How does the 4x4 "Auto" mode actually work?
#1
12-09-2016, 07:11 AM
How does the 4x4 "Auto" mode actually work?
So, I have a 2017 Super Duty, and of course no 4x4 auto mode is offered. However, I understand one has been optional on the F-150 starting in 2013 with higher trims.
I'm quite familiar with how the GM trucks work with their 4-auto setting. Basically, the electric transfer case shifter motor ramps up varying pressure on a clutch in the transfer case, based upon speed differences between the front and rear driveshafts. 4x4 Hi and Low provide full pressure on the clutch and "lock" the front and rear shafts together.
Is this how it works in the Ford? My thinking is that with lots of 4-auto use, the clutch could eventually wear out...and even in 4x4 Hi or 4x4 Low, the clutch is still in place, meaning extreme use of throttle, particularly in 4-low, could wear the clutch. Overside tires would wear the clutch when using 4WD.
That would make sense why neither GM nor Ford offer an auto setting in their HD trucks.
Anyone have info or a technical writeup?
I'm quite familiar with how the GM trucks work with their 4-auto setting. Basically, the electric transfer case shifter motor ramps up varying pressure on a clutch in the transfer case, based upon speed differences between the front and rear driveshafts. 4x4 Hi and Low provide full pressure on the clutch and "lock" the front and rear shafts together.
Is this how it works in the Ford? My thinking is that with lots of 4-auto use, the clutch could eventually wear out...and even in 4x4 Hi or 4x4 Low, the clutch is still in place, meaning extreme use of throttle, particularly in 4-low, could wear the clutch. Overside tires would wear the clutch when using 4WD.
That would make sense why neither GM nor Ford offer an auto setting in their HD trucks.
Anyone have info or a technical writeup?
#2
12-09-2016, 11:02 AM
I'm curious as well. The steering definitely feels different when in 4A. It's heavier and the front end feels more planted, almost like the system was fully engaged. But it doesn't bind up when turning. I used it this morning in the snow and it worked really well. I typically use it when needing to merge quickly onto a busy street and the wet roads make things too slick.
#3
12-09-2016, 11:16 AM
I'm curious as well. The steering definitely feels different when in 4A. It's heavier and the front end feels more planted, almost like the system was fully engaged. But it doesn't bind up when turning. I used it this morning in the snow and it worked really well. I typically use it when needing to merge quickly onto a busy street and the wet roads make things too slick.
I'm guessing the Ford system is very similar. GM uses Magna to make its auto t-cases and Ford uses Borg Warner. There are plenty of writeups online about the GM system but I cannot find anything on the Ford.
I'm also looking to try and find out who is making the transfer cases in the 2017 Super Duty; it is a new unit for this year. Previously, it was always NVG / Ford clone.
#4
12-09-2016, 12:05 PM
The system is the same basic system Ford has used since 1995 in the Explorer and it was called "Control Trac 4x4". It locks the front end in so it's turning and the transfercase clutch engages the front driveline as slippage is detected from the rear wheels.
My 2011 F-150 limited has it, they called it "AWD" then, which it is not. But when you put it in A4x4 or "AWD" the front hubs are engaged the same as in 4x4, then as you already described the front axle is engaged as needed by the clutch in the transfercase. They have used this type of system on the 2006-2010 Harley Davidson F-150's also.
My '96 Explorer had 150k miles on it and it's early BW case and still worked well when it was totaled. I do know the 99-02 Expeditions that use the same system have an issue with the clutch getting stuck or locking up causing it to be in 4x4 all the time and bind on high mile units, these trucks did not have a 2wd setting.
I'm sure some improvements have been made over the years but the basic system is the same.
https://en.wikipedia.org/wiki/ControlTrac
My 2011 F-150 limited has it, they called it "AWD" then, which it is not. But when you put it in A4x4 or "AWD" the front hubs are engaged the same as in 4x4, then as you already described the front axle is engaged as needed by the clutch in the transfercase. They have used this type of system on the 2006-2010 Harley Davidson F-150's also.
My '96 Explorer had 150k miles on it and it's early BW case and still worked well when it was totaled. I do know the 99-02 Expeditions that use the same system have an issue with the clutch getting stuck or locking up causing it to be in 4x4 all the time and bind on high mile units, these trucks did not have a 2wd setting.
