What You Need to Know About a Solid Axle Swap

In terms of performance, it’s easy to move from truck to truck to get the capabilities and features you desire. This is especially true for those who are looking for a change in suspension or drivetrain features. However, even amongst the most laidback enthusiasts are those capable of tackling some major overhauls underneath. And when it comes to enhancing off-road capabilities, you really can’t beat how much you can do to a tried-and-true solid axle suspension. Now, a solid axle swap is not exactly an easy feat. But for those with the right skill set or will to learn, it’s definitely doable.

This offroader opted for a solid axle swap to get better wheel travel and articulation.
Despite the old Toyota IFS being a great system, it lacks wheel travel and articulation. That‘s why this serious off-roader opted for a solid axle swap.

In a previous piece here on the blog, I explicitly stated that—in theory—all-around independent suspension is much greater than a sold axle suspension. (And I still stand by my opinion.) However, to argue that setting up an independent suspension will provide the same results in today’s day and age as a solid axle, on the same dollar, is a stretch.

Why do a solid axle swap?

There’s a lot of information on the web about this exact topic, but we really wanted to get input from someone who has a substantial amount of first-hand experience with rock crawling and custom off-road builds. So, we reached out to our friend Dan Guyer at Keystone Automotive for his professional opinion on the subject.

“The potential for IFS (Independent Front Suspension) is only in dedicated race cars with tube chassis built around the IFS,” explains Guyer. (Think something like Shannon Campbell’s King of the Hammers-winning rig.) “In a normal truck or SUV, the SFA (Solid Front Axle) will beat it hands-down when the off-roading is truly difficult. So, who should do a solid axle swap?” he asks. “Anyone who plans to rock crawl.”

“You’re enhancing flex, strength, reliability… and reducing cost of repairs.” -Dan Guyer

No one’s arguing that an Ultra4 race car isn’t an incredibly capable and impressive off-road build. But the amount of money and time invested to refine such a setup—as well as craft custom parts—is extreme. “People nowadays are spending more on their front suspension than they used to on the whole car,” says Guyer on the evolution of these builds. “In order to get the same amount of suspension travel as a solid axle, you have to run a very narrow center section, long A-arms, and specialized CV-joints.” According to Guyer, this ends up dictating the entire build. The whole anatomy of the vehicle surrounds the demand to run independent suspension. “It has been perfected. It just costs too much money [for the average consumer].”

However, with a solid axle suspension, you can get more travel on a rugged design for a much lower dollar count. And you can do so reliably.

What exactly does a solid axle swap entail?

If you are considering a solid axle swap, it’s a good idea to understand everything you’ll be addressing. Simply put: you are taking out the independent axle and swapping a solid axle in its place. However, like most things in life, one change can cause a Domino-effect, and a solid axle swap involves much more than a simple switcheroo.

The type of suspension used on a 4-wheel-drive vehicle surrounds the type of axle underneath. Because of this, making a swap means that you will be changing up the suspension, too. And that means the characteristics of the suspension will change, so sacrifices will need to be made. For example, allowing the wheels to move independently of one another makes for better handling and comfort. A solid axle suspension won’t give you this ability, so those qualities will be greatly reduced. (Though, when you consider the durability of a solid axle design and the suspension travel it allows, it’s better to consider these as trade-offs rather than sacrifices.)

Solid axle swap on an ‘87 Toyota 4Runner.
Solid axle swap on an ‘87 Toyota 4Runner.

With a solid axle swap, prepare to rip everything out of the truck pertaining to steering, suspension, and the axle. Depending on the application, cutting off mounting points on the frame may be required as well. And even with a direct swap kit, welding will be necessary for mounting the springs and suspension system. Swapping to a solid axle suspension that uses leaf springs will be easiest, but there are options for those who want to use coil springs. The steering will also need to be reconfigured to work with the new axle design. And of course, there will also be time spent figuring out the brakes. But the real trick is removing everything that was used to mount the IFS and converting the truck’s chassis to mount the solid axle.

