The Centre Diff On Hills Problem: Grenadier vs Patrol vs LC300 vs Defender - Part 6

#grenadier #patrol #defender #lc300 #centrediff #cdl
Why is it important to lock your centre diff offroad and especially on hills? Explained in this video. Some modern vehicles such as Defenders in this example have 'smart' centre diffs or clutches which vary the front/rear lock. This is done to improve performance, eliminate transmission windup or bind, and make the vehicle easier to use, but if not implemented correctly can lead to the lock unlocking when you don't want it. We noticed this with the Defender on test, and show some ways to drive around the problem.
Some L663s Defenders have CTR, or Configurable Terrain Response which can force a centre lock and that seems to really force it on most of the time, but as it's software controlled you can never be sure what the computers will do. Other L663s don't have this option and nor does any other Land Rover.
More and more 4x4 companies are moving to smart centres, and I hope they all pay attention to this problem and address it. Ford didn't on the Gen 1 Everest, but fixed it on the Gen 2 as an example.
Some vehicles have centre diffs, others clutches, others a combination. Functionally they all do the same thing; allow 'drive' to be sent to both front and rear axles which can turn at different speeds to allowing cornering.
Windup Explained (reason for centre diffs)
• Transmission Windup Ex...
Ford Everest issues
• How (not) to park a 4x...
Part 1 Intro, suspension, climbs • 4X4 Tourers Offroad: G...
Part 2 Slow Race; crawl ratios, descents • Grenadier vs Patrol vs...
Part 3 Slippery Climb • Grenadier, Defender, P...
Part 4 Clearance Climb • Grenadier vs Patrol vs...
Part 5 Momentum • Grenadier vs Patrol vs...
Part 6 The C/D Problem on Hills • The Centre Diff On Hil...
Part 7 Lockers vs BTC • 4X4 Tourers Offroad: G...
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[@NSBCruiser]

I have a 2022 Defender 110 with the locking center and rear differential. I have run into this issue while on the trail here in the USA. I overcame this by using Hill Decent Control wile in Reverse. I did a full day private driving lesson at my local Land Rover Experience center. They specifically taught me this technique for this exact issue. New tech for off roading…definitely a learning curve vs the old school off roading driving techniques.

[@paulelledge8977]

Yep, but the plus side to the defender system is it's always on nature when just driving in, say, icy or slushy situations. You don't have to put it in 4H or anything, it always just does great.

[@atoieno]

I have a new Defender and previously a "classic" Defender. Old school offers much more opportunity for driver error between the binary choices of high and low range, CDL locked and unlocked than the much unfairly maligned new tech in the new one. As you say getting to know the new ways is an interesting challenge: man and machine,

[@atoieno]

@@paulelledge8977 Ice and slush are not a hazard where I drive but here outback roads vary over small distances between firm-packed dry clay, gravel, very soft bull dust and sometimes wet clay. Misreading the conditions can result in disappointing outcomes. The new Defender takes out some of the guesswork.

[@hedydd2]

Reverse up hill puts extra weight and bite on the axle with the most traction. A front wheel drive car will have amazing traction reversing up a slippery hill with the limiting factor usually being the high gearing and inadequate engine torque rather than loss of traction.

[@bogo1992]

Appreciate your analytical breakdown competing 4wd models.

[@jameshoward9700]

Very good Robert. The 'backwards toboggan' is one of the more alarming scenarios off road! One method I've used to counteract this, especially on wet mud/snow, is judicious application of the parking brake which gives you controllable rear wheel (now front) bite, leaving the front wheels (now rear) to steer. Of course, the widespread adoption of E parking brakes makes this impossible - a real safety flaw. This is one reason I went Grenadier (proper handbrake) - potential failed climbs (especially with trailers) is so risky in wet /snow conditions. This is a serious problem for Defender though - it's carried over from Disco 5 (no surprise) and is a sign the engineers prioritised road braking over off road. I'd say that's an acceptable decision on Disco, not so Defender.

[@L2SFBC]

I wouldn't even say it's acceptable on Discovery! Yes that technique can work but it shouldn't be necessary. As I said in the video...yet to see any clever centre improve on a lock, and nobody has ever said I'm not pro-tech.

[@defender1323]

I have the original defender where manual cdl and manual everything gives you far greater control and not relying on technology to do that as long as you are experienced. I am an Electronics Engineer and yes electronics can make our life easier but you need to draw the line in many situations where it can in fact introduce safety and reliability issues. The new defender as we all know is built on the range rover and discovery platform and the amount of automation make so much easier for novices to drive offroad without having any experiences but as we see it has its limitations and introduces safety concerns.

[@dickinaroundoutdoors8609]

The use of these models is genius Robert, so helpful in your explanation. Super job.

[@L2SFBC]

Glad it was helpful!

[@jamesdavidsmith4033]

Really easily understood explanation. Great job 👍 I wish my 2G Sequoia and Tundra were available to you for testing.

[@petermenzies1714]

A potentially complex to describe and understand issue broken down to it's fundamentals, illustrated clearly off road and with the help your great model to make us all able to understand the problem and solution. thanks.

[@HardstylePete]

Nothing can replace a mechanical 4wd engagement selector. Either mechanical locking the centre diff or part time to full time 4wd engagement.

[@user-tz9of6nw8g]

Great use of models and, as usually is the case, excellent teaching. There are no software replacements for knowing how one’s machine works. I would rather make a bone headed mistake myself than have the computer make the mistake for me. My Golf R periodically, on the highway at 70 mph, decides to slam on the brakes because the computer thinks there is an obstacle in our path… there is usually an inappropriate word from me that follows… Thank you for your efforts in helping us to understand our machines.

[@L2SFBC]

My pleasure and yes agreed - it's not knowing how the software reacts is the problem.

[@markrigby9588]

In the UK we need to be aware of this is there's the possibility of a failed hill climes in Snow and Ice on narrow streets. As the front could swing hitting walls and parked cars.

