Full Float vs Semi Float: Is There Really a Big Difference?

This full float vs semi float comparison article will take you through the differences between the two types of axles. Drive axles are designed to transmit power to wheels and support the weight of a vehicle.

It’s important to know the differences between the two axles, especially to help you determine which is right for your driving applications. We’ll highlight the differences between the two rear drive axles below, so continue reading.

Features	Full Float	Semi Float
Application	Perfect for heavy-duty applications	Ideal for light-duty applications
Weight	Heavy	Lightweight
Cost	More expensive	Cheaper

 

What Is the Difference Between Full Float and a Semi Float?

The difference between full float and a semi float axle is the applications they are suited for. Semi-float axles are the ideal option for regular daily driving without heavy-duty applications.

Full floats are suited for off-roading and heavy-duty applications. To understand their differences, read a comprehensive overview of their features.

Key Features

Both float axles are designed to be durable, and they are mostly found on most light-duty 4WD vehicles. However, they also have their respective advantages and disadvantages. Full-floating systems are designed with an axle shaft that helps in transmitting rotational torque between the differential and the wheel.

The setup isn’t designed to hold the weight of the vehicle. Basically, the spindle in a full float system is attached to the exterior end of the axle housing. The spindle also houses the wheel hub, which features a tapered roller bearing. This is what helps in holding the weight of the vehicle in full-floating axles, and it also makes the axle stronger than the semi-floating counterparts.

On the other hand, semi-floating axles feature an axle shaft across all sides splined on the interior end that is attached to the differential. It also features the wheel flange, on which the studs are mounted.

A bolted flange arrangement is used in holding the assembly to the end of the axle housing. Another thing to note is that the shaft rides on a large ball bearing or roller at the exterior end of the axle housing.

If your driving applications mostly involve heavy loads, the load capacity on the axle of a full float will be increased. Basically, axle type significantly increases load ratings, even for similar vehicles. If your vehicle has big tires, you’ll be able to handle more load with a full-float axle than with a semi-float axle.

Full floating systems can be detached without altering the functioning of the rolling tire. This is because bolts are used in holding the wheels to the wheel hub, and this rides on the spindle within the axle housing. Another thing to note is that axles that are fitted manually with locking hubs can be used for towing applications.

Semi-floating rear axles can be converted to full-floating rear axles with the aid of aftermarket kits. With these kits, vehicle owners can upgrade their axle shaft to make it stronger. The main thing to note is that these kits don’t upgrade the differential assembly, and this feature on axles offers few benefits.

Full Float and Semi Float: Which Is Better?

Between full float and semi float, both axles are designed for different applications, and determining the best depends on budget, personal preference, and applications. Full floats are generally more expensive than semi floats. Therefore, they are not the best option if you’re on a budget.

Another thing to note is that full float is heavier, and this can affect fuel consumption if it is installed on smaller vehicles. This is not an issue of concern with larger vehicles. In addition, full float is less hazardous, and even if the shaft breaks, the tire will continue to rotate.

With a semi float, the tire will pull out immediately after the shaft breaks, and this can cause serious accidents. For heavy-duty applications, the better axle to get is the full float because they are designed to hold more weight than semi float.

What is a Full Float Axle?

A full float axle is a type of rear axle configuration that features two bearings, which allows the axle to float simultaneously in place and still retain its position. This is the ideal type of axle for use on larger vehicles, particularly heavy-duty trucks with large towing capacities.

Even though the axle is better suited for larger vehicles, you’ll also find it on a range of mid-size trucks and four-wheel drive vehicles. Apart from being widely used for heavy applications, it’s also suitable for applications involving high pressure.

One of the key things to know about the full-float axle is the casing around the axles. This provides enough space for the axles to float, and it also implies that the vehicle’s pressure rests on the axle casing instead of the axle.

Benefits of Full Float Axle

There are many benefits offered by a full-float axle, and among these includes the fact that it’s generally a safer option for vehicles. One of the main benefits is the weight capacity it provides. This is aided by the secure and stable structure provided by the attachment of wheels to the hubcaps, and this gives the vehicle more carrying capacity.

It’s also one of the reasons why they are the preferred choice for use on SUVs and trucks. However, it’s important to note that the carrying capacity offered also depends on some factors, but what’s certain is that vehicles with this type of axle will be able to carry more load.

Another benefit is the flexibility it offers, especially for other types of axles, like the semi-float axles. These axles can be easily converted to full float with the aid of aftermarket kits. However, their conversion doesn’t include the differential assembly.

Full float axles provide enough accommodation for larger tires. You can use up to a 40-spline or 1.75-inch axle with full float, which is also good for heavy-duty vehicles that haul larger loads. If you have a broken shaft, you can easily remove it and enjoy the functioning of a rolling tire on the affected shaft. This is because the wheels are attached to the hub using a bolt, making it easy to rotate without the axle.

As mentioned earlier, one of the main benefits of the axle configuration is safety. With other types of axles, there’s a higher chance of the wheel coming off if the axle breaks and this can cause dangerous accidents. That’s not the case with full floats, as even if their axles break, you won’t have to worry about your wheels flying off.

Drawbacks of Full Floating Axle

Despite the benefits above, there are a few drawbacks associated with axles that are full floating. The major benefit is that they are expensive, unlike other options available. Whether you perform the installation yourself or not, you will end up spending so much on the process.

Another thing to note is that they are heavier than other options, which is not great for fuel efficiency. However, this is not always an issue of concern as they are mostly installed on heavier vehicles that can bear this weight, and fuel efficiency won’t be a problem. Also, people that drive SUVs or heavy trucks don’t always worry about fuel economy.

What is a Semi Float Axle?

A semi float is also a rear axle configuration that connects the exterior shaft to the wheel via the flange. The setup is firm, with one bearing supporting the axle casing and the other bearing supporting the axle shaft. These two bearings make the axle to be larger in size.

Semi float is also the preferred option for mid-size trucks, SUVs, cars, and vehicles used for light duty pickups. In this type of axle, the shaft and the wheel are directly connected to each other, and this transfers power to the differential. Also, the axle rod of the setup allows the axle to endure torque and bending effect, as well as the vehicle’s weight.

Since the rod is designed to hold weight, it can effectively handle more weight than a non-float axle. Most 4WD vehicles have semi floats. However, this doesn’t imply they are great for heavy-duty applications like pickup trucks and SUVs. The axles are only meant for use on cars that are used for daily commuting.

Benefits of Semi Float Axle

Semi float axles offer many benefits, but the most notable of these is the fact that they are generally cheaper than their full float counterparts. Therefore, if you don’t use your vehicle for heavy-duty applications, you don’t need to spend extra money on a full float. This doesn’t mean that you can’t use a semi float to haul weight.

Another benefit is that the axles are easy to install because they are lighter, unlike full float. This means that a mechanic will be able to lift them easily and install the axle in your vehicle. Apart from the cost of buying the axle, installation, and labor cost is also cheaper than other types of axles.

Because of their lightweight and use on smaller vehicles, you won’t have to worry about their effects on fuel economy. That’s not the case with full float, as they are heavier and can significantly affect the fuel efficiency of your vehicle.

Another benefit of this type of axle is that it can be easily converted into a full float. As mentioned earlier, most 4WD vehicles come with semi float, but this isn’t great for heavy-duty applications. Fortunately, there are different aftermarket kits on the market that you can use to convert your axles to a full float without hassle.

Drawbacks of Semi Float Axle

Even though a semi float has many amazing benefits, there are a few drawbacks associated with the axle. The most notable drawback is that the shaft is likely to break when driving. If this happens, the wheels of the vehicle will lose since they are attached to the shaft. Another thing to note is that they are not great for heavy-duty applications, but you can always convert them to a full float.

Conclusion

It’s important to understand the differences between the two axles before you choose one, which is why we have highlighted their differences in this comparison article. As mentioned earlier, the choice between a full float and a semi float depends on budget, application, and personal preference. For someone who only drives their vehicle for daily activities, without heavy-duty applications, the best option to get is the semi float.

However, if you use your vehicle to haul much weight regularly or you’re actively involved in off-road driving, full float is the best option to get. If your vehicles have a semi float, and you want to use it for these applications, you may need to convert it to a full float using aftermarket kits available. Finally, full floats are more expensive, and it’s best to only get them if you intend to use them for heavy-duty applications.

Reference

• https://snscourseware.org/snsctnew/files/1585119585.pdf
• https://www.news.benevelli-group.com/index.php/en/100-semi-floating-vs-full-floating-transaxles.html