Quadra Drive II in Current Jeeps

[w squared]

For on-road use in poor traction conditions (snow/icy), the ELSD system is far superior to a conventional 4X4 with selectable lockers.

The Jeep JK is available with a rear LSD and also with a Brake-Lock Differential system - it actuates either the right or left rear disk brake to deal with excessive wheelspin. Sound good, right? It is. But it's still not as good off-road as actual selectable lockers. That's why e-lockers are offered from the factory on the JK Rubicon models.

For off-road use, selectable lockers do provide an edge. There are times (mostly when mud or ice is involved) when you need to combine good line choice, a locked rear (or rear and front) diffs, and a little bit of momentum to get your through. In these situations, you'll want to have the appropriate axle(s) locked before you begin tackling the obstacle.

Granted, these obstacles are right at the limit of what can be accomplished by a given vehicle...but there are times when getting through relies on all the elements of that line/locked/momentum equation being there. With a ELSD system, you would have to wait for:

1. wheelspin to start
2. the computer to decide it's a problem
3. the diff to lock
4. the wheel speed across the axle to equalize
5. the non-spinning wheel on the axle to start providing forward impetus again

At that point, you may well have frittered away your forward momentum, leaving you looking for the best spot to hook up your winch.

With selectable lockers, you can go into the obstacle with the axle already locked - you will consistently get the same revolution speed on both wheel without having to wait for anything. For an experienced offroad driver who knows their vehicle, can read the terrain ahead, and knows when lockers will be needed, selectable lockers will provide better offroad perfformance in select situations.

ELSD and/or AWD is a far more advanced and civilized system than 4X4 with selectable lockers, and is better for 99% of all the "4X4" drivers out there...but if you're willing to accept a little less in the way of manners and performance at 60 MPH, you can get a little performance at 5 MPH. :smiley_drive:

 

[winkosmosis]

I don't know if I'd want that ELSD on the road. Go through a patch of ice, and the ELSD locks. Then for 90 seconds you have a locked diff... on the street.

 

[modelbuilder]

The computer is smarter than that. Never heard of anyone with that system have any trouble what so ever. It knows when to lock fully, when to just send power to the wheels that are spinning, and what wheel needs the brake applied.

It's a great system.

 

[alexrex20]

not a single complaint about the QDII in my '07 Overland. the system works flawlessly and effortlessly. the truck is point and shoot and has excellent traction.

 

[bugman]

My concern is not when the axles lock but when they unlock. When slow rock crawling I've needed to disengage the front locker immediately after passing over the obstacle to steer. When traveling through snow I'm using the rear locker until I hit ice. I NEED that rear wheel to pivot around the turn so I don't lose traction. I don't need 90 seconds from a computer program based on statistics to do that for me. I'll trust my own instincts thank you.

 

[alexrex20]

Ya. Its capable...although if I had done my research before buying it I would have gotten the HEMI with Quadra Drive II or a Toyota Landcruiser!

i had an 07 Hemi and traded it in for an 07 CRD. best money ever lost!

actually, i think i may have made the money back and then some, in fuel savings alone. my Hemi was averaging 10-12mpg and my CRD easily averages 22-23mpg. if you really wanted the extra horsepower (and willing to not have QDII), then you could've spent the same money to get the SRT8 with 425hp. i know a guy with a lifted SRT8 on mud tires. it wheels pretty damn good and still has plenty of getup on the highway.

 

[alexrex20]

My concern is not when the axles lock but when they unlock. When slow rock crawling I've needed to disengage the front locker immediately after passing over the obstacle to steer. When traveling through snow I'm using the rear locker until I hit ice. I NEED that rear wheel to pivot around the turn so I don't lose traction. I don't need 90 seconds from a computer program based on statistics to do that for me. I'll trust my own instincts thank you.

maybe you should switch back to carburetors and manual transmissions. also, lose your ABS and any traction/stability control.

trust me, the computer is FASTER and SMARTER than you.

 

[bugman]

Granted, the computer is quicker than I am, in many respects. But if this 90 seconds to disengage is true, and not some off the cuff remark, then in this case I'll stick to manually doing it. I'm referring to mainly slow speeds here. For those who feel it necessary to rocket through the snow to be the first to lay tracks then by all means the computer will be much more efficient.

 

[modelbuilder]

You gotta realize these on board computer contraptions are smart...very smart.

It does not stop working after 90 seconds. If the computer senses that the axles still need to be locked it will stay locked. So if you are going up a steep and smooth rock it will not disengage 90 seconds after the discrepant event. Instead the computer can essentially tell (by the RPMs, pushing the gas pedal, braking) if it needs to stay locked.

If you are driving up a hill that has loose rock and the axles need to lock the computer will kick in automatically. The driver won't even know at what point it locked...it happens so fast the rig just keeps going.

Take a look at this video to see Quadra Drive in Action with the ELSD computer system.

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

All the proof I need. Would have been able to do it faster if he had better tires.


Second Video..

http://www.youtube.com/watch?v=IXx5aiQRH8I




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[bytehoven]

Would have been able to do it faster if he had better tires. .

Still, not bad for a very friendly daily driver, on road tire.

Wrangler Silent Armor

 

[w squared]

maybe you should switch back to carburetors and manual transmissions. also, lose your ABS and any traction/stability control.

trust me, the computer is FASTER and SMARTER than you.

Maybe faster, but not smarter. The computer is taking a guess at what you want to do with your vehicle, based on your control inputs, the current wheel speed, and it's programming. That code is written based on how a soccer mom wants her family truckster to handle. :smiley_drive:

I have different priorities than most soccer moms, which means that I'll probably drive my Jeep in different places and want it to respond in different ways.

