Front Lockers On 3rd gen

Locked center dif/transfer case. Front and rear locked difs.

Vehicle is up on jack stands 4 tires in the air. Now we attach a 10 foot beam to one tire with a 10lb weight on the end of it.

Put it in gear and apply 100ftlbs of torque from the engine. Then just a little more and the beam rotates and lifts the weight. (Would actually be a little more torque depending on the weight of the beam but let's assume our beam is magic and doesn't weigh anything)

The amount of torque on the other 3 wheels is 0 and we've got 100ftlbs on the one that's rotating the beam.

All the torque is going to the tire with the traction.

Open difs equalize the torque, locked difs equalize rotational speed.

 

It doesn't matter if it's a dog clutch locked differential, spool, welded diff, or automatic locker, they all behave the same when it comes to how torque is biased. Only caveat is an automatic locker allows a tire following a larger radius (outside tire) to overrun the carrier, leaving only the inside tire driven.

So it doesn't matter, there still is a right and left axle driven through a carrier with a locked diff (aka spool), and torque is not split equally at all times. I can't explain it any clearer. I've tried my best. But it's known fact that a locker/spool does not sent torque equally to each wheel at all times.

 

Thats correct but your "power source" is the wrench on a single tire. Thats not how drivetrains work, there is a single source applied equally to all wheels.

You could technically have 4 different people applying different % of torque to each wheel but that would be like having 4 different motors, one for each wheel.

If 100 ft-lbs is needed to rotate a tire, one person applies 80 and another 20 it will be enough to rotate the tire, BUT thats not how power is distributed.

Thats actually not how automatic lockers work, the inside tire isn't necessarily "driven," applied torque is what locks the locker to begin with, its an open dif when unlocked.

Torque is always applied evenly when locked, and torque is applied to overcome the combined resistance of the tires and resistance is shared between the tires. If one tire needs 200 ftlbs to turn and the other needs 50 ftlbs then 251 ftlbs is needed from the drive-train to rotate both tires and a locker has no idea which needs what. Its just straight 251ftlbs for both tires to turn. You increase torque with throttle input which is singularly applied through the driveshaft into the differential and torque values increase until both tire resistance are overcome and the wheels turn.

You can keep repeating yourself and you will still be wrong. At this point we can agree to disagree but you aren't convincing anyone in this thread any different.

This is why it's called a DIFFERENTIAL, a locker, spool etc, does not differentiate! a Locker when locked acts like a SPOOL which I will say again DOES NOT DIFFERENTIATE.

 

I think the simplest way to put this is that while locked at all four corners, the potential power at all wheels is equal. But in practice, the power being transferred to the ground is not equal and is dependent on the traction available to each wheel. If only one wheel is on the ground, only one wheel is putting power to the ground. In this scenario, tell me how is it possible for the work being done at each wheel to be equal? There is practically no load on three of the wheels, the only way they could equal the one is with wheel speed. Impossible if they're locked.

Edit: TLDR, being all locked up means basically 100% of engine power is going to the ground, assuming at least one wheel is not slipping.

 

So the problem is that you are looking outside in instead of inside out. The 3 wheels may not have ground resistance but internally, as power is applied to a locked axle, power is sent indiscriminately to both axles, they are locked, they receive equal power, equal torque, its basically a solid steel rod at this point. Technically yes, power is "going to the ground" on 1 wheel because its the only one touching of course. Using your scenario, 1 wheel requires 100 to turn and the other 3 with no resistance require 0, we have a combined resistance of 100 which means when power is applied 100 is sent to all the wheels to overcome the one wheel thats resisting.

 

Yeah we're not really disagreeing. I get it. Its all one system tied together. You could think of it as one long drive shaft with four wheels in line on it. I'm just making a stupid point that those other three wheels are along for the ride. I'm not sure what point you're making. You said it yourself, 0+0+0+100 = 100. Those three are accomplishing zero work. If three wheels are in the air and one is jammed between a couple rocks, where is all the stress?

 

Ya you're right, my point is if the resistance is 0+0+0+100 then a full locked 4wd will send power as 100+100+100+100. The power is 1:1 basically which is why you hear things like 50/50, etc. It's just 1:1 power distribution, there no torque biasing like a LSD or positraction, etc.

but man we got some real problems if we have 3 wheels in the air haha!

 

There are multiple aspects being looked at here and it does depend on where you analyze/cut up the problem.

In a static situation, with the center locked, and the front and rear locked, all axles are seeing the same input torque, that is true, but if three of them are in the air, that input torque is only being reacted at one wheel. If you have 500 lbf-ft of torque being input to each axle, but only one axle is reacting that input torque, that wheel is seeing 500 lbf-ft of torque. If all 4 wheels are on the ground, each axle is now reacting 125 lbf-ft and consequently each wheel is having 125 lbf-ft of torque applied equally.

500 lbf-ft of torque needs to be reacted, and so you need to think about where that is being reacted. If it is being reacted by one wheel, that wheel needs to react 100% of the applied torque. If it is reacted by two wheels, the 500 lbf-ft is getting split up between them, and so on.

