4 Wheel drive off road, have I been doing it wrong ?

[brrapp]

I've been driving off road for over 40 years, tractors, motorbikes, landrovers, quads, dumptrucks etc. and thought I had a reasonable level of skill, however my daughter has just been on an off road driving course and apparently what I've taught her and what I've been doing all these years is wrong. Maybe someone on here could give me some advice.

Many of the vehicles I have driven including three which I currently use (series 2 Landrover , Ford Ranger pickup, and Polaris atv) have selectable 4 wheel drive and lockable diffs.
I was always of the school that you should proceed as far as possible in 2 wheel drive/unlocked diff until you get to the point that you need to engage them, that way if you do get stuck, you've always got something in reserve to get you out of trouble. Obviously I would engage them in advance for something that I'd almost certainly need them and where it wouldn't be practical to stop mid manouvre such as a 45 degree descent or mud or river crossing, but for general driving across fields/hillsides, I'd run in 2wd as much as possible.

My daughter's employer has brought in a specialist trainer to their estate to train all staff who use quads, tractors landrovers etc (for insurance purposes) in the art of off road driving. While he was complementary about my daughter's general skill levels (she went round the full course first time without stopping, something which he failed to do), he was critical of her not being in 4wd for the whole course. He told them all that they should engage 4wd and lock diffs as soon as they left 'normal' roads as being in 4wd 'just in case' is the safer thing to do.

Any comments/advice?

[300bhp/ton]

I don't disagree with you. But I think there are several things here.


1. You need to be able to read and assess the terrain. Often easy, but sometimes hard to do. Using high range and 2wd could be potentially dangerous if you should really be in 4 low. And if you get it wrong, it could end badly. While using 4wd when not really needed has no real negative effects.

And I don't really believe that nobody will get it wrong sometimes.


2. Leading on from this. If training and somewhat being responsible for the people based on your training. Surely it's a 'safer' easier thing to teach. If off road, use 4wd. Because there simply is less risk of something going wrong to begin with.

[TurboHatchback]

Firstly you certainly shouldn't lock the rear or front diff as soon as you leave the tarmac, they should only be locked when travelling in more or less a straight line and when actually needed. The argument for preemptively engaging 4wd is that once you're stuck and the rear wheels have dug themselves a hole it's harder to get out than if you'd been in 4x4 to begin with and not got stuck.

The best course of action depends entirely on the vehicle in question. In a permant 4x4 vehicle with lockable centre diff I wouldn't go for low range and locked centre diff just for driving fields and easy tracks, I would before trying steep gradients or really slippery surfaces. In a selectable 4x4 with no centre diff (so locked when in 4x4) I would leave it in 2x4 for easy fields and tracks but engage 4x4 as soon as I thought there was a risk of losing traction (before getting stuck).

Basically 4wd with locked diffs is great where you need it but if there is plenty of grip without it just puts more strain on the drivetrain, wears the tyres, rips up the ground and uses more fuel. The trick is knowing the limits and engaging just what's needed before getting stuck.

[anonymous-user]

I agree you shouldn't just reach for 4x4 any time you leave the road, but you also need to be sensitive to the damage that leaving your vehicle in two wheel drive can do to the trail. Engaging four wheel drive BEFORE it is needed avoids tearing up the ground unnecessarily - not great for the trail and not great for the people who follow behind you.

[brrapp]

thecook101 said:

I agree you shouldn't just reach for 4x4 any time you leave the road, but you also need to be sensitive to the damage that leaving your vehicle in two wheel drive can do to the trail. Engaging four wheel drive BEFORE it is needed avoids tearing up the ground unnecessarily - not great for the trail and not great for the people who follow behind you.

I don't 'trail' , I'm mostly off road on my own land or if on others' land it's because I'm working there. Yes, I've no wish to tear up my own or employers land so along with the need to keep a little something in reserve, and also minimise wear on the vehicle, avoiding damage to the ground is part of the reason I avoid permanent 4wd.

[anonymous-user]

brrapp said:

I don't 'trail' , I'm mostly off road on my own land or if on others' land it's because I'm working there.

