Suspension 101 - Rock Racing

Nearly every rig we build has one. And on this episode of Xtreme 4x4, we'll take the mystery out of building the popular four link suspension.

Plus before you bolt on an aftermarket part, it's tested here in the extreme rock racing association

when we're talking about off road vehicles and the suspension systems underneath them. We can usually sum it up using one word. That word is links, whether it's a low buck trail rig like our Bio Zuk or maybe it's a dual purpose ride like our daily driver, a weekend wheel and Jeep TJ or at the other end of the spectrum, a high dollar core truck tearing across the desert in a weekend race. All of these vehicles have link type suspension systems underneath them. How they benefit from having them in different ways.

Over the past five years, we have built countless link suspension systems here at extreme,

but it is still one of the most common areas of misunderstanding.

How do they work? What difference does link placement make and much more.

So today we're gonna look at all the different types of link suspension systems, the proper way to set them up and also different option when it comes to shocks and springs. But before we do that, let's look at what we normally replace when we link up a truck and that is a set of leaf springs. Now, leaf springs have been around forever. They were installed on the very first car ever built and they're a fine piece of technology, although they're slightly outdated now, they do have a couple of benefits. Number one, they can handle huge loads, which is why you see them in the back of pickup trucks. And number two, not only are they the spring in the suspension system, they're also act as the axle locator which makes them very simple to install. Now, the drawbacks of the leaf spring is you can't get a lot of wheel articulation out of it because you're limited by the length of the swing shackle in the system.

You've also got a spring that protrudes all the way to the front of the vehicle. So you usually have some frame horns sticking out past your tires. And the worst thing in high horsepower applications, the engine's torque will try to twist your axle housing because the leaf spring is in essence of spring, it will actually move and create a wave that wave creates wheel hop. Now, by installing a four L,

you eliminate that wheel hop. That's the number one reason that drag racers use it.

Now to help you guys visualize all the different types of link placement. There is I went ahead and put together this mock up frame section. It has two parallel frame rails as well as a belly pan skit. I set a rear axle housing in behind it to act as the rear axle. And then I'm gonna go ahead and lay out a bunch of different link setups using this green tape.

The parallel for

link uses four parallel bars traveling from the frame to the axle and then 1/5 bar, a pan hard bar to keep the axle from moving side to side. The downfall of this set up is you have very little articulation because the joints begin to bind.

The three link with a pan hard bar is very commonly used in the front end of four by four link vehicles because as the suspension articulates the panhard bar and the drag link will move in the same plane and you won't get any bumps.

The single triangulated four L

is the first suspension that doesn't need a pan

bar. The angle bars actually locate the axle. The downfall here is the lower links that are running parallel can bind before maximum articulation is reached.

The double triangulated four L

is probably one of the most common you see in hardcore off road buggies, you have two different link, be

located the axle, so it's super strong. Plus you can reach huge amounts of articulation because the joints never bind.

Now, the reason that the joints don't bind has to do with the design of the suspension set up itself. When the tire articulates the housing moves in an arc because these two bars are at angles opposing each other, you're actually pivoting on the bolt itself that holds the hind joint, you're not twisting it on its misalignment spacers. And that's why this set up here is very commonly used. And this is the first step the designing A four L picking which type you want. Now we're going to build a complete mock up for L on this frame to give you an idea about link placement.

Our mock up links are going to be made out of some inch and a half 120 watt dom tubing

at either end, we're gonna have some ballistic fab tube adapters and some Q A one rod ends, setting up a link suspension is usually done at either ride height or full compression

to locate the axle behind the chassis will measure from a common point on the frame

and then cross measure to ensure it's square,

then brackets are mounted to both the frame

and the actual housing

and the links are installed.

Now, we've gone ahead and set our chassis up at ride height. We have the belly pan 24 inches off the floor and the housing on a set of stands 20 inches up to simulate the sink, sitting on a 40 inch tall tire. Now, we have used this exact same suspension design in our projects before. And we know that it works very well for the type of train that we go four wheeling on and we spent a lot of time fine tuning it to make sure that was very predictable. We paid attention to three key measurements.

The first measurement was vertical separation.

Vertical separation is the measurement from this lower link mount to the upper link mount. Now, this distance here does two things. Number one, it locates the axle and keeps it from twisting on those high horsepower loads. Number two, it determines the angle that these links run at. You want them running almost parallel, but you want the upper coming downhill slightly so it converges with the lower, but we'll get more on that later.

Now, the second thing is our len length,

we like to run the uppers at 70% of our lower length length just make very predictable and keeps the pinion at a good angle. This is easy to adjust by moving the lower length mount forward or back and changing this length right here. Now, this is a triangulated four lengths. So there's no pan hard bar.

