4x4 operation questions
Elder User
Joined: Nov 2012
Posts: 642
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From: Onlsow, NC
If you have a floor shifter instead of the **** on the dash panel you probably have only manual locking hubs. The purpose of leaving the hubs engauged while in 2wd is the convienence of not having to get out and lock your hubs when you shift into 4wd. The down side is, loss in mileage and increased wear on front diff and the transfer case. Which is not a big deal if you do it in isolated situation, however if you leave it that way all the time when 90% of your driving is on pavement....
Posting Guru
Joined: Aug 2012
Posts: 1,144
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From: ALPHA ,NJ
If you have a floor shifter instead of the **** on the dash panel you probably have only manual locking hubs. The purpose of leaving the hubs engauged while in 2wd is the convienence of not having to get out and lock your hubs when you shift into 4wd. The down side is, loss in mileage and increased wear on front diff and the transfer case. Which is not a big deal if you do it in isolated situation, however if you leave it that way all the time when 90% of your driving is on pavement....
With that being said. I already get low mpg and couldn't afford to lose more of it for 6 months of the year. So I only leave them locked if I know it's going to snow. If it wasn't daily driven I would probably leave them locked for the winter.
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Senior User
Joined: Sep 2001
Posts: 196
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From: Chicago
Don't confuse front axle binding due to a spool with the minor binding when hubs are locked on a normal front axle. A front spool causes the front tires to turn at the same speed, and any turn at all will cause binding. This is binding of the tires.
A normal front axle with a normal differential may do what sounds like a little binding when in full turn when the hubs are locked, due to the limitations of the u-joints inside the hubs. No harm done, just a little more wear and tear on the u-joints and related parts. But the differential allows the tires to turn at different speeds. The tires are not binding. In this case, the binding is in the axle, and it's doing what it is designed to do.
Leaving the hubs locked is OK on pavement, if the transfer case is in 2wd. Like mentioned above, it just causes a little drop in MPG, and a little less power. But it is real handy to do when travelling at times when 4wd may be needed in a hurry. I do it when 4 wheeling trails, and in daily driving when the possibility of 4wd is needed, generally, wintertime.
A normal front axle with a normal differential may do what sounds like a little binding when in full turn when the hubs are locked, due to the limitations of the u-joints inside the hubs. No harm done, just a little more wear and tear on the u-joints and related parts. But the differential allows the tires to turn at different speeds. The tires are not binding. In this case, the binding is in the axle, and it's doing what it is designed to do.
Leaving the hubs locked is OK on pavement, if the transfer case is in 2wd. Like mentioned above, it just causes a little drop in MPG, and a little less power. But it is real handy to do when travelling at times when 4wd may be needed in a hurry. I do it when 4 wheeling trails, and in daily driving when the possibility of 4wd is needed, generally, wintertime.
Post Fiend
Joined: Mar 2009
Posts: 11,798
Likes: 14
From: Mt. Shasta California
Don't confuse front axle binding due to a spool with the minor binding when hubs are locked on a normal front axle. A front spool causes the front tires to turn at the same speed, and any turn at all will cause binding. This is binding of the tires.
A normal front axle with a normal differential may do what sounds like a little binding when in full turn when the hubs are locked, due to the limitations of the u-joints inside the hubs. No harm done, just a little more wear and tear on the u-joints and related parts. But the differential allows the tires to turn at different speeds. The tires are not binding. In this case, the binding is in the axle, and it's doing what it is designed to do.
Leaving the hubs locked is OK on pavement, if the transfer case is in 2wd. Like mentioned above, it just causes a little drop in MPG, and a little less power. But it is real handy to do when travelling at times when 4wd may be needed in a hurry. I do it when 4 wheeling trails, and in daily driving when the possibility of 4wd is needed, generally, wintertime.
A normal front axle with a normal differential may do what sounds like a little binding when in full turn when the hubs are locked, due to the limitations of the u-joints inside the hubs. No harm done, just a little more wear and tear on the u-joints and related parts. But the differential allows the tires to turn at different speeds. The tires are not binding. In this case, the binding is in the axle, and it's doing what it is designed to do.
Leaving the hubs locked is OK on pavement, if the transfer case is in 2wd. Like mentioned above, it just causes a little drop in MPG, and a little less power. But it is real handy to do when travelling at times when 4wd may be needed in a hurry. I do it when 4 wheeling trails, and in daily driving when the possibility of 4wd is needed, generally, wintertime.
Can you clarify that?
New User
Joined: Jan 2014
Posts: 11
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From the OP;
I'm a bit confused, as I have only had binding happen with spools, in which case, it should happen any time both hubs where locked, 4wd engaged or not, as the binding is across the tires, not the T-case. You are really confused
Binding is not across the wheels. It involves the t-case and all 4 wheels
from what I can gather, it means that it has to have a locker (or a limited slip where the clutches are stuck?), but for some reason, it is applying equal torque to the outside tire while not letting it spin faster than the inside.
That's because all 4 are locked up. LS clutches never stick.
does this make sense? Is this how they all work, at least when locked in?
Yes.
Lastly, can I drive the truck safely, without compromising breaking something, with both hubs locked but the truck in 2wd, and put it in 4H only when crossing bridges/overpasses?
Yes, good idea.
what about just driving it in 4wd with locked hubs the entire way? will the binding be enough to break something, hubs or diff most likely?
