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David K
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Location: San Diego County
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Beach Sand Test of Toyota Traction Systems
First, a little info. on four wheel drive and Toyota's systems:
The 2009 and newer Toyota Tacoma 4WD OFF ROAD TRD TRUCK (and other models of Toyota and Lexus 4WD vehicles) have, in addition to 4WD, several traction
options.
Traction Control is a limited slip system that utilizes the brake system to slow a spinning tire so that the power can be transfered to the tire with
traction (and move you).
Open differentials (without traction control) will transfer power to the tire the spins the easiest (the one in the air, on ice, mud, sand, etc.) and
the other tire might be on solid ground does nothing.
When off roading, having the tires on firm ground working for you are a big advantage... a spinning tire doesn't do much. Limited slip differentials
can slow down the spinning tire so that more power can transfer to the 'good' tire.
TRAC is Toyota's limited slip system, and does a really good job when four wheeling in HIGH RANGE.
The OFF ROAD TRD Tacomas have a locking rear differential and greatly enhance the abilty to climb steep, rough roads or get through mud.
Locking diferentials lock both tires on an axle together, so one cannot spin faster than the other, even if it is in the air.
Hard Core off roaders love to have front and rear locking differentials... makes them pretty near unstoppable. The dark side of lockers is that they
make steering quite difficult and must be unlocked in order to make sharp turns on the trail... When you turn a vehicle the 4 tires all must rotate at
different rates. One reason why you don't use 4WD on dry pavement is that the front and rear pairs of tires rotating differently can only happen on
loose surfaces without binding the front and rear drivelines. All Wheel Drive vehicles have a third differential that permits the front and rear
driveshafts to rotate differently, so they can be driven on dry pavement. Power is not equal between the front and rear on AWD vehicles, so they are
not a able to off road as 4WD vehicles (unless equipped with a middle differential lock-out switch).
4WD + lockers (specially front lockers) are greatest for traction but hard for steering!
Toyota has added 'Active Traction Control' (A-TRAC) to many of their off road oriented vehicles giving them the benifit of front and rear locker-like
traction but keeping the differential open for ease of steering. The A-TRAC uses spin sensors on each wheel and will match rotation speed across an
axle by applying the amount of brake pressure to the loose wheel to match it to the traction wheel... giving as much power as possible to the wheels
that move you. It is like having automatic lockers anytime you are in LOW RANGE (and have selected the A-TRAC).
So, last week... I wanted to compare the various drive modes my Tacoma has (9) on the beach...
4th of July 2011 weekend, 20 miles south of San Felipe, Baja California, Mexico...
Deep sand (bottomless some call it), coarse and fine grain mixed with crushed sea shells.
Steep beach, as well.
4WD alone will get stuck with tires at street pressure... low range, lockers, etc. only make things worse (on this beach).
The only improvement comes from lowering the air pressure about 50% of normal... 32 psi to 16 psi, for example. Street or All terrain, P rated, 2 ply
sidewall tires do better than Mud/snow, heavier, 3 ply sidewall tires... which will require even more air removed to gain 'floatation'.
I am running Hankook Dynapro ATm, P rated tires... normally inflated to 37 psi. Upon arriving at the beach, I drove across the dry sand and went until
the truck began to struggle... then lowered all 4 tires to 18 psi... and drove on easily, the rest of our time on that beach.
This photo taken the next day is the deep tracks I made before deflating:
See the tire at 18 psi not digging in, but floating on top:
Driving on wet sand after the tide goes down from the high point can be easier, as well.
However, with the right amount of air removed, driving on deep, dry sand is not a problem... Here, I backed up to our sun shade...
THE TEST... Driving down to the water's edge and pointing my truck UPhill on a steep slope of sand, I tried various selections of 2WD, 4WD, TRAC,
LOCKER and A-TRAC to compare the traction (or maybe better 'floatation' up the beach. The truck was empty and tires at 18 psi...
2WD VSC OFF, TRAC, and AUTO LSD all failed to move me more than a couple of feet... of interest, all three modes spun both back tires equally... Which
means the sand was uniform under the truck.
If one side was firmer than the other, we would see the open differential mode (VSC OFF) spin the tire on the loose sand and the limited slip modes
dig in on the firmer sand and not spin much on the loose side.
4WD HIGH: VSC OFF and TRAC modes BOTH did well, in this short sand climb... I could tell no difference between them (at 18 psi).
On another beach, I could drive with the tires at street pressure using the TRAC limited slip syatem. As soon as I turned it off and went to open
differentails, I dug in (one tire in front and one in the rear spinning)... A-TRAC drove the stuck truck out, without deflating.
4WD LOW: Truck dug in a bit... had to feather the gas to climb the beach.
