Should I Use 4H Or 4L? - Ridgeback Service Bodies

Understanding 4WD Modes

To fully understand when to use 4H and 4L, it’s important to first grasp the basics of 4WD systems. When you engage 4WD, power is distributed to all four wheels, enhancing traction and stability, especially in difficult conditions where a two-wheel-drive (2WD) vehicle might struggle. In most modern 4WD vehicles, you can switch between high-range (4H) and low-range (4L) gears based on the driving conditions.

2H (Two-High)

• Use for normal driving on paved roads.
• Powers either the front or rear wheels (depending on the vehicle).
• Provides better fuel economy and a smoother ride.

4H (Four-High)

• Best for driving at higher speeds on loose surfaces like gravel, sand, or snow.
• Engages all four wheels without changing the gear ratio.
• Allows for faster driving while improving traction.

4L (Four-Low)

• Best for slow, difficult driving conditions like deep mud, rocky trails, or steep hills.
• Engages a lower gear ratio, delivering maximum torque to the wheels for better control.
• Limits speed to a maximum of about 40 km/h but offers significant power for tough conditions.

When to Use 4H

4H is ideal when you’re navigating rough terrain at moderate speeds and need better traction than what 2H offers. Here are some common scenarios in Australia where 4H is your best option:

1. Unsealed Gravel Roads

If you’re driving on loose gravel or dirt roads, 4H improves grip and prevents skidding. It helps you maintain control even at higher speeds, making it ideal for road trips through rural or outback areas.

2. Beaches and Sand Dunes

When driving on soft sand, such as at Fraser Island or Stockton Beach, 4H helps you maintain speed without getting bogged down. Lower your tyre pressure to around 16-20 psi for better traction and floatation on the sand.

3. Snowy Conditions

For areas like the Snowy Mountains, 4H provides stability on snow-covered roads. It ensures that each wheel gets enough power to grip the slippery surface, improving your control in wintry conditions.

Best Practices for 4H

• Speed Limit: 4H allows you to drive at speeds up to 80 km/h, but avoid using it on hard, dry surfaces like asphalt. Prolonged use on such surfaces can lead to drivetrain wear and reduce fuel efficiency.
• Surface: Engage 4H only when on loose or slippery surfaces like sand, snow, or gravel.

When to Use 4L

4L is your go-to mode when you need maximum control, power, and torque, but not speed. This mode is specifically for challenging off-road environments where slow, deliberate movements are crucial.

1. Muddy Terrain

In Australia’s wetter regions, like Cape York or the Victorian High Country, muddy tracks can quickly trap vehicles. 4L keeps your wheels turning steadily, helping you avoid getting stuck while maintaining traction in deep, sticky mud.

2. Rocky Trails

Places like the Blue Mountains and Flinders Ranges are known for rocky, uneven trails. 4L enables you to crawl over large boulders and obstacles at a slow, controlled pace without damaging the undercarriage.

3. Steep Inclines and Declines

Whether you’re climbing steep slopes in the Simpson Desert or descending long, steep hills in the Great Dividing Range, 4L provides better engine braking and control. This reduces the need to ride your brakes, which can overheat on long descents.

Best Practices for 4L

• Speed Limit: Keep your speed under 40 km/h when in 4L to avoid overloading the engine and drivetrain.
• Engage on Loose Terrain: Use 4L only on soft, loose, or rugged surfaces like mud, snow, or rocky trails. Avoid using it on firm, dry roads.

How to Shift Between 4H and 4L

Switching between 4H and 4L is generally straightforward, but it’s crucial to follow the correct procedure to avoid damaging your gearbox.

• Shifting to 4H: Most modern 4WDs allow you to switch from 2H to 4H “on the fly,” meaning you can engage 4H while driving without stopping the vehicle.
• Shifting to 4L: You will usually need to stop completely, place the vehicle in neutral, and then shift into 4L. Always consult your vehicle’s manual for specific instructions, as procedures can vary between models.

Need to boost the functionality of your 4WD? Service bodies or fleet solutions can increase the utility of your 4×4, whether for work, off-road adventures, or heavy-duty towing.

When to Use 2H

While 4H and 4L are crucial for off-roading, most of your regular driving will be done in 2H, especially on sealed roads. This mode offers the best fuel economy and smoothest ride for everyday driving conditions.

Ideal for:

• Highway driving: On city streets or highways, 2H delivers better fuel efficiency and less wear on your drivetrain.
• Dry conditions: When the road surface is firm and dry, there’s no need for extra traction, so 2H is the most economical choice.

In Australia, where long stretches of highways are common, 2H is your default mode for day-to-day driving.

Important Considerations for Off-Roading in Australia

1. Tyre Pressure

Reducing your tyre pressure before hitting sandy, muddy, or rocky trails can significantly improve traction. For soft sand, lowering tyre pressure to around 16-20 psi is ideal, while for rocky terrain, 20-25 psi works well. Just remember to reinflate your tyres before returning to sealed roads.

2. Speed Control

In both 4H and 4L, maintaining a steady speed is key. In 4L, avoid speeding, as it can cause unnecessary strain on your drivetrain. Likewise, in 4H, keep speeds under 80 km/h to ensure control and safety.

3. Avoid Sharp Turns

Making sharp turns in 4WD can cause issues due to the locked front wheels. Instead, aim for wider, more gradual turns to avoid excessive torque build-up that could damage the vehicle or cause it to jerk.

4. Don’t Forget to Shift Back

Once you’re back on hard, smooth surfaces, remember to shift back to 2H. Driving in 4H or 4L on firm roads can damage your differential and lead to costly repairs.

Common Mistakes to Avoid

1. Driving Too Fast in 4L

4L is meant for slow, controlled driving. Attempting to drive faster than 40 km/h in this mode can strain your engine and drivetrain.

2. Using 4WD on Dry Roads

Engaging 4WD on hard, dry surfaces causes unnecessary wear on your vehicle and reduces fuel efficiency. Stick to 2H when driving on regular roads.

3. Forgetting to Reinflate Tyres

After lowering tyre pressure for off-road conditions, always reinflate them before getting back on paved roads. Driving at highway speeds with low tyre pressure increases the risk of a blowout.

Conclusion

Whether you’re navigating Australia’s beaches, tackling the rugged trails of Cape York, or driving through snow-covered roads in the Snowy Mountains, understanding when to use 4H or 4L is crucial for safe and effective off-roading.

• 4H is best for driving at higher speeds on loose surfaces like sand or gravel, providing improved traction while maintaining speed.
• 4L is essential for slow, technical driving through deep mud, snow, or steep inclines, offering maximum control and torque.

By shifting into the correct mode for the conditions and following best off-road practices, you’ll ensure both your safety and the longevity of your vehicle. With this knowledge, you’ll be ready to tackle Australia’s most challenging terrains with confidence.