When to select 4x4, when to lock the centre diff

[@desertpair2]

This series is SO excellent. I wish I had seen it sooner. Keep up the good work, you guys.

[@1malikalik]

Am American and I generally have a hard time understanding the Australian Accent but this guy is clear as a whistle. He is also a GREAT TEACHER.

[@brendansmoother]

I beleive Andrew is actually South African and definitely has that accent. However he does now reside in Western Australia.

[@1malikalik]

@@brendansmoother Oh Thanks for your reply and clarification 👍. Greetings from USA 🇺🇸

[@sugarnads]

Hes south african not australian.

[@jimbobjones3391]

Quite informative. I'm just amazed how everyone within the Land Rover sphere of influence uses the term "third differential" for what is actually a transfer case with a differential function!

[@bradley5819]

I was amazed land rovers had the center diff how about the first land rovers?

[@trainy1795]

@@bradley5819 the first land rovers had part time 4wd and so no need for a locking center diff

[@denisleblanc4506]

On my FJ Cruiser with VSC I prefer to keep it in 2Hi unless I'm driving in deep stuff like mud and snow. It's my experience that VSC maintains much better control in 2Hi than in 4Hi without VSC.

[@saeedalmazrouei4230]

Thanks a lot for explaining the real usage of 4x4 and center diff really i was not know that and when i go desert jut i am using the normal 4wd with low gears and flatten tyres

[@tomvalter720]

Nice! Didn't know the difference was that noticeable! Nice videos!

[@toddb6576]

Very comprehensive. Thank you

[@johnbebe297]

I thought the terms were 4 wheel drive and all wheel drive. A defender without the centre diff locked is in all wheel drive. When the centre diff is locked it is in 4 wheel drive

[@4xoverland]

I think that's a very good way of putting it.

[@Detroit642]

This is prob one of the best educational videos ever Thank you 👍

[@BubblesTheCat1]

Amazing. Thanks for this information Andrew. 👍

[@geoffgeoff143]

So, what you are saying is the transfer box is a differential? Is it a LSD when its not locked?

[@jimmyjohn5692]

Perfect simple explanation.

[@tmlesetla979]

The Hummer H3 is a permanent four-wheel-drive, yes, with the following modes; 4H Open - Centre Differential Open, with a 60/40 split back to front with Traction Control doing most of the work. 4H Locked - Centre Differential Locked, 50/50 split between the front and rear axles. Can be engaged on the fly up to ca. 72km/h. 4L Locked - Same as above, with the multiplying effect of the transfer case. 4:1 in the case of the Adventure. Additionally, on the Adventure models, Rear-differential-lock, which is of course, an axle lock. Later Adventure models also had in addition, Front-Differential-Lock.

[@Doctoberfest]

TM Lesetla I'm still a little fuzzy on the H3 technicalities but let me see if I have this right. So 4H Open (is the 4^ with no padlock) and you get 60% power to the front and 40% to the rear. But you still get the spinning tires like this video showed with the rock?

[@tmlesetla979]

It is 60/40 with a rearward bias. With Traction Control doing most of the work, which, as we know, is a tad reactive, even if it is within milliseconds. With 4Hi Locked, the centre differential is actively locked, similar to 4Lo, except the transfer case ratios are still 1:1.

[@tmlesetla979]

Then finally, 4Lo, which in the case of the Adventure, the TC multiplying factor is 4. Well, 4.03:1 to be exact, giving a low-range overall transfer ratio of ca. 57:1 in 1st Gear for the automatic, disregarding the torque convertor.

[@Doctoberfest]

TM Lesetla Okay that makes sense. Thanks for clearing that up for me. I'm looking at purchasing one this weekend for my wife to drive during the crappy midwest winters while I fat bike. And secretly I can take it out to the trails every once in a while. Managed to find an 06 fully loaded with 71K miles with locking rear diff. I'm going to see if they'll haggle quite a bit on the price though.

[@tmlesetla979]

That would be the Adventure version, the one to go for. 4.03:1 transfer case ratio and 4.56:1 axle ratios.

