Off-Road Suspension 101: What To Know Before You Go

Not many companies want to admit this, but when it comes to off-road suspension there are two unofficial schools of thought:

1. Here are some parts to help you fit bigger tires
2. Here are some parts to actually improve your vehicle’s performance off-road

Now don’t get me wrong, #1 is not a knock against anyone! Not everyone has the same goals for their vehicles, and just wanting to fit bigger tires while leaving overall suspension performance about the same is certainly no sin. If it was, I would be the first to admit guilt, because I feel like almost every vehicle looks cooler with big knobby tires — so much so that I lifted and fit beefy tires on a 20 year old Audi wagon. 

With that being said, this article will be covering the fundamental basics in upgrading your suspension for off-road and the positive and negative repercussions of doing so. Whether that means just fitting bigger tires, getting some real improved performance out of your vehicle, or hopefully both. Whatever your goal is, there is a right and a wrong way to go about it.

My job is to make sure you’ve got the essentials down so you’re in a good position to move forward with your project. You don’t want to under prepare and end up costing yourself more money down the line, and you also don’t want to go overboard and spend more than you need to.

What makes a good off-road suspension system?

A pretty common misconception is that beefed up off-road suspension stiffens the ride and makes it so you’ll be bouncing all over the road. That may have been true back in the day, but with a combination of off-road racing technology and performance trickling down to consumers as well as steadily growing popularity on off-roading, you would be surprised at just how nice a well sorted rock crawler or desert rig rides.

Think about the job your suspension has off-road. It needs to be able to soak up smaller bumps, washboard, and rocks not only to keep your spine in one piece, but also to be able to maintain a good contact patch for your tires. If you and your tires are bouncing all over the place, you’re never going to get enough traction to make it up that boulder or blast over those whoops safely. At the same time, the suspension needs to rebound quickly enough to be able to maintain enough suspension travel to soak up that next bump.

Here’s an example for you. Ever notice that the super off-road trims of different trucks like the Raptor or TRD Pro trucks have a lower payload rating than other trims? That’s because the softer, more specialized suspension just isn’t designed for hauling heavy loads. Ever drive a big 3/4 ton truck on a dirt road without a load in the back? It’s a pretty punishing ride because the suspension is tuned for basically the exact opposite purpose.

Determine what you’re realistically using your rig for

There’s a big difference between using your truck/SUV to explore some mild fire roads and some light overlanding (more on that later) and wanting to blast over whoops at triple digit speeds or climb up rock walls that would be difficult to free climb up, let alone getting a car up and over. One thing I want to say is that people tend to vastly underestimate what a stock 4×4 can do. I ran into this in my early days running with Jeep clubs where there were stock Jeeps right along side me, running the same trail that I had dumped thousands into my rig to do. Granted I tended to have an easier time of it, but they still made it to the top just as I did. That changed my perspective quite a bit.

Don’t pay for what you don’t need, is the point. 

How will a lift effect how my pride and joy drives?

The point of this section is not to talk you out of lifting and modifying your vehicle. I’m a realist. Everything in this industry is a compromise of some sort and these are some good things to be aware of and keep in mind. Just like your body, your vehicle is a complicated system of interconnected and co-dependent processes to get anything done. Changing one thing can have effects in other areas, with varying degrees of severity depending on what you modify and to what extent.

Ground clearance comes at a cost:

In more recent years the off-road industry as a whole has been moving away from sky-high lifts in favor of striking a balance between fitting as larger a tire as you can while lifting the least amount possible to achieve that goal. It makes complete sense, everyone knows a lift and big tires will change your center of gravity, potentially to the point of being dangerous depending on how you drive. The trend now is not only more tasteful aesthetically (in my opinion), but is safer, more practical, and helps to preserve what precious little fuel economy we can hope cling onto.

I want to emphasize the point about fitting the largest tire you can within reason. While a lift kit does increase ground clearance in terms of approach, break-over, and departure angles — larger tires do that as well, but are the only thing that will give you more clearance under your axles.

Also, the bigger your tires are, obstacles effectively become smaller. Picture hitting a pebble on a skateboard VS running over it on a mountain bike — it might knock you right off a skateboard, but with the larger diameter of a bike tire you might not even feel it. But still, there are other limitations on how large a tire you can run, more on that below.

Putting power down safely:

You still need to put that power down to the wheels, right? Well by lifting your vehicle, you’re changing the angle of the driveshaft or CV axle joint to drive the wheels. If this angle is too sharp (generally anything over 2″ for a CV, possibly more for a driveshaft depending on your application), then you’re going to have premature wear on these parts. Pair this sharper angle with bigger, heavier tires, and you’ve got yourself a recipe for snapping an axle or turning your driveshaft into a pretzel. Most lift kits that put you in this danger zone will either include or recommend ways to alleviate these issues, but that comes at a cost.

Another big consideration is in how big tires effect your ability to put power down onto the road in a practical sense. Not only are big chunky tires heavier and require more power to overcome that weight to get rolling, but a set of taller diameter tires also changes your final drive ratio. Your final drive ratio is basically the sum total of all gearing between (and including) your flywheel and tires.

By running larger tires you are effectively lowering your final drive ratio so that at any given speed, your engine will be turning at a lower RPM. While a lower drive ratio can be beneficial for fuel economy, running huge tires is not the way to go about it. In practice, a larger rolling diameter tire means it needs to make fewer revolutions to travel the same distance as your smaller tires did. What this means for you that is your acceleration will take a hit, and you’ll find yourself needing to give it more juice to maintain the same pace you’re used to.

