Needed: 4x4 Option Explanation

[BAUS67]

......one more thing I would point out is that part-time 4WD has a gear reduction ( in 4L) of 2.72 and the auto 4WD has a gear reduction of 3.06. Lower gearing aids on off road performance. Crawl ratio as you may have seen around Bronco press releases.

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[Mattwings]

Thank you guys for your answers. It’s funny you used a Subaru comparison because that’s what my wife drives and I like that when we have slippery icy conditions here in So Oregon the AWD is nice feature. Me on the other hand have an older 4WD Tundra. I’m pretty much stuck with 2WD because if I stick it into 4H I get the hopping of the front end during turns. Due to the excellent advice you guys have given me on the differences between the two I am going to go with the automatic system.

In Oregon you will love the Advance case. Living in the PNW was when I most appreciated the option (had it in our Explorer, not in our Bronco or F150). Going from the valley, into the mountains, into dessert and back would change conditions several times in just a few miles. 4A is much better in those conditions. Another issue not generally mentioned, 4H leads to some situations where the front wheels “lock up” because the back wheels are sliding, leading to “power off” understeer. 4A helps mechanically and electronically avoid this condition. It is a great feature and value IMO. I am definitely going with Advanced Transfer case if I go BD (it is included on BL).

 

[FerkinBlonco]

In Oregon you will love the Advance case. Living in the PNW was when I most appreciated the option (had it in our Explorer, not in our Bronco or F150). Going from the valley, into the mountains, into dessert and back would change conditions several times in just a few miles. 4A is much better in those conditions. Another issue not generally mentioned, 4H leads to some situations where the front wheels “lock up” because the back wheels are sliding, leading to “power off” understeer. 4A helps mechanically and electronically avoid this condition. It is a great feature and value IMO. I am definitely going with Advanced Transfer case if I go BD (it is included on BL).

Well put. I'm a PNW'er and this is my exact use case. When doing a long haul to go ski it comes in really handy to have a system akin to AWD. Back when I had a rig with 4H (FJ cruiser... I miss it) I was constantly wondering when to engage it on those trips, as it was not rated for high speeds and was generally bad to have engaged on pavement. I'm looking forward to having a 4WD SUV with some AWD-style capability. For me it's going to make those trips a bit more easygoing compared to my old FJ.

 

[wjfawb0 [hacked account]]

My only concern with the 4A system is how much torque and shock load can the center diff and clutch plates take compared to the standard part time transfer case? If you're going to rock crawl a Bronco, that might matter at some point. If Badlands has it standard, than I would think they have the torque management and center diff clutch controls setup to prevent clutch drops, neutral drops, and heavy right feet from breaking stuff.

I daily drive an STI and the AWD system in that car is nice. Tight turns on concrete with some throttle will actually cause some binding due to the limited slip center diff and helical front and rear diffs. It's a lot of fun.

 

[Mattwings]

My only concern with the 4A system is how much torque and shock load can the center diff and clutch plates take compared to the standard part time transfer case? If you're going to rock crawl a Bronco, that might matter at some point. If Badlands has it standard, than I would think they have the torque management and center diff clutch controls setup to prevent clutch drops, neutral drops, and heavy right feet from breaking stuff.

I daily drive an STI and the AWD system in that car is nice. Tight turns on concrete with some throttle will actually cause some binding due to the limited slip center diff and helical front and rear diffs. It's a lot of fun.

My understanding, it is the same case used in the Raptor. If it is, it should be well within design limits in the Bronco. I don’t know if we have actual part numbers to compare, but it has been mentioned and seems likely it is . Bronco is likely not high enough volume to design a new case.

 

[FerkinBlonco]

My only concern with the 4A system is how much torque and shock load can the center diff and clutch plates take compared to the standard part time transfer case? If you're going to rock crawl a Bronco, that might matter at some point. If Badlands has it standard, than I would think they have the torque management and center diff clutch controls setup to prevent clutch drops, neutral drops, and heavy right feet from breaking stuff.

I daily drive an STI and the AWD system in that car is nice. Tight turns on concrete with some throttle will actually cause some binding due to the limited slip center diff and helical front and rear diffs. It's a lot of fun.

Interesting question. My Subi OB doesn't have a center diff and instead just a wet multiplate clutch set (or so Engineering Explains tells me). Maybe it's because of that, but I don't seem to get any bind during tight cornering. I wonder if the Adv. transfer case relies solely on a clutch pack, or if it is some sort of combo unit. I had thought just clutch, but now I'm curious.

Edit: if we really are the same as the raptor, I found this vid helpful. Sure it's been shared 1001 times on the forum already. However, in the spirit of this duplicate-ish thread, I'll make this duplicate-ish post:

 

[wjfawb0 [hacked account]]

According what I've read online, it's a planetary setup with electromagnetic plate clutches in the STI's DCCD.

Good writeup with pictures found through pinterest: http://subaruidiots.com/dccd-subaru-sti-explained/2/

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