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A-TRAC/TRAC/AUTO LSD Explained (Easy to understand, I hope!)

Discussion in 'Technical Chat' started by David K, Jan 19, 2010.

  1. Mar 14, 2014 at 2:20 AM
    #1401
    MudFlap

    MudFlap Well-Known Member

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    I think I'm gonna go tie myself off to a big ass tree and set up a couple of cameras to record how the wheels pull in the different drive modes. Just for illustration purposes. :D
     
  2. Mar 15, 2014 at 10:57 AM
    #1402
    David K

    David K [OP] Well-Known Member

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    SWEET! :cool:

    I took photos of how the tires dug or didn't dig into the sand in the different modes...
     
  3. May 12, 2014 at 12:51 PM
    #1403
    PPower05

    PPower05 Well-Known Member

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    Also something to maybe try/note, a lot of the 4runner guys are saying that A-Trac works best with a steady RPM (2K), don't accelerate over obsticals , let the A-Trac and truck do the work for you.
     
  4. May 20, 2014 at 3:54 PM
    #1404
    David K

    David K [OP] Well-Known Member

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    It is like a tractor and will crawl you up and over or through most anything. The A-TRAC adds a level of security that makes getting stuck or halted by terrain a thing of the past.
     
  5. May 21, 2014 at 5:44 AM
    #1405
    Spencer

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    It almost makes it too easy though...
    I spend my time in 2wd/ open diff to see how far I can make it & 4x if I get stuck & ATRAC when I'm REALLY stuck because the damn truck controls itself and you kinda just point and hit the gas & it does everything else for ya.
     
  6. May 22, 2014 at 9:44 AM
    #1406
    David K

    David K [OP] Well-Known Member

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    Differential Breather Mod Light Bar: 2 Hella 4000 HID, 1 Kragen HID, 1 Cibie Halogen.
    I am sure that's the affect Toyota was looking for!
     
  7. Jul 25, 2014 at 6:33 AM
    #1407
    MateoTorgy

    MateoTorgy Well-Known Member

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    I think this is sticky worthy. Mods...?
     
  8. Jul 25, 2014 at 7:23 AM
    #1408
    HBMurphy

    HBMurphy Ban Pending

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    It would be even better if the douchebaggery was eliminated so that it would help those that care to know. :) :(
     
  9. Jul 25, 2014 at 9:52 AM
    #1409
    TacomaTruckParts

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    Well said !
     
  10. Jul 31, 2014 at 6:16 PM
    #1410
    David K

    David K [OP] Well-Known Member

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    Differential Breather Mod Light Bar: 2 Hella 4000 HID, 1 Kragen HID, 1 Cibie Halogen.
    Was there something ugly posted then removed?
     
  11. Jul 31, 2014 at 6:20 PM
    #1411
    MonkeyProof

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  12. Sep 22, 2014 at 8:52 AM
    #1412
    MateoTorgy

    MateoTorgy Well-Known Member

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    Once more, I'd like to thank DavidK for his generosity and hard work in sharing this information with us. Outstanding sir.

    I do have an issue relevant to this thread, and perhaps you or someone else can address or even resolve it for me.

    After reading several pages of this thread last night, I decided to once again test some of these drive systems out before work this morning. Everything seemed to work just fine except for, yes, the RR DIFF LOCK. While in the work parking lot (dry surface staying in a straight line), I stopped the truck, put it in N, and then went into L4 mode. While there and still at a complete stop, I depressed the RR DIFF LOCK button. Rather than the red instrument panel indicator light going red and staying red, it simply blinked. I put it into gear and slowly proceeded, and it still kept blinking. I then shifted into reverse and slowly proceeded backward a dozen feet or so until I braked. When I hit the brake, that's when I heard a click sound and the red light stopped blinking and stayed on. I'm wondering, is this normal? I have a 2014 TRD 6 cyl OR edition that's two months old. I checked the owner's manual and it stated that the rear diff lock should be used only when stuck. If a motorist needs to travel forward and backward and brake etc before the actuator kicks in and locks the diff, what good is it?

    Thanks again, David, and anyone else who cares to share their wisdome and experience.
     
  13. Sep 22, 2014 at 11:52 AM
    #1413
    David K

    David K [OP] Well-Known Member

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    The pleasure is mine. While it sometimes seems like it gets more complicated with every post, many of us hear things (read things) differently. That is why I attempt to explain these functions in several ways.

    Here is today's explanation of locking up the rear diff. (Yes, it is an off pavement mode, but it will lock on pavement to test it if no dirt is available... just don't be driving it for any distance locked or in L4. In H4, do not turn sharply on dry pavement either)...

    1) Start engine, turn dial to H4... move a few feet if need to engage H4 (light stops blinking and stays on solid). A loud 'clunk' is normal when going into or out of 4WD!

    2) Put tranny in N (neutral not park), turn the selector from H4 to L4, and depress while turning... put truck in D (drive) and roll a bit if L4 indicator does not go solid. In L4 your truck is in much lower gears, and you will feel the power if you tap the gas!

