WJ LSD - Dana44a question

[billsta]

you jacked your back up and drove it?!?!?!?!?!

dont you have constant 4WD???
shouldnt the front start to grab???
and i was told that the QT2 normally has something like 40-60% power split and it should do what you said when the rear loses traction... man these 4WD systems sounds iffy if you ask me....

however.
i didnt think the QD is electronically controlled...
reason being, (or i thought that)..
1, the QD diff has a viscus coupling based on oil pressure build ups as one side loses traction, then it will engauge, hence, the QD will not work when there is a broken seal in the unit & the odd drive shafts & i think the different oil that you suppose to use from mopar......
2, the same/similar viscus coupling are present in the transfer case (247) that works similar, when the rear drive is losing traction the pressure will build up in the transfer case and transfer more power to the front drive.... and hence, different oil supposet to be used in the transfer case...
3, i have replaced the front diff & transfer case and as i remember there isnt any wire that controls the QD.. definately not the front diff...

maybe im wrong. does anyone know an article that explains all these??

[omaroo]

Four-wheel-drive systems vary by model. Four-wheel-drive Laredos use Jeep's Selec-Trac system, whose planetary center differential sends a fixed proportion of torque to the front and rear axles. Manually selecting the low range locks the center differential for maximum traction. Limited-slip differentials are available for both front and rear axles.

Standard on four-wheel-drive Limited and optional on Laredo, is the Quadra-Trac II on-demand transfer case, which incorporates a progressive, speed-sensing torque transfer coupling that varies torque automatically between the front and rear axles, depending upon which has more traction. A low range is standard on Limited, optional on Laredo; and limited-slip axles are available.

Source: http://www.jeep.com/jeep_life/news/g...emap&type=link

[billsta]

[goodol55]

Originally Posted by billsta

you jacked your back up and drove it?!?!?!?!?!

hehehe, wot R u on Billsta - of course I didn't have the motor going

Chris - those excerpts u posted r ok for yank market but not correct here. Quadratrac 11 and low range are standard on our Laredos. As far as the machinations go I suppose thats right - we have to order LSD's front and rear - well mine aint got it but from your initial enquiry you may have jagged them - good luck to you ol buddy

[wrench]

Your right billsta. They are all hydraulic control systems with no electronics. Quadratrac 11 & quadradrive are similar in operation. The 247 transfer case is shared & uses a 'gerotor coupling' which works like a viscous coupling but is different.
The diffs on quadradrive use a visous coupling to lock & tranfer drive when 1 wheel is slipping. The QT11 has open centre diffs front & rear.
I wasnt aware of this prior to buying my Grand as I assumed the non QD cars would have the old trashlok like before (bit of a con if you ask me). It seems fawking stupid that a 4by of this value still comes with open diffs & I can only blame myself for not studying the specs closely enough. I could understand if there was traction control fitted, but to delete a LSD is a backward step.
www.jeep.com did have a section with animated schematics showing the opeation af all the driveline options.
HTH
David

[goodol55]

So Chris, any further news on this topic.
Did u jack er up and try spinning it (still talkin bout your jeep here )
to see what happens.

David, how does the system work when you option up the lsd's for front and rear - that would only work for QT2 system - maybe you can't order them for QDrive.

ciao

[wrench]

LSD diffs are not an option for Aussie V8s. tho I'm not sure about the six cylinder. I did hear that they were available with selectrac & LSD, (this may be American spec only - not sure). So if you didn't get quadradrive you will have the quadratrac II with open diff centres front & rear.
In all fairness I haven't been stuck yet & some of the loose hills I thought would give problems. I think the good wheel travel helps here.
It is quite interesting to feel the QTII system work on gravel & sand as if you hammer it the rear can be felt to spin or dig in before the front starts driving & pulls you forward. On my outback trip last year I found it almost impossible to hang the rear end out & I believe the transfer case was transfering drive to the front as soon as any rear slip occurred.
Just my attempt to confuse everyone more.
David