FAQ Discussion: Crawl, Multi-Terrain, Optional Lockers or ATRAC when best to use each (1 Viewer)

[Romer]

I started old school wheeling back in 79 with a 74 FJ40. Open diffs, you used a combination of braking and power to get over things.

20 years later I put an autolocker into my 77 FJ40.

Then I bought an 80 with electronic selectable lockers. Things became much easier and using a new technique called power braking was able to get over most obstacles as long as the clearance was there. I would not have made it through the Rubicon trail without a combination of lockers and power braking. Power braking is you put your foot on the brake, rev the engine to 1000 rpm or slightly more depending on the terrain. You keep the rpms constant and use the brake to move forward

Then came my 100 with ATRAC. I didn’t need to use lockers as much, but still needed them for when I wanted to power brake as that shuts off ATRAC. ATRAC brakes a spinning wheel to enable traction on the non spinning wheel

Now the 200 series has multiple capabilities. It has ATRAC like my 100. I also installed lockers like my 100 and 80.

We now have Crawl Control: Allows travel on extremely rough off-road surfaces at a fixed low
speed without pressing the accelerator or brake pedal. Minimizes
loss of traction or vehicle slip when driving on slippery road surfaces,
allowing for stable driving.

with Turn Assist

We also have Mult-terrain Select:

using the same switch as Crawl Control brings upon additional capabilities

Lets discuss when to use each setting for maximum effect and when to use one over the other

This is an FAQ thread, so please keep the chat to a minimum and keep the Discussion on-point

 

[kreiten]

While going down steep icy hills I have found that "crawl control" works excellent! For most of the trails I do(mud & dirt mix) I use 4low(terrain selector set to MUD & SAND) and the center diff not locked. When things get tricky I will lock the center diff, if they get even trickier then I engage "crawl control". "Crawl control" has worked very well for me on steep muddy hill climbs, ice, sand and getting over large slick tree roots... The turn assist works great, the looser the dirt, mud etc the better it works, I like a slower speed of crawl mode while using it as you are normally trying to avoid and obstacle. One thing to keep in mind is that "turn assist" will not work if the "center diff" is locked.

 

[chilibit]

Kreiten: Your comment gets right to the crux of the matter. To leave we our place we must descend an often icy, twisty, paved downhill (15%) for a quarter mile. If I start sliding the likelihood of multiple roll overs is very high if I slip off the edge of the drive and over the side. I have hesitated to use crawl control over merely using low range because I did not know if the system was monitoring steering angle input while in crawl control. Also, how do you "drive back under the slide" by using higher speed to control front wheel slippage if you are "stuck" in crawl control mode? If all four wheels are sliding have you tried shifting to reverse and how did that compare to depending solely on braking? In season I used a set of wheels with dedicated Blizzacks and that makes a huge difference. Even so it is not a fun ride. And despite having owned LCs for 40 years I not sure that I can convincing argue why any of these would be better than just riding the brake to control descent speed and letting stability control handle things.

 

[Willy beamin]

I like 4lo and 1st gear for downhill such as you described @chilibit - I like to be in control on slick downhills and not letting a system take over

 

[M1911]

One thing to keep in mind is that "turn assist" will not work if the "center diff" is locked.

Huh? I thought turn assist was specifically designed to help turn radius when the center diff is locked?

 

[chilibit]

I like 4lo and 1st gear for downhill such as you described @chilibit - I like to be in control on slick downhills and not letting a system take over

Unfortunately the steepness will overwhelm 1st gear in low range and suddenly you are looking at 4000 RPMs or more. By the time you get there you wish you had used the brakes. Among other choice words.

 

[Markuson]

Huh? I thought turn assist was specifically designed to help turn radius when the center diff is locked?

Wouldn't center diff still allow one rear wheel to remain braked for turn assist?
I dunno... don't have it on a 2008...

 

[chilibit]

Huh? I thought turn assist was specifically designed to help turn radius when the center diff is locked?

I think you must be in crawl control but without the center diff locked. And it also watches for large steering angle input which seems logical but sneaks up on you. Or at least it does me.

 

[kreiten]

Kreiten: Your comment gets right to the crux of the matter. To leave we our place we must descend an often icy, twisty, paved downhill (15%) for a quarter mile. If I start sliding the likelihood of multiple roll overs is very high if I slip off the edge of the drive and over the side. I have hesitated to use crawl control over merely using low range because I did not know if the system was monitoring steering angle input while in crawl control. Also, how do you "drive back under the slide" by using higher speed to control front wheel slippage if you are "stuck" in crawl control mode? If all four wheels are sliding have you tried shifting to reverse and how did that compare to depending solely on braking? In season I used a set of wheels with dedicated Blizzacks and that makes a huge difference. Even so it is not a fun ride. And despite having owned LCs for 40 years I not sure that I can convincing argue why any of these would be better than just riding the brake to control descent speed and letting stability control handle things.

