4x4 with Open Differential
01-01-2018, 07:57 PM
#21
We got a little snow the other day. I used to drive a school bus on some pretty slick back roads. The older busses had limited slip very good limited slip. Barking at a locker we would get a bang pretty often driving on dry roads. We could chain up one back wheel and go just about any where.
The newer busses came with a brake assist rear end. One tire spins it applied the break to that side. On slick roads you could feel and hear this going on. And the bus would walk up snow covered roads. Better than the old rear ends IMO.
Being as they made the change to a school bus they must have thought it was better. Were carrying kids safety is tops.
Ok back to my 2016 f150 its 4x4 and has the breaking limited slip ill call it. And it has the locker. With stock Good year trackers. I live on a gravel drive way that was covered. And a grade not steep. In 2 wheel drive i lost traction and spun out. Remembering the Busses i just held the gas steady. And the truck started crawling up the drive way. I could feel it applying the breaks.
I backed back down and used the locker. It went up the hill but i had to watch it. It wanted to fishtail over the hill. I had to play with the gas. But it went right up. required more driving skills lol.
4x4 i just drove up it like it was June
.
Then i tried to pull in the mother in laws driveway. 2 wheel spun out put it in 4x4 and went a little farther and spun out. Locked the locker in and went right up the hill with out spinning.
I was trying to get stuck driving slow. I just wanted to see what every thing did. Thats how my truck acted 5.0 373 gears. If that matters.
I need better tires IMO.
The newer busses came with a brake assist rear end. One tire spins it applied the break to that side. On slick roads you could feel and hear this going on. And the bus would walk up snow covered roads. Better than the old rear ends IMO.
Being as they made the change to a school bus they must have thought it was better. Were carrying kids safety is tops.
Ok back to my 2016 f150 its 4x4 and has the breaking limited slip ill call it. And it has the locker. With stock Good year trackers. I live on a gravel drive way that was covered. And a grade not steep. In 2 wheel drive i lost traction and spun out. Remembering the Busses i just held the gas steady. And the truck started crawling up the drive way. I could feel it applying the breaks.
I backed back down and used the locker. It went up the hill but i had to watch it. It wanted to fishtail over the hill. I had to play with the gas. But it went right up. required more driving skills lol.
4x4 i just drove up it like it was June
.Then i tried to pull in the mother in laws driveway. 2 wheel spun out put it in 4x4 and went a little farther and spun out. Locked the locker in and went right up the hill with out spinning.
I was trying to get stuck driving slow. I just wanted to see what every thing did. Thats how my truck acted 5.0 373 gears. If that matters.
I need better tires IMO.
01-02-2018, 01:55 AM
#22
If the traction control is designed and working properly with an open differential, the power will go to the wheel thats 'not' spinning.
If both wheels are spinning say on ice, it'd be a crap shoot.
In certain situations like being hopelessly stuck in snow, turning off the traction control could help.
Wish Ford would incorporate a rear LSD differential on the F150s.
The locker is useful in some situations but is limited to around 23 mph where it disengages automatically.
If both wheels are spinning say on ice, it'd be a crap shoot.
In certain situations like being hopelessly stuck in snow, turning off the traction control could help.
Wish Ford would incorporate a rear LSD differential on the F150s.
The locker is useful in some situations but is limited to around 23 mph where it disengages automatically.
Only 1 wheel pulls with an open diff, ever. Never will both wheels get power if you have an open diff, regardless of traction control.
01-02-2018, 04:34 AM
#23
What you state is entirely wrong. Both wheels get torque / power all of the time in an open differential. That is indisputable fact. The amount of torque that gets put down to the ground to each wheel is dependent on the available traction.
What I wrote earlier is the most common way of discussing open diffs and traction control.
From a purely nerdy / engineering standpoint the following is even more accurate:
In an open diff, BOTH wheels get exactly 50% each of available torque ALL THE TIME. (That is fact). There is never a time when both wheels are not getting 50% each of the torque. The amount of torque to each wheel is the amount of torque that can be applied without any wheels slipping. If one wheel slips, the amount of torque to BOTH wheels is reduced to the amount of torque necessary to cause that one wheel to slip. When both wheels are on dry pavement and not slipping, the torque put down to each wheel is thus the max the engine can put out. However, if one wheel is on ice, then the principle I just mentioned kicks in, and the torque put down to BOTH wheels is equal to the amount necessary to spin the tire on ice. It requires very little torque to keep a tire that is already spinning on ice to keep spinning. So the torque to BOTH tires is reduced to that tiny amount of torque. The tire on ice keeps spinning, and that tiny amount of torque is not even enough to rotate the tire on pavement and so you go nowhere. When traction control senses the wheel spinning on ice, it applies the brake to that wheel, essentially faking traction. Since it now requires more torque to spin that wheel with the brake applied, the torque to BOTH wheels goes back up to its normal level, and the tire on dry pavement (now with the proper amount of torque) starts rolling and you're on your way. That's how it works in an open diff. Any other way to look at it is inaccurate.
