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The debate between solid axles and independent front suspension (IFS) has been going on for years—and for good reason. It’s one of the things that makes cars and trucks so fascinating: the endless variety of setups and combinations means there’s no one-size-fits-all answer. That’s why this topic keeps coming up, again and again.
If your vehicle is built purely for extreme off-road use—rock crawling, extreme articulation, rugged trails—go with a solid axle. Otherwise, go with IFS.
If you’re wondering why that’s the answer, read on—T.G.Q’ll break down exactly what makes each setup works, and why one might suit your needs better than the other.
What is solid axle?
The solid axle is one of the earliest suspension systems ever created. In fact, it’s been around for over 200 years. However, it hasn’t been phased out—because it still offers real advantages even today.
The most important of these is its simplicity. And that simplicity shouldn’t be underestimated. A straightforward design can bring a wide range of benefits: higher load capacity, lower development cost, increased durability, and more.
Structurally, a solid axle is incredibly simple. At its core, it consists of just three main components: a metal bar, a damper, and a spring. The damper and spring are mounted to the metal bar, and wheels are attached at both ends. That’s essentially it. Because both wheels are connected by a single solid rod, the axle moves as one piece—hence the name “solid axle.” This also means the geometry of the axle remains fixed during suspension movement.
Dead Axles and Live Axles
Solid axles can be further divided into two types: live axles and dead axles. The only difference between them is whether or not the axle transmits power. A live axle is connected to a differential and delivers power to the wheels. A dead axle, also called a non-driven axle, has no differential and simply supports the weight of the vehicle without providing any power.
What is IFS
IFS stands for Independent Front Suspension, and in a way, it’s a bit of a word game. You don’t need to dive too deep into terminology to understand it—just know that it’s basically the opposite of a solid axle.
A solid axle connects both front wheels using a single metal bar, so when one wheel moves, the other moves with it. On the other hand, independent suspension uses two separate arms—one for each wheel. This allows the left and right wheels to move on their own without affecting each other. That’s why it’s called “independent.”
By contrast, a solid axle is often referred to as a non-independent suspension, since both wheels are physically linked and can’t act separately.
Now, independent suspension comes in many forms—like MacPherson struts, trailing arms, multi-link and double wishbone. But when it comes to off-road vehicles equipped with IFS, over 70% of them use double wishbone suspension.
Compared to a solid axle, the double wishbone in IFS is much more complex. But that complexity brings advantages in terms of handling and ride comfort.
How good is it? Well, Formula 1 cars use double wishbone for precise handling. And on the other end of the spectrum, Rolls-Royce uses it for a superior ride comfort.
So, IFS and Solid Axle which one is better?
Well, again, it depends—it really comes down to how you define “better.”
if your car needs to handle more everyday tasks—maybe your wife takes it to Walmart for groceries or uses it to pick up the kids from school—and you just want to hit some light trails or forest roads on the weekends, then IFS is the better choice. But if your focus is on off-road performance and lower cost, then solid axle takes the lead.
Why Do Some Automakers Use IFS in Their Off-Road Models?
It’s simple—because people today want it all. We’ve become a little greedy, in a good way. We want one vehicle that can do everything.
Picture this: you’re a dad who’s passionate about off-roading, but also deeply devoted to your wife and kids. You love your family, but you can’t let go of that adrenaline rush you get on the trails. On weekends, you crave that off-road escape—and for that, solid axle is perfect.
But during the week, life is different. You commute to work, pick up the kids from school, and your wife might need the car to run errands. That’s when the rough ride of a solid axle can become a real problem. Let’s be honest: no one wants to hear complaints from their spouse and kids about how uncomfortable the car is.
So, automakers started designing vehicles with IFS-equipped suspensions—built for people like you who want to enjoy the outdoors but also keep their families happy. While IFS might not match the extreme off-road capability of a solid axle, it offers a much smoother ride and makes daily driving far more pleasant for everyone onboard.
In reality, this is all part of a spectrum. On one end, you have vehicles built 100% for urban use. On the other end, you have purpose-built machines for extreme off-roading.
Merits and Demerits of IFS and Solid Axle
1. Cost
When it comes to cost, IFS tends to be more expensive than solid axle setups—especially if we use the double wishbone design as a reference point.
Like solid axles, a double wishbone suspension includes essential components such as the steering knuckle, spring, and damper. But it doesn’t stop there. The system also requires upper and lower control arms on both sides, stabilizer links, a stabilizer bar, a subframe, along with ball joints and bushings. That’s a lot more hardware to design, manufacture, and maintain.
1.1 Design Cost
Engineers don’t need to analyze everything on each individual suspension part one by one, which helps reduce the design cost.
1.2 Production Cost
The parts are divided into many types, and each part has its own production specifications and molds. The complex design of IFS increases the complexity of the manufacturing process, which in turn raises the overall production cost.
1.3 Ownership Cost
IFS has many parts and is very complex, which also means all these parts have the potential to fail. For example, a single lower control arm can cost over 250 bucks. And that’s just one part—don’t forget that all parts have a limited lifespan. On top of that, owners of off-road vehicles are likely to use their cars for off-roading, which accelerates wear and tear. In other words, this leads to higher ownership costs.
1.4 Repair Cost
IFS has a more complex structure. When the vehicle breaks down and needs repair, mechanics may have to remove many parts just to replace the damaged one. The extra time spent on disassembly and reassembly results in additional labor charges for the owner. This is another reason why IFS tends to have higher repair costs.