[@L2SFBC]

yes and not just with 4WDs. A 2WD car will behave the same way on a hill when you hit the brakes.

[@jerrymyahzcat]

*climbs

[@BorisEkner]

About brake bias … Sometimes, when off-roading downhill, it can be beneficial to pull the handbrake up 2-4 notches. I.e., to move the brake bias a little bit to the rear securing steering in the front while under braking.

[@nigelsim18]

Great video seeing the different systems side by side.

[@L2SFBC]

Glad you liked it!

[@andrewhurstcars]

Hi Robert, interesting - but you can actually manually lock the Defender diff-locks if you option the Advanced Off-Road Pack, which has Configurable Terrain Response. Edit: at end of video.

[@carlbeveridge384]

Correct and this point seems to be always overlooked but It was mentioned in the video.

[@L2SFBC]

Yes I did cover CTR.

[@LetsGo-wf1dy]

Why did you not locked the center diff of the Defender just like what you did to the other vehicles? The Defender has the auto setting for the car to instantly lock & unlock the center diff but it also has the option for you to manually configure to lock or unlock the center diff and also even the rear diff. Does this vehicle have this pack?

[@peopleschamp7258]

​@LetsGo-wf1dy because you can't lock the center diff unless you have the advance offroad package. All the other vehicles come with locking center diffs. His example is showing what a normal situation for most set ups.

[@LetsGo-wf1dy]

Then a degree of validation in practice for the cause/solution for the C/D diff problem would be to have these particular vehicles C/D unlocked and locked to compare the results if they would have the same problem as the unlocked defender. To see if they did better or worse. Observing the problem from the vehicle and solved by the same vehicle by applying a solution ( c/d locking) would have been nice.

[@GavinEarnshaw]

Mate, these are great videos. As a BORDA off-road trainer this side slip is one of the main reasons we teach no braking on slippery hills. Training is primarily for professional users doing a job. Realistically we would suggest a driver walk this first, understand what is likely to happen and then decide what to do. In this set of hills probably not today (water, surface, slope, cross-axle and trees). The fact that none made it back up i.e. going home. Recreational off road is different.

[@L2SFBC]

Thanks, and agreed - you want to reserve all your traction for lateral grip as sideways = problems, and braking just use grip for braking not sideways. More here kzbin.info/www/bejne/mouWZH6AZsiflcU

[@rhetth-s8082]

I sometimes or often rather brake to avoid generating momentum and sliding off the track. If tyre pressures were lowered to say 12psi this track might have been okay to drive.

[@L2SFBC]

Yes, 12pis may have worked but we were there to test the cars, not get over the hill.

[@cyclemoto8744]

Thank you Robert. Cheers

[@mikeattheimagebusiness6215]

Excellent video Robert and it’s good to see the debate in the comments. The electronic systems are clearly confusing for many people and the lack of straightforward mechanical control takes away the confidence afforded by such. I’m looking forward to you trying out the full TR system, HDC and CTR in various situations the future, should be fascinating. Cheers, Mike😊

[@L2SFBC]

Thanks Mike, coming soon-ish, and yes the discussion is nice and constructive (so far!)

[@mokhtarsairi4714]

Hi Robert, is there anyway I can get a hold of the 4 wheel drive RC model car. Please send me the necessary information to buy it, thanks

[@pammotorsport9743]

Hi Robert, I had a TD5 Discovery 2. 2001 model with no centre diff lock. It tried to kill me twice with this issue on two difficult climbs. Another issue that car had was the traction control cutting out or just failing leaving you with just one wheel drive. I loved the car when it worked. In the end the oil leaks got the better of it.

[@L2SFBC]

That's why Land Rover put the centre lock back. Dead customers aren't good for business.

[@jasonwishart6800]

Impressive. You’ve made buying Lego a tax deduction. Nice.

[@user-wx2el5jy2t]

Very interisting video and goog explication !

[@L2SFBC]

Glad you liked it!

[@mrphillipthomas]

I've just modified my old 4x4 which has a Borg and Warner TOD (Torque on demand) transfer case. One of the issues it has is unlocking the centre diff (if you even want to call it a dif) as soon as you take your foot off the gas.. making hill decent and braking in 4wd a nightmare. I've modified it to add a dummy load to the clutch coil effectively locking it in place at the flick of a button which is super useful when pulling the boat out of the water and trying to get traction on seaweed. Usually the back wheels would spin first, then the transfer case would pick up on the spin and add torque to the front wheels.. but by that stage you've already started to dig a hole and bog down at the back, so locking the centre helps a lot. Poor man's answer to a locking center dif I suppose! Oh and I never even considered breaking force while the centre dif is locked! Bloody legend

[@L2SFBC]

Great mod and thank you!

[@overlandready]