Now, the axle is located by this angle of these two links. Now, ideally, this angle must be 40 degrees or higher. But a good rule of thumb is to take these lower links and run them as far out on the housing as you can get without interfering with the tire itself. Now this whole set up here comes in fact, with

three different things. Number one, it affects our squat ratio.

It

interprets our roll axis and it also determines our rear steer. All that is affected by where the buggy's center of gravity is.

Now. The standard that hutches dropped into this chassis is going to represent the center of gravity of this buggy. This roller right here. It's just above the middle of the transmission. Now, this affects the squat based on the link placement. If you could draw an imaginary line off the lower link and the upper link, they would converge right at the center gravity. That's because this suspension is set up to run neutral, almost no squat. When you accelerate, it's dead flat. If this imaginary lines came forward and crossed above the center of gravity, the vehicle would have a large amount of squat. And that means that when you drop it in gear and accelerate the back end would drop down a little bit. And the opposite is also true. If these lines came forward and they cross below the center of gravity, the vehicle would have anti squat. And that means when you accelerate, it lifts up. Now, depending how far from the center of gravity that intersection

happens, depends on how much squat or anti squat you have. Now roll axis is the buggy's ability to twist on its center axis. Now, these two lower links meet really close together and that basically means that this buggy right, right on a knife edge right here and that's great for crawling. If we wanted to go high speed, we go ahead and move these links a little bit further out. So the imaginary lines would conversely cross closer to the buggy center of gravity. And that would make the suspension a little bit more stiff. Now, rear steer has to do with the distance the axle is from the link mounts as the axle articulates the link moves in an arc, ok. If the link is really short, the tire gets really close to the frame as it goes up and gets further away as it drops down.

That basically means that the axle can move around underneath the bug at the back can make the suspension really squishy. Now, obviously, this is just one set up. You can spend months or even years, fine tuning a link suspension. There's lots of ways to do it. But now that you understand some of the theories, just get out there. Go ahead, link up your junk

up next. No slow

mo cone dodging here

in your face. Rock racing. When Xtreme 4x4 continues

today on Xtreme 4x4, we're headed up the road to a not so sleepy little town about three hours away from us where peaceful weekends are interrupted by

rock racing.

29 of the top rock racers came to Jellicoe Tennessee.

All going for the sport's biggest prize. This is the best of the best in our world. It's the last one of the year. So you got all winter to rebuild your equipment. So it's gonna be all or nothing.

Hammering it side by side against the clock.

It's extreme off road racing. The XRR, a rock racing series is two laps straight ahead. No cones racing where the fastest time wins.

I like the speed a lot more than the slow pace crawling. It's really intense since its debut five years ago. This sport has been a magnet for the fearless and the foolish. A lot of times you almost forget to breathe. You're just working, trying to get everything done just right and as fast as you can go, you're on the throttle,

working the turner brakes, working the shifters. This series tests more than driving skills. It's really hard on the equipment. So it's really survival. This is the most extreme terrain that vehicles go over and we're going up and down hills over jumps. Motocross style jumps through sharp rocks and ledges and people are cutting tires, breaking drive train and just all kinds of mayhem on these rigs

that mayhem has made this series of proving grounds for the manufacturers and part makers. The companies rely on us racers to test their products to the fullest extent. Most of those parts are prototypes which one day will end up in your off road rig.

And there are parts that do get tested and get tested hard

it's a great test bed for all the extreme stuff. They can do lab tests, you know, in the shop,

but it doesn't duplicate what we can do on the course. Being the first to break in and test parts of the future requires trial and error. As well as patience. There's good guinea pig, which is uh prototype products and there's bad guinea pig, which is the first guy on the course. So

sometimes it's good sometimes it's bad. We're beating them so much and you know what I mean? Each time we beat something, you, you go back and you learn, you know, hey, this needs to be a little bit better. Uh We've broken a lot of parts this year.

They beefed up the parts in the places that we've been breaking in. And uh now they're holding up once a motorcycle racing and water skiing. Pro Rick

Dermo. It's all about fashion metal.

It is hardcore

and that's why we do it

at age 49. Rick is the oldest racer out here

and one of the best in the sport's five year history. You're pushing the limits every time you're driving as hard as you can, as fast as you can because 1/10 of a second

is what counts to win this race. His work ethic and no nonsense approach to racing has made him a

model for the younger generation.

