New trucks and 4low...

[rho]

Yeah, that's what made me fall in love with my little Jeep about 11 years ago. It is the first (and only) rig I've owned that doesn't have manual hubs. Going from 2WD to 4H at 30 MPH in a blizzard is really nice...and if the roads is better 10 miles later, just switch back to 2WD.

I'll admit that a computer doing all that for you would be even easier...but I like to be the one making the decisions when it comes to driving. Not sure what the "ESP" really does in my Jeep, but I purposely disabled it when the Jeep was two years old after the first time I started fishtailing around on ice due to that stupid computer deciding that I was out of control when I wasn't out of control. All I could tell is that the Jeep was braking wheels independently. Aint havin' that ********.

Been getting by just fine without it.

The ESC system has almost caused me more accidents and out of control situations than its helped. I've had mine disabled for years as well.

 

[DaveInDenver]

I was thinking more about the on-demand systems that shift torque to the rear wheels, like Honda uses. Also the L/R split used in some torque vectoring systems. Like I said, I'd want to know exactly what was going on before buying an AWD system.

Those are completely different, being front wheel drive vehicles that can vector torque to the rear wheels. Subaru's symmetrical AWD is kind of a hybrid in between. Rear wheel biased 4WD, auto 4WD or AWD can't ever work as well since the primary biased drive wheels aren't the steering wheels so it's possible to keep pushing the vehicle but not be able to steer it. It'll always be easier to end up being a Charlie Foxtrot situation with our old junk.

 

[MOguy]

A friend of mine bought a Jeep Rubicon and proudly showed me it had stabilizer bar disconnect switches. He had no idea what they were for, but he sure was excited about flipping them. After several years of ownership, that Rubicon has never driven over anything rougher than a gravel driveway.

I believe some AutoAWD systems have clutch packs somewhere that will wear out. Not a big deal on pavement, but I doubt they'd fair well offroad over long, hard use. Before buying an AutoAWD vehicle I intended to drive offroad, I'd want to know how it worked, and how it was disabled. I know the various ABS-derived traction aids on my truck can be confusing, but I can turn them on & off at will. Canned terrain systems probably don't allow that level of control.

I had an 01 Grand Cherokee. It had the select trac option. Part time 4Lo, 4Hi, fulltime 4wd (AWD) and 2 wheel drive.

For their AWD or fulltime they used what the called viscous coupling. When things would spin the clutch packs heat from the friction (or whatever they were called) and would swell with the fluid and lock up. Simple enough but they would wear out. After about 120K the fulltime 4wd was about worth less but the part time (not sure if chain or gear driven) still worked fine.

 

[Highlander]

Still no ones has beaten the 90s Land Rover 4DW system even up to this date.
It was a perfect combination of simplicity and ingenuity.
It was full-time AWD with a lockable central differential and low, really low, gear 3.5;1.

1. Default mode - FAWD
2. Locked central differential (equivalent for 4 Hi)
3. Locked central differential with low gear
4. Default mode - FAWD + Low gear.

For that is the very definition of 4DW systems.

locking-differential hosted at ImgBB

Image locking-differential hosted in ImgBB

ibb.co

 

[shade]

Still no ones has beaten the 90s Land Rover 4DW system even up to this date.
It was a perfect combination of simplicity and ingenuity.
It was full-time AWD with a lockable central differential and low, really low, gear 3.5;1.

1. Default mode - FAWD
2. Locked central differential (equivalent for 4 Hi)
3. Locked central differential with low gear
4. Default mode - FAWD + Low gear.

For that is the very definition of 4DW systems.

locking-differential hosted at ImgBB

Image locking-differential hosted in ImgBB

ibb.co

I don't know about beating it, but I believe it's been mentioned that something similar has been available on some Toyota vehicles. I can't speak to the gear ratios used.

An ideal system for on & offroad use would seem to be a mechanical Torsen LSD front/center/rear, with the ability to lock each & all differentials manually, run through a two-speed transfer case. Any torque vectoring could be accomplished through the ABS (easier & cheaper to service than clutch packs), and would likewise be possible to selectively disable that system.

Cost and desirability in the marketplace probably make that an impossibility, though.

 

[luthj]

I am currently building a 4x4 conversion for my van. Based on what parts fit, I decided on a Tcase with 2hi, 4wd full time, 4wd part time, and 4 lo. With a front axle disconnect I also get 2Lo when needed. (great for heavy vehicles on steep climbs). The AWD (4wd full time) option was a must have for me. Being able to travel at speed on icy/snowy roads, or even mixed dirt/rock surfaces is a big part of my needs. Of course the problem with this system for the average operator has no idea what selection to use. And selecting the wrong one can break stuff, or even cause an accident.

 

[DaveInDenver]

I don't know about beating it, but I believe it's been mentioned that something similar has been available on some Toyota vehicles. I can't speak to the gear ratios used.

An ideal system for on & offroad use would seem to be a mechanical Torsen LSD front/center/rear, with the ability to lock each & all differentials manually, run through a two-speed transfer case. Any torque vectoring could be accomplished through the ABS (easier & cheaper to service than clutch packs), and would likewise be possible to selectively disable that system.

Cost and desirability in the marketplace probably make that an impossibility, though.

What you've described is mostly a 2003+ 4Runner or 1998+ Land Cruiser. Lockable Torsen center diff and TRAC/A-TRAC/VSC and with some years having electric lockers. The stock low range on Toyota is around 2.28 for the most part, so not Rover low but there are aftermarket gear sets for 4:1 low range and Marlin can pretty much double (or triple if you want) case any Toyota.

 

[shade]

I am currently building a 4x4 conversion for my van. Based on what parts fit, I decided on a Tcase with 2hi, 4wd full time, 4wd part time, and 4 lo. With a front axle disconnect I also get 2Lo when needed. (great for heavy vehicles on steep climbs). The AWD (4wd full time) option was a must have for me. Being able to travel at speed on icy/snowy roads, or even mixed dirt/rock surfaces is a big part of my needs.

Sounds like the way to go for your Sprinter and where you travel. Is this a conversion kit, or a one-off set up?

I added 2Lo capability to my Tacoma for maneuvering a heavy trailer around job sites. I'm happy to have shift-on-the-fly, but giving up locking front hubs meant that 2Lo disappeared, too. That was something Toyota should've offered standard, since it's little more than adding some logic and a fourth position on the drive mode switch.

 

[shade]

What you've described is mostly a 2003+ 4Runner or 1998+ Land Cruiser. Lockable Torsen center diff and TRAC/A-TRAC/VSC and with some years having electric lockers. The stock low range on Toyota is around 2.28 for the most part, so not Rover low but there are aftermarket gear sets for 4:1 low range and Marlin can pretty much double (or triple if you want) case any Toyota.

I thought that was an option with the Tacoma's well-off brother, but couldn't remember. 4Runners get all the good stuff, but I don't recall them coming with anything other than A-TRAC and an open front differential.

 

[Highlander]

The Land Cruisers, the 80 and 100 series, indeed gave the same results with the fulltime AWD and lockable central differential but there were few very significant differences.

In LR the central diff is locked mechanically with a lever VS LC push button.

In LR, if needed, one could go in the low gear without locking the central diff (see the photo above) VS LC needs first to be in central diff in order to go in low gear.

The LR had 3.5 low gear crawl ratio VS LC 2.6.

The G wagon is like LR too. It is FAWD with lockable central differential and low gear. You can go in ether one or both.

 

[DaveInDenver]

I thought that was an option with the Tacoma's well-off brother, but couldn't remember. 4Runners get all the good stuff, but I don't recall them coming with anything other than A-TRAC and an open front differential.

The 4Runners got was the center diff, otherwise the same. A couple of guys with manual transmissions have adapted the FJ Cruiser AWD transfer case to a Tacoma and done a 2WD conversion. A stick shift FJC doesn't have 2WD high (neither did the old V8 4Runners) while Tacoma does, but it's a matter of tricking the 4WD ECU to unlock and lock the front differential disconnect, so they retain the electronic dial and have a t-case stick for high open-high lock-low lock. With an automatic Tacoma I assume you could just install the 4Runner t-case since they are like a Tacoma with 2WD/Auto/High/Low.

