Florida_F150

I would tend to agree. I thought for a second maybe TC could do just the fronts, but if the fronts spin at same RPM as rears, that doesn't make much sense either... I'll be offroading next Monday and Tuesday, will try some experiments. See if I can get a 4-wheel peel...

2015rubyFX4

johnday in BFE

iTrader: (1)

I think you're right.
Now, how about traction control when in 4H, with an OPEN, or UNLOCKED ELD.
Could be wrong, but in my mind, it would make sense that traction control would still be active. Pretty sure ROLL and STABILITY control would still be active as well.

I do know, since the time I had my '12, and with this '17, in 4H on the highway covered with snow/ice, it amazes me how stable these trucks are. Unlike anything I've had before, and yes, even with the crappy tires on this one.

Florida_F150

Yep, traction control is definitely on when in 4H, open diff, unlocked. That's how I have it most of the time when I off-road.

If I turn on the locker, I turn off the Traction Control. (Whether or not it would have turned off automatically, still not sure...)

johnday in BFE

iTrader: (1)

Cool, just what I thought. It made sense to me.

Florida_F150

Looking forward to my "experiments" next week!

Certain parts of the Ford AdvanceTrac (the formal name for the system that controls all this stuff) definitely deal with the front wheels, since that's what keeps the car / truck from over-rotating and losing control during evasive maneuvers. (Like at the very end of the video below, the system brakes the front wheel). The TC is just a braking mechanism (along with the associated computer stuff that controls it).

Whether or not it's smart enough to prevent front wheelspin when in 4HI, we'll see. I've got my money on a nice 4-wheel peel...

2015rubyFX4

johnday in BFE

iTrader: (1)

Very good video, thanks. Gave a good explanation as to what's going on.

2WD

Big thread but I'll offer my perspective.

I have a 2WD Supercrew with ELD. While I'm sure the traction control system is good in some cases, I have experienced 2 instances where I was stuck (1 snow, 1 mud). I could not get free until I engaged the ELD - traction control alone would not do the job in those cases.

Eric Kleven

TL,DR;
Open differentials physically can not dictate if one tire or another gets more or less torque. Torque has to balance, there is no other option. If one tire exceeds its coefficient of friction, all power goes through the path of least resistance. It's the mechanical equivalent of a short circuit.

Brake-grab electronic traction control will apply brakes to the spinning tire, which puts a torque on that tire. Because an open differential must balance torque from side to side (there is physically no other option) that same torque appears at the other tire as well. There is no torque bias through an open differential, it balances at a 1:1 ratio from side to side.

Computer/system sophistication is sufficient enough that it works pretty well for normal driving, as posters on this thread have said.

I've had torque-biasing differentials installed in a '97 Mountaineer. Tru-Trac in the rear, Torsen in front. There were no drawbacks to this system, unless you don't want ALL THE TRACTION ALL THE TIME. Highly recommend the tru-trac if the computerized traction control isn't enough for you.
Bonus: the Tru-Trac had about a 3.5:1 torque bias ratio. If you were on glare ice on one side, it would be possible to spin that tire. BUT the other tire would still be getting 3.5x the torque of the spinning tire. If you factor in the brake-grab traction control, the non-spinning tire would get 3.5x the torque applied by the brake. Maybe it sounds complicated, but the result is traction and vehicle movement.
Also, the Torsen front diff from the Raptor is available from your local Ford dealer.


My God, I do miss those differentials.