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Difference bewteen terrain settings

12K views 34 replies 7 participants last post by  Benn0 
#1 ·
Does anyone actually know the exact difference between the "mud/snow/Sand/rock"ect.. settings for the QD2 ...

like for SNOW, does it give more power to the front wheels and starts you out in second grear? :confused:
 
#3 ·
Thanks, as it was enlightening, it did not tell me what I was looking for, neither did jeepwiki.
 
#9 · (Edited)
Actually it does. I also think Bill did a pretty good job of explaining in layman's terms how the software parameters play a part in the Select-Terrain operation.

There are two separate operations explained in the OM and you need to consider how they both work together...

- QDII operation.
- Select-Terrain operation.

Quadra-Drive® II System – If Equipped

The optional Quadra-Drive® II System features two torque transfer couplings. The couplings include an Electronic Limited-Slip Differential (ELSD) rear axle and the Quadra-Trac II® transfer case.

The optional ELSD axle is fully automatic and requires no driver input to operate. Under normal driving conditions, the unit functions as a standard axle, balancing torque evenly between left and right wheels. With a traction difference between left and right wheels, the coupling will sense a speed difference. As one wheel begins to spin faster than the other, torque will automatically transfer from the wheel that has less traction, to the wheel that has traction.

While the transfer case and axle coupling differ in design, their operation is similar. Follow the Quadra-Trac II® transfer case shifting information, preceding this section, for shifting this system.

So on the WK2 QDII you have torque transfer front to rear but you only have side to side torque transfer on the rear axle. This is different from the older QD system that used gerotor couplers in the transfer case and in both Vari-Lok axles. On that system, 100% torque could be applied to any of the 4 wheels.

The WK2 system is relying on traction and stability control software to make up for the lack of a limited slip differential up front.


SELEC-TERRAIN™ — IF EQUIPPED

Selec-Terrain™ combines the capabilities of the vehicle control systems, along with driver input, to provide the best performance for all terrains. Selec-Terrain™ consists of the following positions:

• Snow – Tuning set for additional stability in inclement weather. Use on and off road on loose traction surfaces such as snow. When in Snow mode (depending on certain operating conditions), the transmission may use second gear (rather than first gear) during launches, to minimize wheel slippage. If equipped with air suspension, the level will change to Normal Ride Height (NRH) if the transfer case is in high range. The level will change to Off-Road 1 if the transfer case is in Low range.

• Auto – Fully automatic full time four-wheel drive operation can be used on and off road. Balances traction with seamless steering feel to provide improved handling and acceleration over two-wheel drive vehicles. If equipped with air suspension, the level will change to NRH.

• Sand – Off road calibration for use on low traction surfaces such as sand or wet grass. Driveline is maximized for traction. Some binding may be felt on less forgiving surfaces. The electronic brake controls are set to limit traction control management of throttle and wheel spin. If equipped with air suspension, the level will change to Off-Road 1.

• Mud – Off road calibration for use on low traction surfaces such as mud. Driveline is maximized for traction. Some binding may be felt on less forgiving surfaces. The electronic brake controls are set to limit traction control management of throttle and wheel spin. If equipped with air suspension, the level will change to Off-Road 1.

• Rock – Off-road calibration only available in 4WD Low range. The vehicle is raised (if equipped with Air Suspension) for improved ground clearance. Traction based tuning with improved steer-ability for use on high traction off-road surfaces. Activate the Hill Descent Control for steep downhill control. Use for low speed obstacles such as large rocks, deep ruts, etc. If equipped with air suspension, the vehicle level will change to Off-Road 2. If the Selec-Terrain™ switch is in ROCK mode, and the transfer case is switched from 4WD Low to 4WD High, the Selec-Terrain™ system will return to AUTO.
 
#5 ·
How is this telling me what the differentials, transfercase and transmission are doing exactly?

"Sand – Off road calibration for use on low traction
surfaces such as sand or wet grass. Driveline is maximized
for traction. Some binding may be felt on less
forgiving surfaces. The electronic brake controls are set
to limit traction control management of throttle and
wheel spin. If equipped with air suspension, the level
will change to Off-Road 1.


Mud – Off road calibration for use on low traction
surfaces such as mud. Driveline is maximized for
traction. Some binding may be felt on less forgiving
surfaces. The electronic brake controls are set to limit
traction control management of throttle and wheel
spin. If equipped with air suspension, the level will
change to Off-Road 1."

First of all besides the fact that they say the same thing for these 2 settings, all I'm gather is that it is trying to "maximize" traction and clearance.. it fails to give me anything specific, mechanical, gearing, ratios, power front to rear, side to side, locking which differentials or not.. lol I'm looking for more useful information.


