Can you switch to 4 wheel drive while driving? While it is easy to say that yes, you can do it, things are not really as simple as that.
We’ll get into the details of what happens when changing from 2WD to 4WD and provide you with must-know info about 4WD vehicles, plus best practice operation and maintenance requirements. You need to know such information to help you understand how, when, why, and if you can switch to 4-wheel-drive while driving.
Can You Switch to 4-Wheel Drive While Driving?
Yes, you can switch from 2H to 4WD while driving as long as you maintain the 60mph limit. You should also go down to below 5mph when switching from 4Hi to 4-Lo. You can do this without necessarily depressing the gas pedal or transmitting the gears to Neutral or Park mode.
However, these automatic locking hubs are not fitted in older 4WD models. So, when driving the older 4WD series, you still have to exit the car to engage the front hubs manually. Nonetheless, it is good to engage and disengage the 4WD system when the vehicle is parked to avoid stressing the vehicle gears.
So, when is it safe to engage 4WD, and in which driving conditions are you required to switch from the 2H system completely?
Well, several factors should be considered when deciding between the three control systems: 2H, 4H, and 4-Lo. These factors affect the core components of your vehicle, including drivetrain, tires, gearbox, differentials, and steering.
We’ll assess each of these components to understand what happens to the vehicle when you engage the 4WD system while driving.
Before we can discuss the safety of switching to 4WD while driving, it is important to understand what happens when you turn that button from 2H to 4WD.
What Happens If You Switch to 4 Wheel Drive While Driving?
The following components are affected during the 2H-4H switching while the car is in motion:
A part-time 4WD vehicle is always on 2H mode until the 4-wheel drive is switched on.
When the 4WD mode is engaged, the drivetrain is bound to all 4 wheels. This situation enables the rear diff to split power uniformly between the two rear wheels through gears inside the differential.
The diff then shifts power as per the required cornering action to enable a smooth and safe ride through hostile terrains. This process allows the outer wheel to rotate faster than the inner wheel, hence, it prevents the undesirable effect called drivetrain “binding” or windup.
Basically, switching to 4H connects the front to the rear driveshafts through the transmission box to create unified rotation. Since the power is now split evenly between the front and rear axles, the driveshafts cannot rotate at different speeds. This situation locks the drivetrain in 4H.
Therefore, switching to 4WD mode while driving at the above-recommended speed limit causes drivetrain “binding.” Consequently, it disables the varying speeds between the front and rear driveshafts. This outcome negatively affects the safe turning requirement.
Switching to 4WD mode while driving can interrupt the power and torque balancing in the transmission process, i.e., between the gearbox, gears, transmission box, axles, and the driveshafts. Suppose you are switching on no “give” surface with enough traction. This imbalance will cause the excessive amount of torque generated to be retransferred to the drivetrain and then into the gearbox and transmission case. The end result is stiffened and jammed gears.
To avoid the stiffening and jamming of the gears, you should lower the speed to below 60mph if you cannot pull over to switch to 4WD.
Driving at the recommended speed limit (below 60mph) will minimize the pressure input into the vehicle’s engine system. Hence, you create appropriate conditions for balancing power and torque from the gearbox to the front and rear driveshafts.
Switching to 4WD while driving can negatively affect your steering system. This is worsened if the transition is done on tarmac or pavement surfaces with enough traction. Steering feel effects are translated to the drivetrain, which, in turn, leads to windup or “binding” issues.
An intense under-steer effect also arises as the front wheels clash with the rotational force from the front driveshaft in an attempt to slow down the wheels.
Therefore, you should avoid engaging the 4WD mode while driving above 60mph and during high traction surfaces.
Engaging the 4WD mode while driving can disrupt the dynamic engineering design inside the diff. This will then disallow the safe turning of the left and right wheels at varying speeds.
So, you should always try to switch between 2H and 4H at low speed or when the car is not in motion. Proper functioning of the diff enables both wheels on the same axle to turn at different rotational speeds when receiving power.