A lot of vehicles now only use caliper piston size to atain a greater brake force to the front axle. For example, the D2 (and also my '97 Defender300tdi 110 commercial) there is no bias valves, it's all done in equal pressure to the calipers and the piston size distributes the force. Here is the absolutes: At low speed, brake force is fairly even (especially at the speeds you're showing), the force needed to lock a brake is minimal, in fact virtually mothing on mud like you have shown. The ABS also regulates bias on brakes as when a wheel locks up (usually opperational over 5mph/8kmh) then the electronics reduces pressure to that wheel - hense the lack of need for a bias valve. Lets consider braking from 100mph, it as you describes requires a lot more force to stop the wheel rotating, to the point not many brake systems will actually be able to lock the brakes at all at that speed, so speed is relitive to the force needed to lock a brake. The problem I see is no one actually knows the force applied to the brake pedal and thus the wheels, the Freelander 3/Defender driver could have been applying more force, thus the wheels will lock, the fronts will unlock later for the reasons you have said, but that means there is not enough traction to overcome the brake force applied. Generally it is what it is. I did have a look to see if the L663 was viscous or manual locking or clutch pack, I couldn't really find out a lot about it but seems you can have either a "manual" proper lockeing diff or a viscous/clutch locking diff - this obviously makes a difference to how the vehicle distributes the forces from the drive or the brakes. HDC will, I would have thought engage the clutch pack in the centre diff if it has one and HDC off won't (why use something that's not needed!). The question would be; would it be considered driver or machine error for not applying the centre diff/HDC? Does the Freelander 3/Defender know what angle it is on? I doubt it. But it could be handy for the braking system and transmission to know as it can then act accordingly and aadding drive also works to sort out the drivelinepply HDC or varied brake force without it needed to be manually selected. All the vehicles suffer loss of traction due to higher than necessary brake force, it's life. ps, it's not understeer, it's skidding! the wheels were locked. That is 100% skidding, you can't blame steering and suspension geometry for that. All vehicles skidded down the hill as they suffered loss of traction, even the gren, it just had it on the rear axle. Adding drive can also stop skidding on hills, but suggested to be a more expert method. as it gets all wheels moving at the same speed and thus gives ability for traction. HDC only opperates at a set speed so it's design is to slow you to a specific speed, under that you can still use the brakes or not as you like, even if you are on the brakes the HDC on some vehicles still activahes the brakes more to slow the vehicle. I tried this yesterday in a Freelander 2. When I get some time I will make set of lego models to show you what understeer and oversteer actually is, it's characteristics of the design, all else is skidding.

[@hedydd2]

Top models of Ford Ranger and VW Amarok have smart centre diffs with the option for both locking the centre diff or disconnecting the front prop to give rear drive only. Yes these can be driven in 4wd on the road using the smart diff function called 4A on the Ford. These are very similar to Mitsubishi’s well established ‘Super-Select] 4wd system. They also have rear axle diff lock available on Tremor and above. Downhill brake assist? Yes. On Wildtrak X models they even have Trail Steering assist, which is a form of independent rear brakes, like a farm tractor, to assist tight turns on a trail.

[@L2SFBC]

Indeed...Toyota and GWM have had the rear skid-steer for a while, and you're right it's similar to Super Select.

[@No-thing-ness]

Well done mate another great one

[@L2SFBC]

Thanks 👍please share

[@robinhodgson7629]

Great video, while my D3's are all very capable vehicles my fun car is a 3 door D1 with only a CDL, it's a lot more stable and responsive on wet, slippery slopes. As you say a manual CDL gives you more control over the electronics. Weight of vehicle and the line also comes in to play in my case.

[@nirfz]

14:55 Itnerestingly i even encountered exactely that "Defender Problem" at home on a flat paved piece in front of my carport with a normal rwd, automatic vehicle: the ground was still frozen (winter) but the air had been above freezing and it had rained. So the rain hit the cold ground and immediately froze. The surface was a slippery as it could get. I tried to go back in a 90° turn to get the car under the roof, and there was no chance. I couldn't lift off the brake enough to unlock the front wheels (especially when turning the steering wheel) while the rear wheels were already providing movement for the car. Thankfully my car is old enough to have a mechanical parking brake and that's what i did. Applied it two notches and was easily able to lift off the brake enough so the front wheels were turning and were able to provide steering input.

[@L2SFBC]

that's it, add braking to the rear in this case. Not possible with L663 Defenders.

[@mas921]

super valuable! i know of at least one total loss due to a stopped 4x4 sliding off the cliff.

[@300bhpton]

Another good video. The centre locking diff or just a traditional 4wd setup like in an old Jeep or Series Land Rover can do wonders for stopping distances in the snow too. For the exact same reason of brake bias. As for HDC, by brother was setting up a trials event on a wet grassy hill earlier in the year in a Freelander 1 and with someone who had a new Defender. When the grass was wet early in the morning, neither vehicles HDC could cope and induced sliding, while just using engine braking provided more control and slower descents, even despite the Freelander not having a low range. Also to add to your point 3 about varying brake pressure. The next step is to actually accelerate (gently) down a slippery slope rather than brake. It feels counter intuitive, but can reduce or remove lockup and skidding giving you steering control. We sometimes set up sections at trials events where you need to do this in order to avoid hitting a cane/gate. Obviously it needs to be safe to do so in terms of space and run off and it shouldn't be lots of power, just enough to rotate the wheels a little faster to stop a slide.

[@L2SFBC]

A good point. In Part 2 of this series I show the effect of accelerating downhill, although I would prefer to say "reduce brake pressure" first. Experience can guide. As for braking, yes - in another video I show an LC80 braking on dirt with and without CD locked, and without there is unused braking grip at the rear. Modern vehicles have EBD (electronic brake distribution) so in theory shouldn't benefit...but I am yet to test this theory.

[@tyeetamer]

@@L2SFBCDo you know which video shows the LC80 braking w/ diff locked/unlocked?

[@L2SFBC]

kzbin.info/www/bejne/eJiunHxmgdljidk

[@ronaldrrootiii6040]

Yeah exactly why not just to make them not all wheel drive and just have selectable four-wheel drive. I feel like 90% of the time people who buy these don't actually need to be going down the street with their front drive shaft receiving power to the front differential it's just extra wear and tear. Plus if you watch a Jeep Rubicon Wrangler in two-wheel drive the rear articulation and the rear Locker will get it through all of this stuff without even going into four-wheel drive. But it seems like a lot of these non-american SUVs obsessed with being all-wheel drive . I wish the jeep was made more high-quality luckily we have the full size Bronco which is absolutely mind-blowing good off-road still has Towing still has ifs in the front with long travel and solid axle in the rear. Probably the most all around vehicle ever made. Yeah the Toyota is great but it doesn't have Factory 35 or as much travel, the defender raises Wheels constantly and has air suspension and lacks articulation and really top heavy. The Jeep is absolutely stunning but doesn't tow as much which apparently Towing over 3,000 lb off-road is important to some people's brain and the reliability of the Jeep is better than Land Rover but not quite the Ford Bronco or even the Toyota of course. My dad is purchasing a Sasquatch Edition Bronco and the more I learn about it I'm just blown away by how awesome it is and kind of how versatile it is in between the straight up hardcore Jeep abilities and the street Comfort IFS world Land Cruiser world. You should watch that big Bronco Beast go around tight switchbacks with the steer assist that locks up the rear inner wheel of the direction you're turning and literally makes you slowly skid avoiding go forward reverse multiple times to make a tight turn for its overall size

[@Ks-zz9lh]

excellent video! Many thanks.

