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I could never understand why you would have to change a full synthetic gear oil every 15,000 miles. Mine too looked brand new when I changed it out.
 

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I could never understand why you would have to change a full synthetic gear oil every 15,000 miles. Mine too looked brand new when I changed it out.
If it's QDII the gear oil is much more than a simple lubricant ..

Inside the diferential is a hydrulic pump that is powered by the movement of the axles, a hydrulic acumulator so it has preasure even when the axels are stopped, clutches, a number of check valves, a filter, presure regulating valves, a hydrualic manifold, preasure piston and an electronic actuator.

All these components need clean oil to work properly ... with proper oil changes the whole system will last the life of the vehicle with no other maintance.
 

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How hard is it to change the rear diff fluid? Can anyone with a service manual post the step by step instructions?
 

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Removal

1. With vehicle in neutral, position on hoist.
2. Remove differential cover (1) fill plug (2).
3. Remove differential cover (1) and drain fluid.

Installation

1. Apply a 6.35mm (1/4 in.) bead of Mopar® Gear Sealant RTV Silicone Rubber Adhesive MS-GF44D or equivalent to the cover.
CAUTION: If housing cover is not installed within 3 to 5 minutes, the cover must be cleaned and new RTV applied. Failure to follow these instructions will result in a leak.


2. Install cover and tighten cover (1) bolts in a criss-cross pattern to 41 N·m (30 ft. lbs.).
3. Fill differential and install fill plug (2).



same for ELSDs and normal axles


straight from the manual
 

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If it's QTII the gear oil is much more than a simple lubricant ..

Inside the diferential is a hydrulic pump that is powered by the movement of the axles, a hydrulic acumulator so it has preasure even when the axels are stopped, clutches, a number of check valves, a filter, presure regulating valves, a hydrualic manifold, preasure piston and an electronic actuator.

All these components need clean oil to work properly ... with proper oil changes the whole system will last the life of the vehicle with no other maintance.
I didnt realize all that stuff was in the rear differential. When I had the diff cover off it looked like a normal differential to me.
 

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I didnt realize all that stuff was in the rear differential. When I had the diff cover off it looked like a normal differential to me.
I'm not familiar with the other diffs ... but the QTII has that stuff ... it's small and most of it is contained on one side, but it's all in there.
 

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I'm not familiar with the other diffs ... but the QTII has that stuff ... it's small and most of it is contained on one side, but it's all in there.
I think those components is for the QDII system not the QTII system. The QT is simple just a ring, pinon, and spiders.
 

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I think those components is for the QDII system not the QTII system. The QT is simple just a ring, pinon, and spiders.
My appologies, and thank you ... I edited my post to reflect the proper abreviation :(

Yes I meant Q DRIVE II not QTII

Sometimes I think I'm getting old :)
 

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My appologies, and thank you ... I edited my post to reflect the proper abreviation :(

Yes I meant Q DRIVE II not QTII

Sometimes I think I'm getting old :)
No worries, The QT system, like all diffs, have lube ports that do require clean fluid to operate properly but it would take some seriously funky oil to clog them up. The QD systems are as you noted and have a lot more involved in the lubrication system to keep the ELSD working that is why they also require the special friction modifier to be added to the gear oil. Most limited slip diffs require the same friction modifier.
 

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How hard is it to change the rear diff fluid? Can anyone with a service manual post the step by step instructions?
Bob, drysuit got the rear mostly covered but there are a couple things to point out in addition. It is not always necessary to raise the vehicle on a hoist but be sure you have the room to work under the vehicle. You may only need a set of ramps. If you are working on ramps it may be better to leave the vehicle in PARK with the parking brake on.

REAR DIFF
1. Clean any excess dirt away from the diff cover and mounting area. This will ensure that no dirt falls into the diff when the cover is removed.

2. After the area is clean, position a drain pan under the rear diff then remove the bolts (10-12) around the cover and set them aside. You can remove them in any order you see fit.

3. Once the bolts are removed the cover may still be stuck to the diff. DO NOT PRY OFF! using a rubber mallet lightly tap the edges of the cover to loosen it. With minimal effort the cover should come loose and then a big rush of fluid will come out from the bottom of the diff. You will want to have a couple rags ready to clean any dirt or oil left inside of the diff that did not run out.

4 With the cover removed and the oil drained. Carefully clean the mounting surfaces of the diff cover (both on the cover and the diff). Be sure not to scratch or scrape the surfaces but make sure no gasket material or dirt is left. Then remove the drain plug and clean the area around the opening inside and out to avoid dirt contamination.

