Asking how fast you can drive in 4×4 low might seem like a weird question to some, however, it’s quite relevant since off-road environments pose a variety of scenarios that requires different approaches. This article will discuss how driving in 4×4 low reduces gear ratios and how that affects your speed. We will also look at when we should drive in 4×4 low and how it behaves in various off-road conditions.
So how fast can you drive in 4×4 low?
Driving speed in 4×4 low should never exceed 10mph since the surface conditions are usually low traction, rocky, steep, and uneven surfaces that require low-speed control. 10mph is the maximum recommended speed to drive in low range on technical off-road tracks.
With that being said, we also need to understand when it is applicable to engage 4×4 low and when we should drive in 4×4 high or 4H. The next part of this article discusses when to engage 4×4 low, how fast we should drive in 4×4 hi, and what happens to the driving dynamics of the 4×4 when we engage low range.
Let’s dive in…
When to drive in 4×4 Low
Knowing when to select 4×4 low is very important for the safeguarding of your 4×4 as well as the safety of you and any occupants in your vehicle.
4×4 low should be selected when driving on very low traction surfaces such as:
- Deep Snow tracks
- Rocky uneven surfaces
- Thick loose sand
- Deep Mud
- Steep uneven inclines
- Steep uneven declines
The above-mentioned surfaces are all low traction environments that required absolute vehicle control. How fast you can drive is not always important under these conditions, except maybe in deep sand dunes where momentum is required. As mentioned before, it’s not the speed that’s important in any of the above driving surfaces but rather achieving and maintaining traction combined with maximum power availability.
Always remember to stop or slow down to 5mph before engaging 4-Lo and depress your clutch when shifting from High-range to low-range.
When you driving off-road you need to constantly scan and survey the driving conditions ahead. Sometimes it requires you to exit the 4×4 and walk the obstacle before you attempt driving it. A general rule of thumb or gauge is, if you can walk it, you can drive it in 4×4 low. So take your time to walk the obstacle and choose the best driving line for your 4×4. You as the driver and owner of your 4×4 know the width and ground clearance and break-over angles better than any other driver, so your driving line might not necessarily be the exact same as the next guy or even the 4×4 that went through that obstacle before you.
When you select 4×4 low, the low ratio transfer case is engaged which uses low ration gears. This drastically increases your vehicle’s res or revolutions per second but also drastically reduces the vehicle’s ability to drive fast. 4×4 low is designed to keep the engine in a high revving state to ensure you have all the engine’s power and torque available at all times. This is great since your risk of stalling midway through a dangerous or very technical obstacle is significantly reduced.
If you survey the driving surface and you feel you can drive faster than 10mph without causing damage to your vehicle and without making the driving experience too uncomfortable then it would be safe to disengage 4×4 low and drive in 4×4 high instead. Driving in 4×4 Hi does not limit you to any particular speed and doesn’t negatively affect any drivetrain components when driving off-road.
How fast can you drive in 4×4 (4WD-H)
Before we engage 4×4 High it’s important to make sure you are driving on a very slippery, low traction surface. The purpose of this instruction is due to the fact that a part-time 4×4 is always at risk of drivetrain “binding” if we don’t observe this general rule. With that being said, a slippery surface could be in the form of a dirt road, a sandy or wet jeep track, or a slippery icy highway. These are all textbook driving conditions to safely drive in 4×4 high. When driving in any of these environments, a speed of 55mph and below is ideal.
There are always going to be road surfaces and off-road situations that might afford us the ability to safely drive at 55mph and above. However, when road surfaces appear to be safe, we need not throw caution to the wind but always use extreme caution when driving off-road, since there are always elements that are beyond our control which we need to bear in mind. Examples of these could be wild animals running in front of the vehicle, a sudden tire burst, sharp bends, or blind spots in the road as well as uneven road surfaces.
Driving 55MPH and above on this type of low traction surface with the afore-mentioned potential hazards, we should ask ourselves, will we have adequate time to bring the vehicle to a complete stop or even slow down enough to avoid any possible obstacles?
Remember, you are out in nature, slow down, and take the time to soak up the environment and the scenery, there is no need to rush when driving outdoors.
So what kind of off-road surfaces do we need to engage 4WD-High?
Before we get to the remote outback tracks, in most cases there are long distances that need to be covered on city highways before we reach the off-road trails. When driving a part-time 4WD you will engage 2H mode on a high traction tarmac road with good traction. This is essential to prevent drivetrain binding.
I good rule is when we reach the dirt tracks and leave the tarmac, immediately engage 4H, since this will immediately improve traction and safety. If, on the other hand, you drive a permanent 4WD, then simply continue driving, since your 4WD is always in 4H mode. When 4WD-High is engaged, the engine power is sent to both front and rear axles. This function then splits the 50% of power and torque between each wheel on that axle, meaning each wheel receives 25% of the engine’s total power. This improves the vehicle’s traction and makes it more stable by providing more grip. In 4×4 high, all 4 wheels are propelling the vehicle forward. Fantastic engineering!!!!