[@L2SFBC]

You are welcome!

[@drmarkintexas-400]

Thank you for sharing 🏆😎💙🙏

[@rhetth-s8082]

Really good video! I noticed this exact problem in my Amarok but didn't fully twig why. The irony is they say special braking due to a steering angle sensor and ESP will keep you on course, but in practice it is not as good as a lockable centre diff. Many manufacturers should be ashamed of themselves for pursuing different ways of doing things that are overall inferior. Research and development is supposed to weed out bad ideas.

[@L2SFBC]

How did you notice it in the 'Rok? I noticed it when doing the downhill test you saw with Discovery, Prado and Everest. Same problem, unlocked at rest.

[@rhetth-s8082]

@@L2SFBC I noticed it numerous times. First example, i was reversing and trying to turn but it wouldn't turn. If i had been able to turn i could have tried another line forward or reversed out, but because i couldn't turn i ended up needing to be towed out in reverse. Another example was forwards. The track had a section with poor grading, there was clay on the track and inadequate lip at the edge of the track. It was a slight downhill gradient, narrow track, big dropoff. I was originally driving down at slow speed under constant mild braking (no low range!) and the nose started heading off the track. I reversed back. If i had driven down under power i might have been alright, but i didn't want to take the risk. So i tried inching down . But primarily due to front brake bias and unlocked centre diff the nose just kept sliding towards the dropoff. I parked and walked down the hill to my bogged mate. Helped him out, and he then drove up the hill through that section with no issue.

[@L2SFBC]

Thanks! Yes that's exactly what I'm talking about. Takes a fine eye to notice it and understand why, as sometimes it's masked by driver behaviour, but once you know about it, then you see it quite often.

[@off-roadingexplained8417]

Yeah you make a really good point. Never thought about the braking aspect of center lock. I'll be sure to use descent control in reverse on my vehicle because of this.

[@L2SFBC]

What vehicle do you have?

[@off-roadingexplained8417]

@@L2SFBC Jeep Cherokee Trailhawk. The only thing I can think of that might beat it all the way around (ride and off road capability ) would be a defender to be honest. Maybe Grand Cherokee Trailhawk. What else ? Not many vehicles have a rear locker , crawl control, descent control, terrain modes and a legit low range. Mine is 56:1 with the 2.4 engine . They're stopping production of it and there aren't really any alternatives except for the defender. So maybe the next one I'll get will be the defender. We'll see.

[@off-roadingexplained8417]

​@@L2SFBCdo you know if engine braking engages the center clutch ?

[@L2SFBC]

Can't say as it may disconnect if the engine isn't providing any torque to allow brake force distribution to work. Yet another "only the software knows" thing.

[@NigelNaughton]

Wow!! Super informative. Thanks for this.

[@L2SFBC]

Thanks please share!

[@NigelNaughton]

@@L2SFBC Definitely I will. Makes me feel fortunate to have a 1997 80 series with 3x lockers. 😁

[@mdharrisuiuc]

This is interesting; I've tended to leave the CDL disengaged on vehicles because I want the tighter turning radius. I did not know that having the CDL engaged helps to prevent side-slip on off-camber hills. Have definitely encountered situations where I needed to release the brake by some amount in order to get steering control back. It is counter-intuitive and takes some mental effort to not only remember to do it, but to trust the tires to start gripping by letting off brake pressure.

[@L2SFBC]

If you need to unlock the CD to turn then do so, but then re-lock. However you may as well do a three-point turn. If you keep it locked probably less need to reduce brake pressure.

[@andrewhurstcars]

Robert check out the latest All4Adventure video where they manage to roll a large Chevrolet Ute 4x4 going down a very slippery mud trail on the Crebb track, with all 4 wheels locked up. Perhaps you could do a video on this to explain how this could have been avoided? In that case they probably needed a set of chains, or a long winch down. However, I think the roll could have been avoided if the driver had either not touched the brake pedal, or released it just before the slide into the bank to momentarily regain lateral grip.

[@L2SFBC]

I'll leave A4A to their own devices. If you like react videos @madmatt4WD does a few.

[@AussieDazza]

Grrat video Robert. Thank you

[@L2SFBC]

Glad you enjoyed it please share!

[@ericdavisoz]

Thanks for this excellent series Robert. I have just had an Ashcroft ATB centre diff fitted to my Puma Defender 110. As I understand it, this gives a degree of limited slip between front and rear when the diff is unlocked but when I lock the diff will there be any difference in operation to a locked standard centre diff? Thanks again.

[@GavinEarnshaw]

As I understand it the Ashcroft centre at replaces the diff centre so you can still lock it up as before.

[@L2SFBC]

I have covered torque-biasing diffs here kzbin.info/www/bejne/roi1l4OreMyrnsk

[@Brandon_Rivera]

Super informative video. I have a 22 Defender 90 and never have this issue but good to know if I experience it. Up to this point it turns just fine in slippery conditions up and downhill. My center diff locks up almost instantly in auto mode or I just lock it myself on the terrain response 2 screen.

[@L2SFBC]

Great, now you know! Need to test CTR...stay tuned!

[@mebenderjnr5055]

Great video Robert, thank you. Can you tell me what Lego model 4WD that is you're using please?

[@L2SFBC]

It's a custom build I made myself out of a variety of parts, mostly Unimog I think. Thinking of getting the Audi desert racer next and customising that!

