4x4 question - Page 2 - Ford Truck Enthusiasts Forums

Notices
2015+ F150 Discuss the 2015 Ford F150
Sponsored by:
Sponsored by:

4x4 question

  #16  
Old 10-11-2018, 03:37 PM
nemosdad
nemosdad is offline
Freshman User
Join Date: Jan 2011
Posts: 31
nemosdad is starting off with a positive reputation.
It does indeed have intelligent 4wd. It's called slip logic and it uses advance trac as part of the slip logic control. There is a reason the trucks come with both two wheel in addition to one wheel spin control. 4Lo doesn't disengage one wheel spin control. It does disengage the advance trac and traction control.
 
  #17  
Old 10-11-2018, 03:54 PM
ford390gashog's Avatar
ford390gashog
ford390gashog is offline
Post Fiend
Join Date: Jan 2004
Location: Brentwood,CA
Posts: 15,902
ford390gashog is a splendid one to beholdford390gashog is a splendid one to beholdford390gashog is a splendid one to beholdford390gashog is a splendid one to beholdford390gashog is a splendid one to beholdford390gashog is a splendid one to beholdford390gashog is a splendid one to beholdford390gashog is a splendid one to behold
"Slip logic"? Now you are just creating names. Here is the list of 2018 vehicles from Ford with it. There is no system in a F150 (Exception Being Raptor 2017+ With terrain management and hybrid Borg Warner TOD that has conical clutch and electric locking transfer case)functions as you describe. You also mentioned brake temperature being monitored in another post. There isn't a brake temperature sensor to be found. So I am not sure where you are getting this information. Can you provide a source to this?


Which Ford Models Can Be Equipped with Intelligent 4WD?
Which Ford models can be equipped with Intelligent 4WD? Take a closer look at the Ford cars and crossovers that employ this innovative drivetrain technology.
  • 2018 Ford Fusion
  • 2018 Ford Taurus
  • 2018 Ford EcoSport
  • 2018 Ford Escape
  • 2018 Ford Edge
  • 2018 Ford Explorer
  • 2018 Ford Expedition
  • 2018 Ford Flex
 
  #18  
Old 10-11-2018, 04:20 PM
nemosdad
nemosdad is offline
Freshman User
Join Date: Jan 2011
Posts: 31
nemosdad is starting off with a positive reputation.
I'll try to find the video Mike Levine did way back in 2009 that describes the intelligent slip logic (his words). I am in no way implying that that the part time transfer case is like AWD. It'll never change the power split from 50/50 when locked and power is 100% rear when in 2wd.
The post I was replying to is about how the open diffs work like traction lock (posi) and how both the front and rear axles (all four tires have speed sensors) work together in 4Hi to allow all four wheels to turn at relatively the same speed with out actually locking the rear diff. The system detects slip at all four wheels and uses the slip logic to determine how much slip to let go and how much power to cut.
 
  #19  
Old 10-11-2018, 08:17 PM
Wiggums's Avatar
Wiggums
Wiggums is offline
Elder User
Join Date: Jun 2012
Posts: 852
Wiggums has a good reputation on FTE.Wiggums has a good reputation on FTE.Wiggums has a good reputation on FTE.
The cars with Intelligent 4WD... isn't that AWD? It's always on. It's separate from 4WD.
 
  #20  
Old 10-11-2018, 08:56 PM
nemosdad
nemosdad is offline
Freshman User
Join Date: Jan 2011
Posts: 31
nemosdad is starting off with a positive reputation.
I don't have AWD Wiggums. I didn't realize that was an official name for the AWD system. My bad.
.
I hope the link works. It's essentially for two wheel drive testing and the trucks that do well have LSD. However the TC system is virtually the same in the sense that the brakes are limiting the slip,( not the LSD) to whatever extent the computer deems necessary.
2011 was the last year of the LSD for a reason. The LSD only really kicks in if you overheat the brakes.
The TC system has been refined every year since it was introduced.
 
  #21  
Old 10-11-2018, 09:30 PM
00t444e's Avatar
00t444e
00t444e is online now
Elder User
Join Date: May 2017
Location: Southern OH
Posts: 884
00t444e is gaining momentum as a positive member of FTE.
There is a lot of misinformation on this thread. First of all an open differential always sends equal torque to both wheels, since energy always takes the path of least resistance the amount of torque that goes to both wheels is determined by the wheel that has the least traction. So for example say it takes 200 ft lbs of torque to move a vehicle but one wheel is on a slick surface that only requires 50 ft lbs of torque to spin it, the wheel with the least resistance will spin but both wheels are getting an equal amount of torque. A limited slip differential also known as posi track and a few other names uses either clutches or gears depending on the type to transfer torque from the wheel with the least resistance to the wheel with greater traction. A locking differential locks both wheels to spin at the same speed regardless of torque. Traction control does two things it reduces engine power and applies the brake to the spinning wheel so it takes more torque to turn it which therefore sends more torque to the other wheel that has greater traction. Some traction control systems only reduce engine power, some only apply the brakes and some do both. Traction control is not desirable in most off road conditions because you need wheel speed to get through or over many obstacles and traction control is designed to limit wheel speed. Traction control applying the brakes to the spinning wheel is not the same thing as a limited slip transferring torque to the wheel with greater traction, the traction control is resisting acceleration, where as a limited slip is not.
 
