A-Trac or Locker

EXACTLY what's happening. It was new on the 2009 models, didn't exist before, but you can lock the rear and the ATRAC will only engage on the front.

 

No not really. People confuse ATRAC with the VSC. They're necessary option package mates, but they're not the same thing. VSC will kill throttle to regain control, but ATRAC assumes you're off-road, and does its magic by ABS-ing the wheel that's starting to spin faster, which merely diverts the power to the OTHER wheel that's planted.

So it's not killing your power, it's diverting it to the wheel that can use it the best.

 

So when I went shopping for a new truck, I wanted to make sure I got the best equipment. I wanted "the best." unfortunately there's truth & there's marketing. How good is ATRAC? it's good, it's really good. But is it "locker" good? not quite.

It's great in that it will give you most of the benefits of a locker without any of the downsides of the locker. but in all-out off-road situations, the ATRAC is not quite the master of domain a locker can be.

The ATRAC is throttle sensitive. What I mean is, for it to kick in, you have to keep steady on the throttle. If you gun it or get off the throttle when you start getting stuck, the ATRAC will not stay engaged on the tire. so to make good use of the ATRAC, you have to hit the obstacle, increase throttle moderately, and stay the course.

With a locker, it doesn't matter, they're both spinning at the same rate no matter what. hit the gas, feather it down, don't matter. Both wheels will spin at the same rate without you having to *think about it* or try to manipulate anything.

Locker's the best, ATRAC is a great substitute. And if you can have both, the locker in the rear and the ATRAC on your IFS which is hard/expensive to lock, then hey, you're pretty much as set as you're going to get.

 

Locker

 

Here is a great video that illustrates A-TRAC in action

http://www.toyota.com/fjcruiser/demos/active-traction-control.html

 

A-TRAC is like having front and rear lockers, without affecting steering... Don't think you will need the locker with A-TRAC. But, because many of us 'old school' types insist on the rear locker being available, Toyota still has it. Remember, both A-TRAC and the RR Locker ONLY work in L4, and ABS doesn't work in L4...

I am still testing my new truck... but so far, TRAC and A-TRAC are fantastic new features over my 2005 Tacoma!

 

I have tried both. The most capable mode is Locker off, ATRAC on.
"Uh, when it breaks, you're screwed..." Actually, if ATRAC breaks, it's no biggie, if a locker breaks, your pulling driveshafts (if you're lucky) to get home.
My opinion.....I have the locker, and I have ATRAC. One locker does not compare to ATRAC, 2 lockers have way too many liabilties.
The comment about having to use throttle to make ATRAC work, do trucks with lockers magically propel themselves? No, it requires the same horsepower to go up a hill with a locker or ATRAC.
ATRAC is king.

 

Funny you say that. That's why I started this poll/thread. I've experimented a couple of times on a nearby, rutted out, loose dirt hill. I just crawl up it to see what happens.
4hi= Fail
4lo No ATRAC= Fail
4lo Locker only= Fail
4lo ATRAC only= Success
4lo ATRAC and Locker= Success but not any better than ATRAC alone.

I'm SERIOUSLY sold on ATRAC!

 

Another interesting point:
I can get myself stuck on the hill using 4lo and locker and come to a complete stop. Turn on the ATRAC, and go again! Restarting after being stuck with a locker, is no easy task.

 

You missed the point of the statement. ATRAC will not magically engage at all times, and it will not work if you're "playing" with the throttle; if you get into the gas or try to feather it, it will 'disengage' itself or rather it will just not operate. You HAVE to be smooth and STEADY on the throttle to get it working, which in some circumstances is not really in your best interest.

ATRAC requires translation between you and the computer. A locker does not. Locker is king.

I've had the opposite experience of you two, I've had ATRAC just not work enough to get me out. I've had ATRAC try and fail to the point that it just decided it was done, the brake light came on and it was through even trying. I'm not saying it's not effective, just saying that if you're in a hairy situation off road, the locker's what you want.

 

IMO its situational.

The best is locker + Atrac unfortunately till someone figures out a mod or wire hack, this is only possible under 3-5mph

I have been in a situation where I wasnt moving (stock fails played major here) locked and atrac on. Unfortunately it was not a sitation like dry rocks where I could crawl out, so my spinning the tires was obviously over 3-5mph where atrac was not functioning. In that situation, unlocking the rear and going full front and rear atrac got myself right out. Just needed that other front tire to pull.

Slow crawling locker + atrac ftw

>5-10mph or require wheel spin (ice, mud) atrac alone ftw

Just my observations.

You cant beat locker + atrac though..unless it disables over 5mph. Oo

 

This is what I have experienced so far, as well... Hemi and TRDBoy see it the way I have in Baja and Ocotillo Wells. However, there is still more to discover as my truck is still new-ish!

Pyrite FD, the A-TRAC works up to 30 mph, but only 3-5 mph with the locker also activated, as you say.

Since Toyota clearly says the locker is for emergency only and should be turned off as soon as you get un-stuck... why would you need to go more than 5 mph once the system gets you unstuck? ('stuck' means you are going 0 mph).

Once you are un-stuck, turn the locker off... and use A-TRAC to continue in L4. I don't recall ever going faster than 30 mph in L4 anyway... It just works the engine too hard. If you can go more than 30 mph, you can be in H4... and go up to 60!