[@rhetth-s8082]

@@L2SFBC i made one like that as a kid but with solid axles and suspension. It was pushing the limits of the components available at the time. In particular i didn't have a slip joint for the propshaft and tailshaft which was a major problem.

[@jerrymyahzcat]

Defender could have tried HDC reversing back down the slope… Pretty sure a modern 4WD like a new LR would change the brake bias on a slope and also the braking would be quite differently programmed when in low range and/or off-road modes. These vehicles have yaw sensors, pitch sensors and roll sensors so it will know when it’s on a slope. Maybe it needed to be in grass/gravel/snow mode (low traction) when reversing/braking down the muddy slippery slope.

[@L2SFBC]

If it did lock the c/d in grass/gravel/snow, and I doubt it, then that's a fail. You should be able to select Mud/Ruts for a climb that is well...muddy and rutted...and then the car should lock its c/d as required. I consider the Defender not doing that, and all other similarly engineered vehicles, to be a failure of design bordering on negligent and indicative of lack of experience in real-world offroad conditions. I covered the reasons why HDC isn't a complete solution in the video; for reference, consider a hill you can barely hold the car on with muddy rockledges that you need to steer backwards around. Now add rain and subtract daylight. Still keen on letting go of the brakes and coming down even at 1km/h?

[@nawaphansayugala3752]

Another great video! Would you please test the Low Traction Launch function on the Defender in this kind of slippery terrain? I’m wondering if the computer would help solving the situation at all. Cheers

[@L2SFBC]

It wouldn't help to any great degree.

[@GavinEarnshaw]

The issue is that the car unlocks the diffs really early and seems to do it every time the car stops forward motion. So it is out of difflock when you need it in as Robert shows. The 110 new Def I had at our training site last year did this all the damn time. No matter what. We couldn't get it to stay in even with adv config mode.

[@L2SFBC]

Not even with CTR lock?

[@paulelledge8977]

What year is the defender in the test? Apparently in 2023 they changed the drive system. Per Sarek Autowerk: "Yes, it looks to be accross the entire range. The D300 (diesel non US) seems to have had the permanent rear wheel drive system since the beginning of production. The rest have all had the center differential until 23.5 The center differential system which is in all of the US production vehicles until model year 23 (p400) and 23.5 ( p300, p400 ) is set up like this. Power comes from the transmission and enters the transfer case. There it goes into a differential that can be variably locked by the traction control system. So for example, when no locking is applied, the differential puts power 50/50 to the front and rear driveshafts as long as there is no slippage or loss of traction just like any open front or rear differential. If you lift a wheel or slip im mud, just the slipping wheel spins and the other doesn't turn. Path of least resistance. So driving down the highway, the vehicle is in an all wheel drive state with the center differential mainly not locked and power is split to all wheels. The center differential is what allows the driveshafts to turn at different speeds when turning the vehicle to prevent binding since wheels turn at different speeds when rounding a corner. In a situation where 1 axle breaks or cv joint. The broken part has the least resistance and it will only turn. And you can not move. You can sort of move but the computer keeps unlocking the front and center diffs , so you just barely move when going straight. But turns are almost impossible. The center differential uses clutches to variably apply friction to the differential to prevent slipping when needed in turn locking it . The rear factory locking differential behaves very similar. The 23.5 and up system works like this. Power comes from the transmission into the transfer case and is permanently connected to the rear driveshaft. There is no differential in the transfer case. It is what they call permanent rear wheel drive. The tcsse has a torque on demand unit that puts power to the front driveshaft when needed. It uses a similar clutched unit to do this, but the vehicle will always have power to the rear no matter what. Not the case with the earlier unit. Another difference is that the permanent rear wheel drive system has a front axle disconnect built into the front axle tube. At highway speeds the system will actually completely disconnect the front axle. These systems have a much better MPG because of this. I have actually driven one of these without a front driveshaft installed! You can not do that with the previous system. So as i stated in my post previously, if you have this system with our Sarek selectable rear air locker, you can still drive even if you break any one of the axles or CVs . With the factory rear locking diff you can break a front, but not a rear. I believe the later system has many benefits. I really wish i had this system vs the center diff system that i have. I have broken an axle and it is not a good day. I always want to be able to try to drive off the trail even in 2 wheel or 1 wheel drive vs becoming a major burden on my friends trying to drag me off the trails. ​​​​​​Also, because of the axle disconnect, both front axles are the same part number, so u only need one spare for the front. Also much easier to replace the right axle from the previous system. The MPG gain is also a nice bonus."

[@L2SFBC]

I mention that in the video with a diagram. Yes it's different but behaves the same far as I can tell. I have on multiple occasions needed to deal with a Land Rover and broken CV and not being able to lock the c/d is a pain!

[@paulelledge8977]

@@L2SFBC oh I'm sorry I missed that part, I'll have to watch again.

[@L2SFBC]

Great comment thank you, useful info

[@cameronwood1994]

I do wonder if part of the issue with the Defender is that it still uses the now very old Magna-Steyr DD295 transfer box that debuted in the Discovery 3. Sure the issues is most probably software related but maybe the transfer box doesn't allow for this change to happen? I do know that this issue also rears its head when on tight slippery turns on an uphill gradient, because it does disengage quite a lot when you apply steering lock (it only locks to 90% anyway to prevent wind-up). It's very embarrassing when the front wheels spin and the vehicle slides sideways, even with ETC, and quite dangerous too. It also then causes the DSC not fully disengaging issue to arise because the vehicle is sliding under power. Speaking of which, I did notice the DSC issue at the 1:50 mark rearing its head again!

[@L2SFBC]

I think it's software design. I get windup is a problem but safety should come first. Part-time 4WDs run around quite happily even on dirt roads and in the USA they have high traction slick rock yet don't get windup due to suspension flex etc. So I think Land Rover have overdone it.