  #22  
Old 10-11-2018, 10:16 PM
nemosdad
nemosdad is offline
Freshman User
Join Date: Jan 2011
Posts: 31
nemosdad is starting off with a positive reputation.
https://oppositelock.kinja.com/your-...rks-1661277563
Scroll down the LSD portion bout half way down. Torque bias ratio. A LSD with one wheel in the air or on ice or other slippery surface will transfer no power from the free spinning wheel. Any amount of force times zero is zero.
Your post is mainly accurate. However in order to transfer torque, even in LSD, you still need some kind of resistance applied. That's why old school LSD needed an application of the good old brake pedal to get the wheel in the air to transfer torque across to the other wheel. It won't do it on its own.

An electronic locking limited slip differential overcomes these issues. Using a friction material to transfer torque at the end of the axle is the exact same thing as a friction material to transfer torque at the differential. They both do the exact same thing.

Power robbing from the engine is a big problem for most off-roading but not all. The video shows what happens when the computer takes over and limits power and slippage. It's superior in this application. However if the TC was allowed to do its job without power robbing than I think most would prefer it. 4Lo does this by keeping one wheel spin control active on both front and rear axles but stops the power loss.

The point I'm mainly making is that with Traction Control, Elsd, and anti-slip logic (minus the power robbing which I hate), It is about as good as it gets for a factory off roader. Far superior to anything without a computer.

This is also why the elsd is quite useful in numerous situations where a locked rear diff will have you go nowhere.
 

Last edited by nemosdad; 10-11-2018 at 10:20 PM. Reason: addition
  #23  
Old 10-11-2018, 10:34 PM
00t444e's Avatar
00t444e
00t444e is online now
Elder User
Join Date: May 2017
Location: Southern OH
Posts: 884
00t444e is gaining momentum as a positive member of FTE.
Originally Posted by nemosdad View Post
https://oppositelock.kinja.com/your-...rks-1661277563
Scroll down the LSD portion bout half way down. Torque bias ratio. A LSD with one wheel in the air or on ice or other slippery surface will transfer no power to the free spinning wheel. Any amount of force times zero is zero.
Your post is mainly accurate. However in order to transfer torque, even in LSD, you still need some kind of resistance applied. That's why old school LSD needed an application of the good old brake pedal to get the wheel in the air to transfer torque across to the other wheel. It won't do it on its own.

An electronic locking limited slip differential overcomes these issues. Using a friction material to transfer torque at the end of the axle is the exact same thing as a friction material to transfer torque at the differential. They both do the exact same thing.
Only the gear driven limited slips are torque biasing and if you have one wheel in the air you can hit the brakes and it will give it enough torque to transfer to the other. Clutch type limited slips have a set pre-load on the clutches that works even if one wheel has no resistance , and some like the Powerlock will increase the pressure on the clutches when it starts slipping. The big disadvantage to clutch limited slips is they do wear out and lose their effectiveness and most of them aren't set up tight enough from the factory to work that well, to begin with. Traction control applying brakes to a spinning wheel is adding resistance and slowing that wheel down, where as a limited slip doesn't add any resistance to the spinning wheel or slow it down it transfers torque before it even gets there. Also traction control takes time to react, but a limited slip is always working.
 
  #24  
Old 10-11-2018, 10:47 PM
nemosdad
nemosdad is offline
Freshman User
Join Date: Jan 2011
Posts: 31
nemosdad is starting off with a positive reputation.
Yes a limited slip is always working but you can't rewrite the laws of physics. A billion foot pounds of resistance times zero is zero. If the bias ratio is 4:1 with the free spinning wheel being zero resistance the equation comes out to the same. Zero.
A clutch type LSD works by transferring toque (if it can) by robbing power from the free wheeling tire to the higher traction tire. Same exact thing as applying the brakes. It's the engine cutting power so grip can actually be established that snags people in mud, sand and deep snow. In these cases though I'd rather have a locked diff with two wheel spin control.

If you've ever gone up a hill in a snowy icy situation and the rear of the truck moves side to side, that's torque bias in action. It also lets you keep some momentum, where locked diff will have you spun out side ways before you get 3 feet.
 

