National Park Service cited AWD owner on 4WD trail!
- Thread starter edyvw
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Not according to Subbie. Here's a link from them that explains the differences... What’s the Difference Between 4WD and AWD?
And here's a little snippet from that link...
"While AWD automatically varies among front, rear, and center differentials depending on needs, 4WD is typically paired with locked differentials. This means that both wheels on an axle are locked together, and all wheels receive power equally. All wheels in 4WD rotate at the same speed, regardless of which one requires extra traction. This can be useful when drivers find themselves stuck in snow, mud, or rocky terrain and need an extra jolt to free their vehicle. This is also true of AWD, which offers added traction by sending power to all wheels in muddy, sandy, or icy conditions."
I personally still have a hard time wrapping my head around the real-world differences. Subaru is known to have the gold standard of AWD systems, and many other vehicle manufactures are quickly catching up. If an AWD system is able to send power to all wheels at the same time and/or can almost instantaneously monitor slip and send more power to the wheels that have the traction, isn't this just as good (or maybe even better)?
I have a 2018 Honda CRV which in my opinion has a very good AWD system, and I believe the newest versions are even better. I have driven mine on top of a frozen lake with snow on it that was higher than the front bumper. The wheels just chewed right through it. I did have to keep moving in order to keep the car from sinking into the snow and getting stuck, but even so I was pretty impressed. I think with a good AWD system (just like in my example) it's way more about ground clearance than it is about having a locked transfer case.
One more thing that I don't completely buy about true 4 wheel drives being better... In the above quote from Subaru it says "All wheels in 4WD rotate at the same speed, regardless of which one requires extra traction". That's just not true. At least not if you don't have a limited slip or full lock-up rear differential. Besides the CRV, I also own an old 4WD Ford Ranger. In 2WD mode, just one wheel will spin if it looses traction. I'm pretty sure in 4WD you will have 3 wheels that have power, but the rear wheel that's in the snow or mud will just spin and be almost useless, while the other rear wheel that actually might be on solid ground will get nothing. This makes it worse than a good AWD system, no?
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Almost every part time "AWD" system only has a clutch pack in the middle to match the front and rear axle speeds. Which if the clutch locks 100% makes the vehicle had 4wd as there is no centre diff. Front and rear diff locks, hi and lo range, aren't part of the definition of 4WD and AWD.
If I got a big fine, I'd argue that whatever subaru marketing calls it, the CVT models are all part time 4WD as there is no centre diff. And that X-mode essentially preloads the centre clutch to lock which makes in 4WD enough. I still wouldn't do a trail that requires lots of crawling with a vehicle without low range, 4wd or AWD.
If I got a big fine, I'd argue that whatever subaru marketing calls it, the CVT models are all part time 4WD as there is no centre diff. And that X-mode essentially preloads the centre clutch to lock which makes in 4WD enough. I still wouldn't do a trail that requires lots of crawling with a vehicle without low range, 4wd or AWD.
And then you can you can blur more with things like my '03 Sequoia. It was RWD, AWD and 4WD depending what you picked. There was a locking center differential that when open was fine to use on dry ground as AWD. There was also a transfer case that had low range.
The caveat is that front and rear diffs were open and used the brakes to limit wheel spin (until the ABS pump overheats). They didn't even offer factory limited slip or lockers. You could get them through Eaton/TRD if you wanted to go through that afterward. When you locked the center diff it also disabled the ESC so it wouldn't kill throttle.
It did have good ground clearance though, metal skid plates, towed great and I never got stuck in the places I went. I did try one snowy hill my neighborhood in RWD with General Altimax Arctic iirc. Got stuck, lots of clicking and buzzing sliding sideways. Had to use at least AWD to get up it. I went home and grabbed my dads Chevy Express conversion van on Altimax Arctic. RWD with GM LSD, same hill, same spot, both tires spun, rear end hung out and left 2 rooster tails all the way up the hill.
The caveat is that front and rear diffs were open and used the brakes to limit wheel spin (until the ABS pump overheats). They didn't even offer factory limited slip or lockers. You could get them through Eaton/TRD if you wanted to go through that afterward. When you locked the center diff it also disabled the ESC so it wouldn't kill throttle.
It did have good ground clearance though, metal skid plates, towed great and I never got stuck in the places I went. I did try one snowy hill my neighborhood in RWD with General Altimax Arctic iirc. Got stuck, lots of clicking and buzzing sliding sideways. Had to use at least AWD to get up it. I went home and grabbed my dads Chevy Express conversion van on Altimax Arctic. RWD with GM LSD, same hill, same spot, both tires spun, rear end hung out and left 2 rooster tails all the way up the hill.
edyvw
$50 site donor 2025
They do. They clearly say it is AWD that can take on ANY terrain, the worst blizzards, and that if you buy one, you pretty much can drive from here through Bering Strait and Siberia to have coffee at Stephansplatz in Vienna.
That is why they are most common vehicle in the ditch here when it snows.
So yes, they say it is AWD, that can do "everything." Then add to that bunch of people who are too cheap to buy a proper vehicle with locking differentials, so they buy Subaru, add large tires, make a bunch of videos, and you have a bunch of people really thinking their Subaru Crosstreck is Lexus GX470.
