a big difference to being stupid and being brave
and that's what you need to find out
So sometimes being safe and fast are
both connected even if it's hard for us to understand
or for everybody to understand.
Believe me, always in the back of the drivers mind
you have to have a little reserve so you stay safe.