A-Trac or Locker

When ATRAC engages you hear the anti-lock brakes going "pop, pop, pop", or "click, click, click". In the sand, it never engaged long enough to get even two clicks in a row. Basically, I didn't need to have it turned on.

Typically I would do sand in 4hi but I was wheeling in 4lo and just came to the dune. I didn't have any problems in 4lo so just left it alone.

When I started this thread, I mentioned similar stories of getting my truck stuck on purpose on a loose dirt, frame twisting hill. I could even get myself stuck with the locker only on. Turn on ATRAC once stuck and sure enough, up we go!

At the time of starting this thread, my '09 was brand new and most people didn't even really know what I was talking about when speaking of ATRAC. They just automatically said the locker was always better without even really knowing what they were talking about. The owner's manual wasn't much help, so I took it to the hills and figured some stuff out on my own. Nice of you to pick up where I left off and put together a compilation/summary of the umpteen drive modes.

 

EXACTLY!

Right, the poll isn't restricted to those with A-TRAC and have actually used it instead of the locker.

After my last testing, I am convinced that A-TRAC should be the primary mode in L4, and is activated as soon as I engage L4. The rear locker is there if it is ever needed... I just can't picture a situation where it would add anything to what A-TRAC does... Can you??

The clicking/ popping from the A-TRACK/ brakes would be when it is locking a loose traction tire I believe. If it stops making that noise, then both tires have traction on that axle... or real four wheel drive with both axles working!

Thanks!

 

If you're just crawling along, ATRAC works to perfection. I haven't tried it but the locker may give an advantage if you need a quick bump to get up a ledge. It's common to get your front wheels up a ledge and not be able to get your rear wheels up. The most common strategy here is to back up about 2 feet and give it some gas and let momentum bump you up. Like I said, I haven't tried it but if I back up for a bump, the ATRAC may not let me accelerate quite the way I want whereas a locker would. Like I said, that's a maybe.

When anti-lock brakes (ABS) engage, you get the same click, click, click sound as what you get in ATRAC. If you hear it, you're losing traction on a tire. If you don't hear it, you have complete traction.

An open diff sends all of the power to the tire with the least resistance. We have an open diff in front, and the rear too assuming the locker is not engaged. If a tire is up in the air, it is obviously the easiest to spin. It will spin away but the truck will go nowhere. ATRAC activates the ABS on that spinning tire to create more resistance on it than the one that is still on the ground. Thus, convincing the open diff to redirect the power to the other side (the one with traction) and propel you forward.

The only way to get true 4wd is with front and rear lockers. The best we can technically do is 3wd (rear locked=2 + 1 in front). However, the ATRAC system fakes true 4wd very, very effectively. If you're moving, you don't need true locked 4wd. In fact it can be quite the nuisance on your steering if you are moving. If you're stuck, at least one wheel has lost traction and ATRAC goes to work. Arguably better than a locker in two ways. 1) It doesn't affect your steering. 2) If a tire is up in the air, a locker spinning it will do you no good anyway and the unequal stress caused by a locker on the tire in the air vs the one on the ground can seriously strain moving parts. Whereas, ATRAC is just transferring power through a more forgiving open diff.

 

10-4!

Isn't it great... A-TRAC?

I feel like a kid anytime I can take my truck off road and see how well a stock truck can go over any terrain I put in front of it!

I wish I was in the desert or Baja right now...

 

Yep, it's great! I too was impressed with the stock configuration but you should see what mine can climb with aggressive 33" tires. I can crawl up what most guys can't get up without momentum and tire spinning.

I live in a spectacular place for wheeling. Google Chokecherry Canyon, Farmington, NM. You'll get crazy youtube videos. It's 10 minutes from my door. You'll only see the crazy stuff on the Internet. I don't tackle much of that but there is an unlimited amount of all difficulty out there. I live 1.5 hours from the famous mountain trail passes between Ouray/Silverton and Telluride and the Alpine Loop. Google Black Bear Pass. I even live less than 3 hours from Moab.

San Diego has some good stuff too. I grew up in SoCal. You have tons of mountain trails within a couple of hours of you. You also have all the sand one could ever want over in Glamis.

 

I would like to see your four wheeling areas... We went through New Mexico a couple years ago and saw quite a variety of landscapes... some beautiful areas, for sure. Baja is a pretty unique place with a bit of everything real close together... It is really handy to be close to fun places.

