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scooter2131 09-28-2009 10:46 PM

How To: Change Differential (Axle) Fluid
1 Attachment(s)
FYI: I have a 2005 WK, Quadra Drive II, with the electronic limited slip differentials (ELSD). Diff's are 200mm front and 213mm rear.

Buy (4) - 1 quart bottles of fully synthetic 75w-140 gear oil (ex. Mobil 1 ~$18/quart)
Buy (1) 4 oz. bottle of Mopar Friction Modifier (p/n )

Take 1 bottle of gear oil and fill up 2 of the others all the way to the top. You will use the bottle that you poured from in the front diff.
Shake the friction modifier well.
Add 1/3 of the Friction Modifier bottle (1.33oz) to the bottle of gear oil that you poured from previously.
Use this bottle in the front diff first.
Use the unopened bottle in the front diff second.
Use two filled to top bottles for rear diff.

Rear Diff:
Remove rubber fill plug w/ flat head screwdriver
Remove 11 of 12 bolts holding the rear diff cover on, loosen the 12th (leave top center one for this, 1/2" socket needed)
Place large oil drain pan beneath the rear diff
(See Image: IMG_9731)
Pry out on the bottom of the diff cover with the screwdriver; the fluid inside will drain out
When fluid done draining, remove the 12th bolt.
Allow to continue draining
(See Image: IMG_9732)

Cover rear differential w/ a lint free cloth or paper towels. Ensure no debris during the cleaning process can fall into the open diff housing or gears.

Do not spray any cleaner into the rear diff housing!!!

Scrape any residual RTV off of rear diff housing mating face w/ plastic putty knife/scraper.
For RTV that the scraper misses, spray some brake parts cleaner (BPC) on a lint free cloth or paper towel. Rub on mating surface to remove RTV; repeat as necessary. Try to not get any solvent or debris in rear diff housing or gears.

Now, use the scraper to remove RTV from the rear diff housing cover.
Use brake parts cleaner to remove stubborn RTV or RTV that the scraper misses. You can clean out the rear cover w/ BPC or acetone - ensure all solvents and residue is evaporated before reapplying RTV for reassembly.
(See Image: IMG_9734)
Clean RTV off of all bolts using BPC or Acetone. You may need a wire brush for this.

Once rear diff cover is clean and dry, go back and wipe off the mating face of the rear diff housing w/ solvent on lint free cloth/paper towel again.

Apply 1/4" thick bead of Silicone RTV to rear diff housing cover as shown in picture.
(See Image: IMG_9736)
Immediately (no longer than 5 minutes after you started applying RTV) place cover back on Rear diff housing. Take care to line up holes well and do not smear RTV.

Install all bolts by hand. Screw in by hand until finger tight.

Torque all bolts to 30 ft-lbs following a star or some sort of alternating pattern. Work up to final torque in 5 ft-lb increments.
Let silicone RTV set up for about an hour before adding gear oil to rear diff.

In the mean time, now drain the front diff

Front Diff:
Remove skid plate if you have one:
Loosen front two bolts 3-4 turns
Remove rear two bolts
13mm socket needed
slide skid plate forward so keyholes clear bolts/washers, drop down and place off to the side.

Remove front diff fill plug (14mm hex key needed)
Place large oil drain pan beneath drain plub
Remove front diff drain plug (14mm hex key)
Allow to drain, replace drain plug

To fill, I used a small funnel stuck into a piece of clear tubing w/ a small nozzel on the other end. I will upload a picture of this setup at a later time.

Add first bottle of gear oil w/ friction modifier
Add second (only unopened bottle) of gear oil until fluid starts to dribble out of fill plug opening.
(manual says 1.7 quarts...mine only took 1.3-1.35 quarts)
Replace front diff fill plug
Clean off any residual gear oil on front diff housing

Replace skid plate if applicable

Back to Rear Diff:
Now, you can go back and fill the rear diff.
Pour 1 bottle of gear oil into rear diff.
Pour rest of Friction modifier into rear diff (2.66 oz)
Pour in last bottle of gear oil until fluid level is 1/2 " below the fill hole.
Replace rubber fill plug

Go wash your hands, drive some figure 8's in a parking lot to work the new oil around your diffs then pat yourself on the back.

scooter2131 09-28-2009 10:49 PM

Re: How To: Change Differential (Axle) Fluid
I will get more pictures and format this "How to" a little better when I get a chance. I figured this much was better off on here than sitting on my hard drive.