Save time and effort with a direct swap kit.

Now that you know what makes a solid axle swap complicated, let’s discuss what makes it easier. Converting an axle setup under the car takes a lot of calculating and homework in order to be properly executed. Thankfully, there are those who took the time to do that part of the work for you. Companies like Off Road Unlimited, All-Pro Off Road, and Trail Gear are all fine suppliers of kits designed for a solid axle swap.

Prices will vary greatly depending on the kit that you purchase and the platform you’re working with. (This makes pinning down an exact price point difficult.) Do your research to determine what fits best within your budget. And before you open that wallet, make sure you’re choosing the right kit for your axle—and the right axle for your rig.

Don’t be afraid to call a manufacturer and get their opinion. Most companies have excellent technicians on staff who can help you determine what is the best setup for your vehicle. Additionally, spend some time perusing forums and Facebook groups, and ask other off-roaders what modifications have worked best for them. (Better to learn from their costly mistakes than your own!)

Is fabricating an option?

There are a lot of people who are going to approach a solid axle swap with a particular setup in mind and perhaps the aftermarket can’t suit their needs. In that case, their hand will be forced into fabricating. It’s also just as likely that those with the appropriate skill set will try to save some money by building their own kit. It is completely possible to do something like this—it’s even the go-to method for many—and I tip my hat to anyone willing to take this on.

This custom solid axle swap was done by TCS Suspension for a customer‘s already-modified 2008 GMC Sierra HD2500.
This custom solid axle swap was done by TCS Suspension for a customer‘s already-modified 2008 GMC Sierra HD2500. Photo from Diesel World feature.

With any fabrication job, there is a lot to be factored in and this is particularly true when dealing with chassis work. All things considered, you don’t have to tackle this with a blank sheet of paper. If you have an application where aftermarket kits are available, look to them for inspiration. It’s a surefire way to save you time and hassle.

It truly does take a masterful hand to accomplish fabricating an axle swap kit of your own. It will also mean having the right equipment on hand is essential for success.

What You’ll Need:

Since you’ll be working with heavy-gauge steel, you’ll need a way to cut it. Grinder wheels will work, but you’ll go through dozens of them by the time the job is done, so a plasma cutter is the best choice. Of course, you’ll also need a welder that’s capable of welding through such heavy-gauge steel. And you’ll also need a place where you can access the undercarriage of the vehicle to take measurements for proper design. Honestly, without access to a professional grade shop and professional grade skills, this job can be near impossible.

When all’s said and done, the amount of time and money invested into fabricating a solid axle swap makes buying a premade kit the more logical solution.
Photo from Off Road Unlimited

The best tool will be your drawing board—because without a solid planning process, you’re simply setting yourself up for failure. That’s why, in our opinion, when all’s said and done, the amount of time and money invested into fabricating a solid axle swap makes buying a pre-made kit the more logical solution. And our friend Guyer agrees. “BUY. THE.  KIT.,” he stresses. “Saying you fabricated one is cool, but off-the-shelf kits already have the homework done. And they’re always faster and easier to install.”

Capable and Cost-Effective

Independent suspension really does offer a world of potential—and there’s plenty of amazing vehicles out there to prove it. But at the end of the day, consumer cost is still a major issue. “IFS is getting there,” agrees Guyer, “but the cost is astronomical. If you can imagine this, a great IFS system can be $30,000 or more. The new King of the Hammers cars are $300,000 now. Ouch!”

A solid axle swap is going to open up a lot of doors and make for an awesome machine with serious off-road capabilities. Tackling the job yourself is going to take a lot of planning, as well as plenty of time, patience, and a fair amount of heavy lifting. (Having a secure workspace and a helping hand are absolute musts.) But if you’re committed to honing those skills and putting in the effort, we have no doubt you can manage it just fine.

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