[@D4ni3l.Zitzm4nn]

When you only have a open center diff, or lsd an you fail at a hillclimb and would potentially slide back, you could use the handbrake if you have a traditional one as soon as you go off the throttle and slam the brakes. This could help not sliding downhill. Of course pushing the button all the time, so that it doesn't lock in engaged position.

[@GavinEarnshaw]

This was a reply to another comment but fingers ... Isnt Bronco based on Ranger T6? Isn't that pretty much like most pickups (UK based so...) They are pretty much all part-time 4wd. Many US SUV are the same as this. Buyers want it irrespective of actual need or ability. The vast majority of these SUV buyers is that they don't go off road. Can't even drive on wintery roads as they all have stupid sports tyres on... One benefit I have in my old Defender is that I can use low range on a yard for towing/manoeuvring big trailer without concern of transmission wind up as it has a centre diff. Also in less demanding situations I can run 4wd on the road like wintery conditions and if it gets bad add the centre diff. Options.

[@L2SFBC]

Yes Bronco is based on T6, but T6 can do AWD as well. I love low range no CDL, and was pleased to see it in Grenadier!

[@GavinEarnshaw]

I haven't seen a UK ranger with AWD as yet. Maybe that's reserved for the posh(expensive 3.0v6 petrol raptor) version 🙂 Fords website is atrocious for details. Often has the *Not all features available in UK etc

[@christianbolt5761]

Love the Lego model. Great explantion

[@L2SFBC]

Glad you enjoyed it

[@DanUK1984]

Was the Centre Diff manually locked in "Configurable Terrain Response"? Or had you left it in Auto mode?

[@L2SFBC]

See video for explanation

[@DanUK1984]

@@L2SFBC I have watched it, I assume your Defender doesn't have Configurable TR then. If it did, you can manually lock the Centre Diff - it would be interesting to know whether this problem remained in that scenario. Unfortunately your video is attracting the luddites who are anti electronics, but potentially it's not a fair comparison. I also appreciate that your video wasn't specifically aimed at the Defender, but I think it's worth pointing out that with the diff manually locked, it would perform the same as the others.

[@L2SFBC]

We will be testing CTR later. Not all L663s have CTR, and no other Land Rover vehicle has it either, and as you say it was an example. I know CTR does not 100% lock the c/d at all times, that's been proven; unclear if it locks enough. Certainly it'd help.

[@ronaldrrootiii6040]

That's why you don't drive in AWD SUV but instead a full-size Bronco or a full size Jeep with an actual transfer case to go from 2H into 4H or 4L. Might as well not have all those front end parts turning and wearing out driving down the road 90% of the time if you don't need them to be working then. And people can say oh well the all-wheel drive is good because some people live in bad weather yeah that's true but then those people can just purchase the all-wheel drive but most people just get these things and drive them down normal roads and it would make more sense to just make them selectable 4 x 4. And in all reality if you've ever associated with a Jeep Rubicon Wrangler you would know that in 2H it has enough articulation and option of rear Locker to literally get through where all these are going without even going into four-wheel drive hahaha I followed a Rubicon one time on a pretty tough Trail in my disco Series 2 on 33s with sway bar deletes traction control and CDL of course and he stopped to put it into four-wheel drive after a while when I thought that I was doing good by even being able to follow him and then realized wow this guy isn't even in 4wd at all yet.. I like this video and I like the comparison don't get me wrong I'm just throwing in my own personal opinion about what I feel to be overkill on these vehicles always having all-wheel drive instead of just selectable four-wheel drive. Feels like it would save people having confusion over cross axle lockers compared to transfer case Center diff locks whatever you want to call it. I hear people say almost in a braggadocious factor oh mine has a lock and I'm like Oh you mean it has traditional four-wheel drive big deal it seems like the company is just made them selectable they would have less moving Parts they would have lighter overall weight and not make a selectable Center diff lock sound like you have something real special where I joke and say all the all wheel drive vehicle has regular four-wheel drive cool

[@rhetth-s8082]

I wonder if a lot of manufacturer motivation is to avoid drivers doing bad things on high traction surfaces and causing breakages and complex warranty claims. Instead they should just upspec the drivetrain and have appropriate education and warnings.

[@davidkelly3779]

AWD with centre diff lock is superior to 2WD with a 4WD select every time. You have probably never owned an AWD (with CDL) to make the comparison. I have owned both, it is way easier to just engage the CDL than engage 4WD, and you can do it at moderate speeds (most under 50mph). Can also use lowrange in AWD, pretty handy for backing up that heavy trailer on a steep bend.

[@rhetth-s8082]

@@davidkelly3779 my pajero had options but i found it handled more neutrally in 2wd, even though the AWD setting has a torque split something like 40:60. My AWD amarok had a torsen centre diff which has a variety of drawbacks. Yes, ideally 2wd low range is available, but most people don't need that. I grew up in land rovers and i don't have anything against their system, but they were pre 2000 models. I do remote touring in big Australia and reliability is important to me. If i lived in Thredbo with icy roads i might consider getting AWD but i don't live there. Switching between 2wd and 4wd can be a bit tedious but i can live with that knowing that it performs well in each mode.

[@paulbarry1044]

Another great vid with everything very well explained.Don't the later Defenders have some sort of clutch set up that will disconnect the front axle whenever the vehicle decides?So in any situation,the operator would have no idea whether it is locked or not,or the center diff is locked or not.The later model's clutch set up is to reduce fuel burn,keeping the vehicle in two wheel drive.

[@L2SFBC]

Yes they do, diagram is shown later in the video, but conceptually it's the same as a diff.

[@paulbarry1044]

I couldn't see the diagramm clearly,but on a bigger screen it is all well explained.More complexity to save 1.7% emissions,which in real life driving is more than likely a lot less.Probably controlling the right foot,or keeping the tyres at the right pressures on road would save a lot more.🤣@@L2SFBC

[@user-et7rm8fx7u]

In pajero gen 2 with superselect, if you engage 4hllc the drive is split 50/50 front/rear transforming it into full 4wd mode and not part time 4wd same goes for 4llc, whereas 4h is part time 4wd like most offroad suv or pickups. Never had this problem in the pajero in similar situations

[@tedeganagondi]

Super select 2 is an brilliant system

[@L2SFBC]

Correct drive offroad in 4hl not 4h, or use low range as you say

[@davidkelly3779]

The Paj is definitely a capable vehicle, when it can keep its belly off the ground.

