Imagine this – you have a truck or SUV in excellent condition that also looks great, and you enjoy driving it. Furthermore, it proved to be reliable and not that expensive to run. So, it’s an ideal vehicle in every aspect, apart from one – it’s only a 2-wheel-drive model. While this is fine for cruising on highways, it’s less than ideal if you have any kind of all fraud ambitions. No matter what tires or other upgrades you fit, that truck will still be pretty much hopeless when the going gets tough.
Now, one piece of advice would be to sell it and get something similar with a 4-wheel drive. But in reality, that is not that simple, and you could lose a lot of money in the process. And truth be told, many of us form an emotional bond with our cars and don’t like to sell them that easily. So, if that’s the case, you can always consider converting your beloved truck or SUV to a 4-wheel drive. While this is not a simple job, it is also not that complicated, as we will show in this guide to 2WD to 4WD conversions.
How Do 4-Wheel-Drive Systems Work?
Before looking into available 4-wheel drive conversion options, let’s examine how different drivetrain configurations work. This will help you understand how each component works and why it is needed. In a traditional 2-wheel-drive truck or larger SUV, the engine is mounted longitudinally, with the transmissions output shaft facing the back of the vehicle.
From there, the prop shaft transfers the power to the rear axle and turns the wheels. But with 4-wheel-drive models, an additional component, called the transfer box, is fitted at the end of the transmission. Many modern crossovers and smaller SUVs have drivetrains based on front-wheel-drive configurations. Here, the engine is mounted sideways and has a transaxle, which combines transmission and final drive in one unit. Again, there is a transfer box, which sends the power over the prop shaft to the rear wheels when needed.
How and when the 4WD system is engaged is controlled differently, depending on the vehicle. In older trucks, this is done by pulling a lever inside the cab, which is usually just next to the gear shift. This configuration may seem a bit awkward, but it is actually the most reliable one, as there is nothing that could go wrong. In essence, this is a piece of metal that fuses gears and cogs inside the transmission together.
In most newer vehicles, however, a button or know on the center console replaces the lever. Here a solenoid does all the mechanical work when the driver wants to engage the 4-wheel-drive system. I always found this to be a far more elegant solution. But there is no denying it is also potentially less robust, as these solenoids are a potential failure point.
But both of these systems rely on the driver to decide when to engage or disengage the 4WD system, which can sometimes be difficult for someone inexperienced. This is one of the main reasons why some manufacturers have full-time 4-wheel drive on their vehicles. One way to do this is by always sending the same percentage of the power to each axle.
This is a less complex solution, but it also may limit offroad capabilities, as there is no way to vary the power delivery between the wheels. In addition, a 4WD system that is always on adds stress to the drivetrain and increases fuel consumption. This is why most modern vehicles have an electronically controlled 4WD system.
Here, a computer sorts out when to engage or disengage the drive and varies the power distribution between wheels for the best possible performance. Such cars will have most of their power, or all of it, sent to the rear wheels when driving on the highway or other paved roads. But when the ECU detects wheelspin, it will automatically shift some of the power towards the front axle to improve traction.
This all happens seamlessly, and the driver doesn’t need to intervene, which makes this configuration the most comfortable. On the downside, this is the most complex setup, as its operation relies on various sensors and computers. Not only are they a potential failure point, but retrofitting such an elaborate system is a complex job.
4WD Conversion Using Stock Parts
With all the theory covered, we can now turn attention to the main question – how to add a 4-wheel drive to your vehicle. While there are many ways of doing these, they all come down to two options. One way is by using stock parts made by the car manufacturer. This could be an excellent approach if your model was available with a 4WD drive when it was new. But to do so, you’ll have to know which parts and bolts are needed.
There is much more to it than just installing a transfer box and prop shaft. A front axle with hubs and steering assembly is some of the things you’ll have to change. In addition, the suspension might need to be upgraded to cope with the extra weight.
Obviously, you won’t be getting these things as new from the dealer, as this would be astronomically expensive. Instead, you’ll have to source used parts, which you can always fund at scrapyards and similar places. If you run into someone who knows his business, you might even get a good deal on the whole lot.
