- Do you like science?
How 'bout math?
Kinematics?
Physics?
Or were you the kid that was sittin' in class
and only paid attention when it was something car-related,
whether it would be math or science?
Well you've come to the right place.
I'm Gels from Fitment Industries
and today's episode of The Build Sheet
we're gonna be going over what exactly
is the center of gravity of your car,
why it's beneficial, and how you can use it to your benefit.
Before we get into it don't forget to subscribe.
Hit that notification button so you get
notified when we upload next.
And let's just jump into it.
(gears clinking)
(brisk electronic music)
When we go ahead and talk about the center of gravity,
we're referring to the average location
of the weight of an object.
This is the location where you can literally suspend
an object in space and in theory,
the object should balance out perfectly.
Introduced first by our good friend Archimedes
way back in the day, the center of mass or center of gravity
is a very important factor in not only the engineering
and design of cool things such as airplanes
and rockets and stuff,
but also in the cars that we drive every day.
The center of gravity is most commonly known
as the balance point of an object but is
also known as a few other things,
like the point through which a force
will cause pure translation.
And the point at which gravity moments are balanced.
Since objects are three-dimensional,
the center of gravity is relative
to those same three dimensions.
It is measured using a three-dimensional plane,
using X, Y and Z measurements.
Gels, why are you telling this to me?
Why are you using big words,
talking about stuff I never cared about in high school?
I'll tell you why, all the forces that you experience
in your car while driving, whether that be
diving during braking, rolling through hard corners,
or squat when launching or accelerating,
are all acting through the center of gravity of your car.
The diving, rolling and squatting that are
commonly referred to are known as accelerative forces.
And these accelerative forces become more and more
apparent when driving a car more aggressively.
When cars are designed and developed,
Engineers take the center of mass, or center of gravity
into a huge amount of consideration.
Vehicles with a higher center of gravity
are more prone to weight shift and potentially
rollovers if the CG is high enough,
and if a corner is taken too sharp.
- Are you alive?
Are you alive?
- [Passenger] I'm fine, how are you?
- Holy (beep), that was a hell of a ride!
- Trucks and SUVs tend to have a higher
center of gravity due to their design,
but tend to compensate for it by having
a much larger and longer wheel base.
When it comes to the cars we know and love,
they have a much lower center of gravity, typically.
And what do I mean by lower center of gravity?
Like I said before, center of mass or gravity of an object
is determined within the three dimensions.
X and Y being the horizontal axis,
and Z being the vertical axis.
So when we're referring to a low center of gravity,
you're talking about the location along the Z axis.
The lower, the better.
A lower center of gravity will help keep
the car planted to the ground.
It also improves handling and responsiveness of the vehicle,
reducing the amount of dive, roll and squat.
So you ready for some math?
No?
Well, here it is anyway.
The position of the vertical CG or center of gravity
height from top to bottom of a car can be determined
using the following formula.
You take the level wheel base,
multiplied by the raised vehicle wheel base,
multiplied by the added weight on the front wheels,
and divide it by the product of the
distance vehicle was raised and overall vehicle weight.
What does that exactly mean?
I have no idea, apparently you can find those numbers
in like the manual of your car somewhere
if you ever wanted to know.
Which brings us to the horizontal position.
Now the horizontal position of the center of gravity
also plays a huge role in the
performance of a vehicle as well.
Keeping weight towards the center of a car
is generally the way to go,
as keeping the weight closer to the center of gravity
will allow for a lot less polar moment of inertia.
Which basically means that the car will be a lot easier
to move around and it'll be a lot more responsive.
Typically this is why we see cars with mid engines.
By centralizing the part of the weight
that comes from the engine and transmission
and keeping it all together
and out from outer parts of the car,
it's capable of being a lot more controlled as a whole.
Here comes more math.
Front to rear location can be
determined by the following formula.
Rear wheel vehicle weight
divided by the overall vehicle weight,
and multiplied by the wheel base.
And then the side to side position,
which is the other horizontal axis,
can be determined by this formula.
Right side weight divided by the total weight
multiplied by the track width.
All in all this has to do with something
that is known as moments.
At the risk of getting too technical for one video,
and going into an entire lesson on dynamic physics,
you can relate this to using a breaker bar
on a rusted bolt.
Picture the center of gravity as the bolt
and the force you're applying as weight.
The closer you are to the bolt on the wrench,
the harder you're gonna have to pull down on the wrench
and the more pressure you're going to have to apply.
Now, move down the wrench or breaker bar a little bit
towards the end, and you're not gonna have to use
nearly as much force to get the bolt loose.
Now this is what we know as torque or leverage,
for the most part, but it is synonymous with moment.
And it's basically the same principal.
So when we pull weight in closer to the center of the car,
keep it from being further out,
we're reducing the amount of effectiveness
or angular displacement that weight would
originally have when driving.
For the most part, most performance or sports cars
right off the market will have considerably low
center of gravity right off the bat.
Usually located near the center of the vehicle
with the height sitting right above where
the front bumper ends.
So like I mentioned earlier, the lower and more central
the center of gravity is, the better.
And you're probably thinking to yourself,
"Okay, got it.
Is there anything that I can do to like, you know
move it or lower it myself?"
Glad ya asked.
Probably one of the easiest ways to lower
the center of gravity of your car is, well,
lowering your car.
Whether it be with lowering springs,
coil overs, bags, lowering a vehicle's right height
will at the same time lower the center of gravity
on that Z axis.
By doing this you'll get all the benefits of having
some sort of after-market suspension
plus increased lateral grip.
You can also improve vertical center of gravity
by removing weight from a car.
Specifically any weight that sits higher up in a vehicle.
You thought you really wanted that sunroof?
Would you still want it if I told you that's a
25 pounds of weight sitting above your head?
And that the highest point of the car is drastically
affecting your vertical center of gravity?
Other things such as carbon fiber replacement panels,
especially roofs, can reduce and improve
center of gravity as well.
As far as going about improving the horizontal
center of gravity of a car,
it tends to be a little more strategical.
Like I mentioned before, moving the weight towards
the center of the vehicle, is going to be the end goal.
Again we see this achieved with replacement of
lightweight body parts such as fenders, hoods, trunks.
But also moving around other components such as batteries,
that will also help with the horizontal position as well.
Now this can all sound very technical and very confusing.
You might be sitting there trying to take this all in
and be like, "Man, screw that!
That sounds like it takes a bunch of time,
a lot of calculations, a lot of math
that I don't like doing.
And chopping up a car to move things around."
And, yeah!
If you're looking at competing in things like
Time Attack or Formula One or something like that.
Center of gravity is taken into the extremes
when it comes to higher end motor sports.
But in reality, people like you and people like me,
it's really just a matter of keeping a few things
in mind when you're going ahead and modifying your car.
Keep the car low, and keep the weight minimal,
and localized.
Lowering your car will help a ton.
Carbon fiber replacement parts look cool
and actually do benefit you.
Getting seats that sit lower to the floor
will help you a ton and even though it may
take a little bit to relocate the battery,
it is worth it.
So hopefully this gave you a little bit of insight
into actually what center of gravity or center of mass
of your vehicle actually is,
how you can use it to your benefit,
and if you're looking to relocate it
or modify it a little bit,
what you can do to actually do that.
Drop a comment down below if you have actually
tried to modify or relocate the center of gravity
of your car and exactly how you went about doing it.
I'm Gels for Fitment Industries,
don't forget to subscribe and wheels,
tires and suspension over at FitmentIndustries.com.
I'm Gels from Fitment Industries, we'll see you later.
Peace.