Robert Palmer 09-28-2009 10:54 PM

Re: How To: Change Differential (Axle) Fluid
Informative post. +rep

scooter2131 09-28-2009 11:04 PM

Re: How To: Change Differential (Axle) Fluid
P.S. Here's the link I referenced before doing this myself and writing up the WK specific How to:

LTrainGC 09-29-2009 09:59 AM

Re: How To: Change Differential (Axle) Fluid
Each axle requires 4 oz of the friction modifier.

scooter2131 09-29-2009 10:59 AM

Re: How To: Change Differential (Axle) Fluid
Thanks for that link...

I originally read in the manual that only the Vari-Lok diff (available on RWD models only) required the friction modifier. After reading on here everyone said to use 1 4 oz. bottle in each diff regardless of the model. The dealer mimicked the same beliefs, so I bought 2 bottles before doing this job...

However, the instructions on the bottle of FM say to use 2-4% by weight (IIRC the %) assuming the density of the gear oil is not 2x's the density of the FM I used the FM percentage by volume to get the values stated in my writeup. I will look into this matter further and update my writeup if necessary however I'm skeptical of any "fact" or spec. that doesn't come from chrysler/jeep/mopar in a written format.

LTrainGC 09-29-2009 11:02 AM

Re: How To: Change Differential (Axle) Fluid
I'll take a peek in my FSM tonight and see what it has to say.

scooter2131 09-29-2009 12:29 PM

Re: How To: Change Differential (Axle) Fluid
1 Attachment(s)

Originally Posted by LTrainGC (Post 69364)
I'll take a peek in my FSM tonight and see what it has to say.

The FSM is where I read the note about the Vari-Lok diff requiring the Friction Modifier; see attached PDF excerpt. is where I read the blurb about which models have the Vari-Lok differential:

"Differential, rear - Vari-LokŪ progressive differential (2WD only)"
...under the Powertrain and Chassis section about 1/2 to 2/3's the way down the page:

This is why I was so confused when everyone was saying to put a bottle in each diff. I figured I'd split the difference and use 1 bottle total; shooting for the specs listed on the bottle of Friction Modifier.

LTrainGC 09-29-2009 12:42 PM

Re: How To: Change Differential (Axle) Fluid
The ELSD's require a bottle of the FM in each.

scooter2131 09-29-2009 03:26 PM

Re: How To: Change Differential (Axle) Fluid

Originally Posted by LTrainGC (Post 69488)
The ELSD's require a bottle of the FM in each.

Any reference for this statement? Is my FSM incorrect?

LTrainGC 09-29-2009 06:17 PM

Re: How To: Change Differential (Axle) Fluid
The ELSD is not the same as the vari-lok.

The ELSD requires 4 oz per axle.

scooter2131 09-29-2009 07:04 PM

Re: How To: Change Differential (Axle) Fluid
I'm aware the Vari-Lok is different; I'm just curious as to how everyone knows that the ELSD's required 4oz. of Friction Modifier each (other than which is run by one person who is a Jeep enthusiast). Does anyone have a manual, FSM, TSB or some document from Chrysler that says the friction modifier should be used and in what amount? Note: the quantities listed in the FSM vary from the first paragraph in the Axle section to the table listed a couple pages later, so I understand that even Chrysler may not be consistent in what they published, but I'd like to know that they indeed suggest/require that 4oz. should be used in each ELSD.

Sorry for not letting this die, but I still have not been convinced as to the proper amount of Friction Modifier to use and I'd like this writeup to be as accurate as possible.

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