By following the right switching procedure, you preserve the diff’s ability to balance the varying rotational speeds as required when maneuvering the bends.
Engaging the 4WD system while driving stresses both the front and rear tires. This, in turn, puts disproportionate pressure to hold the road surface. Hence, you shouldn’t switch between 2H and 4H on high traction surfaces as the grip will leave extensive wear on your tires.
Basically, wearing off of the tires is caused by a resistance generated in the locked-up drivetrain. This lock-up arises from the imbalance between the two inner and two outer wheels, which are supposed to rotate at differential speeds.
Resistance increases if you switch to 4WD switching on high traction grounds like tarmac and pavement.
The wear and tear of your tires are minimized when you switch to 4WD while driving at low speeds (below 60mph), or on low traction surfaces like snow and mud.
So, since it’s not recommended to engage the 4WD system while driving on high traction surfaces, we evaluated the necessity and safety of switching to the 4-wheel-drive mode below.
When Is It Necessary to Switch to 4 Wheel Drive Safely?
Part-time 4-wheelers can be safely switched to the 4WD mode in the driving surfaces described below:
Muddy tracks provide the right conditions to switch between 2H and 4H and between 4Hi and 4-Lo. However, 4Hi and 4-Lo interchange require you to stop the car or go down to below 5mph.
Nonetheless, deep mud creates a high-resistance and low traction surface that asserts tremendous strain to the clutch and drivetrain system. These circumstances require the power, torque, and wheel balancing provided by the 4WD system.
Sandy tracks provide the two most suitable conditions for switching to 4WD mode. These are low traction and minimal speed. In these conditions, the 4WD system will provide the necessary power and torque to compensate for low traction provided by the loose sandy surface.
4WD mode is also necessary in these circumstances as it allows for the detection of major changes in the shape and sizes of sand dunes.
Note: Driving on sandy surfaces calls for proportional tire deflation to improve control in the steep desert ridges.
Snowy Icy Roads
Low-traction snow roads provide ideal conditions for maneuvering between 2H, 4Hi, and 4-Lo. Hence, it is safe and necessary to engage or disengage the 4WD system as required by the underlying driving circumstances.
Switching from 2H to 4WD enables you to lock the front and rear driveshafts. This gives you improved handling and stability required to maneuver through the snowy and icy surfaces.
However, you shouldn’t be too comfortable since the icy grounds can break the traction and cause the wheels to spin out. Also, don’t fall for the misconception that 4WD mode improves your car’s braking abilities.
Wet roads provide significantly low traction, which requires a full-time 4WD system to compensate for the imbalance. Notably, insufficient knowledge about whether to engage the 4WD mode in wet roads leads to risky driving habits, which are the major cause of accidents.
The 4WD system puts all the 4 wheels in action, thus propelling the vehicle forward through constant push and pull at any given time. This situation considerably improves the vehicle’s traction and stability.
Still, you shouldn’t rush to switch to 4WD in slight rain, as minor wetting on the road does not necessarily require traction compensation.
Premature engagement of the 4WD system, i.e., before the surface loses much traction could lead to drivetrain windup or “binding” situations, as we observed above.
Note: A viscous coupling smart component in the permanent 4WD models is suitable for the extremely wet surface driving conditions. This mechanism enables the rotation of the front and rear driveshafts at varying speeds. Consequently, it prevents drivetrain “binding” even when the 4WD mode is maintained in high traction surfaces for long.
Beach driving surfaces combine sandy and humid conditions, which cause low traction and slippery terrains, respectively. Therefore, it is necessary and safe to switch to 4WD mode under these circumstances.
However, unlike those in the arid and semi-arid surfaces, moist sand along the coastline is sticky and firm. This condition increases the traction as the compact sand allows tires to slide with much ease without sinking.
Nonetheless, you should exercise caution as beach driving surfaces are not predictable enough to guarantee high-speed safety or good maintenance of the vehicle’s essential components such as the drivetrain, gearbox, steering system, and tires.