[@johnny_w]

I have 2 pajeros, a 1th gen. and a 2th gen. , they are great reliable cars ! First gen. has no center diff. , so no problems there 😉 The second gen. with super select works in 4Hlc and 4Llc the same as the first gen. high and low. Sofar I know, "Superselect 4H" is not "part time 4WD", it is a full time 4WD with open center diff. , and there is also a visco clutch that locks the center diff. automatically when a wheel is slipping.

[@user-et7rm8fx7u]

​@@johnny_win 4h power is split 60/40 or close to that, yes it has a viscous coupling that does as you describe but by selecting 4hlc or 4llc wich lockd tje centre diff power is split 50/50

[@fkb9490]

Have you considered the fact that some center differentials could be a ‘Torsten differential’ ?

[@L2SFBC]

Yes. Those need to be locked, and in fact Toyota use Torsen centres...with an optional lock.

[@gavinpatterson7693]

On my G Professional 463, reversing down a steep icy slope with center diff lock, I'm forced to use the handbrake. There is no crawl in LR R. Way too fast compared to LR 1. Mercedes say they can't change this. I'm wondering if there's anything else I can try apart from handbrake? Never had this in my Cruiser 71 which could crawl in LR R.

[@L2SFBC]

No crawl? Are you in low range? Yes, you can drive through the brakes; left foot on brake lightly, increase revs to move.

[@gavinpatterson7693]

Yes I wrote I'm in LR R(Low Range Reverse). I also don't need to use accelerator to move, it's very steep, I'm trying to slow the car. Touching footbrake immediately swings the front to mountain side, hence me using handbrake. If gearing isn't correct(too fast) presumably there's nothing I can do except park lower down. As I said, in the Cruiser 71, I never knew this problem, it crawled. The G practically freewheels backwards. A shame.

[@L2SFBC]

That behaviour looks like centre diff not locked but you note it is. Use the technique above; it's not acclerating to move per se, it's holding on brake, THEN using accelerator.

[@Dorko85]

What mode was the Defender in? It’s very rare the centre locker is off when in most TR modes.

[@L2SFBC]

Mud Ruts and also Rock. However it's not just the Defender, it's a generic problem as you can see across a lot of vehicles. The centre lock is on, to a greater or lesser degree, during the climb, otherwise the front wheels would spin as you saw in the D2. It is when the car stops that the problems happen.

[@Dorko85]

Interesting as my assumption is the centre lock is either on or off. Especially in rock crawl, I have never not seen my diffs unlocked, even at a stop. Very interesting video!

[@L2SFBC]

Modern Land Rovers have degrees of lock, not binary open/locked like say the centre diff of Puma or TD5 Defenders. The computer is always changing the 'lock' according to lots of factors such as turning input, TR mode, wheel spin etc etc. But, they forgot "front wheels locked rears rotating" as use case...

[@beyondthehorizon27]

I am fan of your work and your channel, and understand what are you saying in this video, but i also think the big or biggest “issue” here was the driver and driving style of Defender. Any car will lock the front wheels on slippery surfaces if you hit the brakes, or not release the brake pedal enough… even when he was driving down facing front he didn’t let the wheels go…. Here in europe in winter we see so many drivers on snow and ice standing on brakes and wondering why they can’t steer. Like i said, no hate and i understand the technical stuff behind it and agree some cars are better and some worse, but in this case i would say the bigger difference was made by driver…

[@beyondthehorizon27]

Watched it again, and you can see the defender driver had stopped on descent steered the wheels and than continued with foot on break…

[@L2SFBC]

The point of the CD lock is that the front wheels *cannot* lock without the rear. That clearly happens with the Defender. It's not a driver thing.

[@beyondthehorizon27]

True, but even with cd locked if you slam the brakes you can lock one front wheel… At the beginning of decent defender front right wheel was rolling and if the driver let the brakes he would be fine. He pushed brakes harder and locked both front wheels in a slide… Agree there is a problem and difference between cars, that’s why every car needs bit different approach and driving style. Better driver in worse car can get further than bad driver in good car sometimes… Knowing the pros and cons and knowing how to use them in your favour is what matters to me… Keep the good work you do 👌🏻

[@L2SFBC]

Yes, one wheel locked is shown on the D2 on the hill, and LC300 descending. But one wheel is some control, no wheels is no control. It's not a great solution to have to reduce braking when the rear wheels have grip that can be used!

[@L2SFBC]

If the driver had released the brakes as you suggest the front tyres would have been able to use more grip for turning and less for braking. But then...the car would have gone faster, requiring more turning grip. The other drivers used the same technique but their cars were better able to make use of the traction due to their CDs being locked. It's not the driver, it's the car.

[@stuarthearn9890]

on steep hill in NZwith 2 wheel drice tractors we reverse down diff lock in

[@L2SFBC]

Why so?

[@hege750]

I love when people really understand the physics behind the differentials. There are so many motoring journalists that state "the centre differential is locked so there is a 50-50 torque split between the axles" which is just plain incorrect.

[@L2SFBC]

:-)

[@hi9580]

What's incorrect?

[@hedydd2]

@@hi9580 That it is a 50:50 torque split. Actually 100% of the torque can be utilised by either axle. Light duty Haldex or similar systems may actually have a torque limit on an axle. An example is my 2015 Honda CR-V which has a 70-30, limited by the clutch that drives the back axle. The front can actually still transfer 100% of the available torque while zero goes to the rear. This is true of my Ford Ranger in a different way. It can transmit 100% to either front or back with a normal split on the road in 4A[utomatic] of 100% rear 0% front.

