How To Change Rear Diff Fluid

[nvycrmn]

This is a quick how-to for changing your own rear differential oil. this will save you about $40 or so from taking it to a shop.

1)loosen bolts (dont remove) all around diff cover and allow fluid to drain.

2)after done draining, remove diff cover and set off to side.

3)inspect gears for chipped teeth and look in carriage for debris. clean anything out that doesnt belong.

4)replace new gasket or use RTV (black) and put cover back on.
NOTE: if you are using RTV to create a gasket then wait 1hr after putting cover on to let dry.

5)find fill plug and open (should just require 3/8 ratchet, no socket needed, and maybe 3" extension).

6)Fill using owner's manual preferred oil. Trust me, its in there.
FOR 01 EXPY WITH 9.75 REAR....75W140 FULL SYNTHETIC WITH OIL FRICTION MODIFIER...JUST OVER 3QTS.

And there you have it. It just cost you $75 and about 1hr (drain time, wait time on RTV, and fill time) to do the same job that most places charge $110+tax.

I will have some pics to follow.

 

[walnuts4x4]

you can also spray out the housing and gears with brake clean after the oil drains to clean it out better for a better visual for everything inside.... but good details on doing it.... wanna do mine LOL... wait were is DGray69 he can do it...

 

[nvycrmn]

i was gonna say, where is your mechanic? hahahah

 

[nvycrmn]

just in case any of you were wondering what your limited slip rear end looks like...

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and this is what the fluid is NOT supposed to look like. This is what it looks like when you have water in there...not good.

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[panda24619]

what brand are you using? my dad said he would pay for the oil and gasket. and it is about $75 for everything. we can do that next weekend if you want while we do your short shaft.

 

[drtj]

nice write-up with pics

 

[nvycrmn]

thanks man. just thought i would let everyone know how easy it was.

panda, i used valvoline from napa. it was $14 a bottle (buy 4 of them) and i only bought one bottle of 4oz modifier, but buy the 7oz instead. royal purple was super expensive. i bought the valvoline cuz it said compatible with ford...it shouldnt really matter what brand, as long as you buy the recommended weight. it should be on something like page 252 in your book. just look up fluids and it will tell you the page to find the levels and types. i believe most of the expys take the 75w140 FULLY SYNTHETIC.

 

[panda24619]

that what mine takes. i just didnt know what brand you used. a lot of options out there. ill see what oreileys recommends.

 

[nvycrmn]

i called kragen (oreilly's) and they said they had some royal purple. its $17 a bottle. you can do this as cheap or as expensive as you want. but i think you are just paying for the name in my opinion.

 

[dgray69]

you had that wide open and did not put locker in.mmmmm great oppertunity to throw in that detroit, or arb locker. man thats rough. pull it apart again and at least weld that puppy. lmao

 

[nvycrmn]

dont you worry dgray. im hoping to have new gears put in next month. goin with some 4.88's i think. when i do that, i will put a locker in the rear.

 

[panda24619]

yeah just name i feel too. im going to go with Valvoline. i like them. and remember with new gears and lockers to get new bearings. might as well change the axel shafts too. get some stronger ones. but mainly bearings. holy cow arb made a locker for the 9.75". GET THAT!
http://www.fourwheeler.com/techarticles/drivetrain/129_0802_ford_f150_975_axle_build/index.html
but this also helps.

 

[panda24619]

so heres a question. i dont have a lsd. ive checked my book and the haynes manual. it says add friction modifier if i have the lsd. i dont. should i add it anyways? and my dad didnt buy the gasket. so i gotta go get it and an extra bottle of gear oil.

 

[nvycrmn]

you dont need the gasket, you can just get the RTV. as for friction modifier, i would just do it anyway. not going to hurt anything. its only a few bucks.

 

[Extortion]

i didn't add any friction modifier to mine should i go back and get some?

 

[nvycrmn]

if you didnt use the fully synthetic (royal purple for example) then yes, go get a 4 oz bottle of friction modifier and put it in or you will destroy those gears.

 

[99 Expy]

Hey guys, how many miles, or years do you usually change your diff fluid? I think my rear was done about 2 years ago when the seals were replaced, but I'm not sure about the front. I'm guessing there is a plug in the front?

 

[nvycrmn]

yes, there is a plug in the front as well. not as easy to do as the rear so hopefully you dont have to change the gasket on the front. i think its supposed to be every 60k miles for the fluid change. cant remember. i always do it after a good day of offroading in mud and water.

 

[battmanf16]

this will save you about $40 or so from taking it to a shop. It just cost you $75 and about 1hr (drain time, wait time on RTV, and fill time) to do the same job that most places charge $110+tax.

This entire post is fantastic. It saved me many $$. The Ford dealership quoted $139 to suck out and replace the diff oil. To remove the cover and replace was $259 (which needed doing because of a leak). So, you saved me many more than $40. Thanks!

Bob

 

[David C Bruner]

In case you don't know, at least Valvoline already puts a friction modifier in their 75w140 grease, so if you add more you may go from limited slip to never...