I have a Ford racing rear end girdle/cover on my 99 GT. Last time I changed the gear oil, I used the stock fill hole and added a little over 2 quarts before it started to come out(if I remember correctly). This time, I decided to save the mess(the factory fill plug is in a bad spot) and use the fill hole on the girdle. Here is the problem....I added 3 quarts, and it still wasn't coming out....so I added about 3/4 of another quart, and still not full! I then realized(duh) that the factory fill hole is way lower than the one on the ford racing cover. I didn't feel right about having that much in there, so i took out the 3/4 of a quart that I added. So, my rear end now has about 3 full quarts of gear oil in it. Is this still too much?????? I took for a test drive and it feels fine...also no leaks. Not leaking out of vent either. Just wondering if I still over filled it....also wondering why the ford cover has a fill hole so high up compared to the stock one. Thanks

 

Factory fill is between 1.8-2Q... 3 is too much.

 

2 qts and youll be just right. Drain a little more out so that you dont blow any of your seals out.

 

2

 

Thanks guys! Glad I checked before I did any damage.

 

Does that Ford Performance girdle add any capacity? Or is it the same as the stock cover? I thought I saw it somewhere that aftermarket covers or girdles add 1/2 quart extra capacity.

 

you've answered your own question, @3qts wth an aftermarket cover/girdle....

 

Randy,

That Ford Racing Girdle really adds an extra quart to the capacity??? I thought it was 1/2 quart?

Ok, now I'm really confused. Everyone has a diff answer!

 

no, I said @bout 3qts total....normal diff fluid change is @2.4qts wth the friction modifier and the girdle adds @bout 1/2 qt so that @2.9 qts

 

Just fill it up with the stock fill plug out and stop when the fluid start running out. Of course the girdle adds some capacity, as it is bigger (sticks out further) than the stock cover. Randy is correct (as usual) about the capacity. I just changed my fluid a couple of weeks back and I have that same cover.

Scott

 

I'm gonna have to do what I wanted to avoid....open the factory fill hole and make a mess. Right now, I probably have about 2.5 quarts in there. If that's too much, I have a stinky mess....if too little I will add more. God I hate the smell of gear oil!

 

Randy was right. I had about 2.5 quarts in there. Removed the factory fill plug and nothing came out. Added close to another 1/2 quart. So, the total fill was close to 3 quarts. Next time, I'm just gonna add 3 quarts and avoid the mess.

Thanks guys