4X4 & snow questions

Ok, bear with me as I am not exactly the most veteran offroader!

So, a week ago I was making my way up a dirt road, and attempted to keep going when the road got snowed.

I was in to about my axles, and I kept getting stuck. Now, I know I could/should have thrown on my chains, and snow tires would also help a lot. But it felt like I was getting stuck pretty easily, and my friends (who were outside the vehicle) reported there were times that one or more wheels stopped spinning while the others still spun.

I had it in 4LO with the rear diff locker engaged and ATRAC enabled.

It's my understanding that in 4LO with the diff engaged, that gives me 2/3 locked diffs (center and rear) so I should have 3 tires spinning minimum at all times no matter what. Additionally, ATRAC ought to slow whichever front wheel might want to free-spin, right? That was possibly the weirdest part, I'm pretty sure ATRAC never engaged. In the past when I've used it, it seemed super obvious, with the brakes firing noisily all over the place.

Anyway, so can you confirm what I have said above? Also, are there things I might be overlooking, such as perhaps ATRAC is terrible in the deep snow?

Are there any good ways to verify operation of all the 4x4 systems without running up to the mountain pass, which is several hours away? The snow is finally gone in town.


If I am just being unrealistic and needed to suck it up and put on the chains, that's OK, but I gotta know my 4x4 is behaving first! If all four wheels are spinning and I'm not moving, I'll happily don chains. I wouldn't be wholly surprised; the snow this late in the season is much closer to slush/ice than powder.

 

Tire quality has a lot to do with biting into the snow and not slipping. I was running Hankook Dynapro ATMs and was very happy with them in all surfaces.

I used my A-TRAC + Rear Locker with great success. I was not in as deep a snow drift as you probably where (I am in San Diego after all), but this was up about 4,000 feet in our mountains.

You know that with the rear locked, the A-TRAC only activates when you have nearly stopped (becoming stuck), ie. under 3 mph...

The idea with this is, the rear two tires are locked together, turning the same and so the A-TRAC only applies on the front tires and locks them together only when you are nearly stopped or stuck, to get you out and moving.

It stays 'unlocked' on the front so you have some steering ability. Steering with the rear locked is hard enough. That's why it is only recommended to lock the rear in an emergency to get unstuck.

I would play around with different combinations to see what works best for you.

Low Range is for the most power to pull through or up, and only at low speeds. There is no traction control in low range without pushing one of two buttons... A-TRAC or RR DIFF LOCKER

A-TRAC is an 'automatic locker' like system that works the front and rear tires if and when one spins more than the other on an axle... and matches wheel rotation so power can be shared between the two tires on each axle.

The rear locker only, will be just that... but your front tires will not have any traction control, so when one in in slush, it will spin and the other will do nothing (open differentials).

A-TRAC + Rear Locker... leaves the front diff open for steering ease, but auto locks it if you are about to stop and one tire tries to spin more than the other.

A-TRAC actually 'matches' rotation with the brakes on one tire, but the effect is the same as 'locking' the tire to the other... but it doesn't stay locked any longer than you need it, so you can easily steer the truck... and why some complain that A-TRAC slips and makes more noise than lockers... takes a bit longer to climb... but you still get there, and A-TRAC is included in our trucks, a front locker is not.

 

David K explaining ATRAC in a way that makes it sound really complicated lol

 

Trying to not leave out any important details, so there doesn't have to be 10 pages to clear up any unanswered questions... LOL Besides, I was bored and wanted to write! Have a nice day!

 

I'm kidding man its better to be detailed than just say the thingy stops the wheels from spinning.

 

How good is ATRAC in relation to a locker? I'm sure there are positive and negatives to both but how well does the ATRAC spread the power?

 

airing down the tires for snow makes a huge difference. Last time I was in the snow I went down to 12psi. Pulled out a stuck Jeep who refused my requests to air down.

 

THIS is gold to remember, deflating tires off pavement does SO much more to enhance a vehicle's ability to go places or get unstuck.

The issue is likely no having an air pump, or a fast air pump to refill the tires once you are back to pavement?

