Why Do Some 4WD Vehicles Have Two Gear Shifts?

There's a very good reason why some vehicles with four-wheel drive come with two gear shifts. One is for the transmission, which can be either a manual or an automatic, while the other shift lever controls something that is found in many four-wheel-drive vehicles. It is called the transfer case, which some of the best off-road vehicles have.

The transfer case not only allows you to engage your vehicle's four-wheel drive system, but it also permits you to select either a high-geared version, typically called 4H or 4Hi, for normal off-roading, or a low-geared version, 4L or 4Lo, for slow going in mud, sand, or snow, or when you need increased control over your vehicle. Your transfer case may also offer a neutral setting, shown as N, which disengages the transfer case. This setting is typically used for specific towing situations, such as flat towing, if the vehicle's owner's manual allows it. Be aware that some vehicles may use a dial or a switch for the transfer case, instead of a shift lever. The functionality generally remains the same.

Depending on the specific type of 4WD system you have, the transfer case lever or switch may have an AUTO setting. What this does is let your vehicle operate in RWD mode until it detects the need for added traction, when it automatically switches to 4WD.

You might not think that the 4Lo setting on your transfer case would be very useful, but there are numerous situations when it makes sense. One of these is driving up steep inclines, where using 4Lo gives you better control, plus less likelihood of spinning your wheels, losing traction, and overheating your automatic transmission. It is also a good off-roading strategy to use 4Lo on downhill sections, when the added engine braking from the lower gearing will greatly ease the stress on your braking system. If you should find yourself in soft sand, 4Lo is better for your entire drivetrain, reducing its overall stress level. The 4Lo mode can be very useful in many ways once you venture off the road.

Some vehicles come with four-wheel drive, while others come with all-wheel drive — raising the question of whether AWD or 4WD is better for off-roading. Many traditional vehicles with four-wheel drive will have a transfer case with settings as we have listed above. Conversely, most all-wheel drive vehicles don't have a transfer case with a lower gear setting and do not require much in the way of driver input — just shift into drive and go. While some systems give you AWD all the time, others will drive two wheels until the system senses that you need additional grip, when the system engages all four wheels. For general on-road needs, AWD is fine, but if you plan to go very far off the road, be sure to have 4WD along for the ride.