4WD LOW + REAR LOCKER: Suprisingly WORSE than open differentials in L4. Truck wanted to dig in, even with gas pedal lightly depressed.
Drove around and this time engaged the A-TRAC device... the truck climbed up the steep beach and did not dig in at all.
It did as well as the tests in H4... Low range engine torque tends to dig in with excess power. On the beach sand, it isn't power that gets you
through, it is floatation from low aired tires.. and easy on the gas.
In this photo I took looking down over my tracks, the deep torn up track is with the rear locker on... and the tracks just to the left of them is
using A-TRAC instead of the locker... (the H4 tracks looked the same as the A-TRAC test):
It was more of a surprise for me to see how bad the rear locker did than it was to (again) witness how good the A-TRAC is.
The A-TRAC continues to impress me as the greatest advance in Toyota traction systems to date. Just making all four tires rotate the same (front and
rear lockers) isn't always the best way to get over something... A-TRAC senses the rotation speed of all 4 tires and prevents spinning that would sink
you or stall you by transfering power to the best tires to keep you moving. Because your differentials are open when there is no need to transfer
power/ match rotation (no spinning tires), steering is unaffected... makes the A-TRAC 'golden' for tough trails.
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Neal Johns
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Thanks, DK, good test.
My motto:
Never let a Dragon pass by without pulling its tail!
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mtgoat666
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dk: your test results make a great sleeping pill... yaaaawwwnnnnnn,... thank you for treating my insomnia tonite...
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Maderita
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David K,
Interesting read. Thanks for taking the time to post.
I used to camp on the "island" back in the 70's - 80's when I thought a dozen people at Laguna Percebu was too crowded! Landcruiser FJ40 back in the
day, with all of the typical engine & suspension mods. Always nice to see your photos and to day dream of going back again...
What's your hypothesis on the "4WD LOW + REAR LOCKER" getting worse results? That certainly seems contrary to my experience with mechanical 4WD
systems. There are numerous variables at play, so surprises are not entirely unexpected.
Hope you don't mind a rebuttal regarding this statement: "Locking diferentials lock both tires on an axle together, so one cannot spin faster than the
other, even if it is in the air.
Hard Core off roaders love to have front and rear locking differentials... makes them pretty near unstoppable. The dark side of lockers is that they
make steering quite difficult and must be unlocked in order to make sharp turns on the trail... When you turn a vehicle the 4 tires all must rotate at
different rates. "
In defense of locking diffs, the #1 locker, the original/classic Detroit Locker allows one wheel (the outside wheel) to rotate faster when cornering.
One tire can, and does, spin faster than the other. I have never experienced any difficulty turning in sand or loose dirt; nor have I heard of anyone
unlocking (front hubs or 4WD) to negotiate sharp turns. Admittedly, turning on extremely slippery surfaces, such as snow/ice, requires some "talent."
Detroit Lockers on two of my current vehicles, plus Eaton "E-Locker" (electronic actuator) and ARB "Air Locker" on rear axles. No complaints about any
of those tough units.
It might be a good idea to note here, for the less sand-experienced readers, that 18 psi was sufficient* for the job (described above) of driving down
the beach and pulling in to the campsite. That should not be construed as "ideal" air pressure for soft sand. 10 - 12 psi on a vehicle of similar
weight would be typical, and give better results. The improved flotation would help in preventing a stuck situation, allow for more uphill ability, or
be necessary for hauling a utility/boat trailer.
* Those who know their vehicle's capability and the situation at hand, such as David K, might elect to retain moderate air pressure in order to save
time when airing up again.
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Curt63
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Good info. Thank you
No worries
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David K
Honored Nomad
Posts: 64848
Registered: 8-30-2002
Location: San Diego County
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Mood: Have Baja Fever
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| Quote: | Originally posted by Maderita
David K,
Interesting read. Thanks for taking the time to post.
I used to camp on the "island" back in the 70's - 80's when I thought a dozen people at Laguna Percebu was too crowded! Landcruiser FJ40 back in the
day, with all of the typical engine & suspension mods. Always nice to see your photos and to day dream of going back again...
What's your hypothesis on the "4WD LOW + REAR LOCKER" getting worse results? That certainly seems contrary to my experience with mechanical 4WD
systems. There are numerous variables at play, so surprises are not entirely unexpected.
Hope you don't mind a rebuttal regarding this statement: "Locking diferentials lock both tires on an axle together, so one cannot spin faster than the
other, even if it is in the air.
Hard Core off roaders love to have front and rear locking differentials... makes them pretty near unstoppable. The dark side of lockers is that they
make steering quite difficult and must be unlocked in order to make sharp turns on the trail... When you turn a vehicle the 4 tires all must rotate at
different rates. "
In defense of locking diffs, the #1 locker, the original/classic Detroit Locker allows one wheel (the outside wheel) to rotate faster when cornering.