Yes, never do that unless you stay in a straight line but still not good because even tire differences can affect in binding.
Would this happen with the hubs in auto provided that the auto hubs actually worked correctly? (or are they, and they just require more speed and/or engine or axle RPMs?)
Same as manual lock symptoms.
TL;DR: getting binding on pavement with hubs locked in manually, but I need 4wd tomorrow on the roads due to essentially guaranteed icy roads and it seems that my autos are not working.
You can drive on icy roads in 4wd, it's the turning on dry pavement especially at low speeds that isn't good.
on edit, when purchased, I had been told that the previous owner had had some work done to the diffs, I do not know what exactly, and had had the tranny replaced[
Are you grasping it yet?
The front axle acts the same as the rear when locked, the problem lies when the front shaft tries to spin at a different speed than the rear shaft.
I'm a bit confused, as I have only had binding happen with spools, in which case, it should happen any time both hubs where locked, 4wd engaged or not, as the binding is across the tires, not the T-case. You are really confused
Binding is not across the wheels. It involves the t-case and all 4 wheels
from what I can gather, it means that it has to have a locker (or a limited slip where the clutches are stuck?), but for some reason, it is applying equal torque to the outside tire while not letting it spin faster than the inside.
That's because all 4 are locked up. LS clutches never stick.
does this make sense? Is this how they all work, at least when locked in?
Yes.
Lastly, can I drive the truck safely, without compromising breaking something, with both hubs locked but the truck in 2wd, and put it in 4H only when crossing bridges/overpasses?
Yes, good idea.
what about just driving it in 4wd with locked hubs the entire way? will the binding be enough to break something, hubs or diff most likely?
Yes, never do that unless you stay in a straight line but still not good because even tire differences can affect in binding.
Would this happen with the hubs in auto provided that the auto hubs actually worked correctly? (or are they, and they just require more speed and/or engine or axle RPMs?)
Same as manual lock symptoms.
TL;DR: getting binding on pavement with hubs locked in manually, but I need 4wd tomorrow on the roads due to essentially guaranteed icy roads and it seems that my autos are not working.
You can drive on icy roads in 4wd, it's the turning on dry pavement especially at low speeds that isn't good.
on edit, when purchased, I had been told that the previous owner had had some work done to the diffs, I do not know what exactly, and had had the tranny replaced[
Are you grasping it yet?
The front axle acts the same as the rear when locked, the problem lies when the front shaft tries to spin at a different speed than the rear shaft.
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Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
Wow! I have been pondering how the 4 WD works on my newly acquired used 350. But I am still confused. What happens when one turns the inside 2W/4W ****? I thought it only applied the vacuum to the front hubs. I guess it also does something in a transfer case somewhere - that also allows the change to low range. Correct? What happens in the front diff? If that is limited slip then both fronts would turn when locked. If it is a standard diff, will both fronts still be pulling or will only the slipping wheel spin?
When a wheel breaks free it takes very little torque to spin, which reduces the amount of torque applied to the opposite wheel.
New User
Joined: Jan 2014
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It's really a pretty simple system. When you rotate the switch the transfer case motor applies a clutch that spins up the front driveline in less than a second. Once that happens a locking collar engages and locks the front driveline in. Once this happens a vacuum solenoid applies vacuum to the front hubs to lock them in. None of these trucks ever came from the factory with a limited slip differential up front, they are all conventional open differentials that evenly split torque between the two front wheels.
When a wheel breaks free it takes very little torque to spin, which reduces the amount of torque applied to the opposite wheel.
When a wheel breaks free it takes very little torque to spin, which reduces the amount of torque applied to the opposite wheel.
There is a lot of snow here this winter
. My limited slip rear diff doesn't seem to be working at all - I've tried the 'apply brake' technique that I've seen recommended but to no avail. I can't get up my driveway without the 4 WD engaged. So my next question would be, based on what you just told me about torque, if I put two outside wheels in the slippery stuff on a hill, would I be stuck (without backing up)?
Post Fiend
Joined: Mar 2009
Posts: 11,798
Likes: 14
From: Mt. Shasta California
Thanks. Much clearer now.
There is a lot of snow here this winter. My limited slip rear diff doesn't seem to be working at all - I've tried the 'apply brake' technique that I've seen recommended but to no avail. I can't get up my driveway without the 4 WD engaged. So my next question would be, based on what you just told me about torque, if I put two outside wheels in the slippery stuff on a hill, would I be stuck (without backing up)?
There is a lot of snow here this winter
. My limited slip rear diff doesn't seem to be working at all - I've tried the 'apply brake' technique that I've seen recommended but to no avail. I can't get up my driveway without the 4 WD engaged. So my next question would be, based on what you just told me about torque, if I put two outside wheels in the slippery stuff on a hill, would I be stuck (without backing up)?
Elder User
Joined: Nov 2012
Posts: 642
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From: Onlsow, NC
0 x 5 = 0
So no torque gets applied to the wheel with traction. By applying the brake you will create a small amount of torque on the free spinning wheel, which gets multiplied by 5 and applied to the wheel with traction.
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
Correct. And in that situation on a hill the factory LSD probably won't help you much as the clutch packs are only capable of transmitting so much torque. In that situation you'd want a geared LSD such as a Torsen or True-Trac or a selectable locker.