    3) Press the RR Locker button while stopped... it might go solid right away, often it does not. Roll ahead a bit, and if still blinking, turn the steering wheel all the way to one direction (left or right, but only one) and now roll forward a bit in a turn. The light always goes solid by doing this as a final action and I have had three Tacomas with the locker.

    The locker is an emergency only system, and only for when your rear tire is spinning and if A-TRAC doesn't work (never been an issue for me). You must be in L4 and you must be stopped and then go through the steps in part 3 above. The rear tires will not lock together if one is spinning more than the other, that's why you need to stop to lock.

    A-TRAC has none of these issues to use, and it stops tire spin on the front as well as the rear... making the locker more of a final back up system to get unstuck.

    I have used the locker and A-TRAC together when pulling other Tacomas and tried how it works in deep snow (deep for California, that is). When together, you have no engine regulation, as A-TRAC is in-active unless the speed drops below 3 mph, i.e you are getting stuck.
     
    Last edited: Sep 22, 2014
  14. Sep 22, 2014 at 12:00 PM
    #1414
    David K

    David K [OP] Well-Known Member

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  15. Sep 22, 2014 at 12:05 PM
    #1415
    MateoTorgy

    MateoTorgy Well-Known Member

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    As usual, a thorough yet concise easy-to-understand answer. You are truly a blessing. Thank you so much.

    Another thing I neglected to mention in my post above. Once I managed to actuate the locker, on one of the occasions in which I engaged and disengaged it, it refused to disengage. I pressed the RR DIFF LOCK button and yet the instrument panel light stayed on (without blinking). It wasn't until I put it in reverse again and lightly applied the breaks that it disengaged and the light went out.

    I'm not going to worry about it. I'm thinking that this, like many other issues in my life, is attributable to user error. And, I'll always have the A-TRAC. I want to fully acclimate myself to using these drive systems before starting off-roading in a couple weekends up at the OHV park in Spider Lake MN. My recovery strap and shackle mount are being shipped as we speak.

    Thanks again David. Seriously.
     
  16. Sep 22, 2014 at 12:14 PM
    #1416
    David K

    David K [OP] Well-Known Member

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    El gusto es mio (The pleasure is mine)...

    The locker will not engage or disengage if there is any pressure on the splines, ie if one tire is turning or binding. Only in a relaxed mode... the turning of the steering wheel works when the first attempt doesn't. Getting unlocked will happen, but not always exactly when you want it to... just give it time. Of course, getting out of L4 does it, too. That also takes a few feet to do sometimes.

    By all means, get out in the dirt and play with the thing!!! You will think you are in a Sherman Tank with the A-TRAC, locker and all the features. The Downhill assist is a kick in the pants too, if you are brave enough to test it!!! For very steep, and uneven, rutted, rocky down grades... creeps you down without the chance of slipping and getting sideways!
     
    Last edited: Sep 22, 2014
  17. Sep 22, 2014 at 12:24 PM
    #1417
    MateoTorgy

    MateoTorgy Well-Known Member

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    Hah.... That DAC is what really freaks me out. I'm a control freak by nature (ask my college-aged son and my wife). The mere thought of trusting the truck and its technology to that degree under those circumstances gives me the hot craps.

    Thanks again David.
     
  18. Sep 22, 2014 at 12:32 PM
    #1418
    MateoTorgy

    MateoTorgy Well-Known Member

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    One quick thought, I'm pretty amazed by Toyota's failure to explain in any discernable manner the functions of these various drive systems in the owner's manual. I'm trying to reconcile the comprehensive coverage of, say, the Entrune audio and display module or the rear-view camera, consisting of many pages, but just these few pages devoted to the drive systems. And of the pages that do exist, that which is written on them are equivalent to reading tea leaves. Pretty disappointing Toyota.
     
  19. Sep 22, 2014 at 5:49 PM
    #1419
    David K

    David K [OP] Well-Known Member

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    I agree, it is either there is no way to translate them into English we understand or they believe (likely) that the majority will NEVER use the systems, want to use them, or care a thing about how to use them. Those that do care will find out (as we are here on Tacoma World)!

    "AUTO LSD" and "TRAC OFF" are examples of poor wording, indeed. They are both the same function of TRACtion control: the more powerful level with the engine output regulation turned off, but TRAC is indeed ON! Auto LSD is what it is called in 2WD and TRAC OFF in 4WD-High... since 2012.
     
  20. Oct 28, 2014 at 7:22 AM
    #1420
    Cmurder

    Cmurder 2011 TX TRD Offroad

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    nothing cool
    Hey David. Finally watched your YouTube vid of you pulling the other truck up the hill in the sand. Your comment says you were in 4Lo/Atrac and RR diff locked. When doing something like that do you need to be aware to keep your speed limit under 5mph due to the locked rear?
     
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