Crawl control discussion

[highfructose]

I’ve tried googling and researching the topic of the utility of crawl control compared to lockers but I’ve found no authoritative discussion. Feel free to share if you have a link to one or thoughts on the subject.

part of the reason I purchased a 200 was that I knew I could easily add lockers at a later date. For a while it’s been on my list-I already have the arb compressor.

now I’m having second thoughts. The following are a few YouTube links showing crawl control exceeding the utility of a locker or lockers...these aren’t perfect comparisons but perfect is the enemy of the good.

in trying to parse how crawl control does better in these situations, I had an idea (I might be wrong, feel free to prove me wrong and convince me to buy a rear locker):

lockers, strictly speaking, offer a maximum of 25% of the engines power to any particular wheel and inhibit on the fly steering somewhat.

because crawl control effectively arrests the spinning of a particular wheel, thereby sending power to the wheel across the vehicle...does crawl control technically send up to 50% of the engines power to any particular wheel (when the center diff is locked)?

If so, Wouldn’t that give you double the torque/power at the appropriate wheel compared to lockers? And additionally, since the system is constantly alternating wheels throughout the obstacle, wouldn’t crawl control also NOT inhibit steering the way lockers do?

I’m mulling the idea of not adding a rear locker...I would assume if I added a rear locker I would, technically, reduce the theoretical power to each of my rear wheels by half should I decide to use the rear locker and crawl control at the same time.


Crawl control beats rear and center locker

Crawl control beats triple lock

 

[GOLIGHTLY]

Interesting videos. Following because I don’t know s*** about heck.

 

[highfructose]

Interesting videos. Following because I don’t know s*** about heck.

I admit, I am in the same boat as you.

 

[Madtiger]

Personally, I am a fan of CC. Have used it numerous times. It makes me look good off-road.

 

[tbisaacs]

I’ve used crawl control a handful of times and it’s basically dark magic. It failed me once but I was buried to the frame in hard packed snow.

I don’t have a strong desire to spend 4 grand on lockers but totally get why they are useful. Lockers are great for when some precision is required - like when spinning wheels to find traction would actually compromise your ability to get out / get over. It would be nice to flip a switch and crawl with grace.

 

[linuxgod]

Die hard wheeling guys around here will insist triple locked is the way to get out of the worst situations (or avoid them completely), where CC is good but just not the same. There are 2 use cases where I think lockers are better than CC and MTS:

1. When you know you're going to have lots of wheel spin (sand, mud, etc) being fully locked can ensure you maintain wheel speed. MTS and CC will allow you to spin the wheels and then slow them down, which in sand might dig you in too much.
2. When you need to get all 4 wheels moving at very low speed (like starting on ice, on a steep rocky incline, etc) and you don't want to gas it and wait MTS to brake the free spinning wheel to give you traction or rely on CC to do the same for you at low speed.

I find CC works pretty well. In most cases you don't need lockers, just CC with the right MTS setting and some patience (and practice). In fact I've seen videos of people getting unstuck in sand where I'm pretty sure CC is more capable than 99.9% of drivers.

Then again I was trying to maneuver into my garage last week after we got about a foot of snow and MTS wasn't helping me maneuver into the garage (which is 90 degrees off a narrow alley with a single 7' wide opening that *barely* fits the LC, requiring a 5 point maneuver on a good day). There was about 2" of solid ice under the snow, and even with the CDL engaged I had one wheel in the front and one in the rear which would just spin as soon as I took my foot off the brake. That's a case where MTS requires you to give it some gas before it'll brake the freely spinning wheel and CC requires you to let the truck "drive" itself - neither of which I wanted to do given I didn't want to suddenly grip and smash into the garage door frame. I don't have F/R lockers atm but I'm fairly sure I would've gotten in if I'd had them, though it's also possible I would've had all 4 wheel spinning...