 
#7 ·
since you say you understand, can you please tell me the detailed differences between each of the settings.
 
#8 · (Edited)
I could never find the specifics that are being asked for here. The best I could come up with is that switching to the different modes set a different set of parameters in the software. That causes the drivetrain to react differently to varying amounts of slippage, and send different percentages of power to different wheels as it applies some braking to others.

If I understand it correctly it would take some kind of graph to be able to see what is happening based on the various inputs.

It's a little more involved than switching gears. Unless I totally misunderstood everything I read. The older I get the more often that happens, so feel free to ignore this post. :)


---
 
#11 ·
Thank you, but I don't think you guys are exactly getting what I'm asking. except I think bill is right, with how the information might not be available.

I'm asking how the drivetrain/software reacts or is treated under each different setting in comparison to one another. aka How does the "Mud" setting differ from the "Sand" setting.

I already know how our drivetrain works and how the software keeps traction.
 
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#13 ·
Thanks Specx :thumbsup: that's a lot better than what the manual has to say
 
#17 · (Edited)
LOL... I guess some people prefer pictures to words. :D
you just cut and pasted the manual ... the video has alittle bit more to say then the regurgitated half headed information that I have been receiving. which might I say both the video and the manual leave a lot to be desired still ,but I am giving up with asking.

I have been looking for more detailed information about what the different settings do as well, but most of the information seems to be vague and fluffy, even the video sounds more like a sales spiel than actual technical information.

I think for those of us coming from mechanical 4WD systems, we would like a bit more of a technical understanding about what the computer is doing, as previously we would be doing this ourselves with throttle control, and selecting gears, etc.

Here's what I mean:


All this says is it will use 2nd gear and raise the height, that isn't saying much. What are the tuning changes? Does it take torque off at certain revs? How much? Is the TC less or more aggressive in snow than sand mode?
I often used 2nd gear start in sand, is this tuning similar to sand mode tuning, could I use this mode on sand, why or why not?
I'm guessing this is pretty much like AWD in any soft roader.
Maximised for traction how? Is this more maximised than snow mode, how? I experience binding in Auto, how is this different? TC throttle control is limited, cool, is this similar in snow mode, or does snow mode not limit TC intervention? Does it tune throttle control to limit torque, how does it compare to snow mode throttle management?
This looks like a cut and paste from sand mode, is mud and sand mode the same thing? How do they differ?

How do they achieve improved steer-ability? Is throttle management changed, how? I'm guessing this is the main area they tune rock mode, for low speed control, what do they change to achieve this, other than suggest we use low range?

I'm guessing this is another one of those questions that we would all love to throw at some Jeep engineers some time.... until then it will be trial and error working out how to drive this thing offroad and get use to how the computer manages traction. I'll be giving snow mode a test next time I'm on the beach.
I sitting in the same boat with you with all the same questions Benn0 ...


nice video but it tells me exactly the same as the manual :) i mean what more info do you really require? its electronic not an banger from the 70's
lol I just wanna know the differences with detailed information...
 
#18 · (Edited)
A better understanding of how the system reacts in different modes helps the driver know how to drive it offroad. A good example is driving on sand, in a banger from the 70s you would feather the throttle to maintain momentum, while watching for and avoiding wheel spin which would see you dig down and bog. With the modern terrain control system it seems most drivers have found that you are better off staying hard on the throttle, and letting the system pull back for you if wheel spin starts. That is an example of a driver understanding how the system works, and adjusting their technique to suit. There are lots of various scenarios in sand, mud, snow, rock where a better understanding of how the system is working will help you get through a challenging section, or out of a bog. I'm guessing there may be a scenario where rock mode might help you in sand, it would be good to understand the modes at a lower level to know if and when that is the case....
 
#27 · (Edited)
I'm with you Evolv0 and Benn0, there's heaps more to know about the variations between modes.

I had reason to need similar info regarding the Discovery 3, and after a bit of badgering a matrix was supplied by Land Rover. It was quite insightful... for example, in certain modes it listed the traction control response as "delayed then aggressive", "delayed then minimal" and similar. There were also details for gear shift, throttle sensitivity, ABS, etc.

Whilst some of these variables can be established by trial and error, to know all of them in advance seems far more beneficial.

Cheers,
Steve
 
#32 ·
#33 ·
Well I found something interesting when I put the Jeep into Sand mode, and had terrain selected on the EVIC, it gives a description of the mode settings, for sand it says Traction control off, and aggressive gear selection. It definitely held lower gears for longer. Also found that when the ELSD locked in soft sand it held it locked for a long time, whereas in auto it seems to release within a few seconds....
 
#34 ·
:thumbsup::cool: pretty cool, Thanks for sharing!
 
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