Last edited by Florida_F150; 01-02-2018 at 06:34 AM.
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01-02-2018, 06:45 AM
#24
Circling back to the OP's original post, that's the benefit of a full-locking diff. With the diff locked, a tire with traction is completely unaffected if the other tire has no traction. Each tire gets its torque regardless of what the other tire is doing. That's needed in certain off-roading situations. If you're rock crawling or going through deep washouts and a wheel comes off the ground, no problem. The wheel on the ground keeps turning and you keep moving forward. In an open diff, the wheel on the ground would get almost no torque and you go nowhere while the other wheel in the air spins.
In mud especially, you want to turn Traction Control entirely off, and use a locking diff if you have one. To get through mud you want to keep forward momentum and keep the wheels spinning to fling mud out of the treads. Traction Control would apply the brakes and slow you down, and since both tires are slipping and sliding, the Traction Control would be all over the place. Best to turn it off and use the diff lock.
Don't get me wrong. Traction Control is *AWESOME*. It's great for a huge variety of situations, and works to get you moving or when conditions are slick. My previous truck was a 4x2 Ford Ranger and traction control helped that truck go many places deep in the woods! For many, Traction Control may be all you need.
In mud especially, you want to turn Traction Control entirely off, and use a locking diff if you have one. To get through mud you want to keep forward momentum and keep the wheels spinning to fling mud out of the treads. Traction Control would apply the brakes and slow you down, and since both tires are slipping and sliding, the Traction Control would be all over the place. Best to turn it off and use the diff lock.
Don't get me wrong. Traction Control is *AWESOME*. It's great for a huge variety of situations, and works to get you moving or when conditions are slick. My previous truck was a 4x2 Ford Ranger and traction control helped that truck go many places deep in the woods! For many, Traction Control may be all you need.
01-02-2018, 09:20 AM
#25
Senior Member
Florida_F150's description is spot on. Relate it to tightening a bolt with a torque wrench. With the wrench set at 150 ft/lbs, it won't click until that torque is reached. When the bolt is loose (like when just started on the threads), no matter how hard you try, you cannot apply 150 ft/lbs of torque. The same applies to a tire with no (or very little) traction. Now, imagine if you can dial your torque wrench down low enough to that it does click when the bolt is very loose, that is how much torque the other wheel will also receive. But if you try to tighten down a bolt that is almost tight with the wrench set at that minimal torque, the wrench will click, but the bolt will not turn. Even though you are applying torque (i.e. "power"), the bolt (wheel) won't turn.
The following 2 users liked this post by jp360cj:
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01-02-2018, 11:11 AM
#26
To the OP, you can have a TrueTrac installed, cost for the unit is about $550 and I have no idea on labor since I did mine myself.
It performs somewhere in between a clutch type LSD and a true locker. It locks up much tighter than clutches ever will, but it moves just enough to not break axles on pavement.
It'll help you when pulling that boat out of the water on wet ramps. I had one on my last truck and hope to put one in this truck this summer. It performs way better than the electronic traction control, and unlike the e-locker it's always working.
It performs somewhere in between a clutch type LSD and a true locker. It locks up much tighter than clutches ever will, but it moves just enough to not break axles on pavement.
It'll help you when pulling that boat out of the water on wet ramps. I had one on my last truck and hope to put one in this truck this summer. It performs way better than the electronic traction control, and unlike the e-locker it's always working.
01-02-2018, 11:17 AM
#27
Senior Member
as an fyi on this subject. my 15 has a 3.55 e locker and if I turn off the tc and NO e locker turned on, I burn BOTH rear tires on a launch. This is a fact
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Florida_F150 (01-02-2018)
01-03-2018, 01:56 AM
#28
Open diff on a '2wd' vehicle is what is referred to as '1 wheel peel'.
01-03-2018, 01:57 AM
#29
I'm only going to respond briefly because I'm assuming you're trolling for entertainment purposes, but I do want other people reading this post not to get misinformation.
What you state is entirely wrong. Both wheels get torque / power all of the time in an open differential. That is indisputable fact. The amount of torque that gets put down to the ground to each wheel is dependent on the available traction.
