First time dealing with a center diff. Was looking to shed some light on why when 3 tires have contact with a surface and one does not,with the diff locked why the tire with no ground contact is the only one with power to it while the other 3 have none. Thought The Whole point of locking the diff was for all 4 tires to have power at the same time for better traction. I was told this is exclusive to the 2014 and has been corrected in the 2016. During desert drives I disable ABS and VSC but I doubt this has anything to do with the issue. Can anyone shed some light on this? Thanks
LC200 center diff (1 Viewer)
- Thread starter Jetman
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Taco2Cruiser
Crazy American Off Road
The center locking differential only ties the front and rear axles together for a 50/50 power distribution.
Now that has nothing to do with where power goes once in the axle. The front and rear differentials are still open, meaning the tire with the least resistance will get the most power. If you want all 4 wheels to receive power no matter what, you have to add locking differentials to the front and rear differentials.
Now that has nothing to do with where power goes once in the axle. The front and rear differentials are still open, meaning the tire with the least resistance will get the most power. If you want all 4 wheels to receive power no matter what, you have to add locking differentials to the front and rear differentials.
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We have some remarkably sophisticated systems in our 200s to control wheel spin and torque distribution. Here are 3 threads from the 200 section FAQs that describe their workings.
FAQ Discussion: Crawl, Multi-Terrain, Optional Lockers or ATRAC when best to use each
Welcome to Land Cruiser Owners On Line
Edit: In addition, the '17 LC has a limited slip center differential, as well as the locking feature.
FAQ Discussion: Crawl, Multi-Terrain, Optional Lockers or ATRAC when best to use each
Welcome to Land Cruiser Owners On Line
Edit: In addition, the '17 LC has a limited slip center differential, as well as the locking feature.
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With the center locked you could have one wheel per axle spinning. If the braking system is working then the system will try to brake the spinning wheel on an axle to apportion torque to the non-spinning wheel. One wheel spinning would have me testing braking.
- Thread starter
- #5
Did some further reading and watched some tutorials on YouTube as well. So to achieve the result I require I could either try to trick the system by applying breaking or just install lockers on the front a rear diffs which I hear can be a costly affair.All makes sense now
Thanks all for your replies!
Thanks all for your replies!
no, ATRAC is the system that applies the brakes for you based on when it senses slip
you do not need to ride the brake while trying to accelerate
you do not need to ride the brake while trying to accelerate
One quick followup.......you don't have to trick the system with braking by you. The software seems to pretty much know what to do all the time and will apply brakes on the wheel(s) with less traction for you based on wheel speed sensors and other sensors. The trickery is from the software engineers and hardware engineers who figured it all out. These systems are one of the main reasons my daughter in law said "Land Cruisers rock" after a trip through the dunes.
Correct. Unlocked it is technically possible to have the one ungrounded tire to receive all the torque. However, as soon as the traction control senses the one wheel freely spinning it should apply brake to the freely spinning wheel which would cause the torque to be redirected in equal proportion to the brake force to the other tire on the same axle and a much higher proportion of torque to the other axle via the center diff.
With the center diff locked 50% of the torque will be sent to each of the front and rear axles. The one axle with an ungrounded tire would direct all torque to that tire until the traction control software applies brake.
Taco2Cruiser
Crazy American Off Road
Nice catch, I had to go back and read it again.
What's more fun to think about, is even with the center diff unlocked, the split will still send no less than 30% power to the front axle, and no less than 41% to the rear. So you'll still get the tires to move, just at a much slower rotation.
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- Thread starter
- #11
This is exactly why I was confused when I encountered this. maybe it's due to the fact that I have a kill switch that disables the ABS and VSC? The reason we do this is to prevent them working over time in the sand and countering the movement of the vehicle and making it near impossible to drive. I sometimes have to re-engage the ABS and VSC to activate crawl control if she sinks in the soft sand on level ground.
It works just fine (or seems to) when all 4 wheels have contact and you select low 4.
This only becomes an issue when one wheel has no contact or traction.
It works just fine (or seems to) when all 4 wheels have contact and you select low 4.
This only becomes an issue when one wheel has no contact or traction.
Even if the truck didn't have Atrack to mimic locked differentials, one wheel shouldn't be able to spin by itself if the center differential is truly locked mechanically. Are you sure your center differential is locking?
I don't see why disabling ABS and VSC would prevent you from locking the center differential.
I don't see why disabling ABS and VSC would prevent you from locking the center differential.
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Taco2Cruiser
Crazy American Off Road
To clarify, you've cut and spliced into your wiring harness?
I haven't tested any of this out with my 2016 but my experience with my prior vehicle (Land Rover LR4) which had very sophisticated traction control as well was that you had to be steady with the power your were applying so that the software could detect that something was amiss with the spinning wheel. If I was all over the place with the gas pedal trying to manually get myself out of a spot the software was not as quick to recognize that one wheel was amiss. If I was steady (usually around 1200-1800 rpm) and allowed the system to recognize the issue and kick into action then it handled things I would not have been able to handle myself. Maybe the LC is similar?
The thing is is that the OP is talking about the mechanical center lockable differential. ATRACK or any software shouldn't matter. If it's truly locked then one wheel shouldn't be able to spin by itself at all. This is unless disabling ABS and VSC doesn't allow the differential to be locked, but I doubt this would be the case.
Due to the nature of the traction systems you need to give it sauce and have decent amount of wheel spin for it to kick in and work.
Here's a video of some eastern European guys testing various traction systems on this roller assembly. It shows a good example of how much spin can happen. The 100 and Prado are in there somewhere.
Here's a video of some eastern European guys testing various traction systems on this roller assembly. It shows a good example of how much spin can happen. The 100 and Prado are in there somewhere.
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- #17
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- #18
Ok so a friend of mine has 1998 105 and he has a center diff just like my one does and individual front and rear lockers which mine does not. I think taco2cruisers first explanation was probably correct. I think this video up to the 5 min mark pretty much explains what I am talking about. It has nothing to do with the ABS or VSC as NYC570 has rightly stated. If I want all the wheels to work at the same time when one has lost traction or is airborne then I need individual front and rear lockers.
You got everything right except the part about needing front and rear lockers when only one wheel losses traction. When you lock the center differential it locks both drive shafts as one essentially locking the front and rear axels. It locks the drive train front to back. This means that both axels will spin at the same speed. So let's say your front right tire gets air. It won't be able to spin freely as long as both rear wheels are on the ground with plenty of traction. Now, if one of the rear wheels gets air, then you'd have a front and a rear wheel spinning and the truck won't go anywhere. All this is assuming that we don't have ATRACK.