Toyota only put in rear lockers in IFS trucks, but the 80 series had center diff + CDL + FR and RR lockers. The 80 series didn't have A-TRAC, but triple locked solid axles and the coil suspension the only thing that you can't drive past is a gas station.

In LR the central diff is locked mechanically with a lever VS LC push button.

In LR, if needed, one could go in the low gear without locking the central diff (see the photo above) VS LC needs first to be in central diff in order to go in low gear.

That is a true case, the Cruiser center diff lockup is actuated with an electric motor. There is a switch and a wiring modification (called the pin 7 mod) you can add to directly control the CDL function but it, like 4:1 gears, isn't a stock configuration. Adding the CDL switch gives you the option to lock the center diff in high range (it normally is not) and the CDL switch + pin 7 mod decouples CDL completely from high-low.

 

[rkj__]

I'd say I'm pretty close to "an average pickup buyer" with my driving habits lately. In September of last year, I bought a 2018 Sierra 1500 4x4. 2018 was the last model year the 2-speed transfer case was standard in the 1500. I did not buy the truck with the intention of any challenging off road use. I wanted a 4x4 to deal with snow, and the ability to move a trailer in low traction situations like mud and sand without worry.

In about 10 months, I've used 4L twice. The first time was simply to verify that it worked. The second time was when backing up my trailer, to get it out of a tricky situation. Could I have made the same maneuver in high range? Yes. Was it nice to have the extra control of low range? Yes.

Many have commented about how low the first gear is in current 8 and 10 speed transmissions, but what about reverse? With the V8 in my Sierra, I think I have enough torque, that I could probably get buy without 4L, and have it never be a serious problem, since my trailer is not very heavy. However, I do remember a time with my old I5 Canyon, where I was trying to back up my trailer over a rock, and in high range, I could put my foot to the floor, and it did not want to climb over the rock. I also remember lots of fun trail runs in the old Canyon where I enjoyed 4L. But, as we all know, most people don't take their pickup trucks on challenging trails, just for the fun of it.

Oh, and on the topic of 4 auto. There was exactly one time I wished I had it in my old truck. I was on a long drive through farm country on secondary highways. There was intermittent snow drifts over the road. They were fairly deep in spots. It was bare pavement - snow drift - bare pavement - repeat. In my new truck, I used 4 auto a few times last winter, since it was there. But, for many situations, I still preferred to maunally select 2H or 4H. It is nice to put it in 4 auto if somebody else is driving my truck, and they are not familiar with part time 4x4 systems. Rather than explaining when to, and when not to use 4H, you can just say, "I put it in auto, don't worry about it."

 

[shade]

it's a matter of tricking the 4WD ECU to unlock and lock the front differential disconnect

That's how I get 2Lo. Works very well, but I need to install a separate switch so 2Lo is persistent past engine shutdown. Otherwise, driving in 2Lo and shutting off the truck results in 4Lo when restarted, which gets to be a pain when repositioning frequently.

 

[MOguy]

What you've described is mostly a 2003+ 4Runner or 1998+ Land Cruiser. Lockable Torsen center diff and TRAC/A-TRAC/VSC and with some years having electric lockers. The stock low range on Toyota is around 2.28 for the most part, so not Rover low but there are aftermarket gear sets for 4:1 low range and Marlin can pretty much double (or triple if you want) case any Toyota.

I had an 04 4Runner like described above. The only issue was you could not turn the traction control off. There was a work around some out to do this but then a bunch of lights would be on in the dash area.

 

[Martinjmpr]

On my '07 V6 4runner I'm pretty sure traction control was disabled when you locked the center diff. I seem to recall there was a light that went on telling you that traction control had been disabled.

You could also use 4 low "unlocked" on dry pavement with that setup.

Absolutely the best transfer case setup I've ever had in a vehicle. I wish my Suburban had that instead of "auto 4wd."