Hey all,

The 2013 track pack and Boss cars have drain and fill plugs on the rear diff cover.

I've got a few questions that I can't find answers to... maybe someone here can help?

1) What's the torque spec for the drain and fill plug?

2) Do the drain and fill plug require some sort of thread lock or sealant?

3) How high do I fill the diff? I believe the diff has two fill plugs... one in front and one on the diff case. The track pack supplement says the diff should be filled until it's 1/4-9/16" below bottom of fill hole. Which fill hole are they referring to?

Big thanks for any replies!

 

Most likely all you will need to know https://themustangsource.com/f813/fi...e-pics-497224/

 

Thanks Brandon. I read that thread, and while it was informative it didn't really answer my questions regarding the fill and drain plugs because that guy had the old diff cover.

Also, he filled his diff case to a height that's a little different than was recommended... so it sorta just adds to my confusion! :/

 

I would check what height it is at inside the fill plug, using a piece of paper or something measured to a length (arbitrary). Let me see if I can find the other specs.

 

I think you can assume that the torque spec is somewhere around 24ft/lbs, they are basically the same as the trans plug or the oil pan plug.

 

Thanks Brandon, fair enough... just wasn't sure if this new diff cover was softer.

What about the sealant or thread lock?

 

I would think you could use a little thread tape, call Ford Racing to be certain, they should have all the specs.

 

See the Ford service manual info on this topic here: http://iihs.net/fsm/?dir=757&viewfil...ng%20Cover.pdf

 

Okay, I called up Ford Racing at 800-FORD788 and now I have clarity.

First off, the 2013 track pack cars have two new bolts on the diff cover. I assumed these were convenient "fill" and "drain" plugs. But, they are described by Ford as the "cooling line fittings". So they are there so that folks can add a diff cooling system on there.

The torque specs for these fittings are 17 ft-lbs.

I asked if I needed friction modifier for the Torsen diff. They said no, it's not necessary because there are no clutches... but that it will not hurt if you've already added it.

I asked how the plugs in the diff cover were sealed, and he said it was with a threadlock/sealant... not RTV.

And I asked how far to fill up the diff, he said "well, when you're racing and the diff is overfilled it can cause the fluid to leak out." He suggested filling the diff until the oil is within 10 mm of the bottom of the fill plug on the forward, drivers side of the diff housing. This is consistent with the Boss/Track Pack supplemental material that suggests "Fill 1/4 - 9/16 inch (6-14 mm) below bottom of fill hole."

My problem here was that I thought I had two fill holes... so which was I supposed to use. Now it's clear that I need to use the one on the diff housing.

Thanks for the help!