REAR end FLuid replace

i was curious on how to change the rear end fluid? can someone tell me the steps...

I don't have the service CD on this computer, but having just been underneath mine, I can tell you with good certainty how to do it. There is a drain plug and a fill plug in the rear end cover. You simply unscrew both, drain the old fluid, replace the drain plug, fill up the rear end, and replace the top fill plug. The bottom plug has a 3/4" drive square drive. The top plug is 1/2". You can use a 1/2" ratchet or breaker bar with a 1/2 to 3/4 adapter.

The rear end takes 75w140 synthetic gear lube only. There is a TSB that upgrades the fluid from the origina 75w90 to 75w140. If your vehicle has a posi traction rear end, you'll also need to add friction modifier.

You should go by the stock fluid capacities. But if not, then fill the rear end up until the fluid starts coming out the fill plug. Usually the fluid needs to end up filling the case somewhere to around the bottom of the axle tubes level. You may want to put a little liquid teflon tape around the threads of the plugs when you put them back in. Otherwise, they will seep.

Great description! I recently did mine and the one "gotcha" is to be sure to remove the smaller 3/8" square upper fill plug first so you know you can get fluid back into the diff before removing the larger lower 3/4" drain plug to let out the old oil. There is a horror story here by someone who removed the drain plug first and then couldn't get the fill plug off and had to have the truck flatbedded to a shop.

I filled mine with Amsoil Sever Gear 75W-140 synthetic oil and 4oz of the friction modifier as I have a D4 limited slip diff. My rear end is quiet and smooth and hopefully I won't have to think about for several years now.

Rumple

Pontisteve said:

I don't have the service CD on this computer, but having just been underneath mine, I can tell you with good certainty how to do it.

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Service and Repair

Differential Draining and Filling





Material

Fluid Check

NOTE: When the fill plug is removed, up to one pint will drain from the filler opening.



Remove the fill plug.
Fluid Drain and Fill


Remove the drain plug.
Install the drain plug.
Tighten to 34 Nm (25 ft. lbs.) .
Fill the axle to the bottom of the fill plug hole.
Install the fill plug.
Tighten to 34 Nm (25 ft. lbs.) .
NOTE: For roll stability control (RSC) equipped vehicles, remove the rear wheel speed sensor plug. For non-RSC vehicles, remove the rear wheel speed sensor.







Remove the rear wheel speed sensor.
1 Disconnect the rear wheel speed sensor electrical connector.
2 Remove the bolt.
3 Remove the rear wheel speed sensor.

Add one pint of fluid.






Install the ABS sensor and ABS sensor bolt.
Tighten to 27 Nm (20 ft. lbs.) .

rumpledoll said:

I filled mine with Amsoil Sever Gear 75W-140 synthetic oil and 4oz of the friction modifier as I have a D4 limited slip diff. My rear end is quiet and smooth and hopefully I won't have to think about for several years now.

Rumple

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When I had my axle out, I didn't see a clutch spring inside the diff... or at least didn't see it thru the axle hole. Do you know what codes to look for, and where they are located, that indicate if the truck has a limited slip diff?

Mine is 4wd. I have heard that not all 4wd's have a posi in the rear, but how could that even be?

Should I be worried about changing this fluid on my '01?

I have an '01 Explorer, should I change my rear diff fluid? What happens if I don't?

Pontisteve said:

When I had my axle out, I didn't see a clutch spring inside the diff... or at least didn't see it thru the axle hole. Do you know what codes to look for, and where they are located, that indicate if the truck has a limited slip diff?

Mine is 4wd. I have heard that not all 4wd's have a posi in the rear, but how could that even be?

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Check the axle code on the driver's door and compare it to this chart to determine if you have a LS. If you have the cover off you can check by looking for a big S spring in between the spider gears. If the spring is present then you have LS. Not all 4x4's have a LS in the rear.

bounsoul said:

I have an '01 Explorer, should I change my rear diff fluid? What happens if I don't?

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It's a good maintenance practice to change the rear end fluid. So yes I would recommend that you change it. However since '97 Ford has considered all rear ends "lubed for life" and has stated that there is no need to change the oil unless it is contaminated. Dumb idea IMO. But you probably won't have any problems if you decide not to change it.

James909 said:

It's a good maintenance practice to change the rear end fluid. So yes I would recommend that you change it. However since '97 Ford has considered all rear ends "lubed for life" and has stated that there is no need to change the oil unless it is contaminated. Dumb idea IMO. But you probably won't have any problems if you decide not to change it.

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I would change it. It's a cheap maintenance item. About every 100K it should be done, in my opinion. Gears wear, and all that worn metal ends up in the fluid, acting as an abrasive to what's left. An occasional change of fluids is always a good thing. I THINK that Ford considers these changes unnecessary, because they consider a car's life to be around 100k miles. After that, they want you thinking about buying a new one.

Besides, Ford changed their rear end lube from 75w90 synthetic to 75w140 synthetic via a TSB relating to gear whine. What's that tell you?

Back in the day, with both tires off the ground spin one tire and if the other goes in the same direction it's positive track. This may still apply.


Also on my 05 it states on the housing 75w-140

Where do you get friction modifier? And 75w90 synthetic to 75w140 synthetic via a TSB wouldn't be a recall would it?

This:
Dead Link Removed

With this:
Dead Link Removed

That sound like a good combo?

And should I do the same with the front end minus the friction modifier?

Yeah, that stuff is fine. I used Mobil 1 75w140 synthetic, from Advance auto. You can get the friction modifier from Ford cheap enough, or the aftermarket stuff is fine too. My 4WD (3WD???) didn't have a stinkin posi in the back, so I didn't have to use any. What a crock... a 4wd without a posi. There's a code on the door that will tell you if yours has a posi. Looking inside it isn't an option on the IRS explorers.

On the gear lube, just make sure you use synthetic EP type, which that amsoil you linked is.

Rear end

I just did mine last saturday, I got everything from Advance autoparts, Mobil one synthetic oil and the fircition modifier.
I will post pictures of my spray tank fluid pumping home made deivce.
LOL what a great tool it was.

It's really fairly easy to do, just a bit messy. I don't even bother to jack up the back end, I just crawl under, open the top fill plug, open bottom drain plug, drain, then replace plug drain plug. Squirt in some modifier if needed and then fill with mobil 1 synth dif fluid, takes about 1.5 bottles. I used a cheap pump from the auto parts store.

Thanks guys

Sweet, Axle Code D4, Limited-Slip 3.73 FTW!!! Lol

Plan on doing this on one of my off days starting 0700 tomorrow morning (yes, that does mean I SHOULD be sleeping right now, lol....).

Tell me about friction modifier. Do I need it,how do I know.
Boxwrench

If you have a limited slip differential, you need modifier.

And it smells like roses!

I used synthetic super-tech and all is well.
Used it in all my Jeeps in the past too, no problems. The Grand Chero has over 180k.