(Value chosen to simplify the reader's intuition).

Without a reaction, the input torque effectively doesn't matter, yes it is applied, but the axle is not being twisted.

Jeff

 

Lol, no doubt about 3 in the air! Just a thought excercise to simplify how power is transferred through the drive train.

 

I like this explanation a lot more than mine. Much clearer imo.

 

You seem confused with something in my description. I said the power source was the engine. Going to 4 locked diff corners with a load applied to one of them the rest free to spin. All the work ends up being done at the corner with a load applied. The rest rotate along with the one with a load, but the loaded one is the only place where the torque from the engine is being used.

With locked diffs rotation is applied to both tires, the torque is only being applied to the tire with traction though (the rest rotate at the same RPM but aren't doing any work), that's why a locked diff works when you lift a tire.

 

Differentiation refers to speed not torque. They are not one and the same and I'm afraid you're thinking of them as such.

Read through the first few paragraphs on wikipedia. If you're right you have a lot of editing to do to the wiki on locking differentials.
https://en.m.wikipedia.org/wiki/Locking_differential

This is also a technically sound article stating lockers do not split torque 50/50.
https://www.matfoundrygroup.com/News and Blog/Types_of_Differential_and_How_They_Work

And another. https://www.liveabout.com/lockers-and-differentials-3236

Yes, you will find many YouTube videos and articles that say lockers split power/torque evenly but you need to pay attention to who technically understands the systems versus who takes the intuitive "sounds right" version. This broad misunderstanding of lockers and diffs is why I corrected this thread in the first place (pet peeve) and it's easy to see how rampant the misunderstanding really is. At the very least I've presented the facts so everyone can research, test, and understand for themselves.

 

all this technical info sounds and looks good, but in real life, im like Four Leaf Tayback when he was asked what kind of gun he carried... "I dont know what its called, I just know the sound it makes when it takes a mans life" LMFAO

 

I found this really helpful, cleared it up for me. I'm just running an SR5, so it has the auto lsd function only. I think it might be fine for the amount of light wheeling I will do, but the video below clearly outlined the differences between the differentials for me. I know it doesn't go into the esoteric detail you guys are discussing, just thought others may appreciate the thoughtful delivery.

https://youtu.be/x40WGUtdaLI

 

Plenty of contradicting articles as well. I like Wikipedia but it’s always concerning when there a big banner that says this article needs additional citations.

 

I realize that this thread has drifted from gear to theory, but I'm intrigued by this option to add a mechanical front locker to a 3rd gen for $315:

https://www.lokka.com/

 

We ran a bunch of aussie lockers, lockrites, and all that good stuff back in the day. For the price, there's huge bang for the buck. There are some handling manners with turning in 4wd under power when you run it up front, but it's still worth every penny. I've dd'd these in the rear (and welded spools) and would do it again. I still own one for my project build.

Having said that, the RD111 ARB air locker just arrived for the front of my taco and they are hard to beat if you install them correctly.

 

I think the idea is relativly easyier to understand for an open diff. An open diff slipts the torque 50/50 between the wheel, therefore max torque you can apply is equal to the max torque it would take to slip and spin the lower traction tire. That is why in 2wd, if one tire is on the ice, it will spin while the tire on dry asphalt wont move. This is because equal amount of torque is applied to both tires and the max is limited by how much it wold take to move the lower traction tire. Amoubt of torque required to spin a tire on ice is less than what would it take to push the car forward with the tire on asplhalt.

 

It does until until it doesn't, spider gears cause this, which is why a locked differential sends power equally 50/50 or 1:1.

The only true torque biasing that occurs within a differential is with LSD and torson systems utilizing worm gears

 

Torque is a force unit though not power, to have torque there need to be an equal opossing force (3rd law of Newton), you can generate as much as torque as the opposing resistence force. If you lift a open diff 2wd car in such a way that only one wheel touches to the ground, you can spin the wheel not touching to the ground with your hand. You will feel a minimal mechanical resistance and max torque you can apply is the amount needed to overcome that resistence force. If you apply more force, the wheel will just start to spin faster as inertia becomes the only oposing force and any extra force applied is just spent on acceleretion. At some point you wont be able to spin the wheel any faster, so inertia is no longer a opposing force and amount of torque you are applying to the wheel will drop back to the same initial amount needed to overcome mechanical resistence The wheel on the oposite site is also getting that same amount of torque since there is 50/50 split, but it will ofcourse not be able to push the car forward (for a locked diff, you wont be able to move the tire unless you are stong enough to generate enough torque to push the entire car forward, so since the wheel with traction is "feeling" the opposing force, that wheel has 100% of the torque). Btw this is the reason why rocking a 2wd car back and forward when one wheel is on the ice can get you off the ice, it allows you to utilize the additional force needed to overcome inertia of the tire spining on ice. So momentery you get more oposing force and an equall amount of force can be sent to the tire with traction, which rocks the car forward.

Or lets say I take a helicopter and cut the blades to 1/10 of their size, now the engine still has the same power but you wont be able to get any lift since the blades are not generating enough oposite resistance force to lift you up.