ATRAC / LOCKERS

I just saw a video on how ATRAC automatically senses which tires that don’t have traction and sends power to the ones that have traction almost instantaneously! I saw a video of the new gx550 and they were going through some big holes and the Toyota engineer told the driver “DONT USE THE LOCKER AND JUST LET ATRAC WORK” even though the driver wanted to use the lockers. So my question is why do you need lockers when this is done automatically by ATRAC?

 

I think each has a time and place, and can be useful is different situations. The advantage of a locker is that those two wheels are locked in without any delay, you have power on both sides, and as long as at least one tire has grip, you're moving. A-Trac takes some time to work. It has to sense the wheel slipping and apply brake pressure to that one wheel to throw power to the other side. This takes time, you're generally spinning for at least a few seconds, and the truck may bob back and forth and struggle to move while the system works out how to find traction. Advantage to A-Trac is that you can just leave it on and keep going, whereas you'll want to deactivate your locker as soon as you clear your obstacle. A-Trac is also kind of hard on the brakes after a while.

So the way I think of it is this. If you're about the go up and over an obstacle you KNOW is going to articulate at least one wheel off the ground and want to move smoothly with as little drama as possible, a locker is best because it doesn't need time to think, it just works. If you're tootling along and the terrain is varied and you may or may not end up halfway in the air, A-Trac can decide when it's time to hit the brakes on one side. Both are great. I'm excited my new-to-me Trail Edition has both.

 

https://youtu.be/OwJFV0cp6PA?si=1wRUmn6p0GYZnCxA

 

It’s instantaneous. ATRAC. So why do you need lockers at all?

 

I believe the Lexus in that video has a newer, reworked version of A-Trac, like the 2025 T4R will. I haven't even had time to try the A-Trac on my 2010 yet, but on my 2015, it definitely was *not* instantaneous. It took time. I listed pros and cons to both above. Decide for yourself what you need

 

ATRAC is often sufficient. Sometimes, such as when you want to rock back and forth a bit, the locker makes more sense.

 

If you use a locker each tire gets 25% power (even the tire that’s off the ground). With ATRAC the tire that’s on the ground will get all 50% till the other tire touches down! Notice on the video that the tire off the ground stops spinning while the truck keeps moving smoothly and once the tire hits the ground it’s back in business

 

If you use a locker, each wheel, left and right, receive 50% of the power, instantaneously, without any kind of delay, until you switch it off. A-Trac constantly adjusts, and the process takes time. I used it all the time on my 2015. Helped me get unstuck from snow a few times, too, so it's useful for a lot of situations. That's another nice thing about A-Trac, it does work with all 4 wheels. Unless you add a front locker, you only have a rear one from the factory, if any at all.

 

Did you think that most people here didn't understand ATRAC?

 

Absolutely not. I’m new to off roading and have read a lot and watched a lot of videos. I’m sure you guys are smart and have a lot more experience than I do. After seeing the Lexus video for the 550 GX and hearing the Lexus engineer tell the driver ( who was going to center lock and rear lock) NOT TO and it worked like a beauty, I just wondered what was the purpose of having the locks when ATRAC was instantaneous . I’ll post the video.

 

https://youtu.be/5bGiYY7dNXk?si=QpYpVVZzNYVHe3KQ

 

ATRAC is reactive while lockers are proactive.

 

Didn’t mean to offend anyone but I’m here because I want to learn from guys who have a lot of real life experiences!

 

But if the guy on the video would have locked the rear wheels the one on the ground would have had only 25% power while unlocked with ATRAC gave it all 50%

 

That's not how it works because ATRAC only pulses the brakes, not locks up a wheel completely and even then it has to see slip for it to work. Losing momentum while waiting for the popcorn grinder to start could get you stuck.

Real wheelers use just lockers.

 

Maybe because it’s the newest vehicle everything has improved and it’s instantaneous now because ATRAC is super quick now

 

You know what's faster? A locked diff because there is no delay once locked. It works well but it's no locker.

 

No problem, it's just that there seems to be a thing going around that's more about promoting a technical po.

I'm definitely not knocking ATRAC. It works really well for many sticky situations. Now and then the locker is nice. Regarding distribution of power, there aren't a lot of real-world situations where you can't get enough power to the wheel that's not spinning. The vehicle almost always has enough power.

 

Look at the first video I posted “KANG”. Notice the ATRAC without the locker. Rear wheel behind the driver almost stopped spinning altogether when it had no traction so all the power went to the other wheel

 

Thanks for all the helpful advice!

 

It's a momentary brake pulse so the power transfer is momentary. Like I said, it works well but it's no locker.

 

https://youtu.be/t9o0TUfAFEE?si=Q76OIJG2d_iHquoq

 

The detail that people misunderstand is that for A-TRAC to do its' thing, you have to get the wheels spinning and keep them spinning until it kicks in. Not roasting the tires in a cloud of smoke burn-out, but a smooth, non-lurching or non-bucking, easy slow and smooth spin. It is a bit unnerving at first. I was afraid I was going to break something, but with experience you will get the hang of it. I've been debating for 2yrs about getting a locker. I really see no need for one. A-TRAC has worked every time for me.

 

Boy this last video that I just saw answered my question. Never saw it until just now.. The locker is really not needed because the latest generation ATRAC is so fast that lockers “ are no longer needed”. Toyota /Lexus just “threw it in” just appease people who just wanted it. So I know that everyone has different models and years of your trucks so lockers were helpful in your specific situations and with the new vehicles seems like lockers are becoming obsolete. Thanks for all your help!

 

Also realize ATRAC is working on both axles while a rear locker is on a single axle. If ATRAC was limited to a single axle then it would fail miserably. Also ditch the center lock for AWD and rely solely on ATRAC to transfer power and it would get stuck.

I think OP is David K from TW.

 

Locker > Atrac.

For Atrac to work there has to be slipping and transfer of torque. A locker is already working before slipping and there is no transfer. Both tires have equal torque all the time. Atrac works as you're getting "stuck" or to get you unstuck. A locker keeps you from getting stuck.

 

So, the OP is new to off-roading, and came here to get insight from more experienced off-roaders, but has completely made up his mind that A-TRAC is superior to lockers?

That makes sense.

 

You know, the last guy that was this enthusiastic about the wonders of ATRAC now has an aftermarket front locker to go with the OEM rear locker.

 

My buddy was one of them. He says it’s a night and day difference in his Runner. It’s a great system and most owners will not find the limits but they do exist and this debate of locker and ATRAC is as silly as the locked 2wd vs open/open 4wd debate.

 

The OP joined today, started this thread, and hasn't posted anywhere else. My guess is this is just a BS account to get clicks on his YouTube channel.