 

[Artie]

I’m having a rear locker installed. My thought is it’s never a bad idea to have more tools at your disposal. We will be towing off road in sand, mud and whatever else with the wife and kids. My wife wanted lockers in the front as well, if she had her way we could probably take a helicopter instead and break even. I’m interested in the feedback this thread will bring.

 

[Surfy]

@highfructose: your Test wasnt really fair. You should have compared it to a triple locked verhicle. But you really show - how quick things can go wrong!

My Land Cruiser 200 is triple locked, but has too atrac and crawl.

Here I did collect some videos: Differentialsperren vs LSD vs ATRAC im Reisefahrzeug - https://www.4x4tripping.com/2013/11/differentialsperren-vs-lsd-vs-atrac-im.html

As you can see, At sand even crawl can outperform lockers easily. Guess today both is helpful.

Maybe also my 65`000 miles and 8 yeas: what offroad equipement was usefule or not may be interesting. Additional Arb difflocks wouldn be on my "must have" list. But optional, yes.

Surfy

 

[linuxgod]

I’m having a rear locker installed. My thought is it’s never a bad idea to have more tools at your disposal. We will be towing off road in sand, mud and whatever else with the wife and kids. My wife wanted lockers in the front as well, if she had her way we could probably take a helicopter instead and break even. I’m interested in the feedback this thread will bring.

FWIW if you're not regearing, just considering lockers, you might do just as well to carry a shovel and maxtrax and rely on MTS and CC then supplement with the recovery gear. I've seen CC work a fully stick rig out of deep sand in about 5 minutes. That said if you're towing in sand I can definitely see the allure with the extra weight over the rear and drag of the trailer.

For me I'm set on regearing, so I'm having the shop do lockers "while they're in there" since it's all gotta come apart anyway, but for the frequency that I'll use them MTS and CC are 99% sufficient.

 

[highfructose]

@highfructose: your Test wasnt really fair. You should have compared it to a triple locked verhicle. But you really show - how quick things can go wrong!

My Land Cruiser 200 is triple locked, but has too atrac and crawl.

Here I did collect some videos: Differentialsperren vs LSD vs ATRAC im Reisefahrzeug - https://www.4x4tripping.com/2013/11/differentialsperren-vs-lsd-vs-atrac-im.html

As you can see, At sand even crawl can outperform lockers easily. Guess today both is helpful.

Maybe also my 65`000 miles and 8 yeas: what offroad equipement was usefule or not may be interesting. Additional Arb difflocks wouldn be on my "must have" list. But optional, yes.

Surfy

One of the videos above is of a triple locked vehicle. The Tacoma with crawl control out performs it.

that said, since it’d be apples to apples, if you ever happen to find yourself at a particularly difficult obstacle, perhaps you can make a video testing your land cruiser triple locked vs your land cruiser with just the crawl control activated.

I’d be curious to see. I’ve always wondered why Toyota would put crawl control AND a rear locker on some 4runners and Tacoma’s...but only put crawl control on their 85,000 dollar land cruiser.

it’s either the case that they skimped to make money...or they determined that crawl control plus a rear locker doesn’t offer appreciable utility.

 

[TimCFJ40]

One thing to consider is that your assumption of 25% power to each wheel isn't accurate unless you have perfect traction at all four wheels. If you have perfect traction at all four wheels, you wouldn't have the lockers locked in, as you wouldn't need them. A slipping wheel consumes much less power than one with traction. Consider a situation in the rear axle where one wheel is on ice and the other is on dry pavement. An open diff would send all of the power to the slipping wheel. A fully locked diff will send the power to both sides "equally" but in reality the slipping wheel is consuming very little power, leaving more for the wheel with traction, since both are firmly locked together with the same power coming through the diff from the driveshaft.

 

[slipkid13]

I am not a hard core off roader but I am a fan of CC. I have used several times in my LX and had it in my 5th Gen 4Runner. One of the reasons I skipped over the GX was because finding one with CC is like finding a Unicorn.

Not sure why the 4Runner has a rear diff lock and the 200 has a center diff lock (why not both in the 200?) but for the off roading I have done the Center Diff lock and CC have been sufficient.

