When is it exactly right to engage 4WD?

[grubworm]

Power to wait ratio will cause most trucks to sit and spin in the snow.

i always thought the more power, the less you have to wait

 

[Billiebob]

I don't hesitate to use 4WD, On any road it distributes acceleration and deceleration thru 4 tires, rather than just 2. If you need 100HP to accelerate, 2WD sends 50HP to each tire, 4WD sends 25HP to each tire giving far better control.

I like to drive kinda faster even on a drive to a forestry lookout. We use 4H running mostly in 2nd and 3rd gear on the way up. 4L on the return downhill mostly in 3rd or 4th. My favourite combination was a YJ, straight 6, 5speed, 3.07 ratios. In 4L it felt like a Mustang, easily hitting 60mph. It was a blast to drive.

 

[BensonSTW]

i always thought the more power, the less you have to wait

Good catch. That was sharp witted enough I will not be editing my post.

 

[MidOH]

You'll have to study your trucks drivetrain.

Both of my trucks are real 4wd. You can use it anytime you're going straight, on any surface. Concrete boat ramp for example.

Around turns, in high grip, I might have to select 2wd to avoid binding. Even in heavy snow, tight turns in 4wd can make the truck hop. It's your choice how much hopping is acceptable. For me it's situation dependent. If I'm on a slick switch back, I'll allow more binding, and stay in 4wd. On a gravel switch back, I'd rather select 2wd.

You can swing wider in snow, and get on it harder, to create a little slip, which will prevent driveline windup. Squishy tread on tires can soak up a bit of binding as well. For example, neither of my trucks will bind around a sweeping turn on dry pavement. The tires flex enough to make up for it.

We often use 4wd to smooth out bumpy gravel roads. The truck rides slightly smoother in 4wd. We don't need 4wd on most of those roads.

Keep in mind that it's important to ''exercise'' the 4wd system.

 

[MidOH]

I use 4 low only for precision crossing rocks or a ditch. Or just to exercise it.

It's too much of a PITA to get from 4L to 2wd, and back again. My Olde 2008 F250 and 2015 F350 had 2wd Low. It was awesome for backing up trailers.

 

[izzywolf]

I run 2wd 90% of my offroad travels. 4 hi is for when the tires start to spin. I hate the thought of chunking out 2 grand in tires. I will also use it anytime there is snow. Power to wait ratio will cause most trucks to sit and spin in the snow. 4 low is for when the engine starts to bog down, if I need to go slower than 4 high due to rough terrain, or when 1st or 2nd gear doesn’t want to hold me back on a down hill. I absolutely hate when people ride the brakes going down hill. When you overheat your brakes and start to experience brake fade, it can cause some sketchy scenarios on the trail. It’s actually kind of interesting to see when others will decide to lock in the t-case and why. I know a guy that uses 4hi anytime he leaves the pavement.

If you shouldn't brake downhill what should you do instead?

 

[izzywolf]

60 mph in low?????? are you kidding us??
maybe YOU should go study your owners manual.
i am not aware of any t-case by any manufactor that would give a green light to go anywhere near 60 in 4lo. if you want to grenade a t-case, just follow this dumb advice....
and unless you have diff aids, 100 hp will go to one tire and in 4 wd 50 hp would only go to 2 tires, which is about 90% of 4x4's out there.
to drive a part time case on hard roads is a sure way to destroy all your 4x4 parts.
are you even aware why you shouldn't drive on hard roads? cause your advice sure says otherwise.
your front tire rpm's combined are always greater than your rear tire rpm's combined. as the transfer case is putting equal torque to both axles, it is trying to keep the rpm's the same while the front tires are trying to rotate faster. this is why you need slip under your tires, to relive the stress. but if you want to keep driving on hard roads in 4by, just make sure to post pics when your t-case chain breaks, your output shaft splits, your u-joints explode, your diffs drop their guts all over the road......
jeebus...from the guy who thinks a locker can send 100% of your power to one wheel.....

Actually when I read the part about going 60 I imagined he meant off-road.

 

[ScratchCoin]

I’m going to elaborate on the “read your owners manual” statement….before even thinking about putting your vehicle in what ever drive mode you dont drive around in on the pavement, you need to understand what kind of differentials are in your truck *open, limited slip, locked) and what happens when you put it in 4hi, 4low, or 2wd if you have that one. Do you have a rear locker and if so, how does that change your vehicles driving characteristics…do you have a front locker an how does that change things….do you have a center diff lock, how does that change things, and is there a mode that will automatically turn on the center diff? You really need to know the ins and outs of all this stuff so you can make the best decision based on the situation. Like the other person said, there are many possibilities and for each one of us, the answer to the situation may be slightly different based on our rigs.

 

[MidOH]

If you shouldn't brake downhill what should you do instead?