Last edited by nemosdad; 10-11-2018 at 10:48 PM. Reason: can't spell
  #25  
Old 10-11-2018, 11:00 PM
00t444e's Avatar
00t444e
00t444e is online now
Elder User
Join Date: May 2017
Location: Southern OH
Posts: 884
00t444e is gaining momentum as a positive member of FTE.
A clutch limited slip doesn't rob any power from the spinning wheel, the clutches are keeping constant pressure to keep both wheels spinning at the same speed yet still allow some slip for taking turns on pavement. If you are in a situation where you need wheel speed like a hill climb of powering through a mud hole, you need momentum and wheel speed, traction control would trying to keep both wheels spinning by applying the brakes which would create extra resistance, heat, and a loss of energy and momentum. A limited slip or locker in the same situation would do none of that because both wheels would be spinning to begin with. However on a slow more technical type off offroading like rockcrawling where you are lifting tires, and don't need much wheel speed or momentum, brake bias traction control would work pretty well.
 
  #26  
Old 10-11-2018, 11:24 PM
nemosdad
nemosdad is offline
Freshman User
Join Date: Jan 2011
Posts: 31
nemosdad is starting off with a positive reputation.
Okay. The clutch type lsd does what? It transfers power (if there is some kind of resistance) to the wheel with more grip. How? It robs power from one wheel and tries to give some to the other. It does this by stealing power from the free wheeling tire. Using the brakes does the same thing. It steals power from the free wheeler and transfers some to higher grip tire. Same thing. Nice thing about the computer TC is that you can get a 50/50 torque bias(or as close as it needs to be) if the truck has one wheel in the air.

I'm curious. Did you read the article? It's quite in depth but worth going over a few times.
 
  #27  
Old 10-12-2018, 05:45 AM
00t444e's Avatar
00t444e
00t444e is online now
Elder User
Join Date: May 2017
Location: Southern OH
Posts: 884
00t444e is gaining momentum as a positive member of FTE.
Originally Posted by nemosdad View Post
Okay. The clutch type lsd does what? It transfers power (if there is some kind of resistance) to the wheel with more grip. How? It robs power from one wheel and tries to give some to the other. It does this by stealing power from the free wheeling tire. Using the brakes does the same thing. It steals power from the free wheeler and transfers some to higher grip tire. Same thing. Nice thing about the computer TC is that you can get a 50/50 torque bias(or as close as it needs to be) if the truck has one wheel in the air.

I'm curious. Did you read the article? It's quite in depth but worth going over a few times.
Yes I read it and it confirms what I have been saying. It talks about torque biasing limited slips which are the gear driven ones like the Detroit truetrac, or Torsen, they don't rob power from the spinning wheel they use the available torque and increase it so more will transfer to the other wheel. Clutch limited slips also don't rob power from a spinning wheel, they are constantly holding pressure to keep both wheels spinning, if only one wheel does start to spin then you have overcome it's torque transferring ability, but it still never robs power or keep that wheel from spinning. Try doing a burnout with a limited slip and no traction control and you will have no problem, but try it with traction control and an open differential and you likely won't be able to do one, or it will take much more torque since it will be applying the brakes when one wheel starts spinning.
 
  #28  
Old 10-14-2018, 05:16 AM
Ancona
Ancona is offline
Senior User
Join Date: May 2007
Posts: 155
Ancona is starting off with a positive reputation.
Here is a good video explained clutch type LS. Using the brakes does not do the same thing as a LS.

 
  #29  
Old 10-14-2018, 07:29 AM
ArmamentDawg's Avatar
ArmamentDawg
ArmamentDawg is offline
Senior User
Join Date: Sep 2005
Location: Newport News, VA
Posts: 226
ArmamentDawg is starting off with a positive reputation.
Originally Posted by Wiggums View Post
The cars with Intelligent 4WD... isn't that AWD? It's always on. It's separate from 4WD.
AWD and 4WD systems are two totally different systems. In an AWD system all four wheels are driven all the time. You cannot switch between 2 and 4 wheel drive. AWD has a center differential that automatically splits power distribution between the front and rear differentials. A 4WD as in what we have in the F150 is always in 2WD mode and allows you to manually select 2WD,4WH and 4WL based on your driving conditions. The Ford Explorer Sport and Taurus SHO all have AWD. One negative aspect of AWD systems is that you cannot change or replace ONE tire. You have to replace all tires to maintain the same diameters. Because doing so will cause the difference in tire diameters to cause the differential to always thing there is wheel slip based on different diameters forcing different rotation per mile. It cases the premature failure of the differentials.
 
  #30  
Old 10-15-2018, 12:24 AM
Ancona
Ancona is offline
Senior User
Join Date: May 2007
Posts: 155
Ancona is starting off with a positive reputation.
And there is also full time 4WD.
 


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: