Advanced 4x4 vs the standard option

[Thomman]

Here’s my 2 cents worth on when to use 2H, 4H, 4L, and 4A.

CAVEAT EMPTOR: This is all based on my experience and research thus far, but as we all know there is a lot more that we don’t know about the Bronco than what we know….

Case 1 – Pavement; good grip/traction: Since the Bronco does not have a center differential, it would mean that use of the vehicle in 4H under continuous pavement driving (i.e., where you have good grip/traction) would cause axle windup. This is because the front and rear wheels would have to travel different distances, particularly on winding roads. I think of this “windup” just as the cables on my corded phone keep winding up and getting worse, the more I use it. At some point in time, the cables will just give way and break, unless I “unwind” it. My conclusion: Avoid use of 4H on dry pavement. Best to use 2H, because that’s all you’ll need. This is probably why the Bronco’s “Normal” and “Eco” GOAT modes default to 2H.

Case 2 - Snow/Ice, Mud/ruts, Gravel; intermittent poor traction: This is where 4H would work well, with torque being transmitted to all 4 wheels, thus utilizing the available traction of wheels that don’t slip. Yes, there would be axle “windup” during periods when the traction is good on all 4 wheels, but this would “unwind” during periods of low traction, while torque continues to be transmitted to the wheels with traction, thus allowing the vehicle to move. My conclusion: 4H is great for roads where the surface will allow the wheels to slip, giving you the best of both worlds – traction from 4 wheels, yet preventing “windup”. This is probably why the Bronco’s “Mud/Ruts”, “Sand”, and “Baja” GOAT modes default to 4H.

Case 3 - Rocks/boulders, Low speeds: In this case you will need (1) more torque to overcome the rocks / gradient, (2) low speeds for control / precise steering inputs, and (3) traction to as many wheels as possible. 4L is the obvious choice for this. Would it cause “windup”? Yes, but the likelihood of one or more wheels lifting off the ground often will cause the respective axle to “unwind”. Now, if the terrain gets real bad and there is wheel slippage between the left and right wheels of either of the axles (front or rear), you may want to use the Hero switches on the Bronco’s dash (if you have them) and “lock” the rear and/or front differential(s). This will eliminate slippage between left and right wheels of the axle that you “lock”. My conclusion: Use 4L only for rocks and real bad terrain at very low speeds. And use the Hero switches to lock your differential(s) as required. This is probably why the Bronco’s “Rock Crawl” GOAT mode defaults to 4L, and the rear locker is automatically engaged.

Case 4 – If you are Lazy like me: And don’t want to manually switch between 2H and 4H depending on road conditions, then I would go for the Bronco’s “Advanced 4x4” (or 4A) since this system would automatically transfer up to 50% torque to the front axle if a slip were detected in the rear wheels. This is probably why the Bronco’s “Slippery” GOAT mode defaults to 4A (if you have it). Since a lot is still unknown about the GOAT modes and their Default settings, I’m not sure what the Default drive mode (2H/4H) would be in the “slippery” GOAT mode if your build does not have 4A.

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[De Brus]

Here’s my 2 cents worth on when to use 2H, 4H, 4L, and 4A.

CAVEAT EMPTOR: This is all based on my experience and research thus far, but as we all know there is a lot more that we don’t know about the Bronco than what we know….

Case 1 – Pavement; good grip/traction: Since the Bronco does not have a center differential, it would mean that use of the vehicle in 4H under continuous pavement driving (i.e., where you have good grip/traction) would cause axle windup. This is because the front and rear wheels would have to travel different distances, particularly on winding roads. I think of this “windup” just as the cables on my corded phone keep winding up and getting worse, the more I use it. At some point in time, the cables will just give way and break, unless I “unwind” it. My conclusion: Avoid use of 4H on dry pavement. Best to use 2H, because that’s all you’ll need. This is probably why the Bronco’s “Normal” and “Eco” GOAT modes default to 2H.

Nice writeup. I think the most amazing detail is learning that someone still uses a corded phone!

 

[Garye]

I’m going with OB 2.3 auto trans 4dr. I decided to go with the 4A auto 4x4. During the BP process when I click on auto 4x4 the following happens. Instead of just giving me auto 4x4 it also switches me into the 4.27 axle and a rear locking diff. It adds $1590 to my build. I would be happy with the 3.73 axle that comes with the part time 4x4. Some have said that it costs an extra $600 to go 4x4 auto. I wish that was the case. Seems that in my build going 4x4 auto makes me also go with 4.27 axle and rear lockers. Am I doing something wrong.

 

[Lakelife36]

I meant after accounting for cost of upgrading to different model plus cost of adv4x4

I'm in the same boat as you here - would have to spend another $5k on the BD just to get advanced 4x4, although it gives MGV too. It's really disappointing that we can't get it on non-Sasqued BB.

Without it on the BB I guess I will be sliding all over !! Or switch between 2h and 4h on snowy roads when road driving

Good winter tires make more difference than a fancy 4wd system, although clearly both combined are preferable. Where you live put it in 4H when you get one those ridiculous snow dumps or polar vorteces and leave it in 2H the rest of the time. If you feel it clunking and chattering around hard turns you'll figure out really quickly which occasions you need to switch it back out. Like @robepa said, having to press a button a few times on your drive is definitely a first world problem.

 

[smoot618]

To clear up some things I'll do some editing and make comments to the posts below:




Yeah, pretty much that ^^^. 4H is fine on mixed surfaces as long as you don't move the steering wheel too much, 4A better.

A little of this, little of that. Bronco can probably hit 110mph in 4H desert offroad but stupid to try 110mph 4HI on pavement. Speed limitation probably is just can't shiftonthefly 2H-4H-2H above 60mph. 4LO top speed will be limited by the rev limiter.

Does seem like an awesome, versatile 4WD SUV especially with the Advanced T-case. Even has Neutral. And at a reasonable cost if you don't want the fancy stuff.

I didn't see anything about 4A, just basic 4H and 4LO.

Thanks for the info! Went to Wisconsin for Thanksgiving and roads were pretty slippery/icy but changed to pavement that was cleared frequently. I didn't have to turn much, but I should have been switching on the fly to 2H when needed. Drove like a grandma honestly, so hopefully no irreversible damage in the 2 days we were there!

 

[AZ_Liberty]

At the Drive the Bronco event here in AZ I asked if I should put it back into 2H for the paved section. Guide said just leave it in 4H. It was a short paved section, and I don't think I managed to get it up over 50 mph though. I'm sure I never got it into either 5th or 6th gear.

4H is generally fine on pavement, you just don't want lockers engaged. Remember 4H is really one front tire and one rear tire. The differentials are open, you don't even have a Posi rear on the Bronco

 

[SoCalDawg]

I loved 4A in my F-150. It was always used in crazy afternoon storms when we lived in FL.

 

[lrtexasman]

Leaving in 4H in dry pavement at highway speeds can absolutely damage the differential.

 

[da_jokker]

Leaving in 4H in dry pavement at highway speeds can absolutely damage the differential.

You mean transfer case? You can't hurt the differential if the lockers aren't on. But not allowing the front axle to spin at a different speed than the rear axle can hurt the transfer case since that is where the binding would occur.

 

[lrtexasman]

I thought the same. Two different Toyota dealership’s mechanics diagnosed the issue with the same repair. Specifically the front differential carrier bearing assembly. The bearing actually cracked in half. My dad borrowed my Tundra and forgot to switch out of 4H before heading home on the highway from the lease. $4700 repair.

View attachment 216581

 

[John Whammer]

Pissah that you're all set.

Thanks guy.

 

[markregel]

Advanced is supposedly safe to drive on dry pavement and will function like an AWD system. Kicks in the 4WD only when you need it and then reverts back to 2H.

it will apparently use computer controlled braking on the wheels that are slipping in order to direct power to the wheel that has grip, in the absence of a fully engaged locking differential

standard 4x4 must never be driven on dry pavement. That’s how you cause drive train damage as parts get mashed together due to lack of slipping as you make a turn.

but apparently you can use 4H on snowy pavement? I’m really confused as to whether you have to turn it off as you approach blacktop. Maybe you cannot use 4H on mixed surfaces in the city? I’m confused as to that

the standard 4x4 selector gives you 2H, 4H and 4L.

the advanced system adds another choice: 4A.

EDIT: take my words with a grain of salt. Read the manual. I’m a noob here.

"Standard 4X4 must never be driven on dry pavement" Not exactly true. You will not damage the drive train if you inadvertently drive a short distance on pavement or hit some dry pavement on a snowy road. The drive train can easily withstand the forces and the tires will slip when they need to.

 

[DunawY]

Best explanation of the 4A I've seen.
Worth your time.

Wow he looks so young in this video

 

[Warthog Lover]

Thanks all. Wicked helpful and the similar threads pulled some of the ones I was missing with search

I new you were from Boston before I saw your location with the word wicked lol.

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