[@jpsjg]

Hi Mr Andrew. Congratulations for the video. I like very much your training videos and I consider you a Master Class in 4x4 world. However, I'm not totally agree with the explanation. According to you, Full Time 4WD is the very same that 2WD in most situations because of the fact that, in both 2WD or FT-4WD if you lift a wheel off the ground the car is instantly stuck. Ok, this is true when you are off roading in very irregular grounds, but the tyre behavior in terms of traction is not a matter of all or nothing, always or almost always there is an amount of traction on each wheel, even on snow, gravel, wet pavement, etc, and there are really very few situations in which one wheel loses all traction, like lifted off the ground. If you drive a 2WD car on wet pavement, the most of the time the car will keep moving and it only will get stuck if one wheel loses too much traction, but if you drive the same car in FT-4WD you significantly increase the traction, sending the power of the engine to the 4 wheels. Certainly, even in FT-4WD if you lift only one wheel, you will get stuck like in 2WD, but keeping a very small traction by wheel, FT-4WD greatly improve the movement and safety. If not, what is the reasoning of the Full Time? The best cars in the World Rally Championship are 4WD from the begining. In 1973 a 4WD Jeep Wagoneer AKA Moby Dick won a rally competition where the rest of the competitors were 2WD sport cars. From my experience. I have a Jeep Liberty KJ with Command-Trac system from factory (2H - 4H Part-Time - 4L). A time ago I decided to change the transfer case from NV231 to NV242 with Full-Time because of the improvement claimed by owners in rainy and snowy roads. Well, the improvement was greatly and not only on wet pavement. Before, when off roading, because of the 4WD, for taking curves with small radius I needed to go back and repeat the manuever to exit the corner even in a car with a good steering radius, and now I enter and exit the corner in one maneuver. On the road, this car has a rear LSD from factory and I must say that driving a rear 2WD with LSD on twisted wet roas is like dancing and you have to modulate the gas pedal very careful. Ask to the BMW owners. Jeje... When you drive a car in 4WD center locked, the car always try to go strait even when you slightly turn the wheels and it can get a lot worse on wet or ice. When you drive in Full-Time on wet: CONS: the traction in every wheel is certainly not 100% and depends on the three open differentials. PROS: the car goes exactly where you drive it. If you think about a car with ESP on the road, Its main characteristic is braking differents wheels in different moments of a situation to keep the car in control in the middle of a corner so if you force your four wheels to turn at the same speed putting 4WD center locked, I think you are worsening the behavior of the car in many situations, even in off road and I think it will behave better in FT-4WD. This is the same reason why is not a good idea driving on dry pavement with axle lockers on. I think that every position is good for something: 2WD to improve mileage in dry roads. FT-4WD to improve traction on roads with wet-dry situations when you can't use 4WD all the time. 4WD for gravel roads and light off-road without climbing, rocks, etc. 4L for fun. Here is a very good Toyota 4WD training video that can help to clarify all of this questions. kzbin.info/www/bejne/nn6me5yYeJyhmKM

[@gabrielbirkett3019]

Thank you for your contribution. Great comment for a beginner like me.

[@derciobene3458]

Nice. Andrew seems so young here when compared to today

[@derekomiles]

Now that is interesting. I have an amarok which is permanent 4x4. So what you are saying is that as soon as I am on dirt I should lock the centre diff?

[@4xoverland]

YES.

[@derekomiles]

Great - thanks. Now I know why I got horribly bogged in central Australia just after rain. I didn't have the centre diff locked. You are a wealth of information and I really enjoy your vids. I have watched heaps of them.

[@heiligerjesus1960]

+4xOverland so basically pernant 4 wheel drive isnt any better than a non 4wd??

[@dartmoordave]

You got shafted if your VW has not got some sort of axle locks or traction control. You only got a 4x2 for your money.

[@rebeccaedwards3784]

Heiliger Jesus this is what I'm confused about. If the video is correct, and leaving the centre diff unlocked doesn't give you permanent AWD , how is it that my ur Quattro from 1986 can drive up our hill in the mud and rain with the centre diff unlocked, but a conventional car spins it's wheels and slides back down the hill in the rain? Surely my first gen Quattro system should be getting stuck too? If it is 'not in 4wd with the centre diff unlocked' like the video clams. The hill is a 1 in 4 btw. Hence why conventional cars get stuck on the mud when it rains.

[@qldsalty2969]

So on a 100 series Landcruiser do I push the button displayed as >>> front wheels turned right and a center diff and and two rear wheels straight. I thought it was always in 4x4. Totally unaware of this point to lock it.

[@4xoverland]

I think you are talking about the rear axle diff lock switch. Which does an entirely different job to a centre differential. It can be confusing. What I am talking about here is the transmission between the FRONT and REAR, not left and right. if the centre differential is an open type (not a viscous coupling type) If your vehicle is 'permanent four-wheel drive', and has an open centre diff, it will behave exactly like this Defender in this video. The Defender has a full-time, permanent four wheel drive transmission. And yet, one wheel lifts and the vehicle stops. Its the same with any open centre differential layout no matter what vehicle its fitted to. I do not know your specific vehicle and what kind of centre transmission it has. The locking of axle diff locks is a different subject entirely.

