4A vs 4H Snow driving

[JExpedition07]

Both are true. Ask anyone running same tire pressures front and rear to engage 4h (ESOF, not TOD) and ask them if it's growling running perfectly straight. Yes, yes it is.

Mine doesn’t. I had to drive 55 MPH in 4-High two days ago after I got to a clear spot on the thruway after driving through 2-3” deep stuff for a while. No noises. Only noises when you steer on a semi dry road.

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[DEEPDOWN]

Both are true. Ask anyone running same tire pressures front and rear to engage 4h (ESOF, not TOD) and ask them if it's growling running perfectly straight. Yes, yes it is.

Yes, but that is a marginal reason for the locking/grinding, and is still related to the lack of differential action between the front and rear. Even with wildly different wheel circumferences, 4A (All-Wheel Drive)can compensate for different front and rear wheel rotation speeds in the same way front and rear diffs can compensate for differences in left and right wheel speeds.

 

[Samson16]

4A (All-Wheel Drive) can can compensate for different front and rear wheel rotation speeds in the same way front and rear diffs can compensate for differences in lady and right wheel speeds.

For those of us without 4A trying to maintain close to equal rotational speeds front to rear will help mitigate the binding yes?

Some combination of additional weight to the rear and tire psi are helpful toward that end.

 

[powerboatr]

So what else does Slippery or Snow (whatever it is) mode do, other than switching to 4A?

i noticed here last year the slippery mode also seems to reduces throttle response to a slower rate, i guess to help prevent spinnng
it also feels like truck is being held back a bit.
it worked pretty good, but the tires OEMs are a weak link in icy slush stuff

 

[Oxford_Powerboost]

4A definitely has steering angle as an input…coming out of a steep snow-covered driveway on a turn, the front wheels seem to disengage when the steering wheel is at full-lock. Never an issue though, more of an observation.

I noticed this yesterday. Normally 4A has the front doing at least some work all the time but yesterday I was in a grassy field with 5-6 inches of snow - I had been using 4A on the gravel roads and it was great but tooling around in that field showed me it didn’t want to send power up front steering at full lock. Only initially though. Once the rears slipped it kicked the front back in even at full lock.
But in this case I switched over to 4Hi so as not to tear up the field lol. 4A would’ve been fine, just not as graceful

 

[Spiffers]

I haven't even gotten mine out. Neighbor has been out and about in his Ram but I don't know if it has 4A or not. I've been rolling around in my old AWD explorer and she's been the beast she always has been. 25 years old and still getting us where we need to go when nothing else goes.

 

[gtotco]

I’ve had 4A enabled for the past week here in Michigan. I came from having an XLT with 2H/4H/4L, and realized I definitely wanted 4A for everyday winter driving.

4H worked great last Friday in the deep snow, and I usually use Deep Snow/Sand mode when the deep slush and snow start pulling the truck around on the back country roads. Really helps to keep the revs high for momentum (plus the locker).

Something I just noticed this week is that 4A does not seem to “rotate” the truck as much when you’re briskly accelerating on snow or ice and is much more predictable.

4A definitely has steering angle as an input…coming out of a steep snow-covered driveway on a turn, the front wheels seem to disengage when the steering wheel is at full-lock. Never an issue though, more of an observation.

I’ve got Blizzaks on the truck too and it’s an absolute dream to drive in the snow. Subzero temps, the PB don’t care!

I’m not sure steering angle is an input so much as it just works like any AWD system in that it reduces power to automatically to keep wheel spin constant. There are mechanical fluid based AWD systems that manage this without additional “inputs”. While im sure this electronic im guessing the system just works to just allow more slip on the inside wheel based on torque (I’m not an engineer so someone who understands this shit better can correct me).

That aside - you are correct that the point is to be more predictable - just like any other AWD system. AWD is great at any sort of speed and if you are driving is going to be better than 4wd because of the predictability. Where true 4wd is going to be best is low speed “I’m stuck” where you want power to all 4 wheels so whatever grabs grabs and you are okay with some wheel spin to get there. Same reason you turn traction control over when you are stuck; or if you are launching you want some wheel spin so you aren’t losing power due to disengagement to prevent wheel spin.

If you are driving at a rate of speed high enough for 4wd to provide this sort of “advantage” you probably want the power loss from 4A/AWD type system so you don’t suddenly kick the rear end out or do something else surprising. My first vehicle was a manual RWD vehicle and I definitely remember at least ones accidentally spinning out while driving on an icy road and ending up backwards and it’s not a pleasant experience. When you know it’s coming though and can rev it up and drop down a few gears to get the back tires spinning on a dirt road though? That’s the dream.

Edit: also fwiw if I want to get a bit rowdy and have some fun drifting on a dirt road or in some soft snow as someone who isn’t an expert driver 4wd is my favorite for this. AWD is usually too good and have trouble getting it to let go, and RWD it’s too easy to over rotate the back end. A good 4WD system is perfect IMHO to get all 4 wheels spinning with the rear wheels ideally letting just a bit more loose so you can get a good sideways drift and then reengage into a straight line. Again someone who is a much better driver than I will tell my why I’m wrong, but 4wd is where I always have the most fun.

 

[js312]

So what else does Slippery or Snow (whatever it is) mode do, other than switching to 4A?

In my 2020, it impacted how 4A behaves. For example, it would continue sending power to the front wheels around sharp corners. In normal mode it takes it away to avoid binding. If you watch the power distribution screen in normal vs slippery mode, you can see the difference.

I assume the Gen14 trucks behave similarly, but I haven't compared on my 2023 yet.

 

[Jefe2369]

21 F150 Lariat 5.0. I was using 4A recently in MD in about 4-6 inches of snow. It almost felt like it was engaged permanently. It felt like I was driving a freight train and very throttle responsive. In my 16 same configuration I could feel it engage when necessary due to a slight slip or about to slide. Anyone get this impression?

 

[MTMan]

Interesting all the different experiences. I’m running studs unloaded in 4A slippery and it’s working great! 4H would be for deep snow if you have the 4A case. In 4H always think about how you might bind up the drivetrain such as a dry intersection on a turn where it’s been cleared. In those instances shift in 2H until you straighten out.

 

[HammaMan]

Interesting all the different experiences. I’m running studs unloaded in 4A slippery and it’s working great! 4H would be for deep snow if you have the 4A case. In 4H always think about how you might bind up the drivetrain such as a dry intersection on a turn where it’s been cleared. In those instances shift in 2H until you straighten out.

If you have the TOD (lariat/platinum/KR) the clutch slippage will always be the weak link / protects driveline. XL/XLT/Raptor and non TOD tremors are a different animal entirely in 4H vs the TOD's slippable 4H. For wet/slippery roads TOD is the way to go which is why I swapped my XLTs out.

 

[Davexxxx]

My drive has 2, 90 degree turns and almost all of it has an uphill bias. Say, 6 -7' in 100'.

We had 2-3" of ice / sleet /snow mix, with 5" of powder on top. Used slippery (w/ AWD) and it crawled out of there with no problem.

The main roads were mostly clear but the sides weren't. It handled stops on hills with very little slippage. Felt good.

This is my first AWD and first meaningful snow, since getting this truck. I was pleased.

Any 2WD truck, would have been spinning all over and maybe stuck on some of the intersections but there was no need to even test 4WD.

I don't know why people think the OEM Goodyear ATs aren't good. I don't know that I'd trust them in rocks, as they seem a bit soft but for my current needs, I like them.

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