ATRAC Question

[Jeremy556]

So, this past weekend, I managed to get myself into a spot with both back tires off the ground, one front tire close to full droop (no traction), and the other front wheel pretty well stuffed in the wheel well.

I was in 4LO, with ATRAC on, and rear diff lock engaged. From 0-15mph on the speedometer, 3 wheels were spinning, but the stuffed front wheel didn't move at all. I thought that ATRAC would brake the spinning front wheel to transfer torque to the stationary wheel, but there were no lights on the dash, no ABS noises, just the sound of 3 tires spinning.

Am I mistaken in how ATRAC is supposed to work, is it not working as it is supposed to?

 

[Intruder]

I think at most A-TRAC will transfer 50% power. It sounds like in that situation a front locker might have gotten you out, but if both your rear tires were off the ground you probably had something holding your truck up (almost high centred). It's kind of doubtful you could've gotten enough traction in a situation like that to pull yourself off the obstacle even with a front locker.

 

[Jeremy556]

I think at most A-TRAC will transfer 50% power. It sounds like in that situation a front locker might have gotten you out, but if both your rear tires were off the ground you probably had something holding your truck up (almost high centred). It's kind of doubtful you could've gotten enough traction in a situation like that to pull yourself off the obstacle even with a front locker.

Yep, I was almost completely high centered, but I thought that one wheel with good traction should at least move, even a little bit, or make some noises, or something. Even with a front locker, I probably would have still been stuck and had to jack or pull to get out, but I'm just wondering why it seems ATRAC didn't do anything, my understanding is lacking, or it was outside of its parameters.

 

[SEP]

if im not mistaken atrac does not activate above 4mph. sweet spot is around 2000rpm and just wait till the system kicks in. sounds like you were gunning it too hard.

 

[Jeremy556]

if im not mistaken atrac does not activate above 4mph. sweet spot is around 2000rpm and just wait till the system kicks in. sounds like you were gunning it too hard.

Actually, I have read about ATRAC+Locker <4mph, so at first I was running at idle, and even riding the brakes a bit to stay at low wheel speed, with no results. Thinking maybe it needed a bit more wheel spin, I got it up to about 15mph on the speedo, but didn't want to go above that for fear of something catching traction and grenading drive train parts.

 

[SEP]

Here is a supporting thread on atrac. Try to just keep the rpm at 2000 and it will kick in but stay on the gas at same rpm until you get unstuck. First time I did it I took my foot off the gas as soon as atrac kicked in and i didn't go anywhere. So then I kept my foot on the gas longer until i made it through.

Understanding & Using ATRAC II+ - Toyota 120 Platforms Forum

 

[westwind77]

I was in 4LO, with ATRAC on, and rear diff lock engaged. From 0-15mph on the speedometer, 3 wheels were spinning, but the stuffed front wheel didn't move at all.

May be a stupid question, but was the A-Trac light lit up on the dash (you said it was on, just making sure though). The one time I played with it, it did make a huge difference (stuck to unstuck (on purpose to test though)).

 

[rjmckay99]

I thought ATRAC wouldn't work with the rear locker on, seem to remember reading that in the manual. I would imagine with the rear locker on ATRAC would not work because it would want to change the power distribution from 50/50 to brake the spinning wheel. If there was not ATRAC light on the dash then maybe it just wasn't on? Can't remember what it says but I was reading about the locker and seem to remember something about ATRAC in there.

 

[Jeremy556]

May be a stupid question, but was the A-Trac light lit up on the dash (you said it was on, just making sure though). The one time I played with it, it did make a huge difference (stuck to unstuck (on purpose to test though)).

Yep. The dash light was on for ATRAC ON - by default shifting into 4lo it is off, have to press the button on the overhead console to turn it on.

 

[Intruder]

I thought ATRAC wouldn't work with the rear locker on, seem to remember reading that in the manual. I would imagine with the rear locker on ATRAC would not work because it would want to change the power distribution from 50/50 to brake the spinning wheel. If there was not ATRAC light on the dash then maybe it just wasn't on? Can't remember what it says but I was reading about the locker and seem to remember something about ATRAC in there.

Here's what it says in the manual:
When the rear differential is locked (vehicles with a rear differential lock system)
The active traction control system is activated only when vehicle speed is less than 4 mph (6 km/h).

 

[rjmckay99]

Thanks for the clarification Intruder! I knew there was something in there. Seems it was working as it should.

 

[tlflow]

winch in your future?

 

[Jeremy556]

Yep, going to get a VR10K-S, just not sure if I want to go with a hidden mount or Shockworks bumper, and what to do with the suspension...

I get by with a come along and hilift for now. Ended up jacking up the spinning front wheel and put rocks under it.