However, I always found getting a donor car a more feasible option. Ideally, you want to get a crashed or similarly damaged vehicle damage, as this will be a much cheaper investment. And you can even get some of your money back by selling parts not needed for the conversion. With something like that in your garage or backyard, it’s only a matter of transferring everything to be your own vehicle.
But before you dive into this project, make sure to first dismantle everything from the donor car. Trust me, this is a crucial step because many things may go wrong here. Rusty bolts may snap, or you may find out that some of the components are worn or damaged while taking them apart. This is why you want to check everything and see if it’s ready for fitment.
4WD Conversion Kits
In most cases, using stock parts is probably the best and simplest way of doing the 4-wheel-drive conversion. It will allow you to do this without much hassle, assuming you’ve done everything correctly. There are, however, situations when going down the OEM route is not an option.
For instance, your vehicle might not be available with a 4-wheel drive, or the parts are not easy to source in your part of the world. There are also cases when the stock system is just not up to the task, and using it as a basis for the conversion just doesn’t make sense. Lastly, retrofitting modern 4-wheel drives is just too expensive, as it involves replacing many electronic control units. Whatever your situation is, you may consider getting an after-market conversion kit.
These are, in essence, purpose-built sets for a particular vehicle, which use various components already available on the market. These kits usually use OEM parts for complex stuff, like transfer boxes or axles. Then, there are different custom-built components, such as shafts and plates.
These allow straightforward fitment to your vehicle. But the best thing about these kits is they may even be more robust than stock configurations. This is because people who build them are usually seasoned professionals and know all about potential weak spots. So, when designing a kit, they will likely replace any fragile components with uprated ones.
Let me show you what I’m on about by examining this conversion kit made by U-joint Offroad. This particular set is for the Ford E-series van, which many owners convert into campervans. But despite sharing many of its mechanics with the F-150 pickup truck, this van was rarely available with 4-wheel drive.
This kit offers anything from heavy mechanic parts and axles to adapter plates and all hardware necessary for the installation. Similar kits are also available for most trucks, especially older ones.
Frequently Asked Questions
Question: How Much Does a 4WD Conversion Cost?
Answer: To answer this question, you’ll have to factor in several things. First, there is the cost of all components needed for the conversion. If you have an older truck for which the parts are widely available, this doesn’t have to be too high. From my experience, you could find all you need for an older F-150 for less than $2,000.
The price, however, will be significantly higher if getting a custom-made 4WD conversion kit, as these usually have brand new or refurbished components. Prices here can go well above $10,000. Then, there is the installation itself. If having everything fitted by a professional garage, you’ll be looking at a hefty bill afterward. And this brings us to the obvious next question.
Question: Can I Do a 4WD Conversion by Myself?
Answer: Assuming you have all the parts needed for the conversion, installing them is not an extremely complex job. This is, at least, if you have some experience with car repairs and access to necessary tools and equipment. But if you have never held a spanner in your hand, doing the conversion yourself might be a challenge. But, trust me, every job is doable as long as you commit to it. It won’t be easy and will take quite a lot of time, but you’ll learn a lot along the way.
Question: Can Any Vehicles Be Converted to 4-Wheel Drive?
Answer: To be honest, with enough money in your bank account, you can put a 4-wheel-drive system in just about any car. With models available with this option straight from the factory, this might be a relatively simple and inexpensive task. The situation with vehicles that never had this option is a bit more complex. Fitting a 4WD to such cars would require a lot of work and ingenuity, making the project more expensive.
In simple words, 2WD to 4WD conversion is a process of retrofitting a 4-wheel-drive system to a vehicle that doesn’t have it. And I know many of you who have such trucks or SUVs are interested in a such upgrade. One way of doing so is by sourcing all necessary parts by yourself.
This is a feasible and usually cheaper route for models that were available with 4WD as an option. But if this is not the case with your vehicle, you can try finding a custom-made 4WD conversion kit.