[@sniperotto]

I only engage 4x4 when i need it, i do however lock the front hubs if i may need 4x4 so i can just throw in 4x4 if it's needed. In the winter, if i drive with 4x4 my car understeers like crazy. something i hate, much rather oversteer as it is easier to control. So in the summer i drive in 2x4 and the hubs in free to save fuel adn in the winter the hubs are locked and still 2x4. The vehicle is a Y60 Nissan Patrol on a 2 inch lift and 33x12.5 r15 Cooper Discoverer STT tires

[@janhlacer1645]

I have the same problems with my Y61 in winter, but it can be cured with a proper amount of throtle. The car understeers because the front wheels want to travel the same distance as back wheels and because of that they start to slip when cornering. If you accelerate in the corner you thurn this around and the back wheels start to slip and you get oversteer which easier to control. It takes a little geting used to, but it works:D

[@travancorepistons7309]

2.47 pajero .. Mitsubishi Fan 💕💕❤️❤️❤️

[@ktkl68]

I have a 4Runner. In snowy conditions, you’re saying it is safe to drive with High 4 Locked than just full time 4WD with open locks? I would have assumed the latter to be safer because I will have the assistance of Traction Control...unless I do have the traction control even with center locked?

[@PatrickRich]

Its the same for me in my 80 series. I lose ABS if I lock the center diff so in the snow I leave it open. Plus I've found that the vehicle pushes a lot more in the snow locked vs unlocked where it can be coaxed to rotate a little with the throttle.

[@jordanparker882]

awesome video thanks. Wish we could get the defenders like that here in the US without paying $$$$.

[@gelandewagen4394]

super SUV that will give odds to anyone and new models will give your shit and like for a super legendary car

[@HITARENA2]

There is a speed limit for driving with centre differential? thank you.

[@Kiddomike]

I both drive a full-time 4-wheel drive (Land Cruiser 200) and a part-time 4-wheel drive (FJ Cruiser). Is it okay to engage center differential lock or engage 4-Hi range on tarmac on a heavy rains at 60 to 80 KPH? I'm just worried I might twist the drive shaft.

[@dartmoordave]

Read my other comments about what is true 4wd. You can engage the centre diff lock at any reasonable speed as long as all wheels are going the same speed, ie in a straight line. Problems regarding vehicle control differ between types. Cornering with the centre locked may induce steering control problems. Best to read the road ahead, as all off roaders should do, then select what you need. Engaging the diff lock in heavy rain is not an option to just slowing down in adverse conditions, if it all goes wrong, the slower the better.

[@worldhello1234]

"Read my other comments about what is true 4wd." It is garbage, traction control does not constitute 4wd.

[@PatrickRich]

I realize this is an old comment, but just leave the 200 in unlocked mode (its got a torsen center that will do plenty to move the power around). As for the FJC...thats up to you. I say no unless its raining so hard the water is pooling on the road. Most 4hi systems can be engaged on the fly at freeway speeds so you can go from 2hi to 4hi and back on the fly as needed.

[@noregomez]

Hello I’ve a couple questions. First. Can you still turn with the centre diff lock? My own answer would be yes, because the front axels are still free and are able to turn at different speeds. Is that right? Second. What is the specific problem that suggest you to open the centre difflock on the road? I do it but I don’t know what would happen if I don’t.

[@PatrickRich]

The short answer is that when your center is locked you are the same as part time 4wd in which case you SHOULD NOT attempt sharp turns on high traction surfaces. The sum of the distances traveled by the front wheels (left distance + right distance) and the sum of the rear wheels in a corner are different and there will be a "scrub" in the front wheels as it tries to make up the difference...essentially the back wheels pushing the fronts against the drivetrain. No biggie on loose surfaces, but you'll hurt your ears, tires and (hopefully not) your vehicle trying to do a sharp turn with the center locked. 2nd question should be answered by the first answer. 4locked is dangerous on high traction surfaces.

[@Mickey_Bauer]

Oh crap, this guy almost looks like Andrew =)

[@arefeshghi]

What about Landcruiser Prado which is not a full-time 4WD, but has 4WD option and centeral diff lock? Should we just use the 4H or 4H+center diff lock? In other words, what is the difference of putting the car in 4WD vs locking the center diff in Prado and similar cars? Is the diff lock a separate option or complementary option to 4WD which forces 50-50 power distribution?

[@4xoverland]

Prado is full-time 4WD. By virtue of its centre differential, means that it is. Far too much to explain in a comment here. But this is what I have written about it: 4xoverland.com/how-do-4x4s-work/4x4-operations/

[@arefeshghi]

Thank you for your reply. I was wrong. I read some articles plus the one you mentioned above. But still it is ambiguous to me why Prado which is a full-time 4WD has 4H? Shouldn't it just have 4L?

