Diff Whine & Fluid Change

[sfadchi]

Pretty sure I may have gotten muddy water in my rear diff over the weekend. I’m getting a slight whine between 45-55mph. Does the rear diff use RTV or does it have a reusable gasket?

 

[Predator]

No clue, but good luck... and stay out of the mud... sand only from now on.

 

[TK85]

I just changed the diff cover on mine the other day and there was a lot of rtv I had to scrape off. New gasket and new rtv I would suggest.

 

[802Avalanche]

Sounds like a good time for a Ford Performance diff cover to me.

 

[TK85]

Sounds like a good time for a Ford Performance diff cover to me.

That’s the one I just put on. Looks and feels great. I didn’t like the gasket that comes with it so I got the lube locker gasket which is much better and no rtv needed

 

[sfadchi]

That’s the one I just put on. Looks and feels great. I didn’t like the gasket that comes with it so I got the lube locker gasket which is much better and no rtv needed

I just ordered up a lube locker. It will be here Saturday. Hopefully I didn’t do any permanent damage. All of my Jeeps had a little one way value on the breathers. Shocked when I saw this one.


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[Spartan1]

https://www.cjponyparts.com/ford-pe...-cover-9-75-inch-f-150-2009-2018/p/M4033F975/

I thought that this video was worth a look. I am still waiting on the cover but I got my lube locker gasket in 2 days when I ordered from their site directly. CJ pony took a long time to ship this out to me but it is finally on its way.

 

[Spartan1]

https://www.fcsdchemicalsandlubricants.com/main/product.asp?product=SAE+75W-85+Premium+Synthetic+Hypoid+Gear+Lubricant&category=Transaxle Fluid

Note: For a complete drain and refill, limited-slip axles require addition of Friction Modifier, Part Number XL-3 meeting Ford specification EST-M2C118-A. Refer to Workshop Manual or Owner’s Guide. For a complete drain and refill, Torque Vectoring RDU requires addition of Torque Vectoring RDU Gear Oil Additive, Number XL-19

I was going to use the Motorcraft differential fluid but I am not sure what the above means. From what I understand, some differential fluids have friction modifier already in the fluid but the motorcraft does not. I am not sure if I need this friction modifier or not. Does anyone know if I have a "limited slip axle" on my 2017?

It sounds like I do not need torque vectoring RDU gear oil additive like a focus RS would require.

https://driving.ca/ford/f-150/revie...-a-tale-of-two-very-different-off-road-heroes

It also sounds like the front differential is a limited slip in the raptor but maybe the rear is not?

https://www.cjponyparts.com/catalogsearch/result/?q=2017+ford+limited+slip+differential

 

[sobiloff]

The rear diff is an electronic limited slip (AdvanceTrac). (Front is a Torsen.) So, you just need
Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant or equivalent, no friction modifier required.