Useful Feature that Doesn't Get Enough Credit - A4WD

"Jcarr" (jcarr) 02/09/2015 at 16:22 • Filed to: How It Works

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In my time as a licensed driver, I've always had at least one 4-wheel drive vehicle (meaning, in this case, RWD, with a 2-speed transfer case to engage the front axle).

The first was a 1991 Isuzu Trooper that required you to stop, shift into neutral, and shift the transfer case into either 4HI or 4LO. To disengage, you had to stop, shift into neutral, pull the t-case back to 2HI, and then back up for about 20-30 feet to release the front hubs.

Kind of a pain in the ass.

The next two were both shift-on-the-fly capable ('94 S10 Blazer, '03 Ram 1500), which was a breeze compared to the relatively complicated Trooper. No stopping, no shifting to neutral, no backing up. Of course, 4LO still required a stop/neutral cycle, but that was no big deal as it was used so infrequently.

I didn't think a 4WD system could be anymore easy to use until we bought our 2004 GMC Envoy and I was introduced to the "A4WD" setting.

The Envoy (and most of its other GMT360 brethren) used a 4L60E 4-speed automatic connected to a New Venture Gear 226 2-speed electronic transfer case. This t-case, like most others of the era, was shift-on-the-fly capable from 2HI to 4HI and back. So far, nothing groundbreaking.

What set this case apart from others that I had previously experienced was the aforementioned "A4WD" setting. This setting aims to fill in that gray area in which you might need 4WD one minute, and be on dry pavement the next.

!!! UNKNOWN CONTENT TYPE !!!

Here's how it works:

In A4WD, the front differential engages and back drives the front driveshaft. The front drive end of the t-case is not engaged, however, so there is no solid connection between front and rear axles. This allows the driver to corner on high-traction surfaces without experiencing driveline binding.

When the system detects a difference in rotation speed between the front and rear driveshafts (caused by rear wheel slip), a dry, multi-plate clutch in the t-case engages the front drive shaft, splitting power between the front and rear axles. Once rear-wheel slip is no longer detected, the system releases and it's back to 2WD.

This is incredibly useful in situations like the beginning or end of a snowstorm, when there are slippery areas, but not all surfaces are covered.

There are, however, a few disadvantages of this setting. First is that it takes slightly more effort for the vehicle to drive around spinning the front driveshaft and t-case, so fuel economy takes a small hit. Second, since the system engages once the rear wheels are slipping and the RPMs are up, there is a bit of a shock load that, over time, will cause wear and tear.

That being said, our Envoy is 11 years old with a hair over 100k miles and the system still works like a charm.

A little poking around has shown me that a good number of manufacturers offer this type of feature now, but what surprises me is that it doesn't seem to get much press. I don't see it hyped in ads, I don't recall hearing much, if anything about it in car magazines, and I don't really hear anybody talk about it. Maybe it's just taken for granted.

Anyhow, if you made it this far, congratulations. You must not have anything better to do!

505Turbeaux > Jcarr 02/09/2015 at 16:26

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oooh dat Trooper

mazda616 > Jcarr 02/09/2015 at 16:28

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That is one of the cleanest, nicest looking S-10 Blazers I have ever seen! Want.

Jcarr > 505Turbeaux 02/09/2015 at 16:28

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I know. Mine was that color, but instead of having nice, meaty tires, it had rust.

505Turbeaux > Jcarr 02/09/2015 at 16:29

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was it dark red and also from CT? If so it may have been a friend of mines...

Jcarr > mazda616 02/09/2015 at 16:31

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I miss it. Traded it in for Ram in 2006. She had 150k on her at that point and ran like she was new. The Vortec 4.3 was a beast.

Jcarr > 505Turbeaux 02/09/2015 at 16:33

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Gray and from IA.

and 100 more > Jcarr 02/09/2015 at 16:33

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Does this differ significantly from the Auto-4WD system in the 2nd-gen Blazer/S-10?

If not, then I agree! It was a great system, even back in '01. With Auto engaged it was fantastic on icy roads, and the engagement seemed far less dramatic than the latest batch of FWD-based, brake-controlled AWD systems.

Textured Soy Protein > Jcarr 02/09/2015 at 16:33

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Truck manufacturers don't go out of their way to advertise full-time 4wd because enough truck and SUV buyers out there mistakenly believe that full-time 4wd makes a truck worse off-road, even if that truck still has the exact same ability to lock the transfer case as a part-time 4wd setup.

Sure, driving in full-time mode in a situation that calls for locking the front and rear axles together, isn't going to work as well than locking the axles together. But for the most part, trucks with full-time 4wd still let you lock the transfer case.

I've lost track of how many times I've tried to explain why full-time 4wd is better in on-road slippy stuff and still has the ability to lock for all the (largely fictional) off-roading someone might want to do.

505Turbeaux > Jcarr 02/09/2015 at 16:34

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ah well, saw that CT plate on the cover photo, was hoping that beast (with rust) made it on to a new owner

Captain of the Enterprise > Jcarr 02/09/2015 at 16:34

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My 2001 Expedition had A4WD 4H and 4L.

Jcarr > and 100 more 02/09/2015 at 16:36

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I'm not sure, but knowing GM, I'm guessing there weren't many differences, if any.

Jcarr > 505Turbeaux 02/09/2015 at 16:37

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Ah, no the lede image is just a Google find. My Trooper met its fate with a crusher back in 2006, unfortunately.

505Turbeaux > Jcarr 02/09/2015 at 16:38

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head cracked or head gasket? Or did the rust get all up in bad places

Jcarr > Captain of the Enterprise 02/09/2015 at 16:39

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Interesting, did it work the same way?

Captain of the Enterprise > Jcarr 02/09/2015 at 16:41

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To be honest I never looked into it, I assumed it was a form of automatically switching from awd to 4 wheel drive but when I had it in that A4WD it would steer much better and easier unlike when it was in 4h and it felt like the front axle was locked.

Jcarr > 505Turbeaux 02/09/2015 at 16:46

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Died from complications resulting from GM 2.8 V6. One of the heads had been replaced 6-8 years before that. My parents took it back when I moved on to the Blazer in 2001 and drove it for a few years before it died and they decided to scrap it.

Jordan and the Slowrunner, Boomer Intensifies > Jcarr 02/09/2015 at 16:46

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My TB's A4WD saved my ass once on black ice. It was a great feature. It also made controlled drifts on gravel roads, super easy.

If only EssExTee could be so grossly incandescent > Jcarr 02/09/2015 at 17:39

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I drove a '99 Suburban that was equipped with an electronic transfer case. It had pretty much the same thing, but it was simply labeled as AUTO 4WD.

davesaddiction @ opposite-lock.com > Jcarr 02/09/2015 at 17:49

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My recently acquired '03 Pathfinder has this.

Jack > Jcarr 02/10/2015 at 10:59

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As someone with the same drivetrain which just dropped 3rd and 4th gear, I still love the concept and transfer case, but the transmission and I are about to get a lot more intimate than I would ever want to.

MK6GTI-now with added Miata > Jcarr 02/10/2015 at 11:01

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My uncle used to have one of these. I don't think I've seen a single one on the road here in New England in 15 years though.

ezeolla > If only EssExTee could be so grossly incandescent 02/10/2015 at 11:05

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A buddy of mine had an early '00s Silverado that was the same way

44444444444 > Jcarr 02/10/2015 at 11:08

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I've always been partial to full time 4wd because it's always there. The MK II Range Rover used a viscous coupling in the transfer case to allow rotational differences but it's always 50/50. The MKIII used a torsen setup, and the MKIV uses a torque vectoring haldex type system or something. No muss no fuss and you always have 4 driven wheels.

Ford Tempo Fanatic > Jcarr 02/10/2015 at 11:09

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Ah, the Trooper. Now that's an SUV I haven't thought about in some time. Some of my earliest memories are of riding around in my parent's silver Trooper II. Rust was eventually its undoing, despite not being all that old.

As far as 4WD systems go, I'm not entirely sold on the newer A4WD systems. I just have a hard time imaging there is anything better than my 1990 F-150's 4WD system, mated to an automatic locking rear end. Sure, getting out to turn the hubs can be a bit of a drag, but its unstoppable in snow, mud, sand, or on the rocks. Ice is its only weakness, really.

Pheatton > Jcarr 02/10/2015 at 11:09

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My sister has a WK Grand Cherokee with the Quadra-Drive II system. Its incredible what that thing can do even if you leave in default auto mode let alone 4Low...

