I'm Ryan from extremeterrain.com, and in this video, we're gonna be talking about suspension
geometry.
Now, this is a very big topic, we could spend a ton of time talking about this.
But what we're gonna focus on today are the pieces of your suspension that affect suspension
geometry, and how that geometry then affects how your Jeep rides and handles because that's
really what's important to you as the driver of a Jeep.
And maybe more importantly, we're going to talk about how a lift kit can change that
geometry and therefore affect how the Jeep rides and performs.
Because there are lift kits that are very expensive and include a ton of parts, and
some that are much less expensive and include many fewer parts and which one is right for
you can be hard to figure out.
But if you really understand how the suspension geometry works, how the lift kit changes that
geometry, you can make a good, well-informed decision.
So, make sure you subscribe to our YouTube channel, that way you can check out some detailed
product videos on all the different lift kits that we offer.
That will really explain all the different parts and pieces that are going to be in those
different lifts that are available to you.
So, what we're going to do now is get this Jeep up on a lift and jump right into it.
So, the first thing we're going to talk about are control arms, and the control arms are
there to hold the axles in place forward and backward.
They don't do a whole lot to hold the axle side to side, just that forward to backward.
They're going to be a total of eight of them, four in the front, four in the back, and you
have both lower and upper control arms and specifically what we're going to be talking
about today is control arm length.
The control arm length is of course very specifically set from the factory to give you two very
important angles.
One of those angles is called the caster angle and the other is called pinion angle.
So, the caster angle is really the angle that the axle is rolled.
If you were to draw a straight line between the upper and the lower ball joint here, you're
going to have a very specific angle off of vertical, that's gonna be your caster angle.
Now, what is caster angle feel like?
If you picture yourself doing a slow speed maneuver, maybe in a parking lot, you turn
the wheel all the way over to one lock, as you accelerate, you can sort of let the steering
wheel go and it will unwind itself.
Put itself back closer to center.
That is due to the caster angle on the vehicle.
That's important in those slow speed maneuvers, but it's also important at higher speeds,
like when you're driving down the highway, because that makes the front tires want to
stay straight.
So, the caster angle is very, very important.
Pinion angle is another angle that the control arms set and that is the angle of this piece
right here, which is the input pinion on the front differential.
And why that is important is because it affects your driveshaft angle and everything all the
way up the driveline.
So, by having the proper pinion angle, you're going to ensure you have proper U-joint wear
and also no vibrations in the driveline.
So, as you can see, the length of the control arms is very, very important because of these
two angles.
But if you change any bit of the suspension, you're going to start changing those angles
around.
So, if you put a lift kit on the vehicle, longer springs, or a spring spacer, that's
going to move the axle down.
But because of the control arms, the axle actually moves in an arc, it's going to move
down and in toward the center line of the Jeep and it's also going to roll.
So, you can see a lot of things get thrown off just by changing the ride height of your
vehicle.
Now, what you can do is go ahead and throw in a different length set of control arms
to help fix some of those issues.
So, if you've looked at different lift kits out there, some are very expensive and include
a lot more components.
Sometimes those components on the more complete more expensive lift kits, especially the taller
ones, are going to be control arms and now you know why.
So, you can get a lift kit that includes just lower control arms, just upper, sometimes
all eight, sometimes they're fixed length, and sometimes they're adjustable.
But no matter what, the reason for having control arm included in a lift kit is to recenter
the axle forward and backward, so put it back closer toward the center of the wheel well,
and also roll the axle back to where it needs to be so that your caster angle is back closer
to the factory, and also your pinion angle is back closer to factory so you don't end
up with any sort of weird vibrations, premature driveline wear, or a Jeep that doesn't quite
want to recenter the steering wheel like it did when it rolled off the assembly line floor.
To show you how much the pinion angle can change with ride height, we have one of these
magnetic angle finders that we stuck right on the pinion of the Jeep.
When the weight of the Jeep is being supported by the lift and the suspension is drooped,
that's really simulating a lifted ride height.
And of course, when the Jeep is down under its own weight, that's going to be your stock
ride height and you can see as we raise and lower the lift, the angle finder changes right
around four to five-degree mark, which is pretty significant.
One of the other very important suspension components up front in here is going to be
the track bar.
And this is also one of those pieces that is sometimes included, sometimes not included
in a lift kit, so I want to talk about how it affects your suspension geometry, so you
can decide if you want a new track bar or not.
So, in the same way that the control arms decide how far forward and backward the axle
sits in the Jeep, the track bar determines where the axle sits side to side in the Jeep.
So, it connects to the frame up here, it connects to the axle itself down here and is a set
length like the control arms from the factory.
Now, when you do lift the Jeep, because of the way this does attach to the frame and
to the axle, just like the control arms, everything's moving in an arc.
As you lift, it's going to move the axle down and in this case, over to the driver side
of the Jeep, which will throw it out from being in the center of the vehicle.
So, that's why you see some lift kits, especially taller ones and higher-end more complete ones
that are usually more expensive, including an adjustable track bar because you'll be
able to change out this track bar with the adjustable one.
