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

I've lived in the Northeast all my life and never anything fancy. I have the base 09 tacoma 4x4 and I know it will make it through everything big momma can throw at me. Save you cash for cool fun stuff.

 

Now that's music to my ears. If a base 4cyl 4WD for $24K will work, why pay $31K to get a V6 I don't want, just to get A-TRAC, which I don't really need.

 

Now let's explain the wheel speed sensor - specifically why the cost $200!!!! lol :'(

 

When I was testing my new truck out in Borrego, in 2010... on dry mud and sand hills, I could get further up a hillside in H4 in the normal TRAC mode than in L4 with open diffs. The sharing of power with all tires instead of all the power going to the two spinning tires, made a world of difference.

Naturally, I like having the torque of low range for climbing, but without A-TRAC, all I got was one tire in front and one tire in the back spinning when the steepness stopped forward progress.

I did the climb again with just the rear locker added in L4, and climbed much further. With A-TRAC, even more... but only inches more. In H4, it really surprised me how I drove past the point I got in L4 and nearly to the same place as the locker or A-TRAC took me.

 

Like 4WD, it is just comforting to have as much traction as possible. The rear locker was the primary reason for me to get the TRD package on my 2001... and the Off Road TRD package in 2005. When I traded to the 2010, I didn't know about the new gizmos, just wanted the locker, again... A-TRAC blew me away when I compared the 2010 to the otherwise identical 2005 I had.

If you just lower your tire pressure, you can get a 2WD most anywhere, afterall... but 4WD and then 4WD with traction controls are just higher levels of making a truck get further.

 

The '09 has TRAC in H4... and it works, as you have seen!

 

If you did that well in H4 when climbing offroad, I can't imagine ever needing L4. The closest thing to offroad I would ever do, is some pasture driving in dry conditions. Given your testing results, the only things I would be getting from the TRD OR pkg would be the bad mileage of a V6 and the fluff of body colored flares and decals.

 

Now you got me thinking that all I need is a new 5-lug with a 3" lift and taller tires or a PreRunner.

 

You are evaluating the need for the extras of an Off Road... that is wise. All 4WD Tacomas have a 2 speed transfer case, so you will get low range, even if you don't ever use it.

There is a great advantage to driving slow over rough terrain as well as having the gears/ engine compression creep you down steep grades so the brakes are not over-used. Low Range is the great part of having a true 4WD vehicle and not an AWD one, without a low range.

Naturally is you never really go off road, but only need improved traction on slippery roads, sand, or snow... low range is not required. However, if pulling, climbing, descending in off road (bad dirt roads) situations, then a low range is indeed an asset. Adding a limited slip or locker to it, is all the better to not get stuck or be halted by the terrain.

The Off Road TRD does NOT have fluff (beyond the decals). There isn't any color matching trim, fake hood scoop, etc. That would be the SPORT. Yes, a V-6 has more power and uses more fuel. Here is California I only get 15-16 mpg city and 18-19 mpg highway.. maybe more if the truck is unloaded.

 

You rarely see 4WDs driven by the local ranchers or fishermen, in Baja California... they know how to drive in dirt and deflate the tires for more traction or floatation. As I said above, the 4WD is a level of comfort or insurance knowing you have a better chance of getting somewhere without risk or damage.

Some of us use 4WD to go places the locals don't or can't get to with their 2WDs... and that is part of the fun of four wheeling... knowing it takes that level of vehicle to get to where you take it.

Three kinds of people:
1) Those who make things happen!
2) Those who watch things happen.
3) Those who wonder what happened?

 

Your posts are great and have been really helpful. I have had my truck (same as yours) for about a year and I just took it on some trails and to the beach. Seems like every question I had you had a post for it. It had just rained and I wasn't sure how deep I could go through puddles. Saw your mod. Thought it odd that A-Trac was not on in H2 and thought I was looking at it the wrong way. Was nice to hear someone else think the same. Anyway, thanks for sharing. Here is my girl's first trip to the beach.

 

I'm aware that all 4WD have H and L, just saying that I probably wouldn't need to use the Lo range on the roads that I drive on. But clearly you hard core wheelers need it, along with the A-TRAC/elocker of the TRD OR pkg.

However, all the TRD pkgs as well as the SR5 do indeed have the "fluff" of body colored flares, not just the Sport. Without TRD Sport/OR or SR5, you get the black flares and bumpers, which I really like. And by fluff, I also mean stuff like radio controls on the steering wheel, remote entry, sliding rear window, etc., which I don't want or need.

 

I second that - without all these discussions/explanations, I wouldn't have a clue about how TRAC, A_TRAC, elocker, Auto LSD, VSC, etc. actually function.

 

The only thing that could make this thread even better would be video's of situations using all the modes...from 2WD standard through 4LOW.

 

Hey, that's a good idea. I have never made a You Tube video. Something I will try.

 

I HAVE A QUESTION. IF THE DIFFERENTIALS ARE BOTH OPEN WHICH I UNDERSTAND MEANS JUST ONE WHEEL SPINS. THAN HOW DOES THE ATRAC OR TRAC MAKE BOTH WHEELS SPIN. WOULDNT THEY HAVE TO BE LSD NOT OPEN. THANKS

 

SO DOES THAT MEAN ONLY ONE TIRE SPINS OR BOTH.

 

I answered KEN in a PM he sent me, before I saw this... Let me just modify Anthony's answer that A-TRAC matches tire rotation by slowing the non traction tire spin with the brakes (on that tire) so both tires rotate the same and split the power. It is more like an 'auto-locker'. A-TRAC only works when it is needed so steering isn't hindered as it is when lockers are used.

 

Ken uses caps as it is easier for him to read, he is not yelling. He explained that to me in another PM follow up on the spin question.

For anyone else: Instead of gears in the differential or clutch pads in the differential, the ABS brake system is what slows or stops a spinning tire with TRAC and A-TRAC... applying brake pressure just to the spinning tire(s) to transfer power to the non-spinning tire(s) to keep you moving.