Quadra Drive II in Current Jeeps

[w squared]

A TJ Rubicon, and a JK Rubicon unlimited. The other JK Unlimited that got stuck...she didn't engage the lockers until she started having problems. I was successful because I used a little bit of momentum to my advantage, and engaged my lockers when I decided that I would need them, instead of waiting until I ran into problems.

I think that the TJ pilot would have made it if he'd had a longer wheelbase to get his front wheels up and pulling in the right direction before his back wheels got into the truly ugly stuff.:snorkel:

 

[Root Moose]

I think someone with an ELSD equipped Jeep should try shorting out some wires to the differential to see what happens.

What's the worst that could happen? Throw a code (MIL)? I'd recommend flipping through the wiring schematic first though.

Who has a schematic?

 

[Root Moose]

A TJ Rubicon, and a JK Rubicon unlimited. The other JK Unlimited that got stuck...she didn't engage the lockers until she started having problems. I was successful because I used a little bit of momentum to my advantage, and engaged my lockers when I decided that I would need them, instead of waiting until I ran into problems.

I think that the TJ pilot would have made it if he'd had a longer wheelbase to get his front wheels up and pulling in the right direction before his back wheels got into the truly ugly stuff.:snorkel:

Oh, ok.

I thought you were suggesting that you got through due to driving skill versus the other Jeeps having the electronic systems.

Mud is different every time a vehicle drives though it.

 

[w squared]

I have a sneaking suspicion that brake inputs are involved in "locking" the differentials. If they're not, locking up a diff while under load would probably require some pretty high-end viscous coupling technology. That'd kick the Grand Cherokee price tag up even higher than it currently is.

Edit: Hmmm...interesting...the "Jeep.com" 4X4 glossary defines a viscous coupling as:

A speed-sensitive device located in the transfer case that transmits drive torque between the front and rear driveshafts when wheel-slip occurs. Viscous couplings are typically used on all-wheel-drive vehicles and vehicles with automatic and on-demand four-wheel-drive systems.

It specifies that the viscous coupling is located in the transfer case. That'd give credence to my hunch that the "locking" differential would be accomplished by differential braking of the spinning wheel.

 

[bytehoven]

http://www.me.umn.edu/~qhyuan/publication/SAE_2006-01-1963.pdf

http://www.wkjeeps.com/wk_4x4.htm

Here is some good reading on the Eaton ELSD used on the QD system, as well as the QT II & QD II systems.

 

[Backwoods Rambler]

The First Gen (05-08) 4.7L V8 is 235 HP (What I have)

The First Gen (05-08) Hemi is 330 HP

Almost 100 HP difference. Plus the Quadra Drive II.

Oh, I was thinking '08+ 305hp 4.7 vs. 330hp Hemi. I've ridden in a couple of earlier 4.7's and they seemed pretty powerful.

For what it's worth the 305hp 4.7 can get upwards or 22mpg. That's why it's my top choice for a balance of power and economy.....assuming a fairly stock rig, perhaps a 2" BB and 30's/31's (not sure what would fit there)....

 

[w squared]

Interesting reading, Bytehoven. If Eton's lockers are any indication, they probably build a good ELSD.

 

[bytehoven]

The ELSD is clutch pack based engagement, so the system can wear and need clutch pack maintenance. Fortunately, my 09 WK has a lifetime drivetrain warranty and I think they recommend checking the system every 15000 miles.

There is also the possibility to tweak the amount of fiction modifier used in the diffs such that the characteristics of the ELSD off road performance can be changed. Using the minimum amount of modifier can speed up the engagement of the ELSD, but also make the system "chirp/bind" on tight turns.

A QD II that would be used exclusively off-road may be able to run without modifier and be even better.

 

[bugman]

W squared, your points are well taken and I can't agree more. Thank you for taking the time to attempt to explain it to the others that don't understand. I have been driving everything from modest to extreme trails in various rigs for the past 35 years, yeah I guess you could call me "old" at this and I understand how these new systems work. I've been in the industry for a lot of years. Trying to explain these offroad "situations" to someone that doesn't do that type of driving is rather difficult until they have actually done it. These computer programs are designed for a new market and statistically for the most basic, rather inexperienced 4wd owner. That is perfect for them...keeps 'em out of trouble.