When Not to Switch From 2H to 4 Wheel Drive
Even though we all seem to enjoy the power output and performance of the 4WD system, we shouldn’t be overly excited about utilizing this mechanism. As we discussed above, high traction driving surfaces, like cement, tarmac, or concrete, are notoriously unsuitable for engaging the 4WD system. Elevated traction will cause drivetrain windup.
Notably, drivers have been misled by the misconception that locking the center differential with a permanent 4WD will eliminate the risks of drivetrain binding. But the thing is, locking the center diff is equivalent to switching to 4H on a part-time 4WD vehicle. Thus, you risk damaging your drivetrain, gearbox, and steering system, among other related components.
Switching Between 4Hi and 4-Lo While Driving
Switching between 4Hi and 4-Lo requires you to stop or drive below 5mph. However, manufacturers of current 4WD models insist that changing from 4Hi to 4-Lo can only be done in Parking or (N) Neutral mode.
Designers of 4WD engines maintain that the “lo” in 4-Lo signifies the low ratio gearbox meant for significantly low speed and very complicated driving conditions. If you engage the 4-Lo while speeding above the set limit, the 4WD components will malfunction as the low gear ratio is abruptly fitted on high gear arrangement. This results in irreversible drivetrain damage.
The low ratio gears are meant to maneuver the severe rock crawling circumstances and other extreme driving conditions. Therefore, 4-Lo is suitable for high power outputs and significantly low controlled speeds. That is why new 4WD models come with preinstalled safety components to prevent the driver from engaging the 4-Lo while the car is in motion.
When to Use 4Hi and 4-Lo 4WD Configurations
With additional pre-installed components, operating new 4WD series can confuse even the most experienced car handlers. That is why you are advised to stick to the recommendations in the owner’s manual to avoid misusing these operational improvements.
Let’s look at different driving conditions suitable for 4-Lo and 4Hi configurations, respectively.
Engage 4-Lo when:
- You are pulling heavy carts, which require more engine torque but low speeds. The low ratio gearbox increases control, power output, and torque required to negotiate extreme driving conditions.
- You are ascending extremely steep topography and require more power for pulling up against increased gravitational force.
- You are descending an extremely steep landscape, and you require more torque to control the vehicle’s heavy components down a slope. The low gearing ratio provides the much-needed engine braking effects.
Note: Avoid using 4-Lo when attempting to unstuck your truck from mud or snow. More torque will lead to incremental wheel spins, thus further complicating the traction balancing.
Engage 4Hi when:
- You are negotiating wet and slippery surfaces at relatively higher speeds. Here, equal power distribution between the four wheels increases your grip on the road. Therefore, you retain more driving control.
- Your vehicle is trapped in mud, snow, or ice, and you need low torque power distribution on all the wheels to unstuck from such hostile surfaces. Low torque provides moderate wheel spins, which combines with increased grip on the surface area for a successful take-off.
Comparing Permanent and Part-time 4WD Types
Permanent 4WDs get the driving anxiety out of the way since you don’t have to worry about terrain, drivetrain, gearbox, and so forth.
They also come with preinstalled viscous coupling smart mechanism, which enables varying rotations between the front and rear driveshafts. This eliminates the problem of locking the diff between your wheels. Locking the diff between wheels is undesirable since it causes drivetrain windup and transmission jamming, which messes up the whole system.
On the other hand, part-time 4WDs lack the essential center diff unlocking feature. Hence, they are prone to drivetrain “binding” complications when driven on even surfaces. This situation comes with the anxiety of having to judge whether certain driving terrains warrant the 4WD mode or not.
Still, the full-time 4WD can unnecessarily cost you more fuel for tasks that a part-time 4×4 can perform. However, if your driving needs a full-time 4WD, and you can afford it, there is no reason to deny yourself the seamless balance between safety and versatility.