The type of pump that clips onto the battery is the way to go, about 5-6 psi per minute is the rate. They are in the $50+ cost range and up. The kind that plug into a cigarette lighter only can produce about 2 psi per minute, so you will be there 3 times longer to refill the tires... but they are in the $25 range of price, and still better than a hand pump or driving on flat tires to a gas station!

 

These truck are pretty amazing with good tires. Also some wieght in the bed makes a huge difference in the snow. I have been slightly stuck a few times. The locker was enough to get me out. I usually only ise ATRAC for climbing. Its pretty amazing when its doing its thing.

 

Lockers are 100% traction to both tires if you have slippage and engage the locker(s)... and must be unlocked to negotiate tight turns. They are expensive ($1000 +). However, nothing better for climbing or traction.

A-TRAC senses when a tire slips and 'locks' the two tires together so you can move. Once it senses there is no more slippage it 'unlocks', so turning or brake/ drive train wear is minimal. The word 'locks' means here to match tire rotation across the axle with the brake system. A locker locks the rotation with the gears in a differential. A-TRAC is included in the price of our truck (4WD Off Road TRDs). Most of us will need all four tires 'locked' very rarely, so A-TRAC is a great included system for most of us. The few that are using their trucks for pure off roading, rock climbing, extreme four wheeling will probably want a front locker to add to the rear one already on our Off Road TRDs.

 

Been stuck once (my own fault).
Tires, tires, tires. Had the crappy dunflops on from the dealership the first time I went into snow, and was staying at a hotel place. The valet guys asked why I had chains if I had a 4x4 and I told them I hadn't bought new tires yet. They laughed but the next time I came back to the hotel (which was on a pretty considerable hill, I was gearing down to pull into the driveway and instead of slowing, I just slid straight past the driveway and kept going about an extra 30 yards before the street leveled out. Was able to turn around and go up the hill and pull into the hotel driveway and the guys were still laughing (and so was I, it was pretty ridiculous).

I have BFG All-Terrain TA KOs now, wonderful tires, especially in off-road and snow.

 

Cool, thanks for the replies. I will have to remember the "air down" tip, I carry a 120v compressor that I plug into the bed outlet so I have no problems airing up! (I found the 120v one was faster & quieter than the 12v ones, but I probably didn't compare to the ones that clip to the battery)

I definitely was under the 3mph speed (I know cos I was stuck, e.g. zero mph), and there was no problems turning because I was on SNOW

My tires probably aren't helping, they are the factory set still, and for weight in the rear I've just got the topper!

On the bright side I've always been the "least stuck" when other trucks are around, so maybe I'm doing fine & just have unrealistic expectations

P.S. Left side of truck was in deeper than y'all's photos, right side was shallower.

 

Was able to quickly verify all the systems seem to be working this morning, at about 1mph in a parking lot:

- Turning in 4LO gives the expected dramatically increased turning effort

- Locker makes rear tires scrub (they didn't really chirp, probably because I was barely moving)

Although with how finicky the locker is, maybe it didn't engage when I was in the snow, and I just didn't notice... Sometimes when I try to engage it, it locks in a half second. Sometimes it never locks. Speaking of this finicky behavior, is it OK to hold the brakes while engaging the locker?

Anyway, it's starting to look like I just need better tires & to use my chains. I'm excited to try out the chains, they are actual chains rather than the crummy cables...

I guess in a way I am a little sad, because the only thing that stopped my Subaru was bottoming out! Other than that, snow never stopped it. But it did have great tires.

 

I rarely use the rear locker because A-TRAC works all 4 tires, but I find that rolling slowly from a stop and if needed turn the steering wheel ONE direction and keep rolling slow should change the blinking locker light to solid.

 

I use high range mostly in the snow. Too much torque will make the tires dig down and get you stuck. Situations differ, but airing down and keeping momentum to float on top of the snow generally works best for me. If you feel it start to dig, get off the gas.

 

Good advice!

 

I just learned quite a bit, just wanted to leave a little thank you to the gents that posted.