The noun - not the verb. Trail, track, dirt road, whatever you want to call it, there's never a good reason to let the wheels lose traction if it can be avoided. I grew up driving vehicles on the slopes of a wine farm where even the slightest wheel spin could lead to erosion at the next rainfall. I don't get why having a vehicle in 4x4 off road will damage the ground - happy to be informed though.

[TurboHatchback]

thecook101 said:

The noun - not the verb. Trail, track, dirt road, whatever you want to call it, there's never a good reason to let the wheels lose traction if it can be avoided. I grew up driving vehicles on the slopes of a wine farm where even the slightest wheel spin could lead to erosion at the next rainfall. I don't get why having a vehicle in 4x4 off road will damage the ground - happy to be informed though.

Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them, i.e. it forces wheel slip. In a straight line there's no problem. A permanent 4wd vehicle in high range with three open diffs will cause no such issues, a part time 4wd pickup in 4x4 with no centre diff will.

[brrapp]

thecook101 said:

I don't get why having a vehicle in 4x4 off road will damage the ground - happy to be informed though.

Sorry, I'm not trying to be contrary, it's not so much being in 4wd, but having the diffs locked that tear up the ground if you're turning tightly, I suppose it depends a lot on the type of ground too.
As others have said, it's all about reading the situation.
I don't think I disagree with anything anyone has said on here, my original post was questioning the trainer's blanket 'engage 4wd as soon as you leave the road' statement which I don't think any of the replies on here have fully endorsed.

[anonymous-user]

TurboHatchback said:

thecook101 said:

The noun - not the verb. Trail, track, dirt road, whatever you want to call it, there's never a good reason to let the wheels lose traction if it can be avoided. I grew up driving vehicles on the slopes of a wine farm where even the slightest wheel spin could lead to erosion at the next rainfall. I don't get why having a vehicle in 4x4 off road will damage the ground - happy to be informed though.

Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them, i.e. it forces wheel slip. In a straight line there's no problem. A permanent 4wd vehicle in high range with three open diffs will cause no such issues, a part time 4wd pickup in 4x4 with no centre diff will.

I agree if you are talking locked front or rear diffs but my question was on why 4x4 - i.e. on the center diff locked - will cause damage. It is incorrect to say that "Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them". With the centre diff locked there is still a diff on either axle to account for side to side wheel speed differences.

[TurboHatchback]

thecook101 said:

TurboHatchback said:

thecook101 said:

The noun - not the verb. Trail, track, dirt road, whatever you want to call it, there's never a good reason to let the wheels lose traction if it can be avoided. I grew up driving vehicles on the slopes of a wine farm where even the slightest wheel spin could lead to erosion at the next rainfall. I don't get why having a vehicle in 4x4 off road will damage the ground - happy to be informed though.

Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them, i.e. it forces wheel slip. In a straight line there's no problem. A permanent 4wd vehicle in high range with three open diffs will cause no such issues, a part time 4wd pickup in 4x4 with no centre diff will.

I agree if you are talking locked front or rear diffs but my question was on why 4x4 - i.e. on the center diff locked - will cause damage. It is incorrect to say that "Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them". With the centre diff locked there is still a diff on either axle to account for side to side wheel speed differences.

It's not incorrect. A locked centre diff forces the speed of each axle to be the same, in a zero-slip turn the average speed of the front wheels is higher than the rear wheels. The front and rear diffs will determine how the slip is distributed between the wheels on each axle but there has to be slip somewhere.

[anonymous-user]

TurboHatchback said:

thecook101 said:

TurboHatchback said:

thecook101 said:

The noun - not the verb. Trail, track, dirt road, whatever you want to call it, there's never a good reason to let the wheels lose traction if it can be avoided. I grew up driving vehicles on the slopes of a wine farm where even the slightest wheel spin could lead to erosion at the next rainfall. I don't get why having a vehicle in 4x4 off road will damage the ground - happy to be informed though.

Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them, i.e. it forces wheel slip. In a straight line there's no problem. A permanent 4wd vehicle in high range with three open diffs will cause no such issues, a part time 4wd pickup in 4x4 with no centre diff will.

I agree if you are talking locked front or rear diffs but my question was on why 4x4 - i.e. on the center diff locked - will cause damage. It is incorrect to say that "Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them". With the centre diff locked there is still a diff on either axle to account for side to side wheel speed differences.

