Is it possible to reverse in 4WD? This might sound like a strange question, however, it is quite a relevant one. The fact is, when consulting your owners’ manual there are seldom any guidelines regarding reversing safely while 4WD is engaged.
So, can you reverse in 4-wheel drive safely without causing damage to your truck? You can reverse in 4-wheel drive without risk provided you are driving on a low-traction surface. Driving forward while in 4WD is the same as reversing and the functionality inside the transmission and Transfer Case works the same in reverse.
Now, there are two ways you can approach this question. The first approach is purely from a functionality point of view and the second perspective from a vehicle safety aspect where we could potentially risk drivetrain damage. With that being said, there are certain situations where you should never reverse in 4-wheel drive mode. We will discuss this in more detail as well as how a 4-wheel-drive system functions.
If you are interested in learning how to reverse safely, continue reading…
Safely Reversing in 4WD
Let’s break the two-part question up and first answer whether it is even possible to reverse in four-wheel drive. Meaning, does 4WD trucks have the functionality built in to reverse while the four-wheel drive is engaged. Here, the simple answer is a resounding, yes, it does. The 4WD functionality that propels the vehicle forward applies just the same as when the driver is reversing the 4WD vehicle.
Secondly, let’s answer the safety aspect of the question, as in, will reversing while still in 4-wheel drive mode damage any components of the drivetrain. Well, a 4-wheel drive’s drivetrain is still susceptible to drive-shaft “binding” when reversing, exactly the same as when it’s going forward.
So you need to apply the rules just the same. That means making sure the driving conditions are acceptable to driving in 4WD, irrespective of whether you are driving forward or in reverse.
How the 4-wheel-drive system works
A traditional Four-wheel drive system works by all four wheels receiving engine power equally. The power is transferred to each axle by a center differential that has front and rear driveshafts connected. The front and rear differentials further send 25% of the available power to each wheel. The differentials equally divide and manage the transfer of power to each wheel.
(I wrote a comprehensive guide about 4Hi and 4Lo – you can read it here)
When four-wheel drive is engaged, both the front and rear axles receive the vehicle’s available torque and power which is split 50/50. This allows all four wheels to propel the vehicle forward. This is achieved by the rear wheels pushing and the front wheels pulling simultaneously.
Four-Wheel-Drives are produced predominantly in two formats, permanent four-wheel-drive, and part-time 4WD. A permanent four-wheel drive means all four wheels are constantly getting power but the main difference is it manages the transfer of the power by means of a viscous coupling. This component allows the front and rear driveshafts to rotate at different rotational speeds at any given time. This allows the four-wheel drive to drive on a variety of surfaces, whether it’s high traction or low traction without risking damage.
Part-time four-wheel-drive differs in the sense that it can only drive in 2H on a high traction surface. In 2H Power is only sent to the rear axle. When in 4H or four-wheel drive is engaged, the center diff locks the front and rear driveshafts to rotate as one unit. This is fantastic for aggressive off-road tracks and rough conditions where traction is low. 4H should never be engaged on a pavement or on the freeway.
When to avoid reversing in 4-wheel-drive
As previously stated, four-wheel-drive functions exactly the same in reverse as it does going forward. The rules of 4WD driving still apply exactly the same. Armed with this knowledge, what are some of the driving surfaces you would typically avoid when reversing while still in 4WD mode?
You want to avoid engaging 4WD in any high traction surface.
Prime examples of this are:
- Cement pavements
- Tarmac roads
- Concrete surfaces
These surfaces are complete no-no’s to engage 4WD and do not attempt reversing on them while in 4H.
Reversing while still engaged in 4WD on a high traction surface will cause drivetrain “binding” so exercise extreme caution before doing so. A four-wheel driver should learn to read driving surfaces well if he has a part-time four-wheel drive.
When should you engage 4H (4WD)
The following road surfaces are completely safe to reverse while still engaged in Four-Wheel-Drive mode.
- Low traction wet surfaces
- Snowy and icy roads
- Loos sandy tracks
- Beach sand dunes
- Thick muddy trails
While driving on a very wet slippery road, while it’s still raining, and surface traction is low, technically, it should be an opportune time to engage four-wheel drive. However, This option comes with a disclaimer since many tar roads can still have a fair amount of traction which could prevent the wheels from slipping.
So ONLY if traction is minimal, such as when the road surface is covered in ice and water and the tires are still able to slip due to lack of traction, it will be safe to engage 4H with a semi-permanent 4WD.
This option makes me very nervous because I want to say, yes it is safe, however, it could become risky if the surface isn’t slippery enough or consistently slippery. This, in my opinion, is very debatable. This is where the beauty of a Full-time permanent 4-wheel drive and an AWD excel.
However, if it’s only light rain and you drive a semi-permanent 4WD you might want to reconsider your options here since traction might still be acceptable enough for tires to grip. You could risk “drivetrain windup” and “drive-shaft binding” if traction is still acceptable, not allowing the front and rear tires to rotate at different speeds, especially when cornering. The driver needs to make this call by reading the road surface conditions and deciding for himself if it’s really that necessary to engage 4H. He might want to slip between 4H and 2H as the road surface changes, just to be safe.
If you driving a four-wheel drive with 4A (4 Auto) you are safe or if you have a super-select box such as found in the Mitsubishi Pajero you can confidently engage 4H.
Low-traction snow and icy roads are the perfect time to engage your 4H functionality. Engaging 4H will lock your front and rear driveshafts for improved handling and better traction in snow. Snowy and icy road surfaces offer enough slippage, unlike a wet road that might only be slippery in specific areas, but not consistently slippery.
(I wrote a comprehensive guide about snow driving techniques – you can read it here)
Sandy surfaces offer plenty of slippages and it’s 100% safe to engage you 4WD in this environment. Remember, sand is a high-resistance surface, and using momentum is key to successful sand driving. Turning and reversing is all perfectly fine for sand driving.
(I wrote a comprehensive guide about sand driving techniques – you can read it here)
When four-wheeling on soft thick sand or attempting to climb out a steep sand dune, you want to make sure your tire pressures are deflated to at least 1.2 bar. You could go even lower but that is a good starting point. This is one of the first things you should do before you even engage 4WD.
There is nothing more fun to do than drive off-road in the mud. All rules go out the window and it’s free for all where I’m concerned. You engage your four-wheel drive and you have a blast. Keep the momentum up, similar to when driving in sandy conditions, and increase your revs. Correct AT (All-Terrain) or MT (Mud Terrain) tires are essential to enjoying a successful mudding experience.
(I wrote a comprehensive guide about mud driving techniques – you can read more about it here)
So to recap on the original question, yes you can engage 4H and safely reverse in four-wheel-drive if the driving surface is low-traction enough like snow, icy roads, muddy roads, and sand dunes. The four-wheel-drive drivetrain system works exactly the same in reverse as it does going forward.