Owning a 4WD opens a whole new world. Those tracks on the side of the road, or pristine beaches that were off limits before are now accessible with a 4WD, and you can have a heap of fun with it. The thing is though, you need to know when to engage high range, low range and when to leave it alone and do nothing.
The problem straight off the bat is that not all 4WD’s operate in the same way, and that makes explaining this more complicated. If you have a full time 4WD, when I say high range, I mean high range with the centre diff lock engaged. If you don’t have a full time 4WD (like many on the market) then you don’t need to worry about this.
What is the purpose of high range?
High range is the first step into engaging 4WD. Generally to get to low range, you’ll have to go ‘through’ high range. High range makes all four wheels drive, and the front and rear axles should be locked together. In other words, 50% of the drive goes to the front, and 50% goes to the rear.
The only way you can get unstuck is if you get one wheel in the air, and then all of the drive will go to that one. If you get two in the air on different axles, you wont be going anywhere without a differential locker, LSD or a recovery!
High range is designed for higher speed 4WDing including gravel roads, harder beaches, and any 4WDing where you are sitting at over 40km/h. It should be used on any loose surfaces, but never concrete, bitumen or compacted roads as the wheels need to slip independently.
Driving your 4WD in high range on hard surfaces will result in something breaking as you get wind up across the components, until something is stressed enough to snap. Often this is a CV, but you can do damage to lots of different components too.
A lot of 4WD’s can engage high range from 2WD without having to stop today, but read your owners manual to find out more.
What is the purpose of low range?
Low range is a different set of gears that reduces your speeds considerably. Flat out in first gear of low range is generally not much more than walking pace, and that makes it perfect for all of the slow 4WDing work where torque is important, and speed is not. Such things like rock crawling, or crossing a river, or driving down a soft beach are perfect for low range.
Low range is generally capped at about 40 – 50km/h with the revs of your 4WD going through the roof in top gear at this speed. If you need to go faster than 40km/h, you should either move to high range, or slow down.
Its worth noting that most beaches in Australia are limited to 40km/h and there are occasions where the police run speed cameras or mobile radars and will book you for going over this.
What happens if you use high range when you should use low?
A lot of people still use high range on beaches, and that is fine depending on your vehicle, and how hard it is working. Particularly if you have an automatic transmission, if you drive in high range on a soft beach you’ll notice the transmission oil temperatures start to go through the roof, and you’ll eventually end up in limp mode if you aren’t careful.
One of the ways to care for your automatic transmission is to use low range when needed, and not to leave it in high range.
High range puts a lot of stress on clutches, automatic transmissions, oil temperatures and even your motor temperature if you aren’t careful, and if there is no need for excessive speed then low range is generally the go to option if you are working the vehicle hard.