Practical switching between 2H and 4H?

[Techun]

Pretty sure you just want to argue for the sake of arguing, so have a nice day.

Not the case at all, I wish some others would join in because I feel like I'm going crazy here.

Your max cornering ability is not affected by anything to do with throttle or brakes, it would be with a steady speed.
So obviously 4wd is not important there.

So make another scenario, an uphill corner in the snow where you need to apply power. Regardless of what is theoretically best, I think 4wd is best for commuting because if you apply too much power you're going to understeer instead of spinning out. I think that's your point...

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[idontknow]

So I’m gonna ask the question cuz I’m not a physics expert but assuming you’re not on the throttle then I assume that an awd/4wd system isn’t going to help much and the tires you’re using will be the bigger improvement in your cornering ability. But if you are on the throttle and your wheel is slipping isn’t that the point of the awd/4wd system no different than if you are going in a straight line. The wheel slips because it’s under force from the throttle and hits a spot with less resistance not just coasting along. Is that wrong?

 

[MilesTeg]

Not the case at all, I wish some others would join in because I feel like I'm going crazy here.

Your max cornering ability is not affected by anything to do with throttle or brakes, it would be with a steady speed.
So obviously 4wd is not important there.

So make another scenario, an uphill corner in the snow where you need to apply power. Regardless of what is theoretically best, I think 4wd is best for commuting because if you apply too much power you're going to understeer instead of spinning out. I think that's your point...

All I am saying is that 4/AWD helps you turn without losing control, if you are turning under power/throttle. Again, a good example is if you are making a turn at an intersection from a stop. You have to be applying throttle, or the vehicle won't move. Spitting the torque to four wheels instead of two while applying that throttle makes it less likely for any of your wheels to slip, thus improving your ability to maintain control of the vehicle, including not sliding laterally.

Your scenario of an uphill corner in the snow also fits. To get up the hill and maintain speed, you have to apply throttle. 4/AWD will make it less likely that your wheels will slip, because the needed torque will be split to 4 wheels.

(of course, you probably shouldn't be trying to maintain speed in that scenario, but if you DID try to maintain speed, the 4WD would make it less likely for you to lose control).

You seem to be reading other claims into my posts that simply do not exist, such as non-existent claims about 4WD making you be able to corner faster than when cornering not under power or 4WD increasing the amount of traction you have. I assure you, I am not making those claims.

 

[MilesTeg]

So I’m gonna ask the question cuz I’m not a physics expert but assuming you’re not on the throttle then I assume that an awd/4wd system isn’t going to help much and the tires you’re using will be the bigger improvement in your cornering ability. But if you are on the throttle and your wheel is slipping isn’t that the point of the awd/4wd system no different than if you are going in a straight line. The wheel slips because it’s under force from the throttle and hits a spot with less resistance not just coasting along. Is that wrong?

If you are not on the throttle, your 4/AWD system won't do anything for you in a turn.

You are correct that what helps you in a corner is the same thing that helps you going in a straight line. In a straight line, your 4WD helps you make use of the traction you have by making each drive wheel have to push less, meaning it won't slip as easy.

When your vehicle is turning, there are two forces on your drive tires. The lateral force from the turn, and engine torque.

Those two forces combine (with some vector math that I will omit) so if the total amount of friction force your tires have (traction) has to be more than the combination of those two forces to not slip. So, splitting the torque to all four wheels reduces the total force on each drive wheel, meaning your tires require less traction to not slip.

In other words, it gives you a bit more breathing room to not exceed the capabilities of your tires.

 

[Techun]

All I am saying is that 4/AWD helps you turn without losing control, if you are turning under power/throttle. Again, a good example is if you are making a turn at an intersection from a stop. You have to be applying throttle, or the vehicle won't move. Spitting the torque to four wheels instead of two while applying that throttle makes it less likely for any of your wheels to slip, thus improving your ability to maintain control of the vehicle, including not sliding laterally.

Your scenario of an uphill corner in the snow also fits. To get up the hill and maintain speed, you have to apply throttle. 4/AWD will make it less likely that your wheels will slip, because the needed torque will be split to 4 wheels.

(of course, you probably shouldn't be trying to maintain speed in that scenario, but if you DID try to maintain speed, the 4WD would make it less likely for you to lose control).

You seem to be reading other claims into my posts that simply do not exist, such as non-existent claims about 4WD making you be able to corner faster than when cornering not under power or 4WD increasing the amount of traction you have. I assure you, I am not making those claims.

I agree with everything here!

In reference to your "other claims" comment, you earlier said "4/AWD will absolutely help lateral grip if you are under power" which I think we can just ignore since later discussions have covered enough of this.