 

[TheGrrrrr]

I've found CC is great for getting out of trouble, but not as useful for avoiding it. This is because I virtually never start with CC to tackle an obstacle. The full time A-Trac has in my experience done well enough for managing wheel spin that lockers have remained in the category of 'would be cool, but not necessary' for me. I have yet to really see a big benefit from the Terrain Select function, but I suspect there is more benefit than is obvious in the driver's seat. I have yet to encounter a situation where my conclusion is that lockers would have avoided an issue or solved for an issue that making better decisions wouldn't have solved for.

I offer this perspective as someone who wheels a fair amount but doesn't often attempt things that appear obviously unlikely to conquer. The couple of occasions where I have come upon an obstacle that is difficult but unavoidable, the combination of A-Trac and CC have handled them without damage or major issue. The biggest benefit I see from CC is the intelligence for finding traction where there seems to be none, but I think this is more a function of A-Trac leveraging the intelligent use of power from CC in those situations. The point I'm trying to make is that in the 200, none of this functionality should be considered on its own, but instead as part of a suite of tools that sometime work alone or in concert with each other with the added benefit of the way the platform uses the tools intelligently instead of just stacking them. I'm no expert though, and certainly don't push the rig to its limits.

 

[TeCKis300]

I’d be curious to see. I’ve always wondered why Toyota would put crawl control AND a rear locker on some 4runners and Tacoma’s...but only put crawl control on their 85,000 dollar land cruiser.

it’s either the case that they skimped to make money...or they determined that crawl control plus a rear locker doesn’t offer appreciable utility.

In international markets, the 200-series has the option of a rear locker. Toyota deemed the USDM unworthy of the feature unfortunately.

The international 200-series also has a factory winch option.

 

[WesSiler]

I think there's some confusion here about different systems, and also how 4WD and locking diffs works.

4WD and diffs: don't think of this as each wheel get's a percent of power. Think of it as locking speeds of wheels together. Center diff locks speeds of front and rear axles together. The wheel with the least traction on a given axle can only spin as fast as its counterpart on the other axle. Diffs then do that across the axles. With all three diffs locked, the speed of all four wheels is locked together.

That arrangement maximizes traction. But, it also causes problems. Making it hard to steer is the obvious one. Enter ATRAC. That's an electronic system that mimics the function of locking axle diffs using the ABS system, but does so in very short intervals. So, you're driving along and the front left wheel starts to spin faster than the front right. ATRAC will grab some front left brake, and lock the speeds of the front wheels together to add traction. It may only need to do this for half a second, so a normal driver will just hear some noises and note that the car continued through the obstacle. No loss on steering. Another problem with axle lockers is that, on a side slope, a locked axle will slide downhill if it loses traction. You can see the issue if you're climbing a slope at an angle. If you have your front diff locked, and are really giving it gas to make the climb, your car could skid sideways, and risk a rollover if that locked front axle breaks traction. ATRAC can avoid this happening. It can also be programmed for different environments, providing optimal dynamics for those, or for the driver's preferences.

The big downside of ATRAC on our 200s is that you can only use it in 4L. To me, that's the biggest argument for adding a rear air locker. Sometimes I want to drive in sand or similar at higher speeds, but need the traction of a locked axle diff.

Crawl Control works similarly to ATRAC, but also takes control of the throttle. It then manages progress for you in low traction situations, down or up hill. A lot of people look at this as an extraction mode, but by slowly spinning all four wheels at equal speed if stuck in sand or similar, it's really just mimicking left foot braking in 4L with everything locked, which is a skill a lot of people will have learned already.

So, are our systems just idiot proof, or do they add capability over mechanical lockers? There's some different circumstances in which each can excel. Given the desperately low information nature of today's drivers, and the fact that software is cheaper than hardware, I'm sure you can follow Toyota's line of thought.

