Dear Drive… What’s the difference between high-range and low-range four-wheel drive?

We've been asked:

It is often seen as the most important element of an off-roader: a proper low-range transfer case. In years gone by, it was easily identified by the short lever next to the gearshifter. These days, you need to search more often for a dial, button or switch.

Nostalgia aside, the end effect is the same. A low-range transfer case – kind of like an auxiliary gearbox behind your actual transmission – is a powerful ally to have for an off-roader.

More broadly speaking, a transfer case has the job of sending drive fore and aft, turning two-wheel drive into four-wheel drive.

Some transfer cases are referred to as single-range because they don’t offer any additional low-range reduction. Dual-range transfer cases offer two sets of gearing: high and low range. This would be the case in most all-wheel-drive vehicles.

And, of course, there is an important difference between four-wheel drive and all-wheel drive. For more information on that, read this story.

However, back to this case. In high-range, a transfer case will direct drive forwards and backwards without any change to the gearing.

When you select low-range, an additional set of reduction gears are engaged that effectively reduce the overall gearing of the vehicle.

So now at the same engine speeds in the same gear, your vehicle will be travelling at a much lower speed.

What’s less obvious in this case, and more important for off-roading, is that the amount of torque being delivered to the wheels (which gets multiplied through the gears) is greatly improved.

Try driving up a hill, over a boulder, or up a steep sand dune (like the image above), and you’ll notice that the engine doesn’t labour or shudder, and you’ve got significantly more control and confidence from behind the wheel.

The most capable – and best controllable – off-roaders will always have low gearing available for off-road driving, most commonly found in the transfer case.

It’s a little confusing, but lower gearing is represented by a higher ratio number.

The Jeep Wrangler Rubicon and Gladiator Rubicon, for example, have a 4:1-ratio transfer case, which is a significant jump over the 2.72:1 in non-Rubicon variants. Combine that with a low first gear and 4.1:1 diff gears, and you’ve got an overall reduction of 77:1.

Most four-wheel-drive utes have an overall reduction of around 30–35:1, which is good enough for most regular four-wheel driving. But more technical and hardcore challenges will benefit from a lower overall reduction, either through a factory set-up or by serious aftermarket modification.

Have a question about your next set of wheels or just need some car advice? No query is too big, small or obscure! Call in to the radio show (Trent on 2GB Sydney 1:30pm Monday and 9:00pm Wednesday, 5AA South Australia 1:30pm Tuesday, and James on 3AW Melbourne 9:00pm each Thursday), or contact us by email here: contactus@drive.com.au.