We driver the forest roads covered in snow and ice all the time in the winter, some are as you described, steep with a sheer cliff, if something goes wrong it goes bad really fast. For the majority of the time while on roads like that I am in 4low(mud & sand), with the truck in the lowest gear, center diff locked and chains on the back wheels. I think of "crawl control" more for super short distances(just how I use it). For instance a 30 or 40 foot super steep(up or down hill climb) that is super icy. I have never(so far) had the vehicle lose control while in "crawl mode". Keep in mind "crawl mode" can only run for a limited amount of time then the system will shut itself down. I think for the situation you are describing 4low(mud & sand) and throw the truck in low gear and you should be good to go... just my 2 cents

 

[kreiten]

Huh? I thought turn assist was specifically designed to help turn radius when the center diff is locked?

turn assist is designed to only work while in "crawl mode" with the center diff not locked, if the center diff is locked then the vehicle will give you an audible chime and "turn assist" will not function.

 

[kreiten]

Unfortunately the steepness will overwhelm 1st gear in low range and suddenly you are looking at 4000 RPMs or more. By the time you get there you wish you had used the brakes. Among other choice words.

if that's the case you might want to play around with "crawl control" for the super steep parts of the decent, the system works really good for steep descents, IMO... but like I've mentioned I've never tried it on a hill much more than 50 or so feet.

 

[Romer]

For the majority of the time while on roads like that I am in 4low(mud & sand), with the truck in the lowest gear, center diff locked and chains on the back wheels. I think of "crawl control" more for super short distances(just how I use it). For instance a 30 or 40 foot super steep(up or down hill climb) that is super icy. I have never(so far) had the vehicle lose control while in "crawl mode". Keep in mind "crawl mode" can only run for a limited amount of time then the system will shut itself down. I think for the situation you are describing 4low(mud & sand) and throw the truck in low gear and you should be good to go... just my 2 cents

For the multi-terrain switch positions like Mud Sand, how does the switch selection change the performance of the truck? I always like to use this web site when explaining 4WD and diff operations. How would these items change any of this?

How Differentials Work

 

[kreiten]

For the multi-terrain switch positions like Mud Sand, how does the switch selection change the performance of the truck? I always like to use this web site when explaining 4WD and diff operations. How would these items change any of this?

How Differentials Work

Think of it more as a controlled ATRAC setup, i.e. how much slip do you want in the traction control system. Mud & Sand will allow more slip, to allow you to keep momentum and tire spin, whereas Rock will allow the least amount of tire spin prior to kicking in the brakes when a wheel slips. It's almost easier to look at the screen and just think 1 thru 5, how much slip do I want, or wheel spin, or whatever you want to call it prior to the brakes slowing that wheel down. Hope that kinda helps...

 

[Markuson]

Think of it more as a controlled ATRAC setup, i.e. how much slip do you want in the traction control system. Mud & Sand will allow more slip, to allow you to keep momentum and tire spin, whereas Rock will allow the least amount of tire spin prior to kicking in the brakes when a wheel slips. It's almost easier to look at the screen and just think 1 thru 5, how much slip do I want, or wheel spin, or whatever you want to call it prior to the brakes slowing that wheel down. Hope that kinda helps...

We lowly 2008'ers don't have to think of such things, as we don't have those modes...

 

[Romer]

Thanks, to make sure I understand. The Mult-terrain is an adjustment of the ATRAC braking. setting 1 (Mud and Sand) allows the maximum wheel slip ratio before braking where as 1 (Rock) allows the minimum wheel slip ratio before breaking. If I got it right, that's an easy concept to understand

 

[kreiten]

Thanks, to make sure I understand. The Mult-terrain is an adjustment of the ATRAC braking. setting 1 (Mud and Sand) allows the maximum wheel slip ratio before braking where as 1 (Rock) allows the minimum wheel slip ratio before breaking. If I got it right, that's an easy concept to understand

you got it!!!

 

[Markuson]

Think of it more as a controlled ATRAC setup, i.e. how much slip do you want in the traction control system. Mud & Sand will allow more slip, to allow you to keep momentum and tire spin, whereas Rock will allow the least amount of tire spin prior to kicking in the brakes when a wheel slips. It's almost easier to look at the screen and just think 1 thru 5, how much slip do I want, or wheel spin, or whatever you want to call it prior to the brakes slowing that wheel down. Hope that kinda helps...

Helpful, simple explanation that makes sense.
Thanks! (Even though I don't have the setting...)

 

[Romer]

It seems from the description of crawl mode is that it is similar to power braking, you use the dial to control the brakes and how much pressure is releaved

Essentially you are just controlling the brakes ATRC system with these and Crawl mode adds some acceleration to have the vehicle crawl based on how much brake pressure is identified from the switch

 

[kreiten]

They are all kind of one in the same, 3 different systems that all use the same general idea in order to increase traction, but do so at different levels of control. First you have ATRAC, which essential jumps in when needed to limit wheel spin. Then you have "Terrain Select" which only works in 4low and essentially allows you to fine tune the "wheel spin" to the type of terrain you are on. And then you have the version which takes it all to the extreme, "Crawl Mode", basically you are just setting the speed and the system is analyzing each wheel individually to allow for virtually no wheel spin. When I'm in "crawl mode" I use the dial as a sort of gas pedal, adding and subtracting speed as I make my way through the obstacle.

 

[Romer]

Excellent. Nice summary Kreiten.