What I wrote earlier is the most common way of discussing open diffs and traction control.
From a purely nerdy / engineering standpoint the following is even more accurate:
In an open diff, BOTH wheels get exactly 50% each of available torque ALL THE TIME. (That is fact). There is never a time when both wheels are not getting 50% each of the torque. The amount of torque to each wheel is the amount of torque that can be applied without any wheels slipping. If one wheel slips, the amount of torque to BOTH wheels is reduced to the amount of torque necessary to cause that one wheel to slip. When both wheels are on dry pavement and not slipping, the torque put down to each wheel is thus the max the engine can put out. However, if one wheel is on ice, then the principle I just mentioned kicks in, and the torque put down to BOTH wheels is equal to the amount necessary to spin the tire on ice. It requires very little torque to keep a tire that is already spinning on ice to keep spinning. So the torque to BOTH tires is reduced to that tiny amount of torque. The tire on ice keeps spinning, and that tiny amount of torque is not even enough to rotate the tire on pavement and so you go nowhere. When traction control senses the wheel spinning on ice, it applies the brake to that wheel, essentially faking traction. Since it now requires more torque to spin that wheel with the brake applied, the torque to BOTH wheels goes back up to its normal level, and the tire on dry pavement (now with the proper amount of torque) starts rolling and you're on your way. That's how it works in an open diff. Any other way to look at it is inaccurate.
What you state is entirely wrong. Both wheels get torque / power all of the time in an open differential. That is indisputable fact. The amount of torque that gets put down to the ground to each wheel is dependent on the available traction.
What I wrote earlier is the most common way of discussing open diffs and traction control.
From a purely nerdy / engineering standpoint the following is even more accurate:
In an open diff, BOTH wheels get exactly 50% each of available torque ALL THE TIME. (That is fact). There is never a time when both wheels are not getting 50% each of the torque. The amount of torque to each wheel is the amount of torque that can be applied without any wheels slipping. If one wheel slips, the amount of torque to BOTH wheels is reduced to the amount of torque necessary to cause that one wheel to slip. When both wheels are on dry pavement and not slipping, the torque put down to each wheel is thus the max the engine can put out. However, if one wheel is on ice, then the principle I just mentioned kicks in, and the torque put down to BOTH wheels is equal to the amount necessary to spin the tire on ice. It requires very little torque to keep a tire that is already spinning on ice to keep spinning. So the torque to BOTH tires is reduced to that tiny amount of torque. The tire on ice keeps spinning, and that tiny amount of torque is not even enough to rotate the tire on pavement and so you go nowhere. When traction control senses the wheel spinning on ice, it applies the brake to that wheel, essentially faking traction. Since it now requires more torque to spin that wheel with the brake applied, the torque to BOTH wheels goes back up to its normal level, and the tire on dry pavement (now with the proper amount of torque) starts rolling and you're on your way. That's how it works in an open diff. Any other way to look at it is inaccurate.
You are wrong but I can see you are the type who always has the only correct answer to anything.
01-03-2018, 01:58 AM
#30
This is the 2nd time you have posted this the last week or so. Stop spreading your incorrect information and do some research.
Florida_F150's description is spot on. Relate it to tightening a bolt with a torque wrench. With the wrench set at 150 ft/lbs, it won't click until that torque is reached. When the bolt is loose (like when just started on the threads), no matter how hard you try, you cannot apply 150 ft/lbs of torque. The same applies to a tire with no (or very little) traction. Now, imagine if you can dial your torque wrench down low enough to that it does click when the bolt is very loose, that is how much torque the other wheel will also receive. But if you try to tighten down a bolt that is almost tight with the wrench set at that minimal torque, the wrench will click, but the bolt will not turn. Even though you are applying torque (i.e. "power"), the bolt (wheel) won't turn.
Florida_F150's description is spot on. Relate it to tightening a bolt with a torque wrench. With the wrench set at 150 ft/lbs, it won't click until that torque is reached. When the bolt is loose (like when just started on the threads), no matter how hard you try, you cannot apply 150 ft/lbs of torque. The same applies to a tire with no (or very little) traction. Now, imagine if you can dial your torque wrench down low enough to that it does click when the bolt is very loose, that is how much torque the other wheel will also receive. But if you try to tighten down a bolt that is almost tight with the wrench set at that minimal torque, the wrench will click, but the bolt will not turn. Even though you are applying torque (i.e. "power"), the bolt (wheel) won't turn.
You have both been misinformed.