Drivetrain Q: Rear differential girdle/cover install snafu ?


Mod Dude
Sep 22, 2001
Soooo, decided to tackle the Granatelli rear diff cover/girdle installation yesterday on the '94, but Mr Murphy seemed to make an unexpected appearance. I know others in here have tackled this project before so maybe one of you can shed some light on my problem.


Here is where I am hung up at. I removed the the factory diff cover/plate and drained out the old fluid. Went to do a "dry" fitment with the Granatelli girdle/cover to see how it would mate up.

Well, the left side of the girdle sits flush on the housing, but the right (pass) side of the girdle is NOT flush with the diff. It sticks outwards (towards the gas tank). :(

I tried to "back off" that bolt on the right (pass) side of the new girdle as much as possible, but it still touches the inside of the diff - so it won't allow for a "flush" seal if I were to bolt it up to the housing. Not good.

Could I remove the "cap" (pass side) on the inside of the girdle so that it doesn't "touch" the inside of the differential ? If I did do that though, the girdle wouldn't provide the extra "bracing" that it was designed for - correct ?

The interference on the pasenger side is basically causing the girdle to not fit flush - hope I explained it well. Forgive my lack of proper terminology btw.

What should I do ? Should I try to remove that little cap (passenger side) on the inside of the girdle and then install the Granatelli piece (knowing that it won't offer any additional support/bracing) and live with it ?

Anyone else with a Granatelli girdle run into this problem ? I wasn't planning on using the supplied gasket, but even with the gasket tucked in between the housing and the girdle, it won't allow for enough space or "clearance" to provide for a proper "fit" on the passenger side.

Was planning on using Permatex Ultra Grey to make a gasket.

Some pictures:

New girdle sitting on the kitchen counter (problem bolt circled in red):

Picture of the inside of the girdle/diff cover (note fill and drain plugs, in blue - problem bolt circled in red again):

Removed the bolts of the factory diff cover except for the top one (left it loose) and allowed fluid to drain after cracking the cover (used gear oil smells sooo rancid - yuck!):

The guts of the differential - red circle shows the problem area:

:flag: :flag: :flag:

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Well, you do know that those bearing cap supports aren't pre-set right.

Looking at the picture of the passanger side support (the one you circled in red) it looks like it is threaded in so far that it would be impossible to install the cover.

So, from the outside of the cover you loosen the large locking nuts and unscrew the threaded shafts with caps on ends that are the supports for the bearing caps.
Just enough so that the cover will be flush with the differential housing like it should be.
Intall the girdle/diff cover like you would the stock cover.
Setup the bearing supports per instructions.
("basically" screw in the threaded shafts until they just touch the bearing caps, and lock the threaded shafts in place with large locking nuts. You can do this by holding the threaded shaft in place with an allenkey and tightening the nut with an closed ended wrench).


I suggest you goto the granatelli website and read the instructions if you haven't done so already.

Be happy at a job well done.
Like said above, the supports aren't pre set from the manufacturer. You have to loosen them then install the cover and then you can set the supports. A bead of any color ultra permatex is fine.
Thanks guys, I realize the support caps have to be properly adjusted.

BUT, I already loosened the girdle's passenger side (red circle on cover) support cap as far as it will go (towards the rear of vehicle). When I attempt to mate the girdle up against the housing, that passenger side support cap of the girdle is still making "too much" contact with the passenger side bearing cap inside of the diff housing.

I don't understand how to gain more clearance on the passenger side between the support cap (even if it is already backed out all the way) and the bearing. :shrug:
I removed each retaining nut that goes around the allen bolts. With those two nuts removed, the allen bolts can now be FULLY backed out. This allows each support cap inside the cover to sit flush with the inside of the girdle. It seems to fit ok now during a mock up, so I *think* I'm all set.



Loosen the two nuts:

With the nuts removed, you can now use your allen wrench and "back out" each allen bolt far enough...
aPicture054.jpg render the support caps inside the girdle to sit flush with the interior of the girdle, allowing proper clearance for install:

:flag: :flag: :flag:

As for a follow up to the install...

For others tackling this project, it helps to remove the rear sway bar (four 15mm bolts and the little bolt, 10 or 12mm (??), holding the rear brake line bracket) as well to allow more clearance underneath the rear end when installing your new diff cover/girdle.

And for reference: it took about 2.5 quarts of new gear oil to fill the differential back up (Mobil 1 75-90) with the Granatelli girdle in place. I used one of those little hand pumps - screws right onto your gear oil bottle.