You're right. The truck still feels brand new to me as I'm learning its quirks. Reason why I've decided to test ATRAC in isolation from all the other systems.
Off-road situations where the A-Trac really shines?
- Thread starter MoonStorm
- Start date
You're right. The truck still feels brand new to me as I'm learning its quirks. Reason why I've decided to test ATRAC in isolation from all the other systems.
For anyone who watched this video, that is an extract from a demo using crawl control to get the truck out of the sand. The full video, with explanations, is here:
https://www.youtube.com/watch?v=HRLxRiUHvxo
Pretty much the same situation as me getting stuck in the snow testing out the ATRAC, with the truck initially stopped, no momentum given. I doubt the two systems share too much of the logic, as it didn't behave like that in my case. It required a lot of convincing to spin all the wheels but who knows, maybe I caught it in a bad day. But perhaps a better explanation would be the fact that the 2016 Tacoma I believe has an improved version of what we've got on our 4Runners. We might be comparing apples to oranges here.
Good video though. Now I'm gonna have to test the crawl control in similar conditions and start a new thread. :hiding:
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Alright [MENTION=91899]Jhalko[/MENTION], I was wrong, can we please bury the hatchet now and move on with our lives.
And hey, look, I even edited this post to add that I am indeed a condescending prick, but I'm trying hard to hide my true face :lol:
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Jhalko
New member
We're good, this thread has an amazing amount of info in it, thanks for bringing up the topic.
Edit: Now that was funny Moonstorm!
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wfo9
New member
I really don't think most people understand how an open diff vs a spool works. An open diff equalizes torque across both axles 50/50 and allows for different wheel speeds. The wheels speeds can be different, but they always average out to the input shaft x diff ratio. A spool/engaged locker will allow for completely different torque application across axles but guarantee equal wheel speed. This is also why parts are more likely to break with a locker, since all the TQ can go to one wheel vs being equally distributed.
ATRAC or any other brake activated limited slip applies brake pressure to force more torque to the wheel on the opposing axle. Remember, its 50/50 tq, so adding resistance to a wheel in the air (or on ice...) allows the other wheel on potentially solid ground to get some tq. People have been manually doing ATRACish things for a long time via two foot driving/heal and toe.... but the ABS system allows for individual wheel braking and actual wheel speed deltas to be utilized.
And like I stated before, the system is a compromise. It can't be too aggressive or it would compromise overall reliability.
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Apex Overland
New member
any 4wd vehicle would have got out of that, atrac/multi terrain select/crawl control or not. If it kept going UP HILL we would be impressed.
sooperedd
Member
I have used the ATRAC once, just to see how it works and I more than likely needed it to AVOID getting stuck or not making it up the hill.
It was a long (150 yds), hard-packed, wet, slick as snot, steep hill. It was still drizzling rain after raining hard all night and I had to get home.
Went slow and steady, kept momentum; there were deep ruts from water running down the hill and I was sliding from side to side and in and out of the ruts all the way up thinking I am going to get stuck but the T4R walked right up that hill with the ATRAC.
The only way I would have made it in my Suburban would have been to try and stay in the ruts and chew my way to the top.
I was impressed with the ATRAC to say the least.
It was a long (150 yds), hard-packed, wet, slick as snot, steep hill. It was still drizzling rain after raining hard all night and I had to get home.
Went slow and steady, kept momentum; there were deep ruts from water running down the hill and I was sliding from side to side and in and out of the ruts all the way up thinking I am going to get stuck but the T4R walked right up that hill with the ATRAC.
The only way I would have made it in my Suburban would have been to try and stay in the ruts and chew my way to the top.
I was impressed with the ATRAC to say the least.
Dark Lord
New member
This thread is definitely informative. I don't have a lot of experience using ATRAC since I'm new to the 5th Gen, and wheeling in general, but ATRAC did get me out of mud once.
I was stuck in deep mud, and my spotter had me turn on ATRAC then cut the wheel. I kept it at steady 1500 RPM and the truck wiggled its way out of the mud. I was definitely impressed.
I was stuck in deep mud, and my spotter had me turn on ATRAC then cut the wheel. I kept it at steady 1500 RPM and the truck wiggled its way out of the mud. I was definitely impressed.
phillyd2
Senior Member
There is a reason most don’t use a screwdriver to hammer in a nail.