Why You Should Go for Permanent 4WD
If you intend to get yourself a 4×4, the permanent type is the most desirable option. This doesn’t mean the part-time 4×4 is inferior. In fact, the part-time make comes with unique advantages like cost-effectiveness and enhanced flexibility.
Nonetheless, the permanent 4WD model, unlike the part-time series, provides complete off-road solutions. It’s no surprise that over 30% of car sales in the UK are 4WDs.
Let’s look at the benefits offered by a permanent 4WD and why you should go for it.
Better and More Reliable Traction
The permanent 4WD model offers a better and more reliable grip on the driving surface since the power output is distributed equally to all 4 wheels. This setup provides drivers more control and peace of mind, especially when driving on slippery and uneven grounds.
Other than working well on tarmac and even surfaces, the permanent 4WDs offer unmatched off-road capability. So, if your driving routine involves regular off-roading, you should not think twice about a permanent 4WD type.
Raised Driving Position
Permanent 4WD designs are elevated to address important driving and safety concerns. These concerns include road visibility, improved accessibility, and an increased sense of safety and security.
The permanent 4WD vehicles come with a towing capacity of up to 2,000 kgs. This provides ideal solutions for modern lifestyles, which involve a lot of towing, caravanning, and camping.
Note: Despite this improved safety and versatility, you shouldn’t be tempted to tow a weight that is more than 85% of the truck’s tare mass.
Ample and Flexible Storage Space
4WDs designs offer increased flexibility for occupants to adjust, rotate, and even remove the rear seats. This is ideal for both family and work trips since, with increased flexibility, you can always make room for unforeseen transportation needs.
While we all like to drive the permanent 4WD types, the fueling and maintenance costs can be high. Therefore, go for a full-time one if your driving calls for it.
The current part-time 4WD series offers exclusive convertibility features, allowing you to avoid the costs of a full-time model and still enjoy the extensive benefits of a 4×4 vehicle.
So, since we are permitted to switch to 4WD while driving, let’s see how it is done.
How to Switch to 4WD Mode While Driving
Switching to 4WD mode while driving varies between brands and models.
For older models, engaging 4WD requires you to stop and transmit to either Parking or Neutral. These older series use manual switching components. Therefore, you shouldn’t attempt to engage 4WD mode when the car is in motion as you risk causing extensive damage to your engine.
Current 4WD models come with sophisticated switching components, which allow you to engage different driving modes while the car is in motion. The most recent inventions have automatic switching systems, which engage and re-engage the 4WD mode according to the traction changes in different driving terrains.
However, the introduction of more 4WD configurations comes with information overload. This excessive info tends to be confusing. So, you should operate and maintain your 4WD system based on the guidelines in the owner’s manual. This precaution allows you to preserve the system’s ideal working conditions for long.
Let’s look at various switching requirements in popular 4WD brands and models.
Jeep Wrangler can be switched to 4Hi while driving. You can do this while driving at speeds between 7mph and 30mph. Changing to 4-Lo requires you to stop and transmit to Parking or Neutral.
This model allows you to engage the 4WD while driving as long as you maintain the speed at below 60mph. Switching is done by turning the 4WD knob by the steering wheel to 4H. You should drive below 3mph or switch to Parking when switching to 4-Lo.
Note: Driving Ford F-150 below 25mph in 4L prompts automatic disengagement to 2WD.
This model comes with a 4WD auto setting, which increases traction when driving at speeds above 60mph. This switching system is suitable for unpredictable driving conditions as 4WD engagement and disengagement are launched automatically depending on the underlying driving conditions.
You can engage your Land Rover’s 4WD mode while in motion. However, the speed limit when switching should come down to below 3mph.
Nearly all part-time 4WD models allow engagement and disengagement while the car is in motion. Despite this provision, it is not a good practice to switch to 4WD mode while driving. Nonetheless, depending on the prevailing off-roading conditions, you can switch to 4WD while driving as long as you don’t exceed the stipulated limit requirement.