It's not incorrect. A locked centre diff forces the speed of each axle to be the same, in a zero-slip turn the average speed of the front wheels is higher than the rear wheels. The front and rear diffs will determine how the slip is distributed between the wheels on each axle but there has to be slip somewhere.

Fair enough - you are correct in that will be difference in average axle speed. But let's face it, you'd have to be turning pretty tightly for that to affect traction and even in that case I'd wager that an open diff will cause more slippage. A zero slip turn is pretty rare in any sort of off road application. Nevertheless I stand corrected.

[300bhp/ton]

TurboHatchback said:

thecook101 said:

The noun - not the verb. Trail, track, dirt road, whatever you want to call it, there's never a good reason to let the wheels lose traction if it can be avoided. I grew up driving vehicles on the slopes of a wine farm where even the slightest wheel spin could lead to erosion at the next rainfall. I don't get why having a vehicle in 4x4 off road will damage the ground - happy to be informed though.

Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them, i.e. it forces wheel slip. In a straight line there's no problem. A permanent 4wd vehicle in high range with three open diffs will cause no such issues, a part time 4wd pickup in 4x4 with no centre diff will.

But open diffs or 2wd can result in wheel spin, rather than slippage when cornering. I get and understand where you are coming from, but unless you are in a large tractor with implementation tyres on soft soil/grass. It'll probably make little odds overall.

[TurboHatchback]

300bhp/ton said:

TurboHatchback said:

thecook101 said:

The noun - not the verb. Trail, track, dirt road, whatever you want to call it, there's never a good reason to let the wheels lose traction if it can be avoided. I grew up driving vehicles on the slopes of a wine farm where even the slightest wheel spin could lead to erosion at the next rainfall. I don't get why having a vehicle in 4x4 off road will damage the ground - happy to be informed though.

Turning corners with any locked differentials forces the wheels to rotate at a different rate to the speed of the ground underneath them, i.e. it forces wheel slip. In a straight line there's no problem. A permanent 4wd vehicle in high range with three open diffs will cause no such issues, a part time 4wd pickup in 4x4 with no centre diff will.

But open diffs or 2wd can result in wheel spin, rather than slippage when cornering. I get and understand where you are coming from, but unless you are in a large tractor with implementation tyres on soft soil/grass. It'll probably make little odds overall.

Agreed, wheel spin is the worst outcome for both traction and terrain damage so if there's any risk of that then you should use 4x4 and appropriate locking diffs to prevent it. All I'm getting at is that if there's no risk of wheel spin you're slightly better off with 2wd or unlocked 4wd for the reasons stated above. For example If I was driving a pickup round tight turns on a dry flat manicured lawn I'd use 2wd and be gentle to cause as little damage as possible, on the same lawn but wet I'd use 4wd as wheelspin would likely cause much more damage than a little bit of slip due to the locked centre diff.

Of course for the sake of teaching novices and non-4x4 geeks it's simpler just to say off tarmac = 4x4 mode to avoid confusion.

[anonymous-user]

TurboHatchback said:

driving a pickup round tight turns on a dry flat manicured lawn.

Wait wait wait wait wait. Your point re 4x4 causing terrain damage was based on a dry manicured lawn..? Hmm - your anorak is behind the door.

[richs2891]

To go back to the original post, a lot of it depends on the "4x4" in question as lots of different ones out there, with differing systems and abilities. Knowing it and what it can and can not do is important.
If it can run in 4H without a locked centre diff then I cant see the reason not to enable it when get to point where it might be handy, such as wet grass, muddy track etc. A lot come from been able to read the ground, or getting out and checking and this requires practice and can still get it wrong. Been there done it, got stuck, got myself out.
But I do like been able to hold something back in reserve should I get stuck such as locking differentials, and the ability to turn completely off the electronics traction control systems. So I would not normally lock the rerar or front if I can get to where I need with just the centre diff lock in either HI or Low.
I dont think that there is right way or a wrong way, its what works for you, the vehicle and the ground, as no one method is correct for every occasion.

[caelite]

thecook101 said:

TurboHatchback said:

driving a pickup round tight turns on a dry flat manicured lawn.

Wait wait wait wait wait. Your point re 4x4 causing terrain damage was based on a dry manicured lawn..? Hmm - your anorak is behind the door.