Now, I do appreciate the computer in most applications, smog, fuel injection, timing, basically in any engine format. I'm actually running new technology in the Jeep with a new Hemi and all the computers and sensors, wiring, etc. But when it comes to drivetrain and how best to put power to the ground, I'm going to rely on my experience and not some statistical information that someone else has predetermined is the best application for me.

 

[realdeal]

I have a sneaking suspicion that brake inputs are involved in "locking" the differentials.

Doesn't -appear- to be the case.

I've got an '06 QDII Commander and an '04 Land Rover Discovery with center diff lock and traction control. On the Rover, when pulling a wheel in the air, the TC system will brake that wheel, and you will see the truck move forward with that wheel being stationary. Compare that to the Commander in this video:

http://www.youtube.com/watch?v=y1DG-P6oOGY

As he pulls a wheel in the air, the system kicks in, and that wheel turns the same amount in the air as those with grip - similar to a locker.

It doesn't seem like QD2 uses the braking system like the Rover TC system does because of this difference.

Also, the point in the video where he's crossed up with 2 wheels with low traction is the point at which the Rover would have had trouble. The center diff lock system in the Rover paired with traction control is great when you've only got one wheel w/o traction, but doesn't help AS much when two opposite wheels have low traction. You need a bit of momentum to get past that transition point in the Rover, and sometimes that's not quite as comfortably done.

Just my observations of the two system styles

 

[alexrex20]

sounds to me like a few people in this thread should be on the Jeep payroll. apparently they know better than a team of "off road" engineers, how to program the QDII, Jeep's most advanced off-road AWD system to date; they have more experience between them, than the whole of Chrysler and it's long history of off-road vehicles.

i wonder if Michael Schumacher told Ferrari, "i don't need the computers. i'm michael schumacher and i have more confidence in the driving skills i've learned over the years."

odd, then, that the F1 racecars today are faster with computers than they were 15 years ago - with less power, less advanced suspension, less grippy tires, and less downforce. odd, that.

 

[bytehoven]

Regarding QD II performance in the recent snow storm on the east coast...

I had a chance to take my new 09 WK thru some interesting stuff.

I never once got stuck or even slowed down, including stopping and starting in drifts well above my bumper. The QD II and Wrangler Silent Armor tires were unstoppable.

There is a point when the ELSD are engaged, you can hear the clicking actuation, that the throttle response is limited such that you can not spin out while doing donuts. Try that with an engaged locker.

You can spin out if you get going into a turn before the ELSD are actuated, but once the ELSDs are actuated, something prevents excessive wheel spin.

I will have to see about disabling traction control feature, which prevents wheel spin by either braking, throttle limiting or both. There are (2) levels of ON traction control, but I have not reviewed the owner manual info in awhile.

I would also note I don't believe there is much of a delay for the ELSD to disengage. Certainly not 90 seconds as far as I could tell.

I have had (5) other Jeeps, A Durango and a Dodge Ram 2500, all with good to excellent 4WD systems and various types of AT and MT tires. This 09 WK with QD II and Silent Armor tires is better than any of them in the white stuff. Wading into bumper deep drifts with the others was risky business. An '86 XJ with Select-Trac and Trac-Loc rear was almost as good as the QD II.

I had one slick, snow packed hill to climb. The kind you would usually want to keep moving on or risk not getting started again. Stopping and starting, whether slow or quick was no problem. It's the best performance since that '86 XJ.

So far, QD II is pretty amazing. I'm gonna have to continue exploring it's limits.

 

[Backwoods Rambler]

Great post! talk about taking a thread to the next level. Please report back when you have more feedback! :victory:

 

[modelbuilder]

Ya....Quadra Drive II rocks...

http://www.youtube.com/watch?v=DlaHUN8j_dM

This WK has a 3 inch lift with skid plates and rock rails. It has the Hemi and Quadra Drive II. Pretty darn capable.

 

[getlost4x4]

i'd like to see how it does in icy uphill stops. stop on a hill covered in ice and see if it will make it up.

my QT2 won't do it. i usually just end up spinning the wheels.