How To: Change your rear differential fluid - Discussion thread

In this write up, it will show you how to change the rear differential fluid in your Ranger. This was performed on a 2001 Ford Ranger XLT 4x4 rear differential with limited slip. I chose to run synthetic gear oil with the limited slip addidtive

Tools required:
Socket set
Air ratchet (optional)
Sand paper (fine grit auto paper)
Gasket or sealant for differential cover
Eye protection
Brake cleaner
Gear oil
Oil drain pan

Step 1
Remove the fill bolt located on the rear of the differential, by inserting just the 3/8 ratchet head







Step 2
Loosen the bolts holding on your differential cover, pull the cover out slightly and allow it to drain in your oil drain pan.





Step 3
Remove the bolts and the differential cover and allow time for the rear to drain

Step 4
While the rest of the rear diff drains, use a fine grit auto sand paper to sand the surface where you will be sealing the cover again. **In this writeup, I replaced my diff cover with a new one with a gasket, if you are putting the same diff cover back on, you will need to sand the surface of that cover as well to ensure you have removed the old gasket/sealant. Also allow ample time for it to drain well.


Step 5
Clean the rear using brake cleaner. **If you are using the same diff cover, clean it in the same manner. After the rear was cleaned with brake cleaner, you may wipe it down or blow it out with a compressor as I did. Please wear eye protection in this process!!



Step 6
Replace the rear diff cover, using a gasket or a liquid gasket/sealant. **Liquid gasket or sealants must be applied to the cover itself and should be applied around center to inner edge under the bolt holes**
By hand, insert the bolts that will hold on your diff cover, then tighten with a ratchet.


Step 7
Fill the rear diff with your new differential oil. **Check your owners manual for appropriate amount that it needs. Trucks with limited slip rears MUST use a gear oil with the limited slip additive in it**


Step 8
Once the rear diff has reached capacity, replace the fill plug, turn it in by hand first, then using the 3/8 ratchet head tighten the fill plug.

 

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hey did you use a RTV gasket maker silicon stuff for this or did you get a gasket?

 

I got a gasket with the new cover so I used that. I am going to put the Shelby diff cover on soon so I will use the RTV on that

 

where did you get a diff cover from? gasket just from the autoparts store? is there torque specs for that because of the gasket? i have a 7.5 btw
sorry for 20 questions lol

 

I got it on ebay, but you can get them at local auto parts stores, some come with gaskets some dont. I really didnt do torque specs, but check your manual if you have it.

 

ok thanks man

 

I always use silicone.



When using silicone/RTV, I like to spooge a small loop on the diff cover and spread it about with my finger....hand in medical glove. Do the save to the housing. Bolt it up tightening from top bolts to bottom....only snug. Not weightlifter torqued. You don't need much RTV to seal it....no need to put a 1/4" fat and tall bead on both pieces.....just a thin layer on each and she'll hold a seal.



Before applying the silicone, I like to use lacquer thinner on a rag and wipe down both surfaces to get 'em clean, let it evaporate, then apply silicone.

 

Make sure to breathe deeply while doing it too. The smell of diff oil is unlike any other...

 

friction modifier makes the smell even better.

 

Yup like a month old litter box

 

^ I LOVE the smell of gear oil for some reason.

22-25 lb/ft is the recommended torque spec for the diff cover bolts.

With that said, I used to install the covers with silicone but switched it out for a reusable gasket. They're fairly cheap and as many times as I have the diff cover off, it's well worth it.

And the OE gasket from the auto parts store is around $5.00-8.00, depending on where you go.

If you CANT find gear oil with the L/S additive in it, most auto parts stores sell the addative seperately.

Great writeup, Clinton.

 

thanks guys, i got some RTV but i think ill pick up the gasket since theyre cheap. if i get really ambitious ill get a fancy cover off ebay lol