Locks when it shouldn't

Is there a good writeup somewhere that describes exactly (not generally) how the QD-II works? The reason I ask is that I have been having intermittent problems where the drive system seems to leave the system fully locked (I know, being hydraulic, the ELSD never really 'locks' ) and snaps and lurches in corners at low speed in both 4-Hi and 4-Lo. It has been getting progressively worse the last few weeks but I took a trip to Colorado anyway this last week to pick up my son from a summer school class in Pitkin, taking in one hard 4x4 trail for grins. I had no problems on the trail but on pavement it's now making a racket in turns and even 'popping' a bit at highway speed going straight. It seemed like the ABS system was randomly braking one or more wheels, so I pulled the ABS fuses but still had the issue. Next, I tried unplugging the front and rear ELSD cables from the diffs. Still no change. Reading the shop manual, there appear to be a couple of other possible sources of the problem: the G-sensor (used in the anti-roll logic), and the steering position sensor. The manual doesn't cover how those inputs are used but I suspect the steering position is used to predict differential wheel speeds and allow slip while turning. If the G-sensor was bad, it might think the vehicle was starting to roll and brake the outer wheels.

It isn't throwing any codes that I can see, and the behavior was present before I upgraded the front struts/springs so I don't think that was a factor. BTW, it does'nt do it while in Neutral coasting. Any ideas (Matt)?

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Originally Posted by TrialByFire

Next, I tried unplugging the front and rear ELSD cables from the diffs. Still no change.

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This is the troubling part.... if you've unplugged the solenoids the diffs should be open and remedy your issues. Makes me wonder if its more of a t-case issue. Even with open diffs, if your t-case clutches are engaging you'll get driveline binding. Either way it sounds like more of a mechanical issue than a bad sensor since you're not throwing codes.

I know you're usually on top of your game with this stuff.... but when was the last time you replaced all the driveline fluids? And did you add the additive to the diffs?

And just as a side... you're not at fault for saying they "lock". When functioning properly these diffs do provide full axle "lock" (ie not allowing differential wheel speeds).

From: http://www.eaton.com/EatonCom/Produc...disc/index.htm

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EGerodisc™ is a hydraulically-operated electronically controlled limited slip differential that provides variable torque up to full axle lock. It automatically identifies the optimal traction solution at any speed. The EGerodisc™ is a commercially proven technology in production on the Jeep Grand Cherokee. It provides superior vehicle cross-country mobility and improved control for safety and roll-over protection. The electronically controlled actuation provides rapid response for stability and traction control. It eliminates driver interface; no driver training is needed. The EGerodisc uses standard gear oil and is virtually maintenance free.

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Good video showing how it works:

http://youtu.be/FpiFq63N0Ac

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Originally Posted by Matt

I know you're usually on top of your game with this stuff.... but when was the last time you replaced all the driveline fluids? And did you add the additive to the diffs?

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^^^That was the first thing that jumped into my mind while reading this. Have you been adding the friction modifier to the diffs? It sounds like classic symptoms.

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Originally Posted by Matt

I know you're usually on top of your game with this stuff.... but when was the last time you replaced all the driveline fluids? And did you add the additive to the diffs?

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Originally Posted by lekmedm

^^^That was the first thing that jumped into my mind while reading this. Have you been adding the friction modifier to the diffs? It sounds like classic symptoms.

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Well the T/C was replaced more recently but I have not replaced the diff fluids in about 30,000 miles and did not use the friction modifier, so that is a real possibility. When I disconnected the ELSD cables and still had the problem, I assumed it was the brakes doing it. I have always thought that QD-II uses the brakes in addition to the ELSD but nothing I have read recently supports that assumption. I know that the ESP definitely uses the brakes.

I'll change the diff fluids and let you guys know if it helped.

Im gonna say thats a real possibility now. I had a similar issue with my front diff.... had to change the fluid twice to completely resolve the issue I was having (binding popping sound in front).

Get enough fluid and mopar friction modifier for two complete changes. It'll probably get better a few days after the first change... then a week or so of driving change it again and you should be good. It takes some time for the fresh fluid & additives to work its way into the clutches; so dont be discouraged if theres not an immediate improvement.

Oh and QDII equipped vehicles still utilize BTC. But you would know if it was the brakes because you'd hear & feel the ABS pump kick on. Its obvious when it happens too (mine kicks on once in a while if I make a quick sharp turn)

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Originally Posted by Matt

Oh and QDII equipped vehicles still utilize BTC. But you would know if it was the brakes because you'd hear & feel the ABS pump kick on. Its obvious when it happens too (mine kicks on once in a while if I make a quick sharp turn)

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Thanks. I'll let you know.

Any reason why you didn't add friction additive??

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Originally Posted by 07JeepXK

Any reason why you didn't add friction additive??

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I didn't do the work.

Ahhh that makes sense. I was going to say.

Well we changed the fluids Wednesday night and there seemed to be an improvement during straight-line driving, but during turns the violent thrutching was still present unless I threw it into Neutral and coasted through the turns. Friday night while driving home, I lost drive and started hearing some ominous noises in the rear end. I pulled over, popped it into 4-LO and drove home in Limp Mode (FWD only?). A look underneath today revealed that in 4-HI the rear drive shaft is turning but the rear wheels aren't (but they 'try' a little)! Thinking the worst, I suspect the rear diff/ELSD is gone, however I am searching for alternatives so I don't bark up the wrong tree and waste a lot of $$$ and effort tearing the rear end apart. My question is, is the 'default' (i.e. unpowered) ELSD mode unlocked where there is no torque to either rear wheel? I disconnected the FDCM to reset it, then plugged it in again (no difference in behavior with it unplugged). I am now getting a U0114 code (no comm with FDCM) but I expect that to clear after a few (more) starts.

The unlocked (or "off") mode of the ELSD is equivalent to an open rear.

I'd take that diff cover off and go from there. Given your symptoms and how it just ended, it sounds like your gears are shot. Don't drive it. If you've stripped some teeth on the pinion then A LOT is salvageable (though i'd probably replace the carrier too regardless... never know where some metal shavings ended up).

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Originally Posted by Matt

The unlocked (or "off") mode of the ELSD is equivalent to an open rear.

I'd take that diff cover off and go from there. Given your symptoms and how it just ended, it sounds like your gears are shot. Don't drive it. If you've stripped some teeth on the pinion then A LOT is salvageable (though i'd probably replace the carrier too regardless... never know where some metal shavings ended up).

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I was afraid of that. Since the previous post, I checked for voltage on the solenoid and didn't see any. That just means it should be acting as an open diff, no?

I'll pull the cover...

Yeah... no voltage = open diff.

Got my fingers crossed for ya!!

Not good :-(

https://theultimatejeep.com/images/i...0616_001-1.jpg

https://theultimatejeep.com/images/i...0616_004-1.jpg

Now I get to learn a little about pulling axles and working on diffs!

It's hard to tell by the pics.... how do the ring teeth look?

If its just the spider gears, you can get a new set and be on your way in no time!

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Originally Posted by Matt

It's hard to tell by the pics.... how do the ring teeth look?

If its just the spider gears, you can get a new set and be on your way in no time!

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The ring teeth looked good and hardly any wear!

You may come out of this just fine for ~$200. The spider gear set looks like PN 4883087AB. So $150 for new spider gears, $30 for new diff fluid....

$100 from randys
http://www.ringpinion.com/b2c/Produc...rce=DiffWizard

Awesome! Thanks Matt!

Anytime man. Keep us informed on how the repair goes.

Mopar-wholesale.com shows it as superceded (p/n 4883087AC) for $140. Any difference in quality, or do they both come frome the same supplier?

I pulled that PN from the 2006 parts manual. The AB to AC change is probably just an updated contract/PO number or supplier. I wouldn't worry about any changes in quality, they're all going to be supplied to Mopar with the same QA measures in place.

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Originally Posted by Matt

I pulled that PN from the 2006 parts manual. The AB to AC change is probably just an updated contract/PO number or supplier. I wouldn't worry about any changes in quality, they're all going to be supplied to Mopar with the same QA measures in place.

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Good to know. Thanks again.

Hey Matt, what potentially has happened to the clutches?

Sent from wherever my Jeep takes me.

Probably nothing. I'd use some 80w-90 cheap gear oil, drive around the block a few times after replacing the spiders, then drain and fill again with the proper fluid + mopar additive, and give it another change after 5k miles to flush out anything else left behind.

Well I don't know what happened but it looks like those gears are the wrong ones. The box reads Chrysler 8.25" 29 spline, but they are quite different from the OEM.

https://theultimatejeep.com/images/i...0622_001-1.jpg

https://theultimatejeep.com/images/i...0622_003-1.jpg

https://theultimatejeep.com/images/i...0622_004-1.jpg

Hmmm... id give them a call. Might have to get them from the dealer if theres special ones for the qdii. Tell their customer service you have the eaton egerodisc carrier. Or maybe call eaton directly.

Randys site did say compatible with C213RE.... maybe not true

Those look like the spider gears I pulled out of my rear QT II axle when I did the powertrac no slip install. I still have my old spider gears, ill check later to see for sure

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Originally Posted by Matt

Randys site did say compatible with C213RE.... maybe not true

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I'll call on Monday and figure this out. They looked like the right p/n to me also but are short 2 teeth and 3/8" taller. Since they are a matched set the number of teeth doesn't really matter. Randy's lists a Yukon HD set also with almost the same specs ($175). Oh, and the dealer will have to order them, so I might as well order them myself.

Randy's does not carry the spider gear set for the eLocker (QD-II) and told me I would have to go to the dealer. I am confused by the parts list now. It lists two gear sets: 05183520AA and 04883087AB. The one I thought I needed (04883087AB) says "DS8 only" in the description, but is shown on the diagram with the locker (Corporate). The 05183520AA is shown on the diagram for the Dana 44. I suspect that the "DS8 only" is a typo and they meant "DSF only".

Wonder if Eaton tech support can help. It is their carrier. Otherwise maybe the dealer would be nice enough to order both sets and send back the wrong one...

Any scrap yards near you?

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Originally Posted by Matt

Wonder if Eaton tech support can help. It is their carrier. Otherwise maybe the dealer would be nice enough to order both sets and send back the wrong one...

Any scrap yards near you?

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Eaton says that those are OEM-specified spider gears and that I need to buy the whole locker. I guess that's why they are not listed on the parts list. Looks like I need to look for a junk yard unit.

Well thats a bummer. :(

That sucks. I'll keep my eyes open and see if I can find any locally

Well I ended up buying a new locker from Moparwholesale.com. It's finally in and I'm running again! Hopefully, I got the bearing and backlash adjustments correct.