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Front LSD and rear locking differential?

Discussion in '3rd Gen. Tacomas (2016-2023)' started by ethical camper, Jul 30, 2015.

  1. Aug 3, 2015 at 5:08 PM
    #41
    slc_tacoma

    slc_tacoma Well-Known Member

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    I've found my '15 Tacoma to be a hoot with "just" 4lo and atrac enabled. I haven't needed the diff locker yet. For an out-of-the-box adventure appliance, she's plenty capable. I find I don't use the downhill assist very much at all though. Not slow enough for my comfort.
     
    Rattlejay65 likes this.
  2. Aug 3, 2015 at 5:16 PM
    #42
    David K

    David K Well-Known Member

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    You are correct about A-TRAC!
    Think of it as 'Automatic lockers (front and rear)', as it is so much higher a degree of spin control than "limited slip"... more like "nearly no slip".
    The rear locker, is a last resort IF A-TRAC fails to move you (and you actually push down on the gas pedal).
    I think snow driving may be an exception... If you have A-TRAC and the locker on together, you can have fun in the snow without any velocity cut (when tires spin) and the A-TRAC only wakes up under 3 mph (i.e. when you get stuck or almost, in rear locker mode). The A-TRAC is only active on the front tires with the rear locked, so it is pretty close to having a front locker turn on to get you going!
     
  3. Aug 3, 2015 at 5:24 PM
    #43
    slc_tacoma

    slc_tacoma Well-Known Member

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    I've wondered about the snow, and more importantly the ice. I've seen a lot of stability control systems get confused by ice. Interested to see how all that goes.

    Thanks for all of your info on a-trac, David. I've found a lot of it to be very helpful.
     
  4. Aug 4, 2015 at 6:34 AM
    #44
    127.0.0.1

    127.0.0.1 AKA ::1

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    downhill assist....yeah I agree,

    where I'd like to use it, it's too fast, I'd get a wild ride...

    I just use my foot and creep as always
     
    slc_tacoma[QUOTED] likes this.
  5. Aug 4, 2015 at 8:20 AM
    #45
    slc_tacoma

    slc_tacoma Well-Known Member

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    Completely agree. I wonder if the "crawl" mode in the 2016 is any better.
     
  6. Aug 4, 2015 at 9:06 AM
    #46
    David K

    David K Well-Known Member

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    My DAC is VERY VERY SLOW 'speed'. As the manual says, under 3 mph (walking speed).
    You do not touch the brake when using DAC, the only thing you control is the steering wheel. The system creeps you down steep, off road grades, keeping the truck under control so it won't go sideways from sliding. ABS on steroids! Touching the brake or gas pedal disengages DAC if you want to take over.
     
  7. Aug 4, 2015 at 10:10 AM
    #47
    slc_tacoma

    slc_tacoma Well-Known Member

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    Oh, yeah, I know. I've used it several times and while 3mph *sounds* slow. its not very slow when youre going over some very_uneven_terrain. I know you're not supposed to touch the brake. I usually do because I absolutely need to be going slower than the 3mph advertised. I had an old 89 toyota pickup and it was a standard transmission, simply riding the gear out in 4lo in first gear was about half the speed of my 2015 tacoma with DAC engaged, which if my ears are correct sounds like its simply firing ABS constantly to regulate the speed. While I'm sure DAC certainly has its merit, it's not for me. My buddy's grand cherokee also has a DAC, he moves a little less than half the speed. I'm envious. I think Toyota could have, and should consider slowing it down even more. When it comes to crawling down a hill, I personally dont feel there's such a thing as "too slow."
     
  8. Aug 4, 2015 at 10:19 AM
    #48
    David K

    David K Well-Known Member

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    Good point... There is indeed pucker moments when you are going down a near-cliff and not touching the brake. I also am in 1st gear (Low Range), so when DAC isn't braking me, the transmission is. The point is if you use your brain and foot to pedal brake the truck, you cannot react faster than DAC (the computer) at preventing a slide condition on one tire that could put you sideways and roll-over. Maybe have DAC-1 and DAC-2 settings, based on steepness?
     
  9. Aug 4, 2015 at 10:21 AM
    #49
    Herniator

    Herniator Well-Known Member

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    Crawl control allows you to select the speed instead of DAC which has only 1 set speed.
     
  10. Aug 4, 2015 at 10:21 AM
    #50
    slc_tacoma

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    I agree. I cannot actuate the brake more quickly. no doubt. The problem (for me) is that while it can certainly actuate the brake more quickly than I ever could to maintain a constant speed of 3mph, I'd much rather go 1.5 MPH or slower in many cases. I think for a nice, flat downhill slope the DAC would be great.
     
  11. Aug 4, 2015 at 10:32 AM
    #51
    Z50king

    Z50king DCLBOR4X4FTW

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    You will be able to descend at 1mph with crawl control
     
  12. Aug 4, 2015 at 10:33 AM
    #52
    127.0.0.1

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    yup. not slow enough to not bounce rocks into my gas tank skid. I am talking creep speed like 1/2 mph picking
    my way through sharp rocks.

    it would be more ideal on a less chundery road I agree...
     