Usually the new ones are a little bit stronger, sometimes they also have different joints
on the ends to give you different articulation, but what we're really talking about today
is the adjustability of it and you can make that track bar longer to push the axle back
toward the passenger side and get it completely recentered in the Jeep.
Now, that is the main idea of an adjustable track bar, and that is why a lot of you are
going to want to have one on their Jeep, to recenter that axle.
But what you also need to understand is how the track bar works in conjunction with the
drag link.
So, the drag link is the piece that goes from your steering box down to your steering knuckle,
that's this bar right here.
And that is adjustable from the factory and the idea there is that you can completely
center the steering wheel in the Jeep, but what you need to know is that the drag link
and the track bar should be exactly parallel.
And the reason for that is like we keep talking about, everything in the Jeep moves in an
arc as the suspension travels up and down, even if we're not talking about lift and we're
just talking about hitting bumps on the road, you want those to move the same amount in
the same direction.
If your track bar is at a completely different angle because maybe you installed a track
bar bracket but didn't do anything with your drag link, then as you hit a bump, the axle
is gonna move at a different speed, in a different distance than your drag link is going to,
and you're going to end up with what's known as bump steer.
And you can actually see really drastic versions of bump steer if you stand on the front bumper
of a Jeep, and you bounce up and down, looking through the windshield, you can actually see
the steering wheel moving back and forth.
And that is the same thing that happens as you drive down the highway, suspension travels,
steering wheel goes back and forth, that is not what you want.
So, all of that really comes back to going with an adjustable track bar is just fine.
You're not going to create bump steer, you're not going to create any of those other issues.
However, if you add a different track bar bracket, either on the axle side, or on the
frame side, or in some of the older generations, sometimes lift kits included a drop pitman
arm which would change the angle of the drag link, if you change one of those angles without
changing the other one and you throw them out of parallel, you are going to have some
suspension geometry issues and end up with some bump steer which is not what you want.
So, keep in mind, keep these parallel.
If you're gonna change the angle of one, you have to change the angle of the other.
Now, the track bars also affect one other thing and that's known as roll center.
And that is how much the body rolls when you're going around a corner.
Now, there are a lot of different things that affect how much the body rolls, but by getting
the rear track bar a little bit flatter, by adding one of those track bar brackets, you're
helping to get the roll center a little bit closer back to a factory spec and give the
Jeep a little bit more of a stable, more of a factory feel when you're cornering.
Now, one of the other bars that you see up front here is right here, this is the tie
rod.
We're not talking too much about the tie rod today, what its job is is to connect the passenger
side tire to the driver side tire, so when one turns, they both turn.
They're going to turn together.
The reason we're not talking too much about it is when you change the ride height of the
Jeep, when you add a lift kit, it does not necessitate adding a new tie rod.
This is a piece that you can pretty much just leave from the factory, especially on the
JL here.
This is a nice solid piece, it's adjustable, so you can reset the tow and do any sort of
alignment stuff that you need to.
But again, it's not necessary to change out the tie rod if you add a lift to your Jeep.
So, the last bit that we're gonna talk about is something that's included in pretty much
every lift kit of right around that two-inch size or higher and that's going to be a new
set of sway bar end links.
And this is a very easy concept to talk about because things aren't moving in arcs like
they were with control arms or the track bar.
Your sway bar is right here more accurately your anti-sway bar, and what that's going
to do is help to reduce body roll when you're going around the corner.
And this needs to be connected to both the frame and to the axle.
So, the frame side is up here with a couple of brackets and down here, it connects to
the axle with the sway bar end links.
And these are, of course, a set length from the factory, so that your sway bar is at a
specific angle when you're at ride height.
Now, when you lift the Jeep, that sway bar is going to tilt a little bit if you don't
add new sway bar end links, so in order to get it back closer to its factory angle, you'll
put a longer set of sway bar end links on your Jeep.
Now, just like the other components that we talked about you're going to have the same
thing in the front and in the back, your front sway bar and rear sway bar both are going
to have two end links, so most lift kits are going to include, again, the front and rear.
Now, the one thing to note about your front sway bar end links is this is something that
when you're on-road, you definitely want to be connected it has a lot of stability and
a lot of safety, or when you go off-road, a lot of you will wanna disconnect your sway
bar in order to give you maximum articulation off-road.
So, again, some lift kits are going to include longer sway bar end links that are also more
easily disconnected.
You would need tools in order to disconnect this sway bar.
A lot of the aftermarket one will be longer, some will be adjustable, and some will be
a quick disconnect style where you can just pull a pin and pop that sway bar off of there.
Now, you know what they do on the Jeep and why they're included in most lift kits.
That's gonna do it for this video.
We talked a little bit about some of the main suspension components of your Jeep, how they
affect suspension geometry, and what that actually means to you as the driver of the
Jeep.
Hopefully, with this new information, you'll be able to make a good decision when purchasing
a lift kit as far as which components you wanna make sure your lift kit includes.
Now, make sure you subscribe to our YouTube channel.
That way you can check out some of those detailed videos about all the lift kits that we have
available on the site, and also make sure you comment below.
Let me know if you have any questions about any of the stuff we talked about in this video.
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