Could be a groundskeeper? Ive had to make deliveries on to golf course utility buildings, driving a Defender 110 with a 2 ton bowser on the back. Client tends to ask us to be as light footed as possible but a small amount of damage is always expected. Personally I don't touch my diffs unless its boggy, up hill on wet grass can be a bit of a nightmare, thats pretty much the only situation I engage the lockers. If you leave them on when turning you will leave a nasty track.

Although some times damage is unavoidable. Especially when in an unladen pickup, you just get one of those 'urges' to pop it in 2wd and drift around the 18th hole,

Also I tend to leave it in 4wd permanently with the works 4x4s. It wears the front tyres to buggery but it is safer in the wet if you have a weight behind you. My own 4x4 sits in 2wd pretty much all the time because I'm tight and care about fuel usage and tyre wear .

[powerstroke]

Wet and muddy hilly I'm in 4X4 rough and bumpy, tight or steep low range 4x4 , flat dry stony or dry grass 2wd , driving a hilux so part time 4x4 with a rear cross axle lock ...

[LandRoverManiac]

Most of my 4x4s have been permanent 4wd drivelines - so it hasn't come down to choice on my part. In the old Series - I tended to whack it into 4x4 when going off-road as a matter of habit. Low range was engaged as and when - rather than the instant the wheels left the tarmac.

In modern, heavier stuff - I prefer to take things more slowly and deliberately (it's more expensive if contacting a tree!) - so low range most of the time off-road to keep the velocities down and more controllable. Even after six years of using vehicles with it fitted - I don't entirely trust HDC yet to keep me safe when descending a slope; low range/engine braking all the way. Diff-lock as and when needed - although in the past year I can count on one hand how many times I've engaged it. Every time I've got myself stuck - generally due to driver error in misreading the ground and bogging/grounding - diff-lock wouldn't have helped me.

[308mate]

brrapp said:

I've been driving off road for over 40 years, tractors, motorbikes, landrovers, quads, dumptrucks etc. and thought I had a reasonable level of skill, however my daughter has just been on an off road driving course and apparently what I've taught her and what I've been doing all these years is wrong. Maybe someone on here could give me some advice.

Many of the vehicles I have driven including three which I currently use (series 2 Landrover , Ford Ranger pickup, and Polaris atv) have selectable 4 wheel drive and lockable diffs.
I was always of the school that you should proceed as far as possible in 2 wheel drive/unlocked diff until you get to the point that you need to engage them, that way if you do get stuck, you've always got something in reserve to get you out of trouble. Obviously I would engage them in advance for something that I'd almost certainly need them and where it wouldn't be practical to stop mid manouvre such as a 45 degree descent or mud or river crossing, but for general driving across fields/hillsides, I'd run in 2wd as much as possible.

My daughter's employer has brought in a specialist trainer to their estate to train all staff who use quads, tractors landrovers etc (for insurance purposes) in the art of off road driving. While he was complementary about my daughter's general skill levels (she went round the full course first time without stopping, something which he failed to do), he was critical of her not being in 4wd for the whole course. He told them all that they should engage 4wd and lock diffs as soon as they left 'normal' roads as being in 4wd 'just in case' is the safer thing to do.

Any comments/advice?

Its the norm now so that employers can cover their arse. Conditions, driver capabilities etc are subjective. So to cover every eventuality should there be damage or a claim, you're expected to employ every tool you are equipped with, right from the start, regardless of whether its essential or not. Especially as in a work environment, the 4wd feature is likely considered a "safety" measure. I'd hate to be the instructor having to pedal that bks all day but I can see why its done.

[TooMany2cvs]

LandRoverManiac said:

Most of my 4x4s have been permanent 4wd drivelines - so it hasn't come down to choice on my part. In the old Series - I tended to whack it into 4x4 when going off-road as a matter of habit. Low range was engaged as and when - rather than the instant the wheels left the tarmac.

In a series, 4wd is akin to 4wd-centre-locked on a modern 4x4. What you don't have is 4x4-unlocked. You wouldn't lock the centre diff as a matter of course, because you're going to get driveline wind-up. So I'd be sticking with 4x2 - but what I would do as soon as going off is to lock the FWH, if you've got 'em.