Also, as an added bi-product, your speedometer will read slow and your odometer will tick over at a slower rate. For instance my Audi’s speedometer reads roughly 10% low, so while it looks to me like I’m doing 80 like a good Southern Californian should, I’m actually speeding along at 88 MPH. And not the cool, time travelling 88 MPH, it’s more like the “here’s your court date” 88 MPH.

Lift kits VS leveling kits:

You can read my full write-up on this here, but essentially a leveling kit is just a small lift for the front of your vehicle to bring the height of your front suspension level with the rear. Trucks especially tend to leave the factory sitting like a stink bug with the rear end sitting higher than the front. This is done so that your truck doesn’t sag in the rear when you add a decently heavy load. Leveling kits are typically done with spacers above the front coil springs, making installation easy, keeping cost down, and mostly maintaining factory driving characteristics.

A lift kit on the other hand will typically raise the front and rear both — often times lifting the front an inch or two more than the rear in order to still achieve that leveling effect. This can be done with spacers as well, could be a set of height adjustable coil overs, or could be a complete rework of your rig’s suspension. This all depends on what you want to achieve as well as how deep your pockets are.

Body lift VS suspension lift:

Here’s one that will get purists riled up. If you want to talk looks over performance, this is the classic one people have been arguing over forever. While a suspension lift will actually change or work with your suspension components (shocks, springs, control arms, etc), a body lift instead puts spacers between the frame and the body. The ONLY function here is to sit up higher and fit bigger tires — sometimes at the cost of leaving a visible gap between the body and the frame that you can see right through.

Where the purists get bent out of shape is when these kits are taken to the extreme with massive 3″ or more spacers between the body and the frame. These have lead to some pretty gnarly carnage on the trail and in accidents in the past, but these days body lifts have more or less fallen out of favor. For one, body on frame vehicles are becoming less common, but also mild suspension lifts have become accessible enough that there just isn’t as much of a point for them to exist anymore — namely suspension spacer lifts. They’re cheaper, easier to install, and generally safer when done right.

There are a few legitimate other reasons for a body lift that everyone can get on board with, however. These are done sometimes to help fit larger engines, or in Jeeps to tuck the transmission and transfer case up between the frame rails for more ground clearance. These are usually pretty mild, and a 1″ body lift isn’t considered a hazard if it’s properly done.

Spacers & lift blocks VS “true” suspension lifts:

Speaking of purists, they’ll have a thing or two to say here as well. The thing is though, they do have a point with this stuff. Lift spacers and blocks are fine if you just need a little more clearance to fit some bigger tires. When things are taken to the extreme, though, is when they become a detriment to performance and safety at best, and a hazard at worst. Let’s get into why:

Of lift blocks and axle wrap:

Everything is OK in moderation, right? That rings true here as well. So I’ve mentioned spacers that sit above your struts or coil springs (usually in the front) a few times already. For the rear suspension, these could be basically the same thing (Recent Jeeps and Rams for example use coil spring rears), but what about leaf sprung rear ends? That’s where lift blocks come in. It’s the same concept, except these are square or rectangular blocks that are placed between the leaf spring and the axle.

Again, these are fine if done in moderation, but especially with rear lift blocks, people have taken this to absolutely ridiculous levels. On a leaf sprung axle, the leafs act not only as the spring, but also act as the axle’s only control arms to hold everything in place and centered. The issue with adding blocks to the equation (besides being potentially unsafe) is that these taller blocks essentially create a lever arm between the leaf springs and the axle, which can lead to axle wrap.

Axle wrap is your entire axle housing twisting back under load, bending the leaf spring almost in an S shape, and shifting the pinion angle of your drive shaft in the process. Yes, this can happen with worn out leaf springs on a stock truck, or a truck with too much power for what the springs were designed to handle, but the issue is greatly amplified by lift blocks. They give the twisting axle more leverage to work against the tension of the spring. This hurts your trucks ability to maintain traction under acceleration, and also can cause premature wear on your U-joints and axle pinion.

The fix here (besides removing the lift blocks) is to either use beefier leaf springs and have your ride quality suffer, or to add traction bars/ladder bars. These are essentially just added on lower control arms to maintain your stock set pinion angle and hold traction at the right balance between practicality and awesome burn out potential, just as the gods of torque intended.

“Actual” suspension lifts:

Remember what I was saying about actual performance? Here’s where you to look for that, as well as make the purists happy (just kidding, they’re never happy). There are couple different routes you can go here, depending on your vehicle’s suspension design, and how far down the rabbit hole you feel like venturing.

Suspension lifts replace the very components that suspend your vehicle in the first place, instead of augmenting or working around them like other solutions mentioned here.

Good ol’ fashioned shocks and springs:

The shocks and springs are like the meat and potatoes of your suspension. Weird comparison, but you get what I mean. A suspension lift kit will include at bare minimum longer springs, or in many cases longer shocks as well if over 1-2″. 

New coil and leaf springs have been commonplace in lift kits for decades now, but becoming more common and more affordable now with the growing prevalence of struts in our trucks and SUVs are coil-over suspension lift kits like seen in that Icon kit above.

Technically speaking of course, your struts are in-fact coil overs, but the industry seems to have decided that only actual performance kits (and usually height adjustable) are worthy of that designation. 

So there we go. These are the fundamentals that should serve as a good platform for you to base some decisions off of in the future. There are some lessons covered here that I didn’t really have to learn the hard way in hindsight, but here we are. If you’ve made it this far, you’re already a step ahead.

Anything I missed or you’re curious about? Not sure where to start with your build?
Drop a comment below or shoot me an email at gdavis@AutoAnything.com!