Practical switching between 2H and 4H?

[timhood]

It absolutely does when accelerating around a corner and only the rear wheels are providing power. Our F150 has a limited-slip differential and I can absolutely feel the diff between 2H and 4H, and I'm not talking about absurd driving. I've felt the rear break loose a bit on the Bronco, too, but the difference there is the ESC (electronic stability control) kicks in (the old F150 doesn't have that).
I’m speaking to wet or moderately slick conditions where power to the wheels becomes limited, not icy conditions where putting down more power in 4H just means more wheels sliding breaking loose.

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[timhood]

My original post could sound like I'm switching more than I really am

That's how we've driven our 4WD F150 for the past 21 years. If I didn't have 4A in the Bronco, that's what I'd be doing.

 

[MilesTeg]

I'm not aware of Ford specifying not to use 4H above 55 mph on a Bronco. Is that documented somewhere?

Supposedly, you can run the Bronco in 4 LO at nearly that speed (according to the folks at my Offrodeo who had us all do that on the trail). I think our trail guide said 50 in 4 LO -- and he got us all up to that on the trail with us all in low range.

I still wouldn't do it on my own Bronco though, hah!

 

[MilesTeg]

Most recommendations is to do it below 55 I have never personally seen anything official but with that said….

4h is supposed to be use when the conditions warrant it. Those conditions being pretty bad generally speaking. Most people aren’t or at least shouldnt be trying to go 65mph or more on a road if the conditions warrant using 4h. Maybe I’m just more cautious than the average bear….

4HI can be used at any speed. Don't think "I'm on a bad road where it's very dangerous to go fast". Think "I'm doing a Baja course/out in the dunes in my vehicle built to do Baja".

 

[MilesTeg]

Do you really need 4 wheel drive if you are switching that much.

Yeah, as long as you are able to "go" you don't need anything but 2H. It's the stopping and not sliding through a corner that's the problem on snow/ice.

 

[MilesTeg]

I'm worrying you're implying 4wd is helping your lateral grip

4/AWD will absolutely help lateral grip if you are under power. More precisely, it will allow you to make better use of the grip that you do have.

 

[MilesTeg]

I've always thought the same thing. If you are going 50+MPH, you either don't need 4H or you need to slow down.

Although, there isn't anything limiting the Bronco to that speed - there is a governor - somewhere around 104 mph in High and 38 mph in Lo - but it doesn't care if you are in 2wd or 4wd. Just if you are in conditions where you need the additional traction, you probably don't need the speed.

The Bronco is definitely not governed at 38 MPH in Lo -- or all the Broncos at my Off-Rodeo were modified. You can go at least 50MPH (source: our trail guide had us all go ~45-50MPH in low).

I thought it was crazy, and would never do it in my own vehicle (nor advise anyone to do it in theirs), but we all did it and listened to the trail guide assure us Ford had built the transfer case to handle it.

 

[idontknow]

4HI can be used at any speed. Don't think "I'm on a bad road where it's very dangerous to go fast". Think "I'm doing a Baja course/out in the dunes in my vehicle built to do Baja".

You’re not wrong in that case.

I was going more in the context of the OPs original question of Minnesota winter road driving.

 

[MilesTeg]

You’re not wrong in that case.

I was going more in the context of the OPs original question of Minnesota winter road driving.

Oh absolutely! If you think you need 4 wheel drive on a road, you shouldn't be going fast.

 

[Brian_B]

The Bronco is definitely not governed at 38 MPH in Lo -- or all the Broncos at my Off-Rodeo were modified. You can go at least 50MPH (source: our trail guide had us all go ~45-50MPH in low).

Mine definitely is. And given that the transfer cases are roughly 3:1 reduction in 4Lo, that nets out to about the same engine/transmission parameters as 104 in Hi - assuming the governor is looking at something there and not actual wheel speed sensors.

I'll point to this thread as well for some others.
https://www.bronco6g.com/forum/threads/top-speed-in-4l.59413/

I'm not saying you didn't do that at Off Roadeo...

 

[broncobase1]

It sounds to like you are doing it the correct way. What I do is try and get ahead of the game and switch to 4WD or 2WD before it is needed. If I know I'm about to turn on to a dry road I'll switch to 2WD before I get there. It works well, and if you happen to get caught in 4WD on dry pavement its not going to break anything. Having lived in the salt belt with only 2WD my entire life, I usually stay in 2WD unless conditions are pretty bad. Snow covered roads, no problem. If things are icy or deep snow, then I'll go to 4WD. Honestly, I prefer doing this manually over having the complexity of 4A.

 

[Techun]

4/AWD will absolutely help lateral grip if you are under power. More precisely, it will allow you to make better use of the grip that you do have.

If you are sending power (or braking force) to the front, the front wheels will have less grip available laterally. This can be a good thing, because you will understeer instead of spinning out.

Your max grip in a corner will be when not applying power or braking force, and so being in 4wd won't help with that.

If you NEED to add throttle while in a turn...well you're probably better off slowing down if you're that close to spinning out.

 

[MilesTeg]

If you are sending power (or braking force) to the front, the front wheels will have less grip available laterally. This can be a good thing, because you will understeer instead of spinning out.

Your max grip in a corner will be when not applying power or braking force, and so being in 4wd won't help with that.

If you NEED to add throttle while in a turn...well you're probably better off slowing down if you're that close to spinning out.

The situations that are most illustrative are situations like taking a turn at an intersection from a stop, or if you just screw up and don't realize it's as slick as it is.

Regardless of the reason you are in a particular situation, 4/AWD does provide you with more ability to avoid losing grip in turns when under power. It does so by splitting the torque you are trying to apply to all 4 wheels instead of 2, minimizing the net force acting on each wheel.

 

[Techun]

The situations that are most illustrative are situations like taking a turn at an intersection from a stop, or if you just screw up and don't realize it's as slick as it is.

Regardless of the reason you are in a particular situation, 4/AWD does provide you with more ability to avoid losing grip in turns when under power. It does so by splitting the torque you are trying to apply to all 4 wheels instead of 2, minimizing the net force acting on each wheel.

You are talking about multiple things at once.

Yes 4wd will help you from spinning out from a stop by removing some demands from the rear wheels and putting them on the fronts. That will result in understeer when the limit is reached instead of oversteer.

The fact remains that your max cornering ability (say can you take a snowy corner at 30mph) will not be improved by being in 4wd.

 

[MilesTeg]

You are talking about multiple things at once.

Yes 4wd will help you from spinning out from a stop by removing some demands from the rear wheels and putting them on the fronts. That will result in understeer when the limit is reached instead of oversteer.

The fact remains that your max cornering ability (say can you take a snowy corner at 30mph) will not be improved by being in 4wd.

No, as I said in my original post, 4WD helps you in turns by allowing you to make better use of the traction you do have, which is of course all 4WD (or ABS, or traction control, etc.) ever does in any situation. The only thing that gives you more traction is better tires or traction aids (studs, chains, etc.).

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