[@4xoverland]

Full time 4WD means that it can be driven in H4 AND L4. That is why there is a diff in the centre, that is driven unlocked in H4 on road, and then be locked in 4L when off the road.

[@davidallen857]

Are there not 2 other issues on this? If diff lock is applied all 4 wheels turn at the same time so on a sharp bend there is the potential to lose traction due to the inner wheel moving as the same speed as the outer wheel? with all aids being used if you get stuck you would not be able to extract the vehicle. The common sense of driving to the road conditions would remove all need for using these? if you require that then your going to fast for your ability or road conditions in my personal opinion.

[@braydenballantyne9309]

This is not the rear and front axle differentials locked, this is just the centre one. This added safety is not for bad drivers it is for emergency situations when you need to quickly change directions or avoid an obstacle. You may not cause the hazard it may be someone else however having the centre differential locked on a gravel road greatly improves the handling and responsiveness of the vehicle.

[@gmoose777]

since the front diff on land rovers is open the wheel speed differential does not change when you lock the centre differential, in fact if you wish your vehicle with a center differential to last you should engage center diff lock every time you leave the tarmac, it's design is not to accommodate the wild differences in axle speed encountered in low traction driving but to balance the minor differences in axle speeds in normal road use

[@desertpair2]

P.S. Have you done an extensive test of Jeep Grand Cherokee's Quadra-Drive vs Quadra-Trac? Are both of these systems equipped with a center diff? What if you have both systems?

[@denisealvarado447]

I have land rover2003 seems my 4wd stick is stuck in 4wd other then that awesome crawls right up any mountain

[@gmoose777]

That is correct the 2003 is "permanent 4wd you can select hi or low range, and depending on which variant of rover you may or maynot have centre diff lock, between 2001 and 2004 landrover subscribed to the ridiculous notion that traction control could replace a centre diff lock, by 2004 they came to their senses

[@bradley5819]

I was amazed land rovers had the center diff how about the first land rovers?

[@gmoose777]

centre diff and lock became available I believe in 1971 at least here in Australia with the classic rangerover. series landrovers were not equipped with centre diff.

[@dartmoordave]

True 4wd has some sort of axle lock mechanism. I've had 5 LR's and the centre diff is only there to lock the drive shafts to the axles at the same speed. He still thinks 4wd is there, its not. If you jack up both wheels on the same side, even with the centre diff locked, it won't move. Most 4wd's are actually 2wd, the centre diff makes no difference, other than ensuring both axles receive the same drive. Its only a traction control on both axles that will make a true 4x4. Its just an advertising gimmick that we all take as read that its a 4x4.

[@sugarnads]

Use your brake pedal. AMAZING. Instant on demand diff locks. True 4wd at the touch of a button so to speak.

[@jackfairman7371]

The idea to engage centre dif due to a gravel road alone is somewhat crazy, all tires will have approximately the same grip unless its rutted to high hell, which then you should be driving slower anyways. If for any reason you'd expect loss of traction under normal driving circumstances such as wheelspin due to rain and the road being muddy then yes engage centre dif. The idea of using centre dif on a gravel road is overkill in my opinion, and should be avoided unless normal driving conditions would prove genuinely treacherous/dangerous, as stated if wheelspin is anywhat likely under normal driving conditions.

[@4xoverland]

40 years driving overland and over 1 million kms on gravel roads and I disagree utterly. 4wd on gravel is like putting on a seatbelt. You only need it when you need it, but when you need it, you REALLY NEED it. Its safety advantages cannot be over-stressed.

[@jackfairman7371]

@@4xoverland I didn't state 4WD, I said CDL. I agree running 4WD. Does the Nissan shown have CDL also? It would also be interesting to see the difference as per the video but with 4WD and 4WD with CDL engaged. Which Nissan and model are shown?

[@4xoverland]

Here then is the common misunderstanding. A unlocked centre diff is not four-wheel drive. A single wheel lifts, and it will spin out and motion lost. Which means, at speed, one wheel spins out and all drive is lost to the other wheels. Iv'e done experiments and i can tell you, locking the centre diff is a huge safety advantage on gravel roads, even with so called, 'full-time' 4wd transmissions. Its better than 2wd, that is true. But true 4wd is far better still. I have filmed the tests. And I've witness full-time 4wd accidents caused by control loss which I know for surety that had the driver locked up the centre transmission, the accident and in more than one case, death, would not have occurred.