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edyvw
$50 site donor 2025
Some national parks have a clear warning that you should not try trails without genuine A/T tires because of punctures. That Sequoia has a LOT of sidewalls on its tires. It is 4WD, regardless of the weaknesses you mention. You will go through.
This is where the issue is and what NPS is trying to prevent:
This VW Atlas is lifted and as one can see, has beefy tires, it has good, strong transmission, and Haldex can take A LOT of torque. But one can see that it needs a lot of spin to get the rear axle going to the point where it can overcome this, which is tricky terrain, no doubt. But, in process of doing that, one can easily damage vehicle enough to need towing.
This is a very good example of why AWDs are an issue, particularly with Subaru's and CVT's. It is a long video, but to see my point, one should start watching at 10:45min:
And example of 4WD (I bet there are better ones), but the point is, less drama, and lower possibility of something breaking etc.:
I don't even have AWD but the first gear is very low, like 3.5 mph at 1000 rpm. 2nd gear is slightly taller than e regular car's 1st gear
I don’t know. I’ve been to 16 national parks over the past four years. I’ve seen 4WD/High Clearance Only roads that definitely required a proper setup (like around Moab especially) while others were labeled as such and were easily passable with my RAV4 hybrid or a rental Mazda CX-3.
edyvw
$50 site donor 2025
Yes. But, problem often are tires. In the West it is super easy to puncture tire on roads like that. And vehicles like RAV4 or Cx-3 have usually low profile AS tires.
edyvw
$50 site donor 2025
.Pondering on this topic, would the HMMWV meet the definition of 4wd as used by the National Park Service? I think “no” in the strictest legalese due to the TorSen front and rear differentials that never “lock” (the center differential/transfer case can be locked).
Completely irrelevant. If you want some metric, figure crawl ratio which is 1st gear ratio x t-case ratio x differential ratio.
Note here that without low range (typically 2.7:1 give or take) you're missing A LOT of gear reduction. You're even further behind going up against a Rubi at 4:1 (392 excluded)
But then you still need to consider tire size.
Still, speed at a given RPM fails to consider gradient climbing, "compression braking" descending, and torque converter slippage.
And as noted, electric vehicles throw nearly all of this out the window.
If that's what Subie claims, they're dead wrong. The only way 4wd gets truly equal power to each wheel is front and rear diff lockers engaged. A true, part-time t-case goes without saying.
4wd is not "typically paired with locked differentials."
Very few vehicles come stock with driver selectable lockers, and I'd argue something like a GovLok doesn't count because you can't really predictably and repeatedly control when it locks.
Limited slips can be good but they're NOT lockers.
And while driver selectable REAR lockers have grown in popularity the last ~15 years (Tacoma, Nissan, H3s, SuperDuty FX4 and others), OEMs REALLY shy from true front lockers because inexperienced drivers just don't get it.
By Subaru's definition, there's only 3 or 4 very specific models sold that are 4wd. The Wrangler Rubicon, some of the old H3 models.....what else got OEM front and rear lockers? Not brake-based chattering traction control, but lockers? Maybe a G-wagen? Unimogs? H1 Torsens are a gray area.
edyvw
$50 site donor 2025
It is 4WD.
edyvw
$50 site donor 2025
It is not just about lockers. Anyone with center locker and low range would be in most of these areas OK when it comes to actual capability.
The problem is rest too. Transmissions, tires, suspension etc. Subaru claims a lot, but any Audi is far more capable on these terrains simply bcs. they have excellent AWD (Torsen ones), FAR better suspension and transmission. Yet, they don't tell customers to go and do this stuff. Could they? A lot of people use Q7 for off-roading. They lift it, put beefier tires etc. But regular Q7 would get fast in trouble bcs tires etc.
So, I think the idea here is that 4WD vehicles still come with other important variables necessary for off-roading: Tires, equally important if not more, a real spare tire, beefy suspension, etc.
I bet no one would get in trouble with NPS having strictly low range without any locker.
Thanks.
I’d think so, too.
However, if locking axle differentials is a criteria, a TorSen never locks and fails by definition. Hence my question.
The number of ways to distribute torque to driven wheels brings its own complexities to this topic. I suppose the park service needs some criterion and has chosen “4wd” even if there is not an agreed upon definition.
edyvw
$50 site donor 2025
I think it still counts with NPS. The reason for 4WD I think is sum of all things: Tires, suspension, transmission etc. Toyota Sequoia 1st gen would not have an issue with NPS, although it is sketchy with some models.
One other thing is that 4WD vehicles now are trucks and full-size SUVs, and they come with full-size spares.
I have been in some parks where NPS lists what you must have to not get in trouble, and the emphasis is always on tires.
Near me, 25 minutes or so, there is a place called Uwharrie National Park. It has some pretty nice off road trails. There is always some idiot in their longbed, crew cab stock height truck, getting stuck, and holding up the whole trail. Never seen a Subaru though, likely would not get to far.
A fine though? No.
A fine though? No.
