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Bought my 2011 SVTPP a few weeks ago. Had 5600 miles on it. Currently has 6700 miles now. Noticed some groan coming from rear diff turning slowly around corners after everything was good and warmed up. Research indicated that additional friction modifier was the ticket to resolving it. So, why just add friction modifier, why not just drain and refill with the whole diff with nice fresh fluid?! Right? Right!!!

More research indicated there is no drain plug on the diff. Why, Ford, why??? And the fill plug is on the drivers side of the axle housing/pinion.

Here's a pic of the aluminum diff that was on the car. Notice no drain or fill plugs. You can see the vent plug at the top.






Decided I was going to go with a different differential cover, one that has a drain and fill plug -- a novel idea! Basically, it is the same exact diff cover as the OEM one, just with the drain and fill plugs. Ordered these goodies from LMR. What you don't see in the pic (but did come w/ the cover) is the new vent plug that goes in to the top of the diff.



Here is what I ordered from LMR:

https://lmr.com/item/M4033K/1986-11-Mustang-Gt500-Style-Finned-Aluminum-Rear-End-Cover

https://lmr.com/item/LRS-F8805K/88-Rear-Differential-Fluid-Seal-Kit-Mustang-05-14


I'm stock (not lowered) so my ramp and jack setup worked great. Used my Rhino Ramp MAX ramps for the fronts, and jacked up the rear and used floor jacks for the rear axle. It was more level than in looks like in the pic.





1st order of business was to drop the panhard bar from the passenger side. You'll want to do this -- it just makes life easier when removing the cover and getting access to the diff cover bolts. Used this to break loose the 18mm bolt.





Was then able to use a ratchet to back it out. Easy peazy.





Once I got the bolt out, I used both hands to pull the bar down as far as possible. I then used a big screwdriver to dislodge the bar from the "socket" so it would drop down. See pic below.

 

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Nice DIY thread!:bigthumb:
 

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Discussion Starter #3 (Edited)
The panhard bar doesn't fall to the ground -- it just kind of hangs there. I could move it up and down to get to the bolts as needed.

On to removing the diff cover. Loosened the side bolts, top bolts and then bottom bolts. Removed the side bolts, then the bottom bolts. Used a big flat head screwdriver to break loose the cover. A beautiful, steady, controlled stream of old diff fluid came out and went right into the drain pan. Didn't spill a drop!




Removed the top bolts and then removed the cover. Had to move the panhard bar a little to maneuver getting the cover out and down. No sweat.

Now, the "sump". The picture below is of my left hand and fingers recessing in to the "sump" below the bottom level of the diff. I'd say it was at least a half inch deep by 2-3 inches long by a half inch wide. I was able to get in there with my fingers and some shop towels to make sure I got any old fluids out as well as the accumulation of brake fluid that had mixed in with it. I was also able to get my hand and fingers up in there a good way, almost to the pinion. All was clean and dry by the time I was done.

It may be because of the relatively low miles on the gear oil, but the stuff in the sump wasn't much of anything. I'm not sure what it would look like after say 50,000 miles.





Used brake cleaner and a brush to clean up the old gasket sealant. There was no actual felt or other kind of gasket. It was done with some sort of sealant that honestly didn't seem to be that thick at all. Light brushing cleaned it up in no time.

Next was installation of the new cover. Installed the new "vent" plug in the top of the new cover on the workbench. Made sure all surfaces were clean and installed the cover with the Lube Locker gasket. Put a bit of blue loc-tite on the ARP bolts (made sure they were the same length as the OEM ones) and tightened in the order of the pattern that is on the back of the Lube Locker package. Tightened to 24 foot pounds (aluminum cover). Here's a pic of the tightening order:





Removed the fill plug on the front of the new diff cover and pumped in 2 and 1/8 quarts of Royal Purple 75W-140 full synthetic (yes, i bought a 3rd quart at Advance Auto this morning in advance of this adventure) and the 4 oz bottle of the friction modifier. Reinstalled the fill plug.

Reinstalled the pan hard bar. I had to use a short pry bar to get the hole in the bar to align with the hole in the bracket.