 

[gbub]

Quite a few years ago, in a racing series like Trans Am or IMSA that I think it was Audi began using AWD. They dominated the series and eventually AWD was outlawed. Of course, there was acceleration in corners but it indicates AWD and probably 4WD has an advantage. I am sure a some has also to do with being able to use more power in straight line.

Back in the late 70s and 80s I had a FJ55 Landcruiser. One time, I was in the Sierras near Mammoth with a lot of snow. There was a large empty parking lot with deep snow and I decoded to do some donuts in 4WD. It just made big circles without doing donuts. I put it in 2WD and it made perfect donuts because I could break the rear tires loose.

 

[swamp2]

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.

You are missing a use case .

High speed, open desert wheeling in sand. Well over 50 and 4H!

Often you can get by fine in 2WD, but the cornering and climbing parts are much better in 4H.

 

[crenca]

Not the case at all, I wish some others would join in because I feel like I'm going crazy here.

Your max cornering ability is not affected by anything to do with throttle or brakes, it would be with a steady speed.
So obviously 4wd is not important there.

Your looking at this too ideally. You can't drive in most "normal" scenarios and not accelerate and brake most of the time when turning. So under real world conditions 4wd/AWD is an advantage.

Also sometimes off-road the ideal seems to not apply. True story: Just a few days ago I led our club's annual new year's day run. On this level 5 trail was this shelf road going up to a mine (the destination) and a 3 foot+ boulder had fallen in just such a way which forced a line around it that involved a 26 degree tilt off camber drive around said boulder on loose fine "tailings". On the pre-runs I took I noticed that if I stopped, or took it at steady throttle I lost lateral grip and slid (quite literally) into the boulder. However, if I purposefully yet slowly increased throttle as I drove past (in C or 1st in 4L) , and locked my rear axle I could keep my line without sliding laterally.

Don't know what to make of that but it worked.

 

[Pops]

To get back on the original track,
I believe the concern is at what max speed can the Bronco 4H be engaged from 2H, and back again, without leaving some pieces behind on the road.

 

[Ducati1098]

To get back on the original track,
I believe the concern is at what max speed can the Bronco 4H be engaged from 2H, and back again, without leaving some pieces behind on the road.

There is no limit. Shifts can be made at any speed.

 

[Brian_B]

There is no limit. Shifts can be made at any speed.

unless you have whatever update that hit some Broncos and requires <3MPH. But it will be sure to tell you

 

[Ducati1098]

unless you have whatever update that hit some Broncos and requires <3MPH. But it will be sure to tell you

True. Not sure what that was all about, but I do remember that. I’d guess just some faulty programming maybe?

But normally it should work at any speed.

Part time:

4A:

 

[timhood]

To get back on the original track,
I believe the concern is at what max speed can the Bronco 4H be engaged from 2H, and back again, without leaving some pieces behind on the road.

I looked in the manual and couldn't find any reference to a maximum speed for engaging/disengaging 4H. I did find references to the maximum speed to engage the locking differential (20mph) and the speed it unlocks (25mph) and re-engages (20mph). Based on that, it seems there is no practical limit for engaging 4H.

 

[MBelton]

“Quite a few years ago, in a racing series like Trans Am or IMSA that I think it was Audi began using AWD. They dominated the series and eventually AWD was outlawed. Of course, there was acceleration in corners but it indicates AWD and probably 4WD has an advantage. I am sure a some has also to do with being able to use more power in straight line.”

This was the IMSA Audi 90 Quattro. They were absolute monsters!

%100 this system increases grip under acceleration through corners. So much so that they deemed it an unfair advantage.

There is a good reason ALL rally cars at the top levels are awd systems of some sort, ever since the introduction of the quattro. The only car that wasn’t awd that ever beat one was the Lancia 037. And that only happened twice if I remember right.

 

[Techun]

“Quite a few years ago, in a racing series like Trans Am or IMSA that I think it was Audi began using AWD. They dominated the series and eventually AWD was outlawed. Of course, there was acceleration in corners but it indicates AWD and probably 4WD has an advantage. I am sure a some has also to do with being able to use more power in straight line.”

This was the IMSA Audi 90 Quattro. They were absolute monsters!

%100 this system increases grip under acceleration through corners. So much so that they deemed it an unfair advantage.

There is a good reason ALL rally cars at the top levels are awd systems of some sort, ever since the introduction of the quattro. The only car that wasn’t awd that ever beat one was the Lancia 037. And that only happened twice if I remember right.

If you're going to try and accelerate with 500+HP on dirt, you had better be using all 4 wheels!

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