I'm sure some improvements have been made over the years but the basic system is the same.
https://en.wikipedia.org/wiki/ControlTrac
#5
12-09-2016, 12:58 PM
#6
12-09-2016, 01:10 PM
The ControlTrac system is very similar to the GM system. You may be correct about it being used in a few other Fords along the way, but the 2013 F-150 system is something new. There was a write-up online about it a few years back but I cannot seem to find it.
Will keep searching.
Will keep searching.
In 2012 they started offering the A4x4 on lariat and up trucks. This system is the same in how it works as the 2011 Harley/Limited trucks, exception being that they did not have a low range function.
The way the system works though is the same, front hubs engage and the clutch in the transfer case dictates when the front gets power.
----------------------------------------------------------------------
2-speed Automatic 4WD System (1)
• Optimizes traction by transferring power to the appropriate wheels when needed
• The system provides four available modes of operation and is activated by using a rotary switch on the instrument panel
2H (HIGH)
• Vehicle operates as a rear-wheel-drive vehicle
when 2H is engaged
• Helps vehicle provide optimal fuel economy
4A (Automatic Four-Wheel Drive)
• Set-and-forget function provides four-wheel-
drive capabilities when needed
• Under normal road conditions, most power is sent to the rear wheels
• As road conditions require, engine torque is sent to the front and/or rear wheels to help maintain optimum traction
• Setting is appropriate for any driving, whether on dry pavement or in adverse conditions
4H (HIGH)
• Setting provides electronically locked four-wheel- drive power to both the front and rear wheels for use at normal speeds on low-traction surfaces
• Intended for use only in severe weather and off- road conditions including snow, ice, sand or mud
• Setting should never be used on dry pavement
4L (LOW)
• Setting provides four-wheel drive with full power to both the front and rear wheels and includes
a lower gear reduction ratio for increased torque multiplication to all four wheels
• Intended only for off-road applications that require extra power including deep sand, steep grades or when launching or pulling a boat out of water
• Setting should never be used on dry pavement
(1) Include on Lariat 4x4 models and above. July 2011.
Auburn Hills, Michigan, March 22, 2012 – BorgWarner will supply Torque-On-Demand® (TOD®) two-speed transfer cases for the 2012 Ford F-150 Lariat, King Ranch and Platinum models. The first two-speed active all-wheel drive system for F-150 trucks will feature 4-high, 4-low, full-time and automatic all-wheel drive modes. Built with the same high reliability as its previous part-time shift-on-the-fly transfer cases, BorgWarner’s TOD active all-wheel drive technology delivers improved traction, stability and dynamics. Since 2006, BorgWarner has also produced single-speed TOD transfer cases for the F-150 Harley-Davidson edition.
“BorgWarner’s TOD technology automatically redistributes torque from the rear wheels to the front wheels without driver intervention,” said Joe Fadool, President and General Manager, BorgWarner TorqTransfer Systems. “BorgWarner is pleased to continue our long partnership with Ford, providing F-150 drivers with seamless traction control whether driving off-road or on-highway, in normal or difficult weather conditions.”
The vehicle’s control systems monitor signals such as steering wheel angle, accelerator pedal position and wheel speeds, commanding the TOD transfer case to deliver the required amount of torque to the front and rear axles. With both high and low range capability, drivers will appreciate automatic all-wheel drive benefits in a broad range of driving situations, from normal driving to off-roading to towing. By predicting slip and providing pre-emptive torque, TOD technology improves traction, increases stability and enhances vehicle dynamics. BorgWarner also supplies a number of other technologies for the Ford F-150, including timing drives for all models, variable cam timing phasers for the 5.0-liter Coyote and 6.2-liter Boss engines, HY-VO® chain for models with TOD and part-time transfer cases, friction plates for the six-speed automatic transmission, and turbochargers for the 3.5-liter EcoBoost® engine.
“BorgWarner’s TOD technology automatically redistributes torque from the rear wheels to the front wheels without driver intervention,” said Joe Fadool, President and General Manager, BorgWarner TorqTransfer Systems. “BorgWarner is pleased to continue our long partnership with Ford, providing F-150 drivers with seamless traction control whether driving off-road or on-highway, in normal or difficult weather conditions.”
