4-Wheel Drive (4WD): What You Need to Know
Vehicles have many drivetrain options. The drivetrain sends power to the wheels but in most cases only two wheels receive power. 4WD vehicles send power to all four wheels of a vehicle to help with traction, and they have superior traction in the rain, snow, rocks, and mud.
We're going to take you through everything you need to know about four-wheel drive. We'll cover what 4WD is, how it works, and how it compares to other popular drivetrains. We'll also cover the difference between AWD and 4WD.
What is 4-Wheel Drive?
4-wheel drive (4WD) refers to a drivetrain that sends power to all four wheels. 4WD drivetrains are either part-time or full-time, which means that power doesn’t always have to go to all four wheels. For example, many SUVs with 4WD drivetrains use 2WD for everyday driving but have an option to switch to 4WD for hazardous conditions or off-roading.
4WD is almost exclusively found in two-axle vehicles and a transfer case is needed to distribute the torque to each axle. It’s also important to note that some 4WD vehicles are classified as all-wheel drive (AWD) but this is less common. AWD vehicles always have power going to four wheels but the amount of torque reaching each wheel is regulated by the vehicle’s computer.
What are the Advantages of 4WD?
4WD vehicles have several advantages. Many of the advantages are based on hazardous road conditions and off-roading. Whether or not you need a drivetrain that sends power to all four wheels depends on how often you maximize its advantages.
You’ll appreciate things like:
- Easier to gain traction in snowy conditions and on icy roads
- Great for off-roading
- Some 4WD vehicles will climb over large boulders with the right suspension
- In full-time 4WD vehicles, it can be turned off or on to preserve the drivetrain
The advantages of this drivetrain make it the perfect system for off-roading and wintery weather.
What are the Disadvantages of 4WD?
While 4WD has several advantages, it’s not perfect. Some disadvantages are more serious than others, so it’s important to weigh your options.
You might not be too fond of things like:
- Heavier than 2WD and AWD vehicles
- Less fuel efficient than 2WD vehicles
- The drivetrain sustains damage when using 4WD incorrectly
Always make sure you avoid switching to 4WD when you’re driving in regular conditions to avoid premature wear.
How 4WD Works
When 4WD is engaged, power is sent to all four wheels of a vehicle. Torque is sent to the wheels, which forces them to rotate. Power is first sent to the vehicle’s transmission and transfer case, which splits the torque between the front and rear axles.
What is Part-Time 4WD?
Part-time 4WD is when a transfer case can switch from just rear wheel drive to 4WD and back with either a lever in the cab or the press of a button. Once a vehicle is switched into 4WD, power goes to all four wheels to maximize traction. Instead of power going to only the rear wheels, the transfer case rotates gears connected to the front axle. Once the gears match the speed of the rear wheels, the system is fully engaged.
What is All-Wheel Drive?
Vehicles that have primarily FWD systems and engage the rear wheels to assist when traction is lost have all-wheel drive, or AWD. Most automatically engage when the car’s computer detects wheel slippage, although some have selectors to disable AWD or to choose the torque distribution for weather.
Alternatives to 4-Wheel Drive
4x4s are popular drivetrains but there are many effective alternatives. Typically, the alternatives to 4WD are front-wheel drive (FWD) and rear-wheel drive (RWD). Both of these drivetrains are also known as 2WD systems.
Front-Wheel Drive (FWD)
FWD systems send power to the front two wheels of a vehicle. These vehicles have less weight than 4WD vehicles because there’s fewer moving parts since power only needs to travel a few feet to reach the wheels, instead of traveling to the rear of the vehicle.
FWD vehicles are great for driving in almost any conditions, especially when it’s dry, and they’re more affordable than 4WD vehicles. Also, these vehicles are more fuel efficient because of the reduced weight and less friction from moving parts. The downside to these drivetrains is that they don’t handle as well around sharp turns.
Rear Wheel Drive (RWD)
RWD vehicles have drivetrains that send power to the rear wheels. In these drivetrains, power from the engine travels to the rear wheels and turns them to propel the vehicle forwards. 4WD drivetrains are RWD drivetrains when 4WD isn’t engaged.
There are a few benefits to RWD. Handling around turns is improved because weight is distributed more evenly between the front and the back of the vehicle. These drivetrains are also more cost-effective to repair because fewer parts are crammed into a small space.
The drawback to RWD is reduced traction in bad weather.
Whether you have a 4WD, AWD, front-wheel-drive, or rear-wheel-drive vehicle, AutoZone has all the parts and fluids you need to repair and maintain it. For anything you need, from parts to Trustworthy Advice, contact an AutoZone associate who will gladly help.
4 Wheel Drive FAQ
4-wheel drive vehicles send power to all of the wheels, which improves traction in dangerous driving conditions. In normal driving conditions, the mode doesn’t need to be active, and power is only sent to two wheels.
4WD is better for snow, ice, and off-roading, while AWD is better for rain and more temperate conditions.
You should use 4-wheel drive when you’re driving off-road or when it’s snowing. 4-wheel drive vehicles provide more traction in water, mud, rain, snow, and ice.
4-wheel drive vehicles have drivetrains that send power to all four wheels. 2-wheel drive vehicles, on the other hand, have drivetrains that send power to two wheels.
Yes, however, 4WD vehicles typically have a switch from two drive wheels to four. All four wheels only turn when you place the vehicle in its 4WD mode.