Front diff locks and Terrain Management Systems - Prado Kakadu 2016

[pradokakadudavid Member Find all posts View Profile Close pradokakadudavid]

I have a 2016 Prado Kakadu with factory centre and rear diff locks, ARB front diff lock and the usual Kakadu Terrain Management system (TMS) and am obviously an amateur as this is my first ever 4x4. Although I know how all this stuff works and have used it all in various terrain, I haven't really got a clue if I should use the TMS when the lock diffs are engaged or use some but not others. Basically my practise has been to select low range (LR) when I sense the need and usually engage the centre diff lock fairly early. I then engage the rear diff lock when more grip looks like being required, and similarly, the front diff lock. But when, if ever, should I use the TMS with these other features, and in what combination with the other features described above? Is it sensible to have all the stuff engaged at the same time including TMS or does one system negate the other? Obviously the front diff lock affects the steering which can be important when the need to turn arises as the vehicle does not turn as easily. So just wondering if there are any experts in this field out there who can share their experiences and increase my knowledge on this subject. My practise has generally been to turn everything on and hope for the best (lol) but I am starting to question whether this is a sensible thing to do or whether there are more productive ways to use the 4x4 systems for better affect. Any practical advice would be appreciated.

[MacroP Member Find all posts View Profile Close MacroP]

My practical experience is to never really use a front or rear diff lock until you really need them.

My question is, in what scenarios are you using your Kadadu now? As this is your first 4wd, I have to ask. To be honest, in my Kakadu I've only used the rear diff lock a few times mostly when pulling a big boat out of the water on a muddy surface or when towing my camper trailer on very soft sand just to get going from a standing start. You'll be surprised how far a Prado can go without all those locks turned on. Correct tyres pressure are more important in my opinion. Diff locks won't help when you've dug yourself into trenches.

To be honest, I've never selected any of those electronic terrain features and see what they actually do. I should read the manual one of these days.

[HugoStiglitz Member Find all posts View Profile Close HugoStiglitz]

Hi David,

Almost all Traction Control, TMS and such systems work by applying braking to spinning wheels.
The reason this works fairly well is because differentials are lazy. when one wheel has no traction its easy to spin so the diff sends all the power across to the easy side. If you start to apply braking to this spinning side it forces the diff to push power to the stuck wheel and this gets you out of strife

This however can create alot of heat in the brakes when 4 wheel driving.

A differential lock works by locking the gearing inside the diff forcing equal drive to each side. this however makes turning a corner a little more difficult as the outside wheels need to rotate faster than the inside to make the turn. turning with a rear diff lock engaged only has a minor effect on steering. However having a locked front diff makes steering quite alot harder.

Turning on bitchumen with any of your diff locks engaged (Front, Rear or Center) should be avoided. the high levels of grip means much more pressure on your drive line in order to slip the inside wheels.

What you don't want is to have a diff lock engaged and have the Traction control trying to apply braking to a wheel. its unnecessary and just creates brake heat for no reason. Now I don't know if modern TCS is smart enough to deal with after market diff locks. it all depends on how it determines when to apply the brake. I would be sure that the factory rear locker is factored into the programming of the factory TCS but who knows about the after market front.

When doing extreme tracks you can leave the rear locker for quite an extended period. the front however you should only be using it very sparingly and turn it off again as soon as possible. Personally, when hitting the tracks I would turn the TCS off, just engage the rear locker when progress stops. the front locker I would be trying 4-5 different lines with the rear only before locking in the front.

Once you get to know your car and its ability you will get to a obstacle and know if it requires any or all of the lockers before you give it a go.

Always exercise caution when it comes to lockers, they are great at getting you further up the track. they are equally good at getting you into very hairy situations as the car just keeps driving even if you only have 1 wheel on the ground.

[Bobcrusader Member Find all posts View Profile Close Bobcrusader]

In the case of the Kakadu, the Traction Control is disabled front and rear if the rear locker is enabled, but the Multi-Terrain Select (TMS?) is a different system again. https://www.youtube.com/watch?featur...&v=B2-OiFN1cQE. It still tries to limit wheelspin by applying brakes, but in theory there shouldn't be any wheelspin (compared to the wheel across the same axle) with the diff locked. MTS will act like a 'smart' differential - if you apply brakes to a wheel, the diff has to send the torque to the other wheel and in the case of MTS, can send 100% of the torque for that axle to the wheel with grip. MTS will allow some wheel spin to maintain momentum depending on the program.

You have to select an MTS profile if you select low range and I would just pick the appropriate one and leave the read diff open. See how far you go. If you get stuck, engage rear diff lock. If you still get stuck, lower tyre pressures, try a different route and then try the front diff lock.

[pradokakadudavid Member Find all posts View Profile Close pradokakadudavid]

Thanks Macro.

I did buy this Kakadu with the intention of using it for real 4 wheel driving and have been doing so. Re where do I use it, I have been a regular visitor the the Lancelin sand dunes which are pretty awesome and also assorted beaches in WA such as the Wilbinga and the Lancelin to Wedge Island beaches. Perhaps the most demanding terrain I have tackled several times has been the Mundaring Powerline track particularly in the rain when things are very muddy and slippery and wet! A few weeks ago I had my bonnet underwater hence the new Safari snorkel! So crawling over large rocks and ruts where tyres get completely off the ground which happens on the more demanding sections of the Powerline track require these diff locks. I have followed lesser 4 wheel drives and watched their wheels spin in mid air whilst negotiated deep ruts, whereas mine glides effortlessly over most terrain and rarely loses grip. I have to attribute this continual grip to the diff locks and certainly not my skill (lol)! Reading the manual doesn't help at all but using all the trick stuff in demanding situations certainly does. Yep agree with the tyre pressure advice and most certainly so this. I have max tracks and all the other trick recovery stuff (new Warn Zeon winch awesome - but never used it lol) ) but prefer to avoid getting stuck in the first place so I guess I opt for safety in using all the trick stuff rather than waiting to get stuck. I guess I will get more confident in time. Thanks for the advice. Cheers David.

[pradokakadudavid Member Find all posts View Profile Close pradokakadudavid]

Thanks Hugo that's great advice. I should add that once in low range, the 2016 Kakadu automatically turns the traction control off so this is not an issue. My initial questions related to the Terrain Management System rather than Traction Control.
Are you implying that the Terrain Management system uses a form of Traction Control, even though the TC is off when the TMS is engaged? Thanks.

[pradokakadudavid Member Find all posts View Profile Close pradokakadudavid]

Thanks Bob that's great advice. I guess in time persistence is the best teacher.

Cheers.

David