2. Part Strength
The main component of a solid axle is just a single hollow metal tube, and the diameter of this axle tube is usually designed to be quite thick—often over 3 inches. This means the solid axle can withstand large forces without breaking.
In contrast, IFS suspension arms are usually made from sheet metal welded together, and the thickness of this sheet metal is generally less than 0.5 inches. Such parts have no problem handling typical road bumps.
However, when it comes to off-roading, the situation changes. When the vehicle encounters big height differences or when the wheel hits a rock at the wrong angle, the suspension arm can easily bend. This can quickly bring your off-road adventure to a halt.
Sometimes, off-road conditions are unfamiliar or the driver might be a beginner—these situations can cause mishaps. And even minor mishaps can break your suspension arm.
3. Load Capacity
Generally speaking, the load capacity of a solid axle is much higher than that of an independent suspension. That’s one of the reasons why many trucks use solid axles.
Although independent suspension has a lower load capacity compared to solid axles, most vehicles only use IFS on the front axle. And usually, the front axle isn’t meant for carrying heavy loads—the rear axle typically handles that.
According to cars spec from T.G.Q, among off-road or pickup models equipped with independent front suspension, 80% still use solid axles for their rear axles. This shows that these vehicles maintain strong load-carrying capability.
Therefore, in this category, we can say that most automakers have naturally chosen to use solid axles.
4. Weight
Although independent suspension has more parts and is more sophisticated, its overall weight is actually less than that of a solid axle. This translates to better acceleration and improved fuel efficiency. However, when it comes to off-roading, that advantage doesn’t seem to matter much, right?
5. Ground Clearance
This is an interesting topic. In off-road vehicles with IFS, a common design is that the subframe is placed at the highest point, with two downward-hanging lower control arms connecting to the wheels. This setup maximizes the chassis ground clearance. For IFS, the ground clearance is measured from the subframe to the ground.
In the case of a solid axle, since the axle is directly fixed to the wheels, the vehicle’s ground clearance is the distance from the axle to the ground. (If it’s a live axle, then it’s the distance from the differential to the ground.) This means that the ground clearance of IFS is higher than that of a solid axle. So, has IFS finally scored its first win in ground clearance?
Dynamic Ground Clearance
The answer is: NO. What we discussed so far about ground clearance is based on the vehicle being stationary. However, when off-roading, the vehicle is obviously not stationary — it constantly reacts to the terrain’s ups and downs. This dynamic behavior causes the actual ground clearance during driving to be lower for IFS compared to a solid axle.
Examples of how Suspension Movement Affects Ground Clearance
IFS
When the vehicle hits bumps, the wheel compresses the suspension, causing all suspension parts to move upward. When the suspension moves up, the subframe moves downward, which means the ground clearance decreases.
Solid Axle
When the vehicle hits bumps, the wheels are pushed upward. But since the wheels are connected together by the axle, the axle moves up as well. This means the distance between the axle and the ground never changes, resulting in better off-road capability.
This is also why you often see damage or scratches on the front parts or skid plates of IFS off-road vehicles.
6. CV Joint or U-Joint
In order to allow engine power to be continuously transmitted while the wheels are turning or moving up and down, a CV joint or U-joint is needed.
U-Joints vs. CV Joints in Different Suspensions
Generally speaking, solid axles are equipped with U-joints, while IFS uses CV joints. Both types of joints transmit power, but U-joints only work when the wheels are turning, whereas CV joints allow the wheels to both turn and move up and down while still delivering power smoothly.
When a solid axle vehicle moves vertically, the axle and wheels move together, meaning the wheel and axle maintain the same relative position. In this case, the joint only needs to perform during turning, so solid axle vehicles usually use U-joints.
In contrast, with IFS, when the vehicle moves up and down, the suspension compresses but the subframe does not. Since the engine is mounted on the subframe, the joint needs to accommodate not only turning but also vertical movement. Therefore, IFS vehicles are always equipped with CV joints.
Off-Road Challenges for CV Joints
There is nothing wrong with either CV joints or U-joints—they are simply different designs. However, when off-roading, the vehicle often has wheels off the ground or the suspension compressed almost to full travel. This causes the wheels and the subframe to be at very different heights. In this situation, CV joints work under extreme angles, so shorter lifespans are expected.
7. IFS Articulation Issue
On some extremely uneven terrain—where, for example, the left and right sides of the vehicle are at very different heights—wheel lift is often expected with IFS due to its suspension design. This naturally limits off-road capability.
Some vehicles are equipped with electronically disconnecting sway bars to improve articulation, but of course, that comes with a higher price tag.
Conclusion
Through the discussion above, we can see that IFS comes with several downsides compared to solid axles when it comes to off-roading. However, in today’s U.S. market, the number of solid axle vehicles still being sold is very limited—mostly just models like the Jeep Wrangler or the Ram Power Wagon. Most other manufacturers only offer IFS, including Toyota, the Ford Bronco, GMC, Chevy, and others.
At the root of it, the main issue is that solid axles perform poorly in terms of comfort and high-speed stability. Jeep even designed a no-rotate ball joint specifically to improve high-speed handling.
To meet the wide variety of consumer needs and strike a balance, many automakers have settled on a compromise: front independent suspension paired with a rear solid axle. Today, over 60% of off-road and heavy-duty vehicles use this combination.
References
- T.G.Q R&D
- T.G.Q Sales