  13. Aug 4, 2015 at 11:04 AM
    #53
    slc_tacoma

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    very cool! Id love to have that feature.
     
  14. Aug 9, 2015 at 8:31 PM
    #54
    Dagosa

    Dagosa Well-Known Member

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    I think the best feature will be the variability for conditions you can dial in for the craw control. I have the Off road package 2015 and I find out pretty quickly that muddling, rock crawling and off roading in deep snow are quite variable. The locking diffs are useless in snow and on ice and the only thing that works is ATrac. The locker is only a temporary help and in most mud conditons, once moving I have better control with ATrac.
     
  15. Aug 9, 2015 at 8:57 PM
    #55
    Mxpatriot

    Mxpatriot Well-Known Member

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    I wish they would just offer front and rear lockers from the factory. Jeep does it with the Rubicon, Dodge did (does still?) offer it with the Power Wagon. And a complete ABS disable switch, just like the Raptor. Doing the ABS disable switch mod on my truck was the single best mod I've done.

    A-TRAC is a great tool for getting unstuck out of mild "oh shit" moments. It's not a substitute for lockers, but Toyota is charging you 60-70% of the cost of front/rear lockers to get it.
     
  16. Aug 9, 2015 at 9:27 PM
    #56
    David K

    David K Well-Known Member

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    A-TRAC is far more than that...

    Until you have it and use it, seriously use it, no amount of writing or telling you it is like automatic front and rear lockers, without the steering problems that locking the differentials cause, will likely convince you of its abilities.
     
  17. Aug 9, 2015 at 11:27 PM
    #57
    Mxpatriot

    Mxpatriot Well-Known Member

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    Been in trucks with it. It works great to get you out of a situation that an unlocked truck would get stuck in. It can get you up/through some of the stuff that lockers are required for. It will not get you through everything that lockers will.

    No amount of braking (because that is what A-TRAC is doing, it's using the brakes to transfer power to the opposite wheel) is equal to the even and constant power simultaneously to all wheels by a locked F/R set up.

    I'm sure it steers easier, because it's not mechanically locking anything together. It's idiot proof; you're not going to break the truck like you can with a front locker if you don't know what you're doing.

    It's still power to two wheels (one front, one rear) - it's just intelligently picking which two wheels to give it to; compared to an open/open truck that's going to give it to the two with the least resistance.
     
  18. Aug 9, 2015 at 11:51 PM
    #58
    David K

    David K Well-Known Member

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    I understand it is a not front and rear lockers and doesn't work quite the same way, but it matches tire rotation across the axle (as a locked differential does). The difference is, it uses a computer, spin sensors and the brakes to achieve this. By matching tire rotation you have a 50/50 power split, so both tires on each axle are actually driving the truck forward. Again, I know it's a weird thing to think that braking one tire helps you to move forward and crawl ahead, but it does. In the old days, we had turning brakes on our dune buggies that manually allowed us to brake the spinning tire to help move ahead. A-TRAC actually turns the Tacoma into a tank so you can crawl over and up amazing surfaces. It will get you out of a stuck if you forgot to turn it on ahead of time, too.

    Lockers allows you to bonzai the truck, as it turns or spins all locked tires regardless if it helps or not. A-TRAC only powers the tires with traction, causing less damage to the trail and truck while still moving you through or ahead. Again, it is very hard to convince those of us who grew up in the 60's and 70's that computer controlled wheel spin could get a truck to do as much as one with locking differentials... I had to drive it to believe it myself (I graduated high school in 1976, and was driving a Jeep those years).
     
  19. Aug 9, 2015 at 11:59 PM
    #59
    Mxpatriot

    Mxpatriot Well-Known Member

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    A-TRAC stops one tire so that the traction will shift to the other tire across the axle. It can do this very quickly, shuttling the power back and forth as its sensors perceive slippage. For a good chunk of users, this pays the same bill a locker would be required to do.

    That's not the same as providing both tires power at the same time.

    I think we can both agree that A-TRAC is a definite sustain in the Toyota line up (should come standard on all trucks and SUVs, two and four wheel drive) and it would be nice if they offered a F/R locker from the factory - to compete with the Rubicon and to target the 1% that want/need that capability.

    Then we can tackle a Raptor-killer. It's very doable. They just have to talk the lawyers and CEOs into it.
     
    Last edited: Aug 10, 2015
  20. Aug 10, 2015 at 6:49 AM
    #60
    David K

    David K Well-Known Member

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    A friend has a Rubicon... and another has a Raptor... I prefer my Tacoma Off Road 4x4. I can go almost anywhere the Rubicon goes (the rear overhang of the Tacoma is the only limiter on steep drops), and can indeed go further than the Raptor.

    Do look at the videos showing A-TRAC working and you will see the tire that is in the air is not 'stopped', but turns the same speed as the opposite tire on the ground. This is "rotation matching" not just shifting power over to the one from the other (you would think it's a locker when watching the video, but it is on the front tires too). I am not a mechanic, nor am I trained in ABS or the software that makes it work... but I know how capable it is at moving the truck up and over anything you dare it to do.
     

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