Down steep hills, you should select 4L. Engine braking will do most of the work. And with lockers, you'll erode the trail far less.

With the driveline locked in, you're less likely to skid a tire on a slippery spot, since it's directly connected to another in a grippy spot. This is also why 4H in snow, might stop a full car length faster than in 2wd. Negating the old wives tale: "4WD won't help you stop.''

 

[Trail_pilot]

Negating the old wives tale: "4WD won't help you stop.''

In a broad sense offroad yes, but I see too many people thinking that their bald tires on a 4x4 will stop them on an icy road when they slam on the brakes lol.

 

[MidOH]

Don't run bald tires. 4wd works better on the street as well.

41 years in the snow belt.

 

[Trail_pilot]

Don't run bald tires. 4wd works better on the street as well.

41 years in the snow belt.

More snow the better. A lot of people seem to substitute 4x4 for common sense is basically what I'm getting at. I'm in the snowmelt too lol. Canadian side lol

 

[ThundahBeagle]

Don't run bald tires. 4wd works better on the street as well.

41 years in the snow belt.

51 years in New England and I agree. Dont run bald tires. And 4x4 does work better on a snowy or icy street as well. It may stop you a car-lengrh or so sooner. Sometimes that's just enough.

To @Trail_pilot 's point though, everyone is so busy "driving too fast for conditions" that 4x4 often gives a false sense of superiority to the uninitiated, and wont stop some goof from spinning out and flying off the road when they stomp on the brake and turn the wheel to avoid that fender bender on the icy road.

When it gets snowy or icy, I like to get into 4hi. Or at the very least, Auto mode, which is a new feature to me. Evidently it's been available on GM trucks for a while, but my 14 Sierra is my first GM truck made in this millennium, so I've been checking out the auto mode when it's been snowy

 

[Brewbud]

For both my vehicles - Ram 2500 and Jeep LJ

--On dry pavement 2WD
--Snow 4WD
--Dirt trail 2WD until very loose and more traction is needed
--High-speed desert running 2WD unless there is a lot of deep sand
--In the rocks or anywhere low speed and traction is needed 4-Lo

 

[North40overland]

It depends on your 4wd system. As a general rule you should only run AWD (all wheel drive) on pavement in any conditions other than full snow cover. AWD is fine in wet weather for a little extra grip. If you truly have 4WD only engage when your tires are off pavement or again there is snow between your tires and the pavement (if you see black at the bottom of your tracks in the snow then you might want to stay in 2wd. I am sure there are many more complex conversations to be had but this is my general rule and I have not had any issues in over 20 years of driving 4wd vehicles.

 

[ThundahBeagle]

It depends on your 4wd system. As a general rule you should only run AWD (all wheel drive) on pavement in any conditions other than full snow cover.

It definitely depends on your system. Clearly a Subaru is AWD all the time. A newer GMC or Chevy truck with 4x4 has a dial which includes an Auto setting. This is essentially AWD, however, you should not run in Auto in a GM truck as a regular practice. The 4x4 clutch packs wear out faster than they should. In my GMC, I use Auto (like AWD in a Subaru) for wet conditions, light snow, like when the blacktop is visible in my tracks after riding through rain, sleet, *wet snow!* and the like. Full snow cover generally garners the 4 hi setting for me

 

[Downs]

Hi, I'm new to overlanding, and off-roading.

I've read that you should never engage 4WD unless you're in a low traction situation, otherwise you'll mess up a lot of things.

So is there an exact minimum on how, for example, wet the road has to be?

You're looking for black and white answers to a grey question. Go out and experiment, might not hurt to take a 4x4 101 class either.

 

[rubytrailsahead]

Agreed! Similar to comments from the previous ones.. 4-H for off pavement and 4-L when needed or technical. I will generally do 4-L in also a potential downhill situation where applying too much/any brake to keep is a consistent downhill without putting too much pressure on the trail itself and saved for future riders.

 

[Deleted member 82267]

Just my two cents I have used 4hi on pavement in heavy rain, snow and ice. Off road it just depends on my situation, on low speed technical terrain I use 4 low for the traction and the gearing. On maintained dirt I might use 4hi just to exercise the front diff and the transfercase or traction if needed. Really what works for your driving style and the vehicle being driven.

 

[Billiebob]

Actually when I read the part about going 60 I imagined he meant off-road.

Exactly, on forestry roads, but it really makes no difference, I drive the highway often in 4H at 60MPH, on most days there is a mix of snow, slush, dry pavement.

The beauty of 4WD is splitting the power and braking over 4 tires instead of 2 tires.
4WD lets you tread lightly, avoid spinning, sliding tires, and srive slower.
2WD needs more momentum to go the same places and speed often leads to breakage.
Use 4WD, H or L anytime you want more control, regardless of the speed.