Off-road situations where the A-Trac really shines?

[Jetboy]

Should I be suspicious there is a pause before he attempts to get out?

No. There are tons of videos of heavier LC200's in soft desert sand doing the same thing.

 

[CharlestonFisher]

In order to accelerate in the snow or on extremely slick surfaces you need to be on the edge of traction. You know that area between going forward and spinning? Yeah, there. In order to be at that point ATRAC will be DETRIMENTAL to your forward progress instead of helping go forward. That's why Toyota thoughtfully included a "VSC OFF" button. This way if you are stationary on a slick hill and you need to move forward you can turn VSC off and allow your tires to break traction and spin in order to get on that "edge" of traction. ATRAC or VSC in that situation will brake your wheels or retard your throttle and keep you stuck!

Very helpful explanation. I got myself into a pickle this past weekend and we tried ATRAC to no avail. Steep, narrow, muddy hill climb that I was the last one up. Had decent mo, but when I started to spin, I let off the gas (mistake) because of my inexperience and stares from 4 or 5 Tread Lightly trainers (one of which owned the property). Situation was tough. Backing up more than 3 feet would have cause the vehicle to slip and rest against some trees (no thanks). I tried a few more times doing some two peddle driving getting the RPMs up to 1500 (sweet spot imo). We were hoping we could be a 2nd gear start, but it doesn't seem to be able to do that. Kept slipping. Someone suggested ATRAC and gave an explanation that we would hear the ABS working. In retrospect I think that person was confusing ATRAC with crawl control. I realized that engaging ATRAC would require me to drive with one foot so as not to override it. Well... It didn't make a hill of beans worth of difference. Got the car up to 2100 - 2500 RPMs but I never got enough momentum to do anything. Your explanation of VSC would have been helpful to know.

So how did I get out? We checked the tire pressure and what was 18 psi at 7:45 am was 20+ that afternoon. I dropped to 12 psi and hammered the skinny peddle. Crawled out of there like a champ.

 

[wfo9]

Very helpful explanation. I got myself into a pickle this past weekend and we tried ATRAC to no avail. Steep, narrow, muddy hill climb that I was the last one up. Had decent mo, but when I started to spin, I let off the gas (mistake) because of my inexperience and stares from 4 or 5 Tread Lightly trainers (one of which owned the property). Situation was tough. Backing up more than 3 feet would have cause the vehicle to slip and rest against some trees (no thanks). I tried a few more times doing some two peddle driving getting the RPMs up to 1500 (sweet spot imo). We were hoping we could be a 2nd gear start, but it doesn't seem to be able to do that. Kept slipping. Someone suggested ATRAC and gave an explanation that we would hear the ABS working. In retrospect I think that person was confusing ATRAC with crawl control. I realized that engaging ATRAC would require me to drive with one foot so as not to override it. Well... It didn't make a hill of beans worth of difference. Got the car up to 2100 - 2500 RPMs but I never got enough momentum to do anything. Your explanation of VSC would have been helpful to know.

So how did I get out? We checked the tire pressure and what was 18 psi at 7:45 am was 20+ that afternoon. I dropped to 12 psi and hammered the skinny peddle. Crawled out of there like a champ.

I find tire pressure to to be the #1 mistake for most noobs (and even pretty experienced folks). One pressure is not ideal for all situations and it will move around during the day.. Again, no electronic gizmo can overcome the laws of physics and common sense.

I think I mentioned tire pressure in almost all of my responses to this thread.

Mud is a real wild card in any offroad situation. I have encountered many different types... and they each require a different technique... Who would have thought there are so many different types of mud. I generally try to avoid it, but sometimes there is no other choice.

 

[Knight-Errant]

You all don't have A-TRAC signs on the trails in your area?

It really helps take the guess work out of everything.

 

[blues]

If only... I think I'll petition the county commissioners to adopt a new signage program!

 

[J-BlickPhoto]

In my experience I've found ATRAC very helpful. I've been stuck in sand, snow, and mud. In sand and mud (with a bottom) ATRAC is worth it's weight in gold. In snow however, it's a line of diminishing returns. If I find myself stuck in snow (which is often) I immediately engage ATRAC and I begin turning my front wheels back and forth or backing up slightly to gain a bit of momentum. I never floor it and I try my best to never allow my wheels to spin. If you do, you'll polish and melt the snow below your tires and slowly but surely you'll high center yourself.

 

[salong53]

After an exhaustive search of this fancy new thing called YouTube, here are 2 videos produced by ARB that compare open diffs, lockers, and A-Trac side by side on 3 different LC Prados. That should answer any questions about when each system works best.

https://www.youtube.com/watch?v=C2wkW05Pc6c
https://www.youtube.com/watch?v=YNFacsKnswM

 

[N2GLOCK]

Off and on I've been reading up on ATRAC since 2012 and I can honestly say that I really don't understand it yet 100% I understand the mechanics of it, I'm just not sure as to under what circumstances it needs to be used. I've only gone off roading a handful of times, and I never got myself in a situation where I needed it. Needless to say...it's probably one of those features that I'll never end up using. Glad it's there though. I guess it's kinda like a firearm...Better to have it and not need it as opposed to needing it and not having it.