I'm very happy with the systems, once the vehicle is on good tires at appropriate pressures. I'm adding the rear locker because I'd like the truck to have one, not because it needs it. There's no reason to add a front locker. It should also be noted that, while effective, Toyota's systems have fallen far behind the competition in terms of convenience and seamlessness. I can operate all the systems in 4H on my Ford Ranger, for instance, and they're way less noisy and invasive.

 

[WesSiler]

In international markets, the 200-series has the option of a rear locker. Toyota deemed the USDM unworthy of the feature unfortunately.

The international 200-series also has a factory winch option.

You'd struggle to find one in a million drivers in this country that can articulate how 4WD works, let alone understand when it's appropriate to use it, or when not to. Remember, this is the company that lost a lawsuit about runaway vehicles because a good portion of its customers couldn't tell the gas and brake pedals apart, or pay attention long enough to avoid falling asleep on the wrong one. I'd imagine most 200 series owners don't know what all the traction system buttons do, or how to use them.

 

[TheGrrrrr]

The big downside of ATRAC on our 200s is that you can only use it in 4L. To me, that's the biggest argument for adding a rear air locker. Sometimes I want to drive in sand or similar at higher speeds, but need the traction of a locked axle diff.

I was under the impression that ATRAC in the 200 Series is active at all times. Not sure where I got that information, but I remember it coming from someone who I regarded as a knowledgable. Does anyone have documentation either way?

Edit to clarify my understanding:

ATRAC = On at all times
MTS = Engaged in 4L
CC = Engaged Via Toggle Button only available in 4L
TA = Engaged Via Toggle Button only available in 4L

 

[Madtiger]

4-wheel traction control is on all the time, including daily driving when needed. It does slow down/pulsate brake of slipping wheel(s) but is not aggressive and is more for all-weather traction.

A-TRAC was an old system that was present on FJ Cruiser and was the precursor to CRAWL. And that was ON only in 4 low.

But people use ATRAC and 4-wheel TRAC interchangeably all the time since the demise of FJC.

 

[WesSiler]

4-wheel traction control is on all the time, including daily driving when needed. It does slow down/pulsate brake of slipping wheel(s) but is not aggressive and is more for all-weather traction.

ATRAC was an old term that was present on FJ Cruiser that was the precursor to CRAWL. And that was ON only in 4 low. But people use ATRAC and 4-wheel TRAC interchangeably all the time.

Yeah, manufacturer terminology could be designed to create headaches.

Traction and stability control are on nominally. They manage traction using the same sensors and stuff, but are programmed to operate differently. Otherwise your commute would look like a scene from Tokyo Drift.

 

[highfructose]

One thing to consider is that your assumption of 25% power to each wheel isn't accurate unless you have perfect traction at all four wheels. If you have perfect traction at all four wheels, you wouldn't have the lockers locked in, as you wouldn't need them. A slipping wheel consumes much less power than one with traction. Consider a situation in the rear axle where one wheel is on ice and the other is on dry pavement. An open diff would send all of the power to the slipping wheel. A fully locked diff will send the power to both sides "equally" but in reality the slipping wheel is consuming very little power, leaving more for the wheel with traction, since both are firmly locked together with the same power coming through the diff from the driveshaft.

If the axle is locked and each tire spins at precisely the same speed, do they not each receive the same amount of engine output? Wouldn’t that mean a triple locked vehicle only sends 25% of power to each wheel?

and, vice versa, if you limit traction on ALL wheels except 2, on a center locked vehicle, then 50% of of that energy goes to each of the tree spinning tires? This is the situation most people that get stuck in standard 4wd’s have. They are sending 50% of the energy to one of their front tires that has no traction...and 50% of the energy from one of the rear tires that has no traction.

so if you can use your crawl control system to, essentially, arrest all spin on various tires on the front and back as needed, you increase the energy going to a particular tire at a rate of 50%, similar to how a stuck vehicle spinning a tire on the front and back would be...except with crawl control, due to braking, you are just swapping that 50% away from the tire with no traction and to the tire with traction.

im not an engineer, btw, hence the request for discussion/dialogue.