[@Nick-pk3tl]

I'm not convinced by this video.. we had a land cruiser that was always on dirt roads and suffered diff lock up.. the transmission blew up. This video basically says the second your off road you engage 4wd..

[@Human712]

Great 👍🏾

[@dixy2k]

thanks

[@OverlandWay]

While this video is helpful to explain what a centre diff lock does, it's incoherent. If an open centre diff 4WD is not a true 4WD, the only true 4WD is a car with all 3 diffs locked and therefore drive to all 4 wheel as all time.

[@heiligerjesus1960]

therefore - we invented the g wagon :)

[@mikeb53]

If the transmission sends power out to all four wheels, instead of two, then it is four/all wheel drive regardless of differentials. To say otherwise would be like saying your standard road car is only one wheel drive. Clearly it isn't. Locking the center differential doubles the traction, as both axles are forced to rotate at the same speeds now to that end, the intention is to drive all four wheels at the same speed. As Andrew states, "True 4WD".

[@samc12345]

Greeting The World so in terms of the land rover with the diff unlocked, if all 4 wheels have the same traction, they will all have power at the same time?

[@mikeb53]

The three differentials enable all four wheels to be driven and accommodates the rotational requirements of the wheels, some will need more rotation than others. Open differentials follow the path of least resistance, this is essential for normal road driving. If you were to jack up a Land Rover like the one in this video, with all four wheels off the ground and start the engine and put it in gear, all four wheels would turn, regardless of whether the diffs were open or locked. But when steering, or normal driving, the power requirements of each wheel will change, hence, you will need to be able to adjust power to each wheel, just as in a 2WD regular car. This basically all a differential does.

[@samc12345]

Mike B hi Mike thanks the the explanation. I am aware of the concept of open diffs and path of least resistance. My question is: land rover, all diffs unlocked, all wheels on the same ground in a straight line (I.e, all have the same resistance) on a even tarmac road for example, wouldn't all 4 wheels have power being applied to the road?

[@heiligerjesus1960]

so a permanent 4wd doesnt do anything? basically

[@dartmoordave]

There is no such thing as permanent 4wd unless its got axle locks or traction control. Centre diff lock makes little or no difference to axle traction.

[@PatrickRich]

no it can be very helpful even unlocked, it balances the drive force (and under deceleration). Most permanent systems have LSD's in the center diff as well so they wont be as extreme as the defender example. Toyota, for example, started putting torsens in the center diff and they are very effective in the open condition. Frankly I think its safer with a Torsen center equipped vehicle in the unlocked state on most roads compared to locked. The 50/50 speed split of locked can create heavy steering, lots of front end push and can greatly upset the chassis if the traction changes mid corner.

[@gmoose777]

@@dartmoordave traction control has no bearing on a vehicle being 4wd neither do locking diffs front and rear, 4wd simply refers to drive being available to 4 wheels in certain specific conditions. traction control is purely use of braking to fool open differentials into behaving differently from their design

[@kg0173]

A safety tool first

[@4xoverland]

This explains everything: 4xforum.com/transmissions

[@allgood6760]

4x4xfar! 👍

[@charterlau]

1:16

[@Goodsxp]

This does not apply to the Hummer H3 that I drive. My Hummer is in 4x4 drive all of the time.

[@4xoverland]

I am pleased you commented. However, this video was made for people who drive Defenders, Land Cruiser 105s, Hummer H3 etc, Fortuner etc. It's exactly what I am trying to explain. Permanent four-wheel drive, as in the H3, is NOT what it seems. As far as I know, the Hummer H3 has an open, lockable centre differential. You think you are in four-wheel drive all of the time, when in fact you are not. That's the problem. Don't be fooled by the words 'Permanent four-wheel drive'. Lift a single wheel of an H3 and it will spin. Some centre differentials have viscous coupling devises. This is then the proper use of the phrase 'Permanent four-wheel drive', because both front and back axles are powered, even if one wheel lifts. This then is 'always in four-wheel drive'.

[@Dake21]

I wish the did the test with permanent 4 wheel drive.

[@4xoverland]

David Cazes This Land Rover has permanent four-wheel drive. That is why it has the need of a centre differential.

[@Dake21]

4xOverland I was refering to the test with the Nissan truck at the end of the video. My apologies for not being clear.

[@dartmoordave]

Sorry, wrong!! The LR has no axle locks in standard form. Later models have traction control but still have open diffs on both ends.

[@Dake21]

Dartmoor Dave Who said anything about axle lock?

[@dartmoordave]

Sorry Dave, the comment ended up in the wrong place.

[@boikanyoonneng9170]

The overated landcruiser is an example of this

[@ЕгорЕгоров-з2г]

А теперь по русски, а то я ни хера не понял.