I would have no issues with giving up ABS, traction control, and slushboxes. Why? Because I've got eight years of driving on the some of the worst "roads" in North America, sometimes pulling trailers that weigh more than my tow vehicle. I've learned that a well trained, experienced driver can make better decisions than a computer because he has more information than that computer.

I've never owned a a vehicle with an automatic transmission - but I've used plenty of fleet vehicles with slushboxes. For an unskilled driver, the automatic is preferable. They won't burn out clutches, they won't grind the gears, and they won't over-rev the engine by downshifting to second instead of fourth. As a driver that has developed the required skills, I'll take my manual transmission and the ability to effectively use compression braking and work the engine's powerband as I see fit, thank you very much.

A skilled driver using threshold braking can actually stop in a slightly shorter distance than with using ABS. I've done the comparison myself - in a 4X4 one ton truck on a controlled length of gravel track, with a defensive driving instructor in the passenger seat. For me and anyone else that has had this education, ABS qualifies as a "nice to have"...not a "must have". It's comforting to know that when my girlfriend drives my Jeep, the ABS is there for her to lean on if need be. If I'm driving and I feel the ABS kick in, I know that I've misjudged the road conditions and need to re-asses how much traction I'm getting.

There are about three or four "traction control" doozawhatsits on my JK. They do kick in occasionally - sometimes to correct a little bit of oversteer that I'm allowing to happen around a snowy corner (which is not a big deal to me) and sometimes to apply the rear brakes when there's a bit of wheelspin as I drive up a snow-covered or icy incline (which is something of an irritant to me). I could do without this system. I don't "hate" it as some JK owners do, but it wouldn't bother me all that much if it went away.

I will keep my EFI though, please. When a road trip includes five or six thousand feet of elevation change, I'd much rather be running EFI than a carb. :ylsmoke:

 

[modelbuilder]

The system you could do without is pretty darn capable as is shown in this video. Soccer Mom SUV...

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






.

 

[w squared]

I'm not slagging the ELSD system. For most drivers it's probably a far better choice than traditional 4WD and selectable lockers. It will provide better performance in most driving situations.

BUT

For someone that has solid on and off road driving skills and has learned what they and their vehicle are capable of, the on-road benefits are drastically reduced and it still does not provide the same level of performance in challenging off-road conditions.

Here's an example:

Near the tail end of October, I was in a group of three Jeeps. We encountered a muddy area, and could not bypass it. The first two Jeeps had to be winched through. I was able to make it without winching because I was able to read the terrain, pick my line, and have my rear diff locked and my front diff open. That was the my choice because I knew that my right rear tire would have almost NO traction, and I would need to turn hard left as my front tires cleared the worst area of the obstacle.

Neither front tire would have much in the way of traction until they cleared the obstacle, but as soon as they were clear, I needed to be able to steer across the frozen area of ground on the far side of the obstacle.

In addition to that, I had to carry a little bit of speed into the obstacle in order to avoid getting bogged down as soon as my rear tires dropped in, and needed to consistently put power to both rear wheels to maintain that momentum.

ELSD would have "locked" my front diff when I needed it to be open to change direction effectively, and would not have "locked" my rear diff until after I started seeing less torque going to my right rear wheel. Either one of these things happening would have ended up in me winching to get out of the obstacle.

Each type of system has it's strengths and weaknesses. I'm simply saying that for a driver that has the skills and experience to use a true 4WD transfer case and selectable lockers to their fullest, the gadgetry and frills of viscous couplings and drive-by-wire systems is not necessary. The computer may be faster than I am, but I have access to a more complete set of data concerning the situation - and a better set of "reference" data that allows me to make decisions about what to do. It may make decisions faster, but I have the option of making decision and choosing strategies before it even knows that anything is happening.

By the way...I wheel with guys in ZJ's and WJ's fairly frequently. I have a lot of respect for those rigs, especially when they're built well - but nobody with solid off-road experience will tell you that an AWD system is any substitute for 4WD and selectable lockers when the going truly gets tough. If I had the bandwidth available, I would post video of a decidedly low-tech YJ with lockers rolling easily through a mud hole that had just finished swallowing up an ELSD equipped Grand Cherokee that was chipped out and pushing close to 400HP. They ran the same line, they were on the same size of tire, and running close to the same pressure...the difference was that the YJ was locked from start to finish. The Grand driver had to wait for wheelspin to start happening before his vehicle started to respond.

I'll also state that a vehicle with a 2.72:1 low range and independent front suspension is not going to successfully compete offroad with a vehicle that has a 4:1 low range and solid axles. I'm hoping that you already understand why this is true.

 

[getlost4x4]

I have QT2 in my commander. i'd rather have a real rear locker.

has anyone actually tried installing a locker in this 8.25 axle? i know any aftermarket diff. protection covers fit on the QT2 axle. i had a blue torch fab. rear diff. cover on mine for a 8.25" Chrysler axle, and it fit just fine. i sold it and built my own for more fluid capacity and a drain plug.

i don't think a locker will screw up the TCS. all the TCS does is compensate for wheel spin. when it senses a wheel spin it applies brakes to that wheel. so if you have a locker, the TCS will never engage on the rear axle. i really think one locker is enough unless you are rock crawling.

if i had the money i would just buy a locker for the rear now. but right now i have a to do list of: replacing the rear brakes, new front struts, transfer case and transmission changes, and 4 new tires.

 

[Root Moose]

What was the configuration of the other two Jeeps?