5. Next be sure you are ready to reinstall the cover with the bolts and tools near by. The Mopar recommended sealant is a good idea however a standard high temp RTV will work just as well. I will usually apply 2 small beads of sealant around the mounting surface, one towards the inside of the bolt holes and one outside of the bolt holes just to be sure the seal is good. Shortly after the sealant application you must reinstall the cover. Be sure to place the cover squarely on the diff and do not slide it around because you will displace all the sealant. It is a good idea to use the top bolt as a guide to install the cover. Then install all the bolts and tighten them in a cross pattern, just like stated in the previous post.

6. Once the cover is secured allow some time for the gasket material to set. The tube will have instructions on the time to allow. Once the seal is set you will then be able to pour or pump the gear oil back into the diff through the fill plug. A pump or a funnel will help with this. Add fluid until it runs from the fill plug hole. Once the fluid is filled to the bottom of the fill hole you can clean the area around the edge of the drain plug and reinstall the plug.

I know the instructions seem complicated but once you start the process you will see that it is quite simple.
 

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The front is even easier. Follow the same prep steps from the rear.

1. Locate the two plugs on the front diff one is a drain plug on the bottom and one is the fill plug. Clean the areas around both plugs. Both are socket plugs which you will need a 14mm Allen wrench (hex tool) to remove them.

2. With a drain pan under the front diff remove the fill plug first and then remove the drain plug and the fluid will run out.

3. After the fluid is drained you can reinstall the drain plug. Then fill the diff with the recommended fluid until it runs from the fill hole. Then reinstall the fill plug.
 

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I don't have any ramps, but I do have a floor jack and jack stands. Is it ok for me to lift from middle of the diff and then use stands on opposite sides for support?

Thanks for the detailed instructions. Also, thanks drysuitdiver for the torque settings for the bolts. I love to use my torque wrench whenever I am removing important bolts.
 

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I don't have any ramps, but I do have a floor jack and jack stands. Is it ok for me to lift from middle of the diff and then use stands on opposite sides for support?

Thanks for the detailed instructions. Also, thanks drysuitdiver for the torque settings for the bolts. I love to use my torque wrench whenever I am removing important bolts.
I do not like to use jack stands unless I absolutely have to. For the rear you may be able to access it without lifting at all. The front is more cramped but you still may be able to reach the plugs without lifting. You can jack from the rear differential but I do not recommend it.
 

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I do not like to use jack stands unless I absolutely have to. For the rear you may be able to access it without lifting at all. The front is more cramped but you still may be able to reach the plugs without lifting. You can jack from the rear differential but I do not recommend it.
I agree ... I just drive up on some wood blocking ... I find it much safe than jack stands .. especialy on my gravle drive.
 

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How hard is it to change the rear diff fluid? Can anyone with a service manual post the step by step instructions?

Add, the front diff needs a 14 mm allen key to remove the plugs
 

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I considering welding a drain plug to the back diff cover while it's off durring the first oil change (as long as there's a spot to get it right near the bottom so it drains properly) .. it should save some time in the futre.

What do you guys think?
 

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I considering welding a drain plug to the back diff cover while it's off durring the first oil change (as long as there's a spot to get it right near the bottom so it drains properly) .. it should save some time in the futre.

What do you guys think?
Thanks for the tip on the size of the hex tool. As for the drain plug I think it would be very helpful but I am not sure that the OEM diff cover could handle it. It is not very flat at the bottom making it harder to get a good seal or weld. Also the OEM cover is fairly weak and adding a plug in the bottom area may weaken it even more. If you feel you can make it work I would be interested in seeing the result but I would not do it with the stock cover.
 

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Thanks for the tip on the size of the hex tool. As for the drain plug I think it would be very helpful but I am not sure that the OEM diff cover could handle it. It is not very flat at the bottom making it harder to get a good seal or weld. Also the OEM cover is fairly weak and adding a plug in the bottom area may weaken it even more. If you feel you can make it work I would be interested in seeing the result but I would not do it with the stock cover.
Thanks for the advice ... I'll re-coinsider when I have it off and feel the thckness/weight of the cover and see if there 's a good location.
 

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I don't have any ramps, but I do have a floor jack and jack stands. Is it ok for me to lift from middle of the diff and then use stands on opposite sides for support?

Thanks for the detailed instructions. Also, thanks drysuitdiver for the torque settings for the bolts. I love to use my torque wrench whenever I am removing important bolts.
generally I use a breaker bar for removing. using a torque wrench to undo things can be really bad for your torque wrench

I run the bolts in finger tight and then use a torque wrench for final tighten
 
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