One tire can, and does, spin faster than the other. I have never experienced any difficulty turning in sand or loose dirt; nor have I heard of anyone
unlocking (front hubs or 4WD) to negotiate sharp turns. Admittedly, turning on extremely slippery surfaces, such as snow/ice, requires some "talent."
Detroit Lockers on two of my current vehicles, plus Eaton "E-Locker" (electronic actuator) and ARB "Air Locker" on rear axles. No complaints about any
of those tough units.
It might be a good idea to note here, for the less sand-experienced readers, that 18 psi was sufficient* for the job (described above) of driving down
the beach and pulling in to the campsite. That should not be construed as "ideal" air pressure for soft sand. 10 - 12 psi on a vehicle of similar
weight would be typical, and give better results. The improved flotation would help in preventing a stuck situation, allow for more uphill ability, or
be necessary for hauling a utility/boat trailer.
* Those who know their vehicle's capability and the situation at hand, such as David K, might elect to retain moderate air pressure in order to save
time when airing up again. |
Hola Maderita,
Maybe we have been on the island at the same time, in years past? I began camping out there in 1978... Before then, I camped at Nuevo Mazatlan and
would walk onto the island from Bahia Santa Maria.
When I went to Mision Santa Maria with the other four wheelers last year, a couple of the vehicles had ARB air lockers on the front (and one on back)
a couple of us Tacomas had the E-locker on the back... and while they were turning there lockers off to make tight turns, I didn't have to do anything
using the A-TRAC only (and not my rear locker). While using the e-locker in back, in the past, it wasn't hard to turn off road... but Toyota warns to
only use it to get unstuck... I used it to keep from getting stuck!
Unless the road surface is loose, the front locker (ARB) will make steering difficult because unlike a Detroit Locker, it doesn't allow the small
slippage needed to turn.
As for my test on the beach, why the rear locker setting dug into the sand and the A-TRAC did not, might have to do with A-TRAC not allowing any tire
to spin free, and lockers forcing both to spin the same?
A-TRAC matches tire rotation across the axle to distribute torque evenly. No one tire will spin away robbing the opposite tire of power. Lockers do
the same thing, but don't prevent spinning that is counter-productive to movement.
This is just a possiblity, as I am not a Toyota engineer... but I have been enjoying my 2010 Tacoma a LOT!
As for the air pressure statement, yes you are correct... but, while 12-15 psi was required for my previous BFG tires to 'float', these Hankook
Dynapros did so at 18 psi, just as well.
When I ran Cooper Discoverer STT 3 ply, mud tires back in 2006-7, I had to drop the pressure to 10 psi... they were the worse sand tires I have
owned... but they 'look' so good! 
Thank you for your input! See our Mision Santa Maria trip photos... link below...
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MitchMan
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Absolutely great stuff. Thank you both.
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rts551
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drove this beach many times with my jeep and never yet had to do a test. 
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David K
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| Quote: | Originally posted by rts551
drove this beach many times with my jeep and never yet had to do a test.
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Well, instead of drugs or fishing, I find other ways to keep entertained in Baja! 
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rts551
Elite Nomad
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| Quote: | Originally posted by David K
| Quote: | Originally posted by rts551
drove this beach many times with my jeep and never yet had to do a test.
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Well, instead of drugs or fishing, I find other ways to keep entertained in Baja! |
OK you don't like Jeeps. But what do you have against fishing? Drugs are for little big boys who can't find a real job. Myself, I worked in a
drug free environment long enough for a good retirement. The only drug I need is for heartburn, whoops time fro a prilosec.
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David K
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1) I DO like Jeeps... I used to own one and so did Elizabeth, and I love the history of the Jeep vehicle from 1940 on.. I just cannot afford to own
one and need a reliable vehicle that isn't in need of constant fixes every time I go four wheeling. My Toyota allows me to do some pretty hard core
off roading then drive it home and use it for work the next day... I do know that it won't get into the tightest of places as a Jeep Rubicon can,
because I have a longer wheelbase and some extra overhang in back (see my bumper damage at Mision Santa Maria?).
2) I have NOTHING against fishing... That is what brought my family to Baja in the first place... It is that in the past few years, I have just
enjoyed camping, exploring and four wheeling in Baja over fishing, as something to do while on vacation. I love to eat fish, just not as interested in
catching them as when I was younger... Just the opposite of your neighbor, Glenn (who loves to fish, but isn't so big on eating them, as I recall).
3) Good for you on the drug thing... I managed to live my entire life without using recreational drugs or pot... A little beer, wine or booze is fun,
on occaision.