Done!









Took her for a short drive -- no leaks. Then went a bit further to a school parking lot and did about 10 figure 8's to get everything worked in real good. Back home, checked for leaks again and none -- woohoo!!!

Overall, not a hard job, just a little time consuming, at least for me -- I'm not the speediest mechanic. 1st time getting my GT500 in the air, so that took a bit of time. Figuring my way around a panhard bar -- again, 1st time for me so that took some time.

Old diff fluid does stink but it is not that bad. Everything I read made it sound like I needed a gas mask or something. Frankly, the diff fluid on my truck and jeep (sold on) smelled worse.

I think the hardest part is the relatively tight spaces. I've changed diff fluid on my truck and jeep (sold on) and they were much easier to deal with. More room / height AND..wait for it...drain plugs!!!

But now I too have a drain plug!!! :grin: (Though I wonder what the "sump" stuff might be or look like after 50,000 miles -- worth taking the cover off for??? We shall see.)
 

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Discussion Starter #4
Nice DIY thread!:bigthumb:
Thanks, Tim! You read my mind -- thanks for moving this to DIY section. I was going to PM after I got done to see what you thought was the right spot for this -- you beat me to the punch.

The rest of this DIY is directly above.
 

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Nice writeup! Unfortunately, the "two drilled & tapped cooler ports" are used on SVTTP-equipped cars, so I'm not sure we could easily leverage them as drain/fill ports.
 

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Just a thought. I saw the machined surface on the stock cover. Could these be drilled and tapped using a pipe plug?
My 2012 just turned over 6,000 miles so I am getting ready for all fluid changes also. GREAT DYI right up! Is everyone using the Royal Purple? Thanks! FastE
 

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Just a thought. I saw the machined surface on the stock cover. Could these be drilled and tapped using a pipe plug?
My 2012 just turned over 6,000 miles so I am getting ready for all fluid changes also. GREAT DYI right up! Is everyone using the Royal Purple? Thanks! FastE
I'm no expert, but I believe they could be drilled. I actually think that is all that the vendors/manufacturers are doing to make the "newer" cover.

Like motor oil, probably lots of folks using lots of different brands of gear oil, but in my research Royal Purple seemed pretty popular. Saw Amsoil mentioned some as well.
 

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Just a thought. I saw the machined surface on the stock cover. Could these be drilled and tapped using a pipe plug?
My 2012 just turned over 6,000 miles so I am getting ready for all fluid changes also. GREAT DYI right up! Is everyone using the Royal Purple? Thanks! FastE
That's an interesting idea, for anyone without the SVTTP.

Can't speak for everyone, but I run Amsoil in all my vehicles.
 

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Another question Fletch. I have ordered the RP with the friction modifier. Did you use the FM? I saw on the SVT forum that the RP already has it added? Did I read that wrong? saw where some had said it messed up their clutch packs from having too much modifier.
 

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Another question Fletch. I have ordered the RP with the friction modifier. Did you use the FM? I saw on the SVT forum that the RP already has it added? Did I read that wrong? saw where some had said it messed up their clutch packs from having too much modifier.


Yes, I did use the friction modifier. I did read somewhere that RP has the FM in it but never read anything about messing up clutch packs because of too much FM. Now you have me worried!


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Another question Fletch. I have ordered the RP with the friction modifier. Did you use the FM? I saw on the SVT forum that the RP already has it added? Did I read that wrong? saw where some had said it messed up their clutch packs from having too much modifier.
Yes, I did use the friction modifier. I did read somewhere that RP has the FM in it but never read anything about messing up clutch packs because of too much FM. Now you have me worried!
When I did my research on the Royal Purple fluid, many said that even though it "supposedly" had FM already in it, many people still had noise when using it alone, so they added the Ford FM also and that cured the problem. I have RP with the Ford FM in mine and have had no problems so far and is smooth and quiet! :)
 

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I beat the machined surface was to be drilled and taped just like the latter version and for whatever reason was not ever done. I bet it can be done easliy.
 
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