Examples of low traction surfaces include:
- Slippery icy roads
- Sand tracks
- Muddy tracks
- Farm roads
- Wet rocky surfaces
What happens when we Drive fast in 4×4 Low
This is generally not a smart thing to do for a few reasons. Firstly you will be keeping the engine in a high revving state for too long, which is never a good thing for the long-term preservation of your engine and turbo if fitted with one.
Also, your 4×4 won’t have the ability to drive faster than 15mph or perhaps 20mph which means at those high revolutions you are not getting enough cool air into the engine to reduce the heat being generated. The radiator coolant and viscous fans will not be able to sufficiently cool the engine and you are at serious risk of overheating your vehicle.
It just won’t be a very pleasant experience with the engine noise being excessively high, intruding the cabin. Again, if you can safely drive faster than 10mph, rather engage 4×4 high and drive slower.
Driving in 4×4 Low
The driving dynamics of your 4WD are transformed drastically to when you are driving in 4×4 hi or 2WD mode. When you drive in 4×4 low, all four wheels are being powered by the engine simultaneously and the low ration gearing through the transfer case is being used. Wheel turning speed will be drastically reduced when 4×4 low is engaged but more engine power and torque are more readily available. The wheels turn a lot slower when driving in 4×4 low than when in 4×4 high and 2H mode.
4×4 low is always engaged when driving on soft sand, steep hills, declines, deep mud holes, thick snow tracks, and rock crawling.
Older, more traditional 4×4’s use a short gear lever positioned next to the main manual or automatic gear shifter to engage 4×4 Low. Even older models of 4×4’s require you to physically exit the vehicle to manually lock the front hubs by hand before driving off-road. This process needs to be reversed and manually unlocked before switching back to 2H.
What a pain!!! Modern 4WD’s allow you to switch between 4Lo to 4H and 2H on the fly with a flick of a button. This is usually achieved by simply turning a dial or knob or by pressing a few fancy buttons from inside the cabin – yay for technology!!!
In many modern 4x4s you can switch from 2H to 4H without stopping, but still, have to come to a complete stop to switch from 4H to 4L.
When to use low range
We engage 4×4 Low when we require optimal traction and absolute maximum power, available at all times. As mentioned before, in 4×4 Low (four-wheel drive, low range), all four wheels are propelling the vehicle while driving when a low gear ratio gear is being used.
Low-range functionality is one of the tools that affords us the opportunity to explore unchartered beaches, mountains, and bush. Engage low range to get you through soft sand, over soft-sand dunes, up steep hills and declines, through deep mud or snow, and it will especially come in handy when you drive over large slippery rocks.
The lower gearing also improves your 4×4 engine braking, which helps to control your progress on downhill sections.
Driving 4×4 in Sand
Most light sand conditions can be successfully driven in 4×4 High. Once the terrain and sand become very thick and deep it places a lot of strain on your clutch system. This is when you want to engage 4×4 low range and select a lower gear such as 2nd gear. You want to maintain a steady speed and keep the momentum but only drive as fast as necessary. This is the perfect combination of driving beach sand and low dunes.
When you need to climb out high sand dunes you’ll need to engage 4WD high and use a lower gear such as 2nd or 3rd depending on the size of the dune and the looseness of the sand. You will need more speed and good momentum on your side to successfully climb out the dune.
Sand driving is a bit of an art and the correct gear ratio will largely depend on the sand conditions as well as your vehicle’s gearing ratios. Also what plays a large role is petrol vs diesel since they behave differently. Tire size and pressure are also vital considerations when driving on the sand with your 4×4.
Driving 4×4 Low on Rocks
Rock crawling is a very technical aspect of 4×4 driving and requires a lot of patience and skill. Speed is not your friend when driving in 4×4 lo on rocks. More important than speed is vehicle control, maintaining traction, driving line, and ground clearance. All these factors will collectively contribute to an enjoyable rock crawling experience.
Driving fast while rock crawling in 4×4 low will only cause damage to your drivetrain, body panels, and undercarriage components. Again, in this situation, you want to maintain a slow but steady pace and allow the tires to grip at the correct places by always keeping the tires on the high side to avoid bashing drivetrain components or getting hung up on a rock.
Driving 4×4 Low up steep hills
When driving up a steep uneven hill with low traction you will need a combination of momentum, speed, and good traction at all times. You again, want to make sure you walk the track or hill first and choose the correct driving line based on your vehicle’s dimensions and ground clearance. You will need to use a bit of speed but not too much since the danger of vehicle damage and roll-overs are always present.
Engage your 4×4 low and drive at a speed that suits the surface. Slippery surfaces will require more momentum so in the event traction is lost, the momentum can carry you a bit. Again, choosing the correct driveline is probably the single most important aspect of climbing out a steep slippery uneven hill in 4×4 low.
Conclusion
In conclusion, there are certain off-road situations that require you to use momentum and a bit of speed when you are driving 4×4 lo. This is entirely up to the discretion of the driver and the dimensions of his 4×4. When you engage 4×4 lo your main purpose should not be speed but rather control and driving line. 10mph is the recommended maximum speed to drive when 4×4 lo is engaged.