There's so much you can learn from him and I just love to listen to him and try to learn from him and take everything I can from him because he has a great wealth of knowledge about the sport. There are some fast kids out there and I'm still the old guy

and I like beating him. Rick came the Jellicoe with one mission. We want to be the fastest out there

while winning the title is the goal. Rick

DIMO sponsors at new parts that needed urgent testing.

This week, we're testing some axle shafts for spider tracks off road

and also a couple of little uh gears for our A RB. The specs on the new stuff were top secret, hush hush

but having to be a guinea pig for the season biggest race wasn't an issue for Rick. We're very confident that they'll hold up

for the finals. We want to finish and finish top after four runs. The top six drivers would advance to the final shootout. We gotta get our game face on and put on a good show. His time of one minute 55

was the second best and put him in the shootout. It feels great problems during his first shootout run cost him big time. We caught a banner with a rear tire just kind of slid on some gravel and broke the banner.

So it cost us two minutes. Rick finished fourth overall, but his new parts had a feeling like a winner. Everything was flawless. So

I'm happy with them

and I think our sponsors will be happy with their product. You know, I'm so excited. We finished the day

and I got six really good runs.

Now, so far today, we've looked at how you set up your link suspension and how it affects how the buggy acts on different types of train.

The same thing holds true with how you suspend it. One of the most popular ways to do that is the classic coil over shock. We've used these before and you've seen them in action, you basically have coil springs wrapped around a shock absorber that are fully adjustable, but just like the suspension. There's some specific technology that will help in different types of terrain. Now, this is the classic Bill Stein 9100 rock crawler specific shock inside this shock is what's called digressive valving. And what that means is the fluid piston will flow freely through the fluid when you're just traveling under a nice normal pace. But when you have that hard hit, like you've fallen off an obstacle, it'll slam shut and become a lot stiffer making these ideal for rock crawling applications. Now, this isn't your only option. Another one is an air shock.

Air shocks are relatively new, but how they work is very similar to the old coil over shock. It still has a valving and oil inside. But how it supports the vehicle weight is different instead of using a spring, it uses a nitrogen charge above the piston that you add through the strainer valve. Now, the nice thing about the air shock is you can adjust it by changing that nitrogen pressure and they're relatively cheaper than their coil over cousins. Now, ballistic fabrication has recently come out with

a

fleet line of shocks and they took the air shock to the next level. They call it a hybrid shock. It's built like a standard air shock with a large rod and as well as the oil valving and the nitrogen charge, but it's machine to accept a coil over spring. Now, what this will give you is it gives you the adjust ability of the nitrogen shock, but it also allows you to have that stable spring rate when you need it.

Bypass shocks used to only be seen on high end desert racing rigs. But thanks to events like rock

racing, we're seeing more of them show up on trail buggies. Now, they do not support any vehicle weight. They just act as a shock, but they're infinitely adjustable because as you can see on this cut away that we got from King, the oil doesn't always have to go through the shock valve. It can bypass it through the bypass tube and change how the shock acts on both compression and the rebound stroke. As you can see, there are tons of different choices when it comes to shocks. It honestly depends where you go wheeling and what you're building

there is no question that when wheeling traction is king and the pit bull rocker provides serious traction

in the dirt.

The all biased construction and four ply side wall allow the tire to conform to obstacles on the trail when aired down.

Plus the integrated side wall protector will help keep the rocks from damaging the rim. Be

the large lugs clean out easily when the tire is fun.

But thanks to the alternating tread blocks, these tires are more bite than bark.

Now, so far today, we've covered a lot of topics in our suspension 101 show. The one thing that we haven't touched on yet are link and options. And there's a lot when we first started building four links was very common just to use a standard poly bushing.

Now, the problem with these is they didn't provide us a lot of articulation in our axle. So the first logical upgrade was to swap those out for a hem

joint. Now, these are incredibly strong for their size and we still use these today. A

new trend that we see

surfacing is the rebuildable series of joints. Now, the nice thing about these joints is their

sheer size allows them to be incredibly strong, but you can also take them apart and replace the wear items inside. So they will never wear out if there's one drawback to these joints is that they are so big building brackets and tabs can sometimes be a little bit difficult.

Now, there was a time when you wanted to build a four length, you had to cut all your own brackets and tabs with a plasma cutter grinder. But nowadays, it's a lot easier with companies like Ballistic Fab Blue Torch and a and a manufacturing, they laser cut every bracket and tab. You would need to set up a four link underneath your truck. And they also have all the tubing adapters as well as the misalignment spacers. Now, hopefully today you got a glimpse into all the work it takes to set up a four in correctly. There's a lot of variables out there, but a little bit of time and a little bit of effort, you can have a great working suspension under your rig.