 

The only thing I could add here is that in my experience if there is a technical section of trail and tire slippage would be dangerous, then it may be wise to lock the rear end before entering the crux of the trail. Once safely through, unlock the rear end.

Some classic places this worked well for me are: Diablo Drop-off, Anza-Borrego Desert State Park, and Mengel's Pass in Death Valley National Park.

Lots of good discussion here.

I do agree that A-TRAC is superior as a traction system than the locker alone. Mostly for the reasons mentioned: the ancillary benefit of better steering control. But the main reason is that A-TRAC works on and affects all four wheels where the locker only affects two.

My A-TRAC button stays pushed in all the time.

 

10-4 on that!

A-TRAC ... 'to infinity and beyond!'

 

timmer, in the purest of arguments the locker will win because it never allows wheel spin, at least in the rear.

But it should be pointed out that nobody here is debating LSD vs locker like the video suggests, ARB folks do mention "electronic traction control" but fail to tell us the specifics.

We have been discussing A-TRAC. A-TRAC is a new animal-- it's different and it works on all four wheels. A-TRAC is available on 2009+ TRD Off-Road model Tacomas.

Our collective experience has shown that A-TRAC is extraordinary.

Here is a basic video that illustrates A-TRAC in action.

http://www.toyota.com/fjcruiser/demo...n-control.html

 

Hi Timmer, thanks for the input... and the two ARB advertisement videos made with Australian model Toyotas.

Like you, I drove a pre-2009 4WD O.R. Tacoma ... two of them ('01 and '05)...
Until you have a new Tacoma with TRAC and A-TRAC you cannot understand the difference... it is extreme!

Now, ARB front and rear lockers are great tools... but they don't come included on our trucks... they cost extra. Front lockers also tend to make steering difficult, as stated by the ARB factory rep in the video...

Toyota gives us TRAC and A-TRAC with the truck, already built in... no new differentials, air pumps, etc. to buy.

Unlike the example Aussie SUVs, our U.S. model's TRAC in H4 and A-TRAC in L4 do not regulate engine output... as was frquently mentioned being a deficit in the electronic traction control of their vehicle.

The sand dune climb showed all three failing to get to the top, with only a couple feet difference between the three. The expensive ARB set up may be awesome... but A-TRAC is what we have already on our trucks... and it works as well as what I saw in the video. See the FJ Cruiser and other You Tube videos of A-TRAC at work.

You will just have to experience the A-TRAC system that Toyota has included on our trucks in '09... and on the 4Runner, the FJ Cruiser and on the Lexus SUVs for many years now.

 

And that could have NOTHING to do with the fact that that was a 20 minute commercial for ARB, who sells lockers?

I love my rear locker and deploy it with glee, but a-trac is good stuff.

 

That's just not true. ATRAC is NOT new to the game at all. 1st, It is — from personal experience shopping for & buying it at one point — available on at the LEAST the 2008 model Tacomas, probably earlier.

It debuted on the prado platforms overseas. I'm having trouble finding links to definitive dates at the moment, but I'll go so far as to wager all of the internets that those prados in the vids (dated 2009) have ATRAC. ALL of the internets.

2nd, I think that's exactly the debate going on here.

I can attest from personal experience. I have overwhelmed ATRAC on my 2009 Taco in bad situations. Mud, Ice, Snow, etc. Lockers are better off-road, period. ATRAC is still just guessing about which wheel to lock and when and for how long; a locker just locks it, no guesswork. ATRAC has to "hunt" for traction. A locker does not have to do this hunt and continuous checking.

A-TRAC is a great addition, and I feel the videos put it in the lineup perfectly; better than a mechanical LSD or open diff, not as good as a locker. And at least here in the states, there's not a $20,000 option to get into it. it's actually cheaper to get A-TRAC and not locked, which means that it's also in the middle price-wise as well, which is appropriate.

But still, the limitations of A-TRAC are one of many reasons I recently picked up a 2002 DC Taco that I will lock front & rear before summer's end, and maybe even summer's beginning if I get lucky.

 

Randombob, you're entitled to your opinon, I have no issue with that. But you are in error stating that A-TRAC came on any TRD Off-road model Tacoma before the 2009.

 

Great if you got more bucks to add ARB... generally, the cost of our new Tacoma leaves us with little left (in today's economy)!

