differntial fluid ford 9 inch question

[jerry w]

I will be running a Ford 9 inch with posi. My shortnened/reconditioned rear-end came with a bottle of motorcraft additve friction modifier.

1.Does this stuff really help quiet the gears?

2.Anyone have experience with this product who can comment?

3. MOST IMPORTANTLY, HOW MUCH DO I ADD TO THE DIFFERENTIAL FLUID?

APPRECIATE ANY COMMENTS FROM EXPERIENCED BUILDERS, THIS IS MY FIRST BUILD.

Jer

[Bruce Edwards]

Jerry,

Put it all in. It is not for the gears it is for the POSI unit. It helps keeps the clutches from grabbing. Top it off with 90 SAE gear oil.

[wizard]

10-4

[trularin]

Two big bottles and that little bottle and you should be good-to-go.

You must put it in.

[TonyMadrid]

Jerry,

I agree with the others, put it all in and top off with 90W.

Also be sure that the R/E housing is properly vented. When I finished my build I started getting fluid leaks at the rear axle seals. I had used a chrome fitting that I had purchased from Speedway Motors, a hot rod mail order supply house, and it came with a threaded fitting and a hexagon cap that fitted over the threaded fitting. The cap was held in place with a set screw. I tried to raise the cap to allow more breathing room but the problem still existed.

I then used the threaded fitting that came with my A&C kit and the inside opening was too narrow and the problem still existed.

I then used the chrome fitting which had a larger opening and I attached a length of rubber hose to the fitting and routed it up and then pointing downward, tied off to the frame. The problem was solved.

Whatever vent fitting you use, make sure that the opening is large enough to allow good venting. You may have to drill the fitting that came with the kit out to insure enough breathing or buy a new fitting. I believe the fitting thread is 7/16".

Good Luck,

Tony

[NMattison]

Good luck Jerry, on your build also tony i had my axle seal leaking also but i think i overfilled the rear, so i took the fill plug out and drained it until level with the bottom of the hole. i also used a hose for my vent but possibly the adapter is too smalll ill have to check the size of it. Neil

[Excaliber]

The original Cobras used a vent hose with a "loop" at the top to act like a "check valve".

Ernie

[jerry w]

Thanks to all who took the time to answer! You guys are great!
I always appreciate your experiences and comments! I forge ahead with a little more confidence



Jerry