The vehicle’s control systems monitor signals such as steering wheel angle, accelerator pedal position and wheel speeds, commanding the TOD transfer case to deliver the required amount of torque to the front and rear axles. With both high and low range capability, drivers will appreciate automatic all-wheel drive benefits in a broad range of driving situations, from normal driving to off-roading to towing. By predicting slip and providing pre-emptive torque, TOD technology improves traction, increases stability and enhances vehicle dynamics. BorgWarner also supplies a number of other technologies for the Ford F-150, including timing drives for all models, variable cam timing phasers for the 5.0-liter Coyote and 6.2-liter Boss engines, HY-VO® chain for models with TOD and part-time transfer cases, friction plates for the six-speed automatic transmission, and turbochargers for the 3.5-liter EcoBoost® engine.
https://www.borgwarner.com/en/news-m...the-ford-f-150
#7
12-09-2016, 01:21 PM
Russ -
Thanks, you are correct. The Borg-Warner writeup was what I had seen, and apparently the year was 2012, not 2013.
So this system must use a clutch upstream of the front output shaft?
The new Raptor system takes great pains to basically explain that the clutched systems are not "heavy duty" and so it offers both 'clutched' and 'fully mechanically locked' like a Super Duty or non-auto F-150 transfer case.
Thanks, you are correct. The Borg-Warner writeup was what I had seen, and apparently the year was 2012, not 2013.
So this system must use a clutch upstream of the front output shaft?
The new Raptor system takes great pains to basically explain that the clutched systems are not "heavy duty" and so it offers both 'clutched' and 'fully mechanically locked' like a Super Duty or non-auto F-150 transfer case.
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#8
12-09-2016, 01:36 PM
#9
12-09-2016, 01:50 PM
My dad has a 2016 F-150 Crew 4x4 2.7L, BTW, so I'm not out of touch with the new F-150's. Driven it quite a bit, nice vehicle. Shared cabs, so very familiar at this point.
#10
12-09-2016, 01:52 PM
Tuned
#11
12-09-2016, 02:00 PM
#13
12-09-2016, 06:36 PM
Remember seeing this video a few years ago regarding the BorgWarner TOD system:
Quite jealous...this is possibly the biggest object of desire that comes on the Lariat trims. The conventional system in my current truck is quite capable, but there are plenty of situations that I can't use it...like turning out onto dry pavement with the rear wheels on snow. My wife has had an AWD minivan and SUV in the past, and I vastly prefer this kind of system for driving in snow. I shouldn't complain though, I really like my truck. Kinda wish all models got it though.
Quite jealous...this is possibly the biggest object of desire that comes on the Lariat trims. The conventional system in my current truck is quite capable, but there are plenty of situations that I can't use it...like turning out onto dry pavement with the rear wheels on snow. My wife has had an AWD minivan and SUV in the past, and I vastly prefer this kind of system for driving in snow. I shouldn't complain though, I really like my truck. Kinda wish all models got it though.
#14
12-10-2016, 09:50 AM
I have a 2016 lariat 2.7 with the 4A. Seems to work well enough and I definitely can tell there is some force being applied to the front steering but not enough to make it difficult. I still prefer just turning on 4x4 high though. Although in all fairness my studded hakkepelitta lt2's probably add to the friction as well. As well as the fact it sounds like i'm running chains in parking lots. 
#15
12-10-2016, 02:40 PM
I've never had an issue leaving my other trucks with conventional systems in 4 high in situations like this. If the rear tires are on a slick surface it won't bind enough to hurt anything. The binding is only ever a real issue on tight turns at least in my experience.
I have to cringe a little at the gas station and in parking garages (pure dry pavement situation in the winter) when I hear someone making a turn at full lock when still in 4 high with any typical 4x4 truck/suv, they buck and jump and the drivers seem clueless, never have seen a major failure from it though.
That said, I do absolutely love the AWD system in my Chrysler 300c and the 96-01 V8 Explorer's, constant front power with a vicarious coupler giving 50/50 if/when needed.