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Changing the rear diff fluid

So I was under the car today changing engine, tranny (Royal Purple Synchromax...took about 2.8 QT's), and the diff fluid. When I got back to the diff I hesitated because I wasn't sure if there was a gasket required when I pulled the cover off? Also, can I get the cover off without removing the panhard bar? I have an aftermarket Steeda bar. I am thinking about buying the 2013 diff cover because it has the drain plug. I have heard of people taping the 12 diff cover. If anyone has done this and has feedback I would appreciate it.

The car has 3500 miles on it and still has the stock diff fluid. Of that I'd say it has about 3-4 hours of track duty and I'm gonna be heading to the track again next weekend. The Nurburgring isn't as hard on cars as conventional tracks because it only takes me about 8 minutes to do a lap and then I take a break for at least 30 minutes between laps. Anyways, am I good to do another track day without changing the fluid? I know the manual says to change it after the first 4 hours on the stock fluid. Thanks to all in advance.
 

j3st3r

Brian S.
603
365
Tennessee
Torsion said:
I think that's a common mistake.

I too thought my '13 diff cover had a super-cool "fill hole" and "drain hole". But that's not correct... those holes are for a bolt-on diff oil cooler. Right guys?

The proper fill hole is on the main diff housing, not on the diff cover. Look for it above a "ledge" on the front, driver's side, upper half of the diff housing.

It's lower than the top hole on the diff cover.... so when you take it out you'll probably get some spillage.

You can fill the diff from wherever, but you need to check the level via the plug on the ledge on the front, top side of the diff. You should not use the top fill plug on the rear of the diff cover as your fluid level indicator. I usually fill it until it barely starts to run out of that front hole, with the axle fairly close to normal ride height
 
There's a picture on this thread showing the fill hole:

http://forums.themustangsource.com/f813/first-diff-fluid-change-pics-497224/

DSC02124.jpg
 
Torsion said:
I think that's a common mistake.

I too thought my '13 diff cover had a super-cool "fill hole" and "drain hole". But that's not correct... those holes are for a bolt-on diff oil cooler. Right guys?

The proper fill hole is on the main diff housing, not on the diff cover. Look for it above a "ledge" on the front, driver's side, upper half of the diff housing.

It's lower than the top hole on the diff cover.... so when you take it out you'll probably get some spillage.

Well shiznit....I suppose I should've looked on the diff housing. Thx for the tip.
 
I used a lube locker gasket when I replaced my diff cover. It's a lot less hassle than RTV and it makes buttoning things up a piece of cake.
 

isrboss

Has anyone attempted to use a vacuum tool to suck the fluid out of the front fill hole instead of pulling the cover?
 

steveespo

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You won't get it all out. There is the differential in the way and a sump at the bottom of the housing.
When I drop the cover I use the vacuum pump to get as much out of there as possible.
DSC_0003-1_zpsc53c73d4.jpg
You can see where the diff, bearing and ring gear are, the fill hole is right in front of them on the left.
Steve
 
Just don't make the rookie mistake I did and not leave one bolt half way in at the top before prying at the cover... I assumed the stock RTV would be more flexible and sticky and hold the cover at the top while I cracked the bottom to let it drain. Just a little bit of pressure and the cover popped right off into my drain pan. I am really glad I was wearing safety glasses, what a mess that made.
 

isrboss

steveespo said:
You won't get it all out. There is the differential in the way and a sump at the bottom of the housing.
When I drop the cover I use the vacuum pump to get as much out of there as possible.
DSC_0003-1_zpsc53c73d4.jpg
You can see where the diff, bearing and ring gear are, the fill hole is right in front of them on the left.
Steve
This is why I wanted to ask. I did the change and used a turkey baster to clean out the sump. I wondered if a small and flexible enough of a hose could weave it's way down to the sump area. I'm leaning more toward no though. Next time I swap the diff fluid I will try and track the amount of fluid removed. I was thinking, if the fluid gets to the sump area from the fill hole, well?
 
Torsion said:
I think that's a common mistake.

I too thought my '13 diff cover had a super-cool "fill hole" and "drain hole". But that's not correct... those holes are for a bolt-on diff oil cooler. Right guys?

The proper fill hole is on the main diff housing, not on the diff cover. Look for it above a "ledge" on the front, driver's side, upper half of the diff housing.

It's lower than the top hole on the diff cover.... so when you take it out you'll probably get some spillage.

Let's be honest, the lower hole should get majority of the diff fluid out, and the upper hole could fill majority of it back in. I could see having the car on floor jacks under the rear axle only (so that it's raked forward) giving you a little more room to fill the diff with fluid.

Would that be so bad for a quick diff fluid flush? If you needed to fill from the front port, you could always do that too, but for a quick flush of fluid, the ports on the back of the diff cover seem fine to me.

Now if only mine were tapped and had plugs in them!
 
neema said:
Let's be honest, the lower hole should get majority of the diff fluid out, and the upper hole could fill majority of it back in. I could see having the car on floor jacks under the rear axle only (so that it's raked forward) giving you a little more room to fill the diff with fluid.

Would that be so bad for a quick diff fluid flush? If you needed to fill from the front port, you could always do that too, but for a quick flush of fluid, the ports on the back of the diff cover seem fine to me.

Now if only mine were tapped and had plugs in them!
Like this.

P1020819.jpg
 
A little update on this, i was in the shop this week and while fitting the new driveshaft from Pufferfish we changed the Engine, gearbox and diff oil.

When we got all the old oil out of the diff the shop owner suggested he drilled and plugged the lower point on the diff cover so we could drain it in future without removing it.

Seemed like a plan so we went for it
 
Hello -- when changing the diff fluid, is there any modifications to fill procedure that need to be made for the axle cooler? I'm working on a '13 GT500 with cooler...

Thanks!
 

steveespo

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BrianTC said:
Hello -- when changing the diff fluid, is there any modifications to fill procedure that need to be made for the axle cooler? I'm working on a '13 GT500 with cooler...

Thanks!

There is a manual procedure to activate the differential pump to circulate the fluid through the lines and cooler to ensure they are filled. What I did for my setup was fill the diff to the fill plug level, turn on the pump to flow fluid to fill the cooler and lines then top off my differential back up to the fill plug level. Took about .7 quarts on my setup.
Steve
 

Fred G

What Goes Around Comes Around
j3st3r said:
You can fill the diff from wherever, but you need to check the level via the plug on the ledge on the front, top side of the diff. You should not use the top fill plug on the rear of the diff cover as your fluid level indicator. I usually fill it until it barely starts to run out of that front hole, with the axle fairly close to normal ride height

I have a 2013 and used the Lube Locker reusable rear diff cover gasket (bought from Late Model Restoration) and some grey rtv sealer on each cover bolt. Used Royal Purple fluid and Ford friction modifier as well. Filled from the top plug on the cover, until it began to run out of the site plug hole in the front of the housing as noted above. I suppose you could fill from the site plug hole, but it's hard to reach if your doing this on the ground, squeezing the fluid by hand from the bottle.
 

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