[@DarrenBoxhall]

​@@hedydd2um, if you lock the transfer or centre diff in a car, it's locked. 50/50 front and rear. There is no slip anywhere, except in the diff centres if unlocked.

[@hedydd2]

@@DarrenBoxhall If you stand it up on its hind wheels, all 100% of the torque would go to those rear wheels. That’s not a 50/50 split, it is 0/100%. even though the front are equally capable of 100% if circumstances dictated. That is in contrast with my Honda, for instance, where the maximum torque available at the rear wheels under any circumstances is limited to 30%. If the required torque exceeds 30% the wet clutch slips causing the oil to overheat.

[@apostolis2939]

Why doesn't ebd (electronic brake force distribution) or abs kick in to prevent the wheel lock up. Are their thresholds higher because of the low speeds and off road modes? In road mode maybe is there any interference? Also kind of dissapointing you can't lock the diff (or clutches) with the engine off. Land rovers instead of a regular parking brake used to have a transmission brake that worked on all four wheels even with the center diff unlocked.

[@L2SFBC]

ABS prevents a wheel locking. EBD (electronic brakeforce distribution) distributes braking force to the wheels according to their traction, so an electronic, automatic, brake-bias system. Both are disabled at very slow speeds.

[@rhetth-s8082]

A tailshaft handbrake operates on the rear tyres via a typically open rear diff, and on the front tyres via typically open centre and front diffs. If the transmission is effectively locked this means if one rear tyre and one front tyre lose traction all braking can be lost. Parking brakes on both rear wheels are clearly inferior when the vehicle is in RWD mode. [EDITED}

[@apostolis2939]

​@@L2SFBC True, these backwards slides may look dramatic but realistically the vehicle never went above 10-15 kph. Still, with it's accelerometers the car knows it's going backwards so letting the following wheels lock up that much seems like a dangerous omission. On tarmac abs in reverse is much more keen to kick in if you try to activate it, than going forwards, because the axle with the lighter load has the bigger brakes and more braking force.

[@apostolis2939]

Sorry, my mistake, I was under the impression that the parking brake on old land rovers worked on the center diff input shaft, but you are correct it works on the rear output shatf, so in order to work on all wheels you have to lock the centre diff, my bad

[@rhetth-s8082]

@@apostolis2939 not being able to turn while reversing can mean the vehicle ends up in the wrong place and needs recovering.

[@mattymcmacca]

What PSI are those tyres on?

[@L2SFBC]

Road

[@mattymcmacca]

@L2SFBC maybe try 18🤔

[@jamesszabadics5911]

these vehicles dont have the same tyres! I appreciate that was not what you were showing but any comparison should eliminate such a basic difference as tyre differences

[@L2SFBC]

Doesn't make much difference will show later

[@dennis3779]

Exactly what I always have been saying. The front brakes should never lock up first. This new One Ten is crap.

[@dennis3779]

It has not even a centre diff to save 1% fuel but wear out the 2 driven tires faster.

[@dennis3779]

Always remember this movie if not locking the centre diff or have an automatic or computer adjustable viscous locking centre diff or only a viscous unit. kzbin.info/www/bejne/aGPPgWiVhtJ0gJIsi=Uj-NtRwgS3DP2iLz

[@VnazT]

Great reminder that the defender is all marketing and no go. The Land Cruiser is the way to go. It baffles me that people are so irresponsible and ill informed to take landrovers into the bush.

[@Pineboy104]

Can’t wait for TFL to steal this idea for a video.

[@L2SFBC]

I hope they do to get the word out, but if they learn about it from my work, give me the credit due.

[@stuartturkington826]

Nsbcruiser is exactly right . , l also had this problem solved by landrover driving experience, its not the car it's the driver hasn't selected the right configuration for this obstacle.

[@L2SFBC]

How did they do that?

[@lazy_goodwill]

6:26 My ears are dead now

[@granitecolorado]

I won a defender in a raffle and it was so pathetic off road, that I traded it for a subaru crosstrek

[@L2SFBC]

Did you remember to raise the Defender's air suspension from Access?

[@granitecolorado]

@@L2SFBC It broke the second day I had it and became a low rider

[@boc3499]

The defender is just not practical off road, too complicated for use in real world situations.

[@gadgetphilosophy8290]

Driver in defender doesn’t know how to drive. I agree with centre diff arguement. Best thing is use no brakes but low gear.

[@L2SFBC]

Why do you say that?

[@-zerocool-]

Firstly, get proper tyres

[@haanjamiis]

And after 3 years, they still have not fixed it! There was a video 3years ago from a Ukrainian car reviewer InfoCar (Y7KahIfkUwc9) where the reviewer was almost killed by Defender. They climbed a steep muddy hill and the car started to slip down and the brakes were not engaging. At that time it was unclear what caused the software bug. That's one possible deadly bug. I recommend to watch that video too (use translate function if needed).

[@L2SFBC]

Can you post a link please?

[@haanjamiis]

​@@L2SFBC I don't know If YT lets me, but I try: kzbin.info/www/bejne/j2iukpt_m9CIrcU (the hill climb bit is at about 49 minute.

[@philhealey4443]

​@haanjamiis Magic thanks, I've been trying to find this channel again. Commentary largely incomprehensible, but the frequent term "Plastic Defender" is fairly easily understood !

[@L2SFBC]

I have emailed them to ask if I can analyse their raw footage and suggested they review my videos of the Defender.

[@philhealey4443]

​@@L2SFBC I recall some of their test routes caused impact punctures in the ludicr😮ous low profile tyres, much like TFL and Powerful UK off highway experience. I'll stick to ancient electronics-free Unimogging and 14R20s to sidestep all this modernity, best demonstrated as tertiary ownership lunacy by LRTime's weekly bulletin of Disco and now Range Rover repairs. Update, it was a Jimny getting a puncture, not the tobogganing Defender.