 

exactly. unlock the locker and you can have front and rear atrac above that 3-5 cutoff which is why imo it much more useful than being locked if the situation you need isnt crawling

 

Right... (I think)...?

3-5 mph is what I would call crawling... you can do with A-TRAC only... but if you slow down to 0 mph, then try the rear locker to get moving again.

To go faster than 3-5 mph you can either turn off the locker, or the A-TRAC turns off automatically. So, you can choose rear locker for faster speed (not recommended by Toyota) or choose A-TRAC by turning off the locker.

A-TRAC is the new kid on the block and it is supposed to work like (or better than) lockers, front and rear! The rear locker remains available because A-TRAC is so new... and just look at the poll in this thread.
I know I would insist on the rear locker when I got the 2010, without trying A-TRAC first.

People still think a rear locker is better than A-TRAC (front and rear locker-like traction). I would bet most of those who voted for the rear locker either do not have A-TRAC or have not used it enough to see how well it works!

 

um...ok let me re-explain this

you can have it locked in 4L whenever you want. there is no speed limit that will unlock it. to actually engage it thoguh, you have to be under 5 though i believe. ive gone over 40 locked, doesnt matter, nor am I worried about what the manuals recommendation says being the prerunners can stay locked at higher speeds fine, as well as any other rear end built worth much...

you can turn on atrac whenever you want in 4L as well. only two things will fully or partially disenguage it.

1) if you hit the switch it will obviously fully disengage.

2) if the rear locker is locked, it will automatically disengage over that 3-5mph range


you can go faster than 3-5 with the locker on fine, but you will lose the atrac and essentially you will have a locked rear end an 1 wheel drive up front for all practical purposes.

the problem is, when you are going over that speed, traction wise you will have more traction with atrac on all 4 wheels versus rear locked + 1 front wheel. thats the point, and imo the atrac seems to do better in my experiences even up against a full locker. i dont think i would really put atrac in the same boat as a locker , but would put it up there with an aggressive lsd for sure if not near locker. I havent by any means stuck my tire in a vise and tested that theory, but im sure you will get some degree of slip.

if however you are in a high traction low speed situation, which rock crawling is the only thing that comes to mind really, then by alll means rear locker + atrac front would be superior. in the snow or mud or loose gravel etc, many times having both front wheels pulling will outweigh the advantage of having a locker in the rear, and especially so when that unlocked rear is acting like an aggressive lsd via atrac.

to sum it up you have 2 situaitons in 4L both with several options and my opinion of the best combination

situation 1 below 3-5mph

a) rear locked plus open front
b) rear locked plus atrac on front (win) (atrac on rear should be non functional at this point with 0 slip between the two wheels)
c) rear unlocked no atrac
d) rear unlocked atrac front and atrac rear

I choose B as rear locker + front aggressive lsd is the clear choice with the most traction. The closest to real 4 wheel drive.

situation 2 above 5mph

a) rear locked plus open front
b) rear unlocked with atrac front and atrac rear (win)
c) rear unlocked no atrac

Again, I choose B as the best traction aid with the rear aggressive lsd + front aggressive lsd. The closest to real 4 wheel drive. Although I certainly weigh a true locker higher than a simulated lsd, at faster than crawling speeds I consider the above to be better (especially when it really works great).

Bottom line, the difference between chosing locker with atrac or just atrac will be situational depending based highly on terrain, traction, and wheel speed.

 

Right!

I need another Baja trip real bad to further test and compare. I do know what works, however... and A-TRAC with the rear locker engaged did pull me out of the sand, after I allowed my truck to get stuck (by going to open differentials /VSC off mode). I didn't try with just A-TRAC only to get unstuck.

The thrill of how superior my truck drove in the sand with just TRAC in H4 (without deflating tires) blew me away! I have done beach driving in Baja since I was 16 (1974) and this Tacoma with Traction Control beat all of my previous vehicle's performance... Jeeps, Subarus, Dune Buggies, Tacomas.

 

I have a 2009, I see you have a 2010, but I'm curious if there's confusion. I don't believe ATRAC can be engaged whilst in 4Hi. your sig states 4Hi with VSC & ATRAC on, but they're essentially the same system, ATRAC is just minus the throttle blips (and it's more aggressive on the wheel braking). What I'm saying is, if you've got VSC on, then yes you ARE losing throttle, that's the way the system works. It's ATRAC that doesn't do the throttle blips, and it's one or the other, not both, AFAIK.

 

why isn't it recommended to go faster than 5mph with the locker engaged?

 

Trac and ATRAC are two different things. Where you have said ATRAC, the proper is Trac. I dont see anything in his sig that talks about ATRAC and 4hi together.

VSC and Trac are not essenstially the same things, although they are regulated similarly via braking.

Trac, primarily controls wheel spin by braking and in 2H (but not 4H) throttle inversion.

VSC, primarily controls slides by braking and in 2 and 4H throttle inversion.

In 4H, you can therefor have VSC/Trac on and not be losing throttle but still triggering the traction control. If you arent sliding and activating VSC, you arent losing throttle. You can trigger trac all day long with no throttle loss.


In 4H, yes it is possible that you can trigger the VSC and it will cut throttle. Ive done it many times drifting around in the snow. From my experience, it really isnt activated to you start to slide. Trac however will function much more often with no adverse effects.


Atrac is only in 4L. 4L automatically disables both VSC and Trac. Therefore Atrac cannot be on with VSC/Trac.