When ATRAC is effective.
https://www.youtube.com/watch?v=7Rlt-Rhythg
When ATRAC is NOT effective
https://www.youtube.com/watch?v=GmrmM9FoRrc
I’m no fancy Engineer but I would guess that a system designed to detect wheel spin would actually need for the wheels to actually spin. In snow sometimes it’s best to turn off ALL traction control aids because sometimes brute force is slipping are your best friends.
When ATRAC is effective.
https://www.youtube.com/watch?v=7Rlt-Rhythg
When ATRAC is NOT effective
https://www.youtube.com/watch?v=GmrmM9FoRrc
I’m no fancy Engineer but I would guess that a system designed to detect wheel spin would actually need for the wheels to actually spin. In snow sometimes it’s best to turn off ALL traction control aids because sometimes brute force is slipping are your best friends.
He could have had full lockers and he wouldn't have gotten out of that with those rented tires. If your tires can't get a grip it just doesn't matter.
phillyd2
Senior Member
That pit was actually designed to get stuck in to train on other recovery methods so I doubt even different tires would have helped.
FordyceCreek
New member
Not sure its been mentioned but I bet once the locker is triggered the Atrac becomes more aggressive, on the old Monteros back in the day the computer changed performance based on what mode you are in. So no locker on and it may not be as aggressive?
The reality is Atrac will get you further, but never sub for a front locker. And it will reach a point where it simply cannot keep up with terrain changes and you'll end up losing momentum due to braking.
The Crawl control likely dials the Atrac in more allowing you to get further with Atrac by telling it what type of terrain you are on and how fast you need it to respond.
Not tired ours out much either yet, so this is all theory, but we will eventually test it.
The reality is Atrac will get you further, but never sub for a front locker. And it will reach a point where it simply cannot keep up with terrain changes and you'll end up losing momentum due to braking.
The Crawl control likely dials the Atrac in more allowing you to get further with Atrac by telling it what type of terrain you are on and how fast you need it to respond.
Not tired ours out much either yet, so this is all theory, but we will eventually test it.
Intruder
New member
No, sand and snow are very different. Wheel spin will polish snow into ice. Granted you could polish sand into glass but I think your tires would melt before that happened.
Crawl control uses ATRAC. It's pretty much just a smart ATRAC system.
wfo9
New member
Opinion below - not based on viewing any code....
Yes, it is ATRAC in a more aggressive mode, but the algorithm is completely different. It is in compete control of throttle, so things are much more predictive vs reactive. Torque output is very limited, so it can be way more aggressive without compromising reliability.
Unfortunately, this also makes it much less useful than ATRAC mode where the driver gets to actually control the vehicle for the obstacle/situation at hand. In the case of the OP, in deep snow.
I seriously doubt crawl could get him out. A big heavy 5th gen with pretty small tires is probably not going to get out of deep slippery stuff once at a complete stop (especially at street tire pressure). As we all know (but the OP seems to want to ignore) the driver needs to know how to read the terrain and work the situation, sometimes that means not stopping until gravity is working with you... it also often means dropping tire pressure or even avoiding a situation that is beyond your equipment. Electronic gizzmos can't (at least not yet) replace a little common sense. Experimentation is good, but utilize the results and move on to the next approach.....
Jetboy
New member
FWIW - having had both - atrac works very similarly to a torsen style limited slip. It's kinda remarkable how similar it feels at times with the jerky transfer of torque and the lurching motion of it all. I had a toyota pickup with a locker in the rear and a detroit trutrac in the front that is a helical gear limited slip. I was able to break a few axles with the trutrac, so it was a bit tighter, but not a lot. Because of how they work, just a little break application gives a trutrac a near full lock operation. I've always thought a-trac plus a helical gear type limited slip could offer very a very close to full front locker effect with some other benefits, but it'd probably need some testing to make sure it would work like I think it might. It might allow you to get away with more tire size because you'd still have just a little more built in fuse for situations that might otherwise snap a front axle.
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Styer
New member
Found this today. Claims to be using only ATRAC https://www.instagram.com/p/BAYMMrmlMhf/
Intruder
New member
Jetboy
New member
Yep. That's not crawl control. The fastest crawl control would never spin the tires as fast as that vehicle did.
sooperedd
Member
Should I be suspicious there is a pause before he attempts to get out?