 

[Ron4RNevada]

This is by far one of the more civilized threads. When 15 people answer a certain question the same way then the problem is usually not with the 15 people, it's with the one asking the question.

1500 engine RPM has nothing to do with it. You were in one very specific situation and you were immobile. Listen:

The wheel sensors are set up to detect a delta between the wheels, just like VSA. When you have all wheels in the snow who knows WHAT wheel will be the one with traction. So in essence a wheel needs to spin at a differential RPM from the other wheels before the processor will analyze the signal and determine the best course of action for that specific wheel. Now, it has to also determine that this differential RPM is NOT caused by common everyday occurrences like: Sharp turns, worn tires, low air pressure in one tire, etc. You see, all these things will cause a differential RPM between wheels too so the differential between wheels has to be GREATER than it would be in everyday driving. In addition to this, you need to note that ATRAC works at other speeds besides "stuck" which is the ONLY condition you tested. So, while in your specific case the speed the ATRAC actuated "felt" excessive, if you were traveling 15 mph then the ATRAC would be performing it's task of braking spinning wheels without any discernible trigger.

In order to accelerate in the snow or on extremely slick surfaces you need to be on the edge of traction. You know that area between going forward and spinning? Yeah, there. In order to be at that point ATRAC will be DETRIMENTAL to your forward progress instead of helping go forward. That's why Toyota thoughtfully included a "VSC OFF" button. This way if you are stationary on a slick hill and you need to move forward you can turn VSC off and allow your tires to break traction and spin in order to get on that "edge" of traction. ATRAC or VSC in that situation will brake your wheels or retard your throttle and keep you stuck!

Now, if you would have read these very good responses from a lot of good people who took time from their weekend to try to help you understand, then you would have come to the same conclusion as I outlined above. Instead you came here looking for a specific answer to fit your one test. In snow, ATRAC or VSC is not going to help, unless you already are at speed.

Exactly!

Land Rover which has had this system for close to twenty years now recommends that it be engaged before the trucks stops. In fact most LR's have the system ON all the time. It works so well that they don't even offer a locker.

 

[toytruck]

Not sure if this photo would help any but atrac works really well in soft sand/dunes. I was going up very loose sandy hill with a slight incline in 2wd and the rig started sliding. The incline was not much but was there and of course photos dont really portray it well. Came to a complete stop and then dug myself in pretty good. Atrac flipped on and eventually did its job. IMO its pretty darn impressive.

 

[Aquabear]

Thank you for all the input in this thread. Great reading info, esp for returning 4R guys like me who want to again venture in the outdoors. My broken body doesnt hike so well, I'll let the 4R get me uphill but stay in shape to take the bumps!

 

[MoonStorm]

Not sure if this photo would help any but atrac works really well in soft sand/dunes. I was going up very loose sandy hill with a slight incline in 2wd and the rig started sliding. The incline was not much but was there and of course photos dont really portray it well. Came to a complete stop and then dug myself in pretty good. Atrac flipped on and eventually did its job. IMO its pretty darn impressive.

WOW! I'm really impressed you got out of that one.

 

[4Rager]

I was gonna make a new thread about this a while back but decided it wasn't worth it. However this thread is a perfect place to share these pics (even though it's 7 pages later).

This is as far as it made it in 4L (no locker)

Front View:

Turned on A-TRAC (no MTS) and it walked right up. I actually made a video but the second I let off the brake it pretty much crawled up instantly, so the video was kinda lame (definitely did not wait to get to 1500rpms).

Front View. Wheel is off the ground:

Gives you an idea of max down-travel

Onward and upward

Hole from left rear tire before engaging A-TRAC (remember no locker used)

 

[BobsTrail]

For those with a TE and Multi-Terrain, why use ATRAC instead of M/T on the first or second setting? I think ATRAC is similar to M/T on step 4.

 

[4Rager]

For me the reason is 90% of the time I use A-TRAC I'm in a situation where I know I'll need it to act as front locker. This is the case in the situation above which was all done for the sake of illustration. I obviously could have gone around that hump. Basically when I already have the rear locked and it serves as a last resort if I encounter something tough. Or it could be the opposite situation where I don't feel like engaging the locker and I need a little extra to get through a washed out ravine or hill with loose rock. It also should be noted that I do live where the trails are hard packed and dry 90% of the time.

Here's a trail I did use MTS for and it engaged 3 or 4 times on the way up. It was steeper and a bit more moguly than it looks. Can't remember if I locked the rear or not, but I probably did.

 

[pinetar]

Ah yes, those local NV trails.

Glad to see another person who explores around this area!

 

[thennen]

This is actually going to be a really good thread for future people who and learn about atrac. Sorry if I was a little abrasive with my comments OP. This a 4runner forum, not Lexus so we are not always as civilized. I do like me some grey poupon though.

You were right - almost 3 years later, I'm getting good info to keep in mind when I finally take my new TRDOR off road and into snow. Thanks, all!