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dtbushpilot
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Thanks for the research DK, most of it will apply to my FJ. I appreciate you taking the time to do the leg work for those of us who have to figure
this stuff out after we are buried in the sand somewhere....like me......dt
"Life is tough".....It's even tougher if you're stupid.....
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David K
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| Quote: | Originally posted by dtbushpilot
Thanks for the research DK, most of it will apply to my FJ. I appreciate you taking the time to do the leg work for those of us who have to figure
this stuff out after we are buried in the sand somewhere....like me......dt |
Hi Dave, I have posted most of my Tacoma 4WD findings and 'how-to's over on TacomaWorld.com... There are FJ owners there as well...
The traction systems really don't need much input, but I like 'playing' with my truck... so I got into the many options we have to move power to the
tires... Not sure an FJ is exactly the same, but for an Off Road 4WD Taco, we have 9 drive modes available to us...
1) 2WD: VSC and TRAC active, engine regulated ('Limited Slip Lite').
2) 2WD: 'AUTO LSD' ('TRAC OFF MODE'). No engine regulation for 'strong' limited slip.
3) 2WD: 'VSC OFF MODE' (TRAC is off for 'open differential').
4) 4WD-Hi: VSC and TRAC active. No engine regulation for 'strong' limited slip.
5) 4WD-Hi: 'VSC OFF MODE' (TRAC is off for 'open differentials').
6) 4WD-Lo: VSC and TRAC are both off in L4 ('open differentials').
7) 4WD-Lo: 'A-TRAC' on gives a 'locker-like, super strong' limited slip, front and rear.
8) 4WD-Lo: Rear Differential Locked and open front differential (A-TRAC off).
9) 4WD-Lo: RR DIFF LOCK + A-TRAC on, 3 MPH limit.
As you know, the A-TRAC and Rear Locker only work in L4 and they each have switches to activate them.
The TRAC on/off in H2 and H4 are controlled by the VSC OFF switch (the car with skid tracks button):
[Edited on 8-14-2012 by David K]
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David K
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Well, almost 8 years have passed since this post and I am still driving the same Tacoma, now 9 years old + 2 months. I only have 118,000 miles on it
making it the least driven of my 3 Tacomas. The other two had over 100,000 miles in about 4 years!
The traction systems have changed a little, but not too much because they do so well at making the Off Road 4x4 Tacoma so unstoppable.
In 2012, they added one more choice in the traction controls for a total of 10. They made the standard TRAC mode in H4 (4WD HIGH) get engine
regulation and added a button push for TRAC OFF mode (same as AUTO LSD in 2WD). The name Trac Off is terrible because TRAC is not off, but is
stronger, without the engine regulation. So think of it as Regulation Off.
In 2016, Toyota introduced the 3rd Generation Tacoma and the Off Road 4x4 model manual transmission has A-TRAC, as before but the automatics now have
what they call MTS (Multi-Terrain Select) which is an adjustable A-TRAC tuned to different off road conditions. They also added CRAWL which is like a
low range cruise control where you only steer. There are several speed selections of crawl. The handy part is that at the lowest setting, if you are
buried in sand, it will get you out. You can see how it works on YouTube. If you have a second gen Tacoma like mine, you can feather the gas pedal
with A-TRAC and get out of stucks, too.
Oh, What a Feeling!
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John Harper
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Great post, DK! Very good information and testing protocols.
John
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4x4abc
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David,
you wrote:
"Traction Control is a limited slip system that utilizes the brake system to slow a spinning tire so that the power can be transfered to the tire with
traction (and move you).
Open differentials (without traction control) will transfer power to the tire the spins the easiest (the one in the air, on ice, mud, sand, etc.) and
the other tire might be on solid ground does nothing."
Torque, traction, power are not things that you can transfer by opening and closing valves. It is not like plumbing.
By the way, power does not move your car. It is a way to measure work done.
The only 2 forces involved in moving a vehicle are traction (grip) and torque. There has to be more traction than torque, otherwise the vehicle will
not move.
Harald Pietschmann
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StuckSucks
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Impressive video of the CRAWL control. I will be taking delivery of a 2019 Tacoma in the next 30 days and this is one of the first things I'd like to
try (with a friend with snatch strap standing by, just in case)
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willardguy
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not a Jeep fan but that Gladiator RG's wheeling out at KOH is lookin' pretty cool!
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StuckSucks
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THIS is a Jeep? Hit the right arrow to see movies of Robbie
https://www.instagram.com/p/BtmhvTXA_He/
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Mulege Canuck
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I was reluctant to try airing down the tires on my F350 with a large Bigfoot camper. I have to have 65 lbs in the KO2’s to handle the weight of my
camper. Tried airing down to 30 lbs to get out on the deep sand at Los Gatos and I was very surprised. That tank floated right on top of the sand.
I am going to push it more now but I will get stuck sometime for sure.
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