Struts MacPherson > mazda616 02/10/2015 at 11:10

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...If you ignore all the rust.

alan > Jcarr 02/10/2015 at 11:11

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i always felt the same way. i was surprised the 2004-2010 colorado did not have this availiable as i loved it on my parents 2005 trailblazer. It was availiable as an option on the S10s and Blazers but was really hard to find. Its a great feature that you can just leave it and forget it in the winter. and in the summer just leave it in 2wd. i wish it was installed on more 4x4 vehicles.

Russo > Jcarr 02/10/2015 at 11:12

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No idea if I'm way off here...but my Jeep Patriot is FWD, goes into AWD if it needs (does that by itself), and has the lever for "locking" into 4WD. Is this AWD function like your A4WD?

Equana > Jcarr 02/10/2015 at 11:12

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Be sure and change the fluid in the transfer case every once in a while. It is only about 2 quarts of very special blue colored oil but fresh fluid makes the AWD work much smoother.

Also watch for leaks, the 226 T case has a bit of a design flaw that causes pinhole leaks though the rear half of the case itself. 2 quarts can leak out pretty quickly and wreck the T case.

Stuttgart Shuffle > Jcarr 02/10/2015 at 11:13

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Welcome to 1998, your Game Boy Color is in the trunk along with your hopes and dreams.

BigBlock440 > If only EssExTee could be so grossly incandescent 02/10/2015 at 11:13

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1st gen Durangos also had it, labeled as full-time 4wd though.

icelandr > Jcarr 02/10/2015 at 11:14

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Auto 4wd is a good way to burn up the clutch-packs no matter how useful you think it is. It also doesn't work all that slick. Friend with a trailblazer and auto-4 had the back end slide out 20-30 degrees before engaging, and my TBSS doesn't do that with awd.

cazzyodo > If only EssExTee could be so grossly incandescent 02/10/2015 at 11:14

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I learned to drive on a '98 Suburban with that system. Those things were tanks and I loved them so much haha

DirtyVDub > Jcarr 02/10/2015 at 11:14

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No thanks. I'd rather know exactly how my vehicle is going to preform be it RWD or 4WD. Getting one and expecting the other in an emergency situation is not worth the risk.

Drive your own damn car, don't let it drive for you.

icelandr > Jordan and the Slowrunner, Boomer Intensifies 02/10/2015 at 11:14

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and you were burning out your t-case doing that.

Dr. Pirateface > Jcarr 02/10/2015 at 11:15

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My God. An early 90's S10 Blazer, complete with an American flag in the background. The amount of nostalgia for my '91 4.3L 5MT is unreal.

REST IN PEACE, BINGO.

Cap'n Jack Sparrow > Jcarr 02/10/2015 at 11:16

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I love this on my '14 Silverado! I let the wife drive it to work in the winter as its safer for her than the Sebring-death-trap im rolling in right now.

She just leaves it in "Auto" mode during normal driving, and then flips on the fly to 4x4 when Michigan unleashes a frozen hell on us!

Cap'n Jack Sparrow > Jcarr 02/10/2015 at 11:17

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Those 4.3 Vortecs were BOSS.

matt1994xj > Jcarr 02/10/2015 at 11:18

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Very useful when conditions may require it, but I wouldn't drive around all the time in a4wd. Good way to wear out your transfer case.

Quadradeuce > Jcarr 02/10/2015 at 11:19

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In my '11 Sierra, it is extremely smooth and accurate. It detects wheel slip almost immediately and reacts accordingly. I love it in my Wisconsin winters. Plus, if you forget to turn it off when the roads dry up, no biggie.

HelloDoggy > Jcarr 02/10/2015 at 11:20

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Nice article! Would you happen to know how the old, locking hub systems are related to this type of system?

TwoWheelsAmazing > Jcarr 02/10/2015 at 11:24

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Jeep Grand Cherokee's have had this on the higher trims. The WJ's with Quadra-Drive II had auto 4WD the transfer case were 2WD until slip then it transferred power were needed. It had lockers in each axle and the transfer case. It had the ability to send power up to 100% only to one wheel.

Faunafan > Jcarr 02/10/2015 at 11:28

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interesting, I'm new to the world of four-wheel-drive.anyone familiar with a 96-97 fzj 80 land cruisers system?? I would get a model with the elockers but am wondering if there is a way to modify it to run in 2wd when conditions permit and I want to save some fuel.

jmedarts > Jcarr 02/10/2015 at 11:28

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Ever had one where you had to get out of the truck and lock the front hubs? Now THAT was inconvenient,

Just me > Jcarr 02/10/2015 at 11:28

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Nice, this was my old envoy xuv!! it was completely hurculined, 2.5 lifted and mudding tires! It was a beast, never had it get stuck (while driving within its limits).

Even my dog, chewy, was enjoying the ride on this one! Man i missed the license plate, lol!

Achieve > Jcarr 02/10/2015 at 11:28

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Hi! Glad you like the AWD systems. Your welcome.

Jcarr > Jack 02/10/2015 at 11:28

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I must be very lucky with 4L60Es. The Blazer I pictured above had one as well and it was flawless even at 150K miles when I traded it in. The one in our Envoy has been similarly perfect through 100k (fingers crossed).

philsphan09 > Jcarr 02/10/2015 at 11:30

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Is this what the new 4 runners have?

Jcarr > DirtyVDub 02/10/2015 at 11:30

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To each his own. I've never had any problems using this mode in numerous Iowa winters.

Eric Sundell > Jcarr 02/10/2015 at 11:31

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Except that it's a useless gimick feature. Our old tahoe had it, it took a second for it to kick in and would take you buy surprise say while you may be sliding around a bit on slush. You go from low grip to "HOLD THE HELL ON" not exactly seamlessly. It was far easier to control the car in winter leaving it permanently in 4hi or 2hi. I never used it, to me it was kinda pointless.

Tatanko > Jcarr 02/10/2015 at 11:31

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My father had a '99 Grand Cherokee for many years that had Selec-Trac 4WD offering a similar function. They simply referred to it as "4 Part-Time".

Jcarr > HelloDoggy 02/10/2015 at 11:32

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Thanks, unfortunately I don't know off hand how this compares to the older systems, other than it is more user-friendly. I'm sure the Google could shed some light on it.

Dake > MK6GTI-now with added Miata 02/10/2015 at 11:33

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That's because between blown engines, ruined transmissions and rust (notice the rocker panels in the picture), most people were only to glad to dump them.

Jim is one of KFCs secret ingredients > Jcarr 02/10/2015 at 11:34

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t case lever > knob.

and wtf no neutral setting on the Envoy T-Case?

Dake > jmedarts 02/10/2015 at 11:34

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I remember a manufacturer's ad campaign that involved people being trapped inside their manually locking 4WD by mud or a bear while their smarmy buddy in his new from whoever 4WD hit a button and drove off - leaving them to their death presumably.

Jcarr > jmedarts 02/10/2015 at 11:35

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I haven't, but I do remember that some of the older Troopers had that so the system my '91 had was considered more convenient since you didn't have to exit the vehicle.

Brickman > Jcarr 02/10/2015 at 11:36

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Suzuki SX4 has A4WD with locking diff. Just needs a lift to clear some off road inclines :P

Jcarr > Just me 02/10/2015 at 11:36

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Google "Envoy Off Road". I think that's how I found it.

Jcarr > Eric Sundell 02/10/2015 at 11:38

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That hasn't been my experience. As long as throttle application isn't crazy, it seems to transition rather predictably. Maybe different in something like a Tahoe with more low end torque.

JarkBerts > Jcarr 02/10/2015 at 11:38

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I have a Ford Escape 4WD, which is an automatic 4WD setup based on wheel slippage. Front wheels are the all time driven wheels, and rears are engaged when needed. Can someone explain to me the difference between my Escape and the A4WD setup discussed, or are they basically the same?

p.s. My escape does surprisingly well in the snow (4WD + I have Blizzaks on it). I can plow through stuff deep enough that I am pushing snow out of the way with my grill and not worry about getting stuck. I try not to make a habit of that though.

Jcarr > Jim is one of KFCs secret ingredients 02/10/2015 at 11:39

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I think there is one, it's just not marked. I'd have to look it up, but I think you just turn and hold the knob to the left for a few seconds.

HammerheadFistpunch > Jcarr 02/10/2015 at 11:39

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Auto 4wd systems are pretty good, but they are still reactive in nature, the holy grail is a part time system with permanent 4wd as an option as in the Jeep selec trac.

The NV 242 transfer case allows for 2wd, part time 4wd...well I'll just let you read the picture but basically it works by using a center differential in full time 4wd so you are actively driving all 4 wheels but you don't experience driveline bind, in part time 4wd the center differential is locked and you get true 4wd, and of course its a 2 speed case for low range as well. 2wd is accomplished by disconnecting the front driveshaft via a splined clutch engaging or disengaging the center differential.

Jcarr > HammerheadFistpunch 02/10/2015 at 11:42

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I thought of you when writing this up. Should have linked to your piece from a while back.

http://oppositelock.jalopnik.com/a-4-wd-what-is…

Jcarr > Struts MacPherson 02/10/2015 at 11:44

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Ignoring the rust on that generation of S10/Blazer is a prerequisite. Just like ignoring the woefully inadequate rear leaf springs and resulting butt-sag.

HammerheadFistpunch > Jcarr 02/10/2015 at 11:44

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Thanks for the shout out, I love this stuff.

Jordaneer, The Mountaineer Man > Jcarr 02/10/2015 at 11:46

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mine i believe is always like that, I don't have just a permenant 2HI, which is a bit annoying, but oh well.

Just me > Jcarr 02/10/2015 at 11:47

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Yeah, it was on the trailvoy site, we had lots of meets. TOok that thing to george washington nation park in VA, that pic was up at Nepaug in CT. Good times!

colewind > Textured Soy Protein 02/10/2015 at 11:51

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I love driving my Disco 2 on wet and icy roads. It just goes. if I ever take it off road or play in deep snow (once ever, honestly), the CDL ensures I can evenly split the power front and rear.

With my old Jeep TJ, you had to choose between decent on road handling and traction all around. I like the 242 cases in some of the XJs and ZJs, though. The jeep was easier to maneuver down an offroad track, though. I miss it a lot.

colewind > icelandr 02/10/2015 at 11:51

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Worth it.

Danger > Jcarr 02/10/2015 at 11:58

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I agree. My 2005 4Runner has a "full-time 4WD" mode that operates in a similar fashion, with a limited-slip system that sends more power up front when the rear is beginning to slip. It's convenient to not have to screw with anything most of the time, until I need 50/50 power distribution then I can lock the center diff.

zimme71 > icelandr 02/10/2015 at 11:59

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Yup...had an '04 Explorer XLT with this that was my ex-wife's DD. Not sure how, but she burned out my transfer case at 80k miles. I vowed to never own Ford again after that Explorer, and the multiple other issues it had.

r0ckstar87 > HammerheadFistpunch 02/10/2015 at 12:00

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Many of the 80's and 90's Land Rovers used the LT230 transfer case that had a center differential that would vector torque between the rear and front as needed. You could lock for a true 50/50 split if needed. The Toyota Land Cruisers also have a similar feature but I don't know how they work. This is all assuming that you haven't already overheated with the trusty 'ole Rover V8.

marshamallow > Jcarr 02/10/2015 at 12:01

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I love that feature on my 03 Z71 burby. Also, I love that my front axle doesn't go through my oil pan, like in your Envoy. Cheers!

Jon > Just me 02/10/2015 at 12:02

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So...where is it now? It sounds like you don't have it anymore; I'm curious why.

HammerheadFistpunch > r0ckstar87 02/10/2015 at 12:04

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Yes, these full time systems with locking diffs are great in the snow and beyond. ask me how i know.

The disco VC center diff was pretty good, allowing full lockup automatically if needed (not torque vectoring aside from lockup), but at a shortened fluid life interval, its strange that they actually got rid of the locking function for a while before bringing it back.

Kaizer Soze > 505Turbeaux 02/10/2015 at 12:05

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My dad had a red trooper from CT. I think it was an '89.

Jcarr > Just me 02/10/2015 at 12:10

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Trailvoy has saved my time and money numerous times. Love that site.

Jcarr > marshamallow 02/10/2015 at 12:12

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Haha yeah, I know. Wanna drop your oil pan? Need to remove your front axle!

adamftw > HammerheadFistpunch 02/10/2015 at 12:14

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I loved my NP242 in my first XJ. I'm a HUGE fan of my LT230 now though, damn is it a fine transfer case.

Just wear your damn mask... > Jcarr 02/10/2015 at 12:15

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Shift of the fly 4wd?
Auto locking hubs?

Whatever...

Feed your inner Ron Swanson with Old School 4x4. Manual hubs and a big transfer case lever sticking out of the floor, connected to a divorced transfer case. You end up with an extra driveshaft and a couple extra u-joints to contend with, but you can drop the transmission without having to disassemble the transfer case.

marshamallow > Jcarr 02/10/2015 at 12:15

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Also no sizable lift opportunities, bro!

CACressida > Jcarr 02/10/2015 at 12:16

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My 2002 4Runner has multi mode 4WD. I have 2wd or AWD in both high and low ranges. The AWD Low has been extremely useful for me when backing trailers with surge brakes up hill or curbs. I just feather the throttle and very smoothly convince the trailer it's wrong and it needs to do what I tell it to do. When I go off road though, I lock the center differential and get the typical old school 4wd system. Multi mode AWD works well with the VSC system in icy conditions giving it a very odd unstoppable feeling until you decide to go into hoon mode.

Jcarr > matt1994xj 02/10/2015 at 12:18

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Yep, I only engage it in those "in-between" times like the beginning or end of a snowstorm when there's a good mix of covered and uncovered surfaces.

Mercwri > HammerheadFistpunch 02/10/2015 at 12:19

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I'd REALLY like to stuff an NV242 in my TJ and build a Rally-Jeep.

I haven't looked too far into it but the consensus on Jeep forums is that they don't play nice with the shortwheel base on TJs.

Jcarr > Just wear your damn mask... 02/10/2015 at 12:19

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Yours? I love the paint.

adamftw > TwoWheelsAmazing 02/10/2015 at 12:20

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QD and QDII are a bit different.. The WJ had QD which used a NV247 which was clutch based, and those badass gerotor limited slips in the axles. QDII is in WKs and uses a NV245 which has an ELSD capable of full lock, and ELSDs in the axles.

SuPeRcHaRgER > HammerheadFistpunch 02/10/2015 at 12:20

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Yep! Gotta love the good ol' Selec-Trac NP242 in my 1990 XJ Wagoneer :)

HammerheadFistpunch > Mercwri 02/10/2015 at 12:20

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I wonder why?

Textured Soy Protein > colewind 02/10/2015 at 12:21

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I like that the 242 transfer case has a lot of choices of drive mode (2H, 4 full-time, 4H, 4L). Only downside is the center diff is an open diff rather than limited-slip.

Mercwri > HammerheadFistpunch 02/10/2015 at 12:22

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I don't know, I'm half tempted to try it for shiggles anyway, NV242 from wrecked WJs should be a dime a dozen locally.

Mustang 'DontHitTheCrowd' GT > Jcarr 02/10/2015 at 12:23

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In my previous 1999 Trooper, that same process was still used.

It felt pretty badass to engage that 4LO though

torque > jmedarts 02/10/2015 at 12:26

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I was thinking the same thing. You had to get out and manually lock the fronts on Pretty much every 4wd that I can think of before about 1990 or so. I remember a friend's family had a 91? Bronco that had the "auto 4x4" where you could engage it on the fly, but then to disengage it, you had to push the dash button off & reverse 30-60 feet

Jcarr > Mustang 'DontHitTheCrowd' GT 02/10/2015 at 12:26

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Good old Isuzu, never changing. Probably partly why they're extinct in the US, unfortunately.

torque > Dake 02/10/2015 at 12:29

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yeah many years ago there was one where a competitor's 4x4 is stuck in mud and there are alligators outside. It was pretty funny b/c how silly it was

Tobin535 > HammerheadFistpunch 02/10/2015 at 12:34

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I added a 242 case to my old 98 Grand ZJ 5.9 limited after the lousy 249 failed. That 242 worked so nice I barely noticed all the electrical problems that Jeep had.

Garrett Davis > Jcarr 02/10/2015 at 12:35

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My '91 Cherokee had this as well with the NP242 transfer case. It was really handy on trips up into the mountains.

8695Beaters > Jcarr 02/10/2015 at 12:39

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That system waswas basically introduced on the Vehicross. Though the Vehicross had a low range you engaged with a lever, not a switch (the fact that the VX uses the same transfer case and transmission, but is six years older would explain that). Most CUVs have some sort of disconnect system but almost none have the low range gear since it is so infrequently used. Its the worst of both worlds but allows OEMs to claim some semblance of off highway ability. It's a shame more small trucks don't use the Envoy/VX system because damn is it useful.

Steve > Jcarr 02/10/2015 at 12:39

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Kia used a fancy little vacuum locking "shift on the fly" system... the problem with vacuums is a seal (sadly not the aquatic mammal, although I wouldn't put it past them) that when exposed to pretty much anything other than a cigar humidor; breaks down, and requires expensive repair or manual hubs. Cool concept in theory though...

dedavelo > Jcarr 02/10/2015 at 12:44

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i like the setting of that house!

TomMetcalf > HammerheadFistpunch 02/10/2015 at 12:51

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One of the best transfer cases ever. Love them.