Those Aussie videos either had a ARB factory driver in the non-ARB vehicles or that wasn't A-TRAC at all... like what I have on my Tacoma. The second vehicle acted like regular TRAC, not A-TRAC. A-TRAC 'locks' the free tire with the traction tire... very similar to how an expensive locker works. Another point missed, is that all of us with OR TRDs also have a locker in the rear... If there ever is a situation A-TRAC can't handle. That would be a true locked rear axle and an Active Traction Control (nearly the same as locked) front axle...included, at no extra price!

Yes, A-TRAC is not new, FJ Cruisers and Lexus has had it for years... It is new for Tacomas, starting in 2009 model year.

 

how is it that you can completely ignore what we just watched, and/or pervert what was actually said in the video like that?

I mean, so far as to say that the vehicles shown don't have it, saying that the video said things it didn't say so clearly, A-TRAC is something totally new & different and still better than a locker, so there

come on guys. The video showed A-TRAC in action. Everything about it was A-TRAC. you tried to say that since he was saying that vehicular momentum was slowed, it wasn't ATRAC he was talking about but something else because ATRAC doesn't cut throttle.

He never said it cut throttle and slowed the truck down. when ATRAC un-brakes the wheel to see if it's still slipping, if it's still in a loose traction situation or up in the air like it was in the video during the part you're trying to reference, then that wheel spins freely because the axle is open and ALL power is diverted back to it. When that happens, any forward momentum is effectively stopped whilst the ECU hunts & recognizes that the truck is still without traction and brakes the wheel again. Simple and TRUE. And a perfect example of one of ATRAC's limitations. go ahead and watch it again, part 2, 3:10 into it.

point b: I bought & owned for about a DAY a 2008 with a locker but no ATRAC. The dealership had made an error, I wanted an OR model w/ ATRAC & locker, and it was a different package on the 2008's than the 2009's. They had to give me a 2009 model at a loss because of the error, but in trying to find a way around it, there IS/WAS a package for the 2008's that had everything, but the combination of packages necessary to get it was actually *more* expensive than a 2009 anyway, so…

Maybe it was one of those things that was in the system but never existed because they held off on implementing in until 2009 model year, totally possible and if so I retract my statement in that regard, but that WAS my basis for stating as such, that I SAW with my own eyes on the dealership's system an option package for a 2008 with both.

 

Also, Locker+ ATRAC does not work above 3-5mph. Which is silly because if you start to get wheel slip even a bit, you're about guaranteed to spin those wheels faster than 3-5mph, effectively turning off ATRAC anyway. So in most all situations, it's still one or the other. They need to get rid of that limitation, or we need a simple mod to override it.

 

Good points everyone. Let us all remember too that this thread is largely academic and that individuals will use whatever works best for them.

Locker, FTW! A-TRAC, FTW! Everyone wins!

Let's go hit the trails!

 

ATRAC limitations:

**Since it's based on the braking system, you're always at the mercy of its inherent power/weaknesses. If the brakes overheat while locking up spinning tires, it turns itself off for at least a mandatory 2 minutes. If you're in sand or other constantly-loose grip situations, this can happen quickly. That's one reason why Toyota specifically says in their own online videos that the locker is useful/better than ATRAC in sand. And braking a wheel even temporarily in a situation like that is worse than it just not having power to it; it's actually just become a freakin' anchor that you're dragging along.

**It requires computer intervention. The computer does not KNOW the terrain, and it is always acting AFTER THE FACT, to REGAIN traction. So it doesn't even start to engage until AFTER you've lost traction & momentum. Also meaning that in order to know if it NEEDS to continue braking a wheel, it has to let go in order to find out. That means that if the tire is indeed still up in the air or without adequate traction, the computer just diverted power back to the free-spinning wheel "to make sure" before it brakes it momentarily again. You're constantly in a state of grip/no grip, grip/no grip as the computer struggles to determine whether it needs to continue activating the ATRAC system.

It has to do this, because as mentioned in point one, a braked wheel on a tractioned surface (or in sand, etc) acts like an ANCHOR, holding you back and potentially causing mechanical damage.

This is probably the single biggest implementation problem in ATRAC; it's REACTIVE, no PROACTIVE.

**Requires a particular throttle level to work effectively. You CANNOT feather the throttle to ease over an obstacle, because doing so engages/disengages ATRAC, and you're constantly losing too much momentum to drive over it as controlled as you could with a locker. Also, If you're too light on the throttle, it won't work. If you're too heavy on the throttle, the wheel it's trying to brake will just overpower and eventually overheat the brakes, causing a situation as in Point #1 above.

Because of the limitations in point 2, you have to either a) take some momentum with you, or b) stay in the throttle heavier than you'd like and chance overheating the brakes.

**Works in conjunction with locker ONLY under 3-5mph. C'mon, Toyota… if anyone is going to engage both, give us the benefit of the doubt that we're not complete idiots (we did just spend $30k on a truck, no?) and let us USE it. Might as well say 1mph, because as soon as a wheel loses traction? your wheel speed will spike above this threshold.


ATRAC Positive notes:

**Open differential unless actively working. So if you're in a tight situation with the wheels arced heavily and peril is going to jump up and get you without rail-specific steering response, you've still got it that going for you.

**Cheaper to implement. Uses the braking system, it's already installed, easy to monitor (if you're the manufacturer, you can implement "limits" such as the 3-5mph stated above to make sure your customers don't grenade your shit and charge you for it under warranty)

**here's probably the biggest drive behind it gaining "traction" — pun intended — as a drivetrain option: Ease of use. Using a locker requires forethought. What line are you going to take? can you make this turn with front wheels locked? I saw it in a post somewhere else, they called ATRAC the "Easy Button." Yes. If you're not that experienced with it, then that's exactly what it is. You hit the gas, the truck takes care of the rest. Simple. It's a Locker for people who can't drive with a locker, same as VSC is effective driving maneuvers for people who can't pull off good corrective maneuvers.

Case in point: when I drive Mr. Reynolds (the 2009), I turn VSC Off as soon as I get in. Because for ME, it creates issues, as I can sense slippage before the computer does. The times before I decided to just turn it off, what would happen is that I would begin corrective action before the truck's ECU even detected there was a problem. So then you've got ME correcting the situation, and THEN a second later the ECU implements it's own algorithm to correct the problem. It made matters worse. I was more sensitive to the situation but the truck was not letting me be in control like I needed to be. I was abstracted a layer away.

However, when my girl drives it, I'm sure as hell glad it's there and ON by default. Want to make sure she gets home safe. And to me it's the same with ATRAC. It's a great substitute with just a few (if important) drawbacks, and only to those who would push its limits.

 

It's even simpler than that... We like A-TRAC because it comes with our Off Road 4WD Tacomas, standard! No need to fuss over what is better, because it is not an aftermarket option that costs thousands of dollars!

There was no A-TRAC on the 2008 Tacoma... only 2009 and later.

Too bad nobody was video-ing my stock Tacoma with Rugged Trails in Baja where I burried my truck on purpose and then let A-TRAC extract me. Then, at the 'Drug Airport' where I backed into a ditch and high centered the rear axle so both back tires were off the ground... Rear locker no help there.. but the strong A-TRAC working the front tires pulled me out!

I am not new to four wheeling... I can compare this TRD to my last two Tacomas with the rear locker and to my Jeep with Quadra Trac... and this A-TRAC system is a superior traction feature... and it is included.

 

I'm not quite new to it either, and like I said I OWN a 2009 with ATRAC + locker, so I have personal experience with it too. It's hellaciously better than a regular 4x4 w/ open diffs, and probably at least as good as a 4x4 with just one axle locked, too.

I don't think however, having owned an older 4Runner 4x4, 2009 Taco w/ locker & ATRAC, and now a 2002 DC Taco 4x4, that when it comes down to it, the best off-roader is a 2009 W/ ATRAC. Obviously to each his own to meet their needs, I need cargo capacity for people & 4 dogs & the ability to get anywhere. After trying to do it with the 2009, budget-wise I realized that a 1st gen LOCKED up front & rear will be cheaper and *better* in ways the 2nd gens just can't ever match. They're better for that particular need, both the truck & the lockers.

For just about anything else, the 2nd gens are better, and the ATRAC option definitely helps them make up for their other shortcomings. We're keeping both trucks, I'm modding the 1st gen, she's driving the 2nd gen. I feel safe with that setup. If she's ever in a bind, I have confidence she'll get out of it with the help of one of the easy buttons. And my instructions to her are to go with ATRAC first, it'll probably get her where she needs to go.

But then again, she's not going anywhere as harsh in the 2009 as where we're going to take the '02 w/ lockers.

PS: if I had to choose between just a rear locker or having 4-wheel active ATRAC